Patent Application
20090278526
This application claims priority to Japanese Patent Application No. 2008-121089, filed on May 7, 2008.
1. Field of the Invention
The present invention relates to a current detecting device which takes advantage of the Hall effect.
2. Description of the Related Art
In electronic components equipped in a vehicle, a current detecting device in which a core, which passes a magnetic field, and a Hall element are combined is used.
A current detecting device having a structure in which a Hall element and a sensor board are stored in a resin case to which a core is molded is known. In this current detecting device, as shown in an assembly diagram of
Another current detecting device is known in which, as shown in an assembly cross sectional diagram of
In the above-described current detecting devices of the related art, because two Hall elements are placed side by side along the axial direction of the core, there is a problem in that the thickness in the axial direction is increased in the core as a whole. As a result, the cost of the material is increased, and moreover, the size of the current detecting device is increased.
According to one aspect of the present invention, there is provided a current detecting device comprising a plurality of Hall elements, a board on which the Hall elements are surface-mounted, and a core which surrounds a pass-through section through which a bus bar, through which a current to be detected flows, is passed, and which has, at a part of the core, an opening in which the Hall element is placed, wherein the plurality of Hall elements are placed in series along a direction of a magnetic field line formed in the opening when a current flows through the bus bar.
An exemplary embodiment of the present invention will be described in detail based on the following figures, wherein:
As shown in an assembly diagram of
The Hall elements 30a and 30b are magnetic sensors which take advantage of the Hall effect, and are elements which convert a change of a magnetic field through the core 34 due to a change of current flowing through the bus bar 38 into an electric signal and output the electric signal.
The sensor board 32 may be a printed board in which lines are patterned on a resin such as polyimide. As shown in a side view of
The core 34 is formed with a magnetic structure such as ferrite, a silicon steel plate, a layered steel plate in which metal such as permalloy is layered, etc. Preferably, the surface of the core 34 is coated with a resin as necessary.
The core 34 is formed in a tubular shape with an opening 34a which is cut out from an upper surface to a lower surface along an axial direction C. As shown in an internal plan view of
An outer periphery of the core 34 is formed slightly smaller than an outer tubular section of a double hollow portion of a core storage 36c of a core case 36b. In addition, the hollow section of the core 34 forms a pass-through section 34b through which the bus bar 38 is passed. The pass-through section 34b is formed slightly larger than an inner tubular section of the double hollow portion of the core storage 36c of the core case 36b.
The core case 36a is combined with the core case 36b, to store, in the inside, the sensor board 32 on which the Hall elements 30a and 30b are mounted and the core 34. The core case 36b includes the core storage 36c which stores the core 34 and which has the double hollow tubular shape, and a board storage 36d which stores the sensor board 32 provided to protrude from a location at which the opening 34a is positioned when the core 34 is stored in the core storage 36c.
An attachment hole 36e for fixing the current detecting device 100 on a control board or the like may be formed on the core case 36b.
The bus bar 38 is a conductor through which the current to be detected flows. The bus bar 38 is extended from, for example, a power element (power module) to be mounted on the vehicle. The bus bar 38 is inserted to the pass-through section 34b of the core 34 stored in the core storage 36c, in the axial direction C.
When the bus bar 38 is passed through the core cases 36a and 36b having the sensor board 32 on which the Hall elements 30a and 30b are mounted and the core 34, the current detecting device 100 is formed as shown in the assembly diagram of
In the current detecting device 100, the Hall elements 30a and 30b mounted on both surfaces of the sensor board 32 are inserted into the opening 34a of the core 34 along the axial direction C. With this structure, the change of the magnetic flux through the core 34 due to the change of the current flowing through the bus bar 38 can be converted and obtained using each of the hall elements 30a and 30b.
In addition, in the current detecting device 100, by mounting the Hall elements 30a and 30b on both surfaces of the sensor board 32, even if the core 34 is provided covering the entirety of the Hall elements 30a and 30b, it is possible to reduce the thickness of the core 34 compared to that of the current detecting device of the related art. In other words, the size of the core 34 can be reduced while maintaining the precision of detection at the same level as that of the current detecting device of the related art.
With such a configuration, the manufacturing cost of the current detecting device can be reduced. In addition, the size of the current detecting device can be reduced.
With the provision of the two Hall elements 30a and 30b, it is possible to improve the precision and reliability of the current detection by the current detecting device 100. For example, the detected voltages of the Hall elements 30a and 30b can be compared with each other, to check the precision of the detected voltages. Moreover, even when one of the Hall elements 30a and 30b fails, the other Hall element can be used for detection.
In the above-described preferred embodiment, a structure is employed in which the Hall elements 30a and 30b are placed opposing each other on both surfaces of the sensor board 32. Alternatively, as shown in an internal plan view of
In this case, the opening 34a formed in the core 34 is preferably formed slightly larger than a sum of thicknesses of the Hall elements 30a and 30b and the opening formed therebetween.
With the configuration of the alternative embodiment also, the operation and advantage similar to those of the above-described preferred embodiment can be obtained.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2008-121089 | May 2008 | JP | national |
