Electricity: measuring and testing – Measuring – testing – or sensing electricity – per se – Magnetic saturation
Reexamination Certificate
2000-09-15
2003-08-12
Le, N. (Department: 2858)
Electricity: measuring and testing
Measuring, testing, or sensing electricity, per se
Magnetic saturation
Reexamination Certificate
active
06605936
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a current detecting apparatus for detecting a current flowing through an electric circuit loaded on an apparatus such as automobile and a current detecting method, and more particularly to technology for improving detection accuracy for a current flowing through each branch conductor.
2. Description of The Related Art
Recently, with prevailing of, for example, electric car, hybrid car and the like, the necessity of a current detecting apparatus for, for example, charge/discharge control has been intensified. As such a current detecting apparatus, a current detecting apparatus which is installed in an electric connecting box for distributing currents from a power supply and detecting a current flowing through a conductor incorporated in the electric connecting box using an electromagnetic transducer has been well known. However, the current detecting apparatus using the electromagnetic transducer has such a problem that because a plurality of conductors are incorporated in the electric connecting box, an accurate current detection is impossible due to an interference of magnetic flux generated by a current flowing through other conductor than the conductor in which a detection object current flows.
To solve such a problem, a current detecting apparatus for electric wire has been disclosed in, for example, Japanese Patent Application Laid-Open No. 63-63974. In this current detecting apparatus as shown in FIG.
1
, a conductor B in which the detection object current I
1
flows is disposed substantially at right angle to other conductor A and further, a magnetic core
1
a
through which the conductor B passes is disposed substantially at the right angle to that conductor B.
With this structure, magnetic fields H
2
and H
3
generated by current I
2
flowing through other conductor A are canceled in a magnetic core
1
a
and only a magnetic field H
1
generated by a current I
1
flowing through a conductor B passes through the magnetic core
1
a
. Thus, the electromagnetic transducer
1
b
placed in a gap of the magnetic core
1
a
does not receive an interference from other conductor B, the current I
1
flowing through the conductor B can be detected accurately.
However, because this conventional current detecting apparatus for electric wire employs the magnetic core, there are such problems that its weight and occupied volume cannot be reduced beyond each predetermined level and production cost is high. Particularly, if a plurality of conductors through the detection object current flows are arranged in parallel, the same number of the magnetic cores are necessary, so that the weight and occupied volume increase depending on the number of the conductors and further the production cost is increased.
On the other hand, for example, in automotive current connecting box, not only a plurality of conductors are arranged in parallel in some case, but also a conductor is branched to a plurality of conductors in the electric connecting box, so that it comes that those plural conductors are disposed in parallel in other case.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a current detecting apparatus capable of detecting a current flowing through each conductor even if a plurality of the conductors are disposed together, by positively using a condition including branch conductors provided in an electric connecting box, the current detecting apparatus being capable of being reduced in its size and weight at a low cost. Another object of the present invention is to provide a current detecting method capable of detecting a current flowing through each conductor at a high sensitivity even if a plurality of the conductors are disposed together.
To achieve the above object, according to a first aspect of the present invention, there is provided a current detecting apparatus comprising: n (n: integer satisfying n≧3) conductors disposed so as to be branched radially from a branch point; m (m: integer satisfying m≧2) electromagnetic transducers disposed between adjacent conductors of the n conductors; and an operation processing circuit for detecting a current flowing through each of the n conductors based on an operating output obtained from a predetermined operation based on an electric signal from each of the m electromagnetic transducers.
According to the first aspect of the present invention, the electromagnetic transducers are disposed on both sides of each of the n conductors. A current flowing through each conductor is detected by carrying out a predetermined operation on an electric signal from the two electromagnetic transducers. In this case, each of the two electromagnetic transducers receives a magnetic flux produced by a difference between a current before branching and a current after branching. Thus, even if the current which is a detection object is constant, the magnetic flux is converted electromagnetically. As a result, a current flowing through each conductor can be detected with a high sensitivity even if it is small.
Because no magnetism collecting core is used in the first aspect (in principal, it is not necessary to use the magnetism collecting core), the size, weight and production cost of the current detecting apparatus can be reduced. Particularly, this effect is remarkable in detecting a current in each branch route.
According to a second aspect of the invention, there is provided a current detecting apparatus according to the first aspect wherein the n conductors are disposed on a flat plane including the branch point and the m electromagnetic transducers are disposed such that a magnetism sensitive surface of each thereof exists on the flat plane.
According to the second aspect, because n conductors and m electromagnetic transducers are disposed on the same plane, magnetic flux generated by current flow through each conductor enters a magnetism sensitive surface of each electromagnetic transducer. As a result, in the operation processing circuit, an electric signal from each electromagnetic transducer does not have to be corrected, so that operation on the operation processing circuit is simplified.
According to the third aspect, there is provided a current detecting apparatus according to the second aspect wherein the n is “3” while the three conductors are disposed every 120° from the branch point on the flat plane in three directions; the m is “3” while the three electromagnetic transducers are disposed at the same distance from adjacent conductors and at the same distance from the branch point; and the operation processing circuit detects a current flowing through the conductor by obtaining a difference of electric signal between the two electromagnetic transducers sandwiching each conductor.
According to the third aspect, a current flowing through each conductor is detected by obtaining a difference of electric signal from two electromagnetic transducers sandwiching the conductor. In this case, one electromagnetic transducer receives a magnetic flux in a predetermined direction generated by a current before branching and a current after branching, while the other electromagnetic transducer receives a magnetic flux in an opposite direction generated by the current before branching and the current after the branching. Thus, even if the detecting object current is constant, it comes that a magnetic flux three times a magnetic flux generated by a current if there is no branch is converted electromagnetically. As a result, even if the current flowing through each conductor is small, it can be detected at a high sensitivity.
Further, even if there is a disturbing magnetic flux near this current detecting apparatus, it is canceled by obtaining a difference of electric signal from the two electromagnetic transducers. As a result, even if other conductors are provided together, an influence from them is not received. Thus, a current flowing through each conductor can be detected at a high sensitivity. Further, currents flowing through three conductors
Gohara Takashi
Ikuta Yoshinori
Morimoto Mitsuaki
Tamai Yasuhiro
Finnegan Henderson Farabow Garrett & Dunner L.L.P.
Le N.
Teresinski John
Yazaki -Corporation
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