JP2009216456A - Current sensor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a small current sensor capable of detection with stable accuracy. <P>SOLUTION: A current sensor 1 made of a conductor includes a bus bar 2 having a U-shaped conductor part 23 formed thereon and a Hall element 41 for magnetically detecting current flowing through the bus bar 2. In the current sensor 1, a semiconductor package 4 is housed in a housing space 31 in a semiconductor package housing body 3, wherin the semiconductor package 4 houses the Hall element 41, a processing circuit for processing output from the Hall element 41, and a connection terminal 44 connecting the processing circuit with the outside, and is formed by molding a resin material, and the semiconductor package housing body 3 allows both ends of the bus bar 2 to be exposed, and includes a housing space 31 for housing the semiconductor package 4 with the Hall element 41 located inside the conductor part 23, and formed by molding a resin material. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a current sensor that detects a current flowing through a bus bar.

  Conventionally, as this type of current sensor, there is one that detects the current flowing in the bus bar by detecting the intensity of the magnetic field generated by the current flowing in the bus bar by the magnetic sensor. The current sensor is provided with a core for collecting magnetic flux in order to obtain a detectable magnetic flux (see, for example, Patent Document 1). However, the current sensor described in Patent Document 1 requires an arrangement space for providing a core, which leads to an increase in the size of the current sensor.

Thus, a current sensor without a core has been proposed (see, for example, Patent Document 2). In the current sensor described in Patent Document 2, by forming the bus bar in a U shape, conductor portions that are arranged to face each other and in which currents flow in opposite directions are formed, and a magnetic sensor is provided at an intermediate position between the conductor portions. Yes. By configuring in this way, the magnetic field generated by the current flowing in the conductor section arranged oppositely (current flowing in the bus bar) is amplified at the intermediate position of the conductor section, so that the magnetism can be detected without providing a core. Thus, current detection based on the detection signal from the magnetic sensor becomes possible.
JP 2002-243768 A JP 2007-218729 A

  By the way, the current sensor described in Patent Document 2 is provided on a substrate on which a package in which a magnetic detection element constituting the magnetic sensor is accommodated is provided with an arithmetic unit that calculates a current value based on a detection signal from the magnetic sensor. It will be. Since this substrate is provided so as to protrude greatly to the side of the bus bar, the current sensor has been increased in size. Also in the current sensor described in Patent Document 1, the magnetic detection element is provided on the substrate, and similarly, the current sensor is increased in size. These current sensors are used by assembling a board on which a magnetic detection element is provided on the bus bar. When the magnetic sensor is assembled, the magnetic detection element may be displaced with respect to the bus bar, which may reduce detection accuracy. . Therefore, there has been a demand for a current sensor that is small in size and has stable detection accuracy.

  The present invention has been made in view of such circumstances, and an object thereof is to provide a current sensor that is small in size and has stable detection accuracy.

Hereinafter, means for achieving the above-described object and its operation and effects will be described.
The invention according to claim 1 is a current sensor comprising a bus bar made of a conductor and having a U-shaped conductor portion formed therein, and a magnetic detection element that magnetically detects a current flowing through the bus bar. A semiconductor package containing a magnetic detection element, a processing circuit for processing an output from the magnetic detection element, and a connection terminal between the processing circuit and the outside is formed by molding with a resin material, and both ends of the bus bar A semiconductor package housing body is formed by molding with a resin material, and is provided with a housing space in which the semiconductor package is housed so that the magnetic detection element is located inside the conductor portion. The gist is that the semiconductor package is housed in a body housing space.

  According to this configuration, the magnetic detection element and the processing circuit are accommodated to form the semiconductor package, so that the magnetic detection element and the processing circuit provided on the substrate are separately arranged as in the conventional case. And it can be made small. And since a semiconductor package is accommodated in the accommodation space of a semiconductor package container so that a magnetic detection element may be located inside the U-shaped conductor part of a bus bar, a magnetic detection element is conventionally attached to a bus bar or a board | substrate. When assembled, the magnetic detection element does not shift with respect to the bus bar, and the detection accuracy can be stabilized. In addition, when a predetermined detection accuracy cannot be obtained due to a magnetic detection element accommodated in the semiconductor package at the time of inspection of the current sensor, the semiconductor package container is reused and only the semiconductor package is replaced. Therefore, the material disposal can be reduced. Further, the magnetic detection element and the like are molded in a semiconductor package, and the bus bar is molded in a semiconductor package housing body, which is waterproof and dustproof.

  According to a second aspect of the present invention, in the current sensor according to the first aspect, the semiconductor package and the semiconductor package container are fixed to each other by elastically engaging a part thereof. This is the gist.

  Since the semiconductor package and the semiconductor package container are formed of a resin material, they are elastic. Therefore, according to the above-described configuration, the semiconductor package and the semiconductor package container are partly elastically engaged and fixed to each other, that is, by snap fitting, and thus can be easily assembled.

  As the snap fit, as described in claim 3, a convex portion and a concave portion are formed on the inner side surface of the housing space of the semiconductor package container and the outer surface of the semiconductor package, and the convex portion is fitted in the concave portion. It may be fixed by wearing.

  According to a fourth aspect of the present invention, in the current sensor according to any one of the first to third aspects, either the inner side surface of the housing space of the semiconductor package housing body or the outer side surface of the semiconductor package The gist is that a groove for guiding the semiconductor package to the accommodation space of the semiconductor package container is formed, and a convex portion guided by the groove is formed on the other of these grooves.

  According to the configuration, the convex portion formed on the other side of the groove formed in one of the inner side surface of the housing space of the semiconductor package housing body and the outer side surface of the semiconductor package is located on the other side. Are guided into the groove and can be easily assembled to the semiconductor package in the housing space of the semiconductor package housing.

  According to a fifth aspect of the present invention, in the current sensor according to any one of the first to fourth aspects, the housing space of the semiconductor package housing is a connector housing that surrounds the connection terminals of the semiconductor package. Is the gist.

  According to this configuration, since the housing space of the semiconductor package housing is also used as a connector housing, the connection terminal can be protected and the connection terminal of the external device can be guided to the connection terminal at the time of connection. The formation process can be suppressed without being separately formed.

  According to a sixth aspect of the present invention, in the current sensor according to any one of the first to fifth aspects, the semiconductor package and the semiconductor package container are fixed by a room temperature curable adhesive. It is a summary.

  The semiconductor package and the semiconductor package container may be fixed using a room temperature curing adhesive. Here, an adhesive that cures by a heat change requires a step of giving a heat change, and is not simple, so a room temperature curing type is used.

  According to the present invention, it is possible to provide a current sensor that is small in size and stable in detection accuracy.

Hereinafter, an embodiment of the present invention will be described with reference to FIGS.
As shown in FIG. 1, a current sensor 1 provided on an electric circuit that is a current detection target connected to a battery of a vehicle is the center of a strip-shaped metal plate (a copper plate in this embodiment) as a conductor. A semiconductor package housing 3 in which a bus bar 2 whose portion is plastically deformed in a U-shape is covered with an electrically insulating resin material, and a magnetic detection element that magnetically detects a current flowing through the bus bar 2 are electrically connected. And a semiconductor package 4 covered with an insulating resin material. The semiconductor package 4 is housed and fixed in the semiconductor package housing 3.

  At both ends of the U-shaped conductor portion 23 of the bus bar 2, a first connection portion 21 having a first connection hole 21a and a second connection portion 22 having a second connection hole 22a are provided. ing. The first connection portion 21 and the second connection portion 22 protrude from the outer surface of the rectangular parallelepiped semiconductor package housing 3 and extend in the opposite direction on the same axis. In addition, as a formation method of the conductor part 23 of the bus-bar 2, you may form by casting using a U-shaped type | mold.

  As shown in FIG. 2, the semiconductor package 4 includes a Hall element 41 as a magnetic detection element, a thermistor 42 that detects the temperature of the bus bar 2, and a processing circuit 43 that processes outputs from the Hall element 41 and the thermistor 42. Are mounted on a lead frame (not shown) with a conductive paste and molded into a rectangular parallelepiped shape with an insulating resin material. A part of the lead frame protrudes outside the semiconductor package 4 as a connection terminal 44 connected to an external connection terminal.

  As shown in FIG. 2, the semiconductor package housing 3 is formed by molding the bus bar 2 with a resin material having an insulating property. In the semiconductor package housing 3, a housing space 31 in which the semiconductor package 4 is housed is formed in a portion corresponding to the conductor portion 23. And the semiconductor package 4 is accommodated in the accommodation space 31 of this semiconductor package accommodating body 3, and the current sensor 1 is comprised. In a state where the semiconductor package 4 is housed in the housing space 31 of the semiconductor package housing 3, the depth of the housing space 31 is set so that the Hall element 41 is positioned inside the conductor portion 23 of the bus bar 2. Here, the Hall element 41 is provided so that a magnetic sensing axis (magnetic sensing direction) capable of detecting a magnetic field is perpendicular to the long side surface 4 a having a large width of the semiconductor package 4. For this reason, as shown in FIG. 1, the semiconductor package 4 is arranged so that the magnetic flux generated by the current I flowing through the bus bar 2 passes through the long side surface 41 a of the Hall element 41 so as to be vertical.

  Further, in a state where the semiconductor package 4 is accommodated in the accommodation space 31, the connection terminals 44 of the semiconductor package 4 are surrounded and exposed by the inner side surface 31 a on the opening side of the accommodation space 31. In other words, the housing space 31 is a connector housing that covers the connection terminals 44 protruding to the outside of the semiconductor package 4, and the connection terminals 44 of the semiconductor package 4 are connector terminals.

  As shown in FIG. 3A, grooves 32, 32 are formed on both inner side surfaces 31 a, 31 a near the bus bar 2 of the accommodation space 31 of the semiconductor package housing 3. The grooves 32, 32 extend in the depth direction of the inner side surface 31a, and recesses 33, 33 for snap fitting are formed on the inner bottom surface of these central portions, respectively. On the other hand, as shown in FIG. 3B, the semiconductor package 4 is guided by being fitted into the grooves 32, 32 on the narrow side surface 4 b having a narrow width. Protrusions 45 and 45 for snap fitting that are engaged and fixed to the recesses 33 and 33 in the state of being accommodated in the accommodation space 31 are formed.

Next, a method for manufacturing the current sensor 1 including the semiconductor package housing 3 and the semiconductor package 4 housed in the semiconductor package housing 3 will be described with reference to FIG.
First, the Hall element 41, the thermistor 42, and the processing circuit 43 are mounted on a lead frame on which an external connection terminal 44 is formed using a conductive paste. The Hall element 41, the thermistor 42, and the processing circuit 43 mounted on the lead frame are molded in a rectangular parallelepiped shape with an insulating resin material so that the connection terminals 44 protrude. Thereby, the semiconductor package 4 described above is formed.

  On the other hand, the semiconductor package housing 3 is manufactured separately from the process of the semiconductor package 4. That is, the bus bar 2 is molded from an insulating resin material so that the housing space 31 for housing the semiconductor package 4 is formed inside the conductor portion 23 of the bus bar 2. Here, in a state where the semiconductor package 4 is accommodated in the semiconductor package housing 3, the accommodation space 31 is formed so that the magnetic flux generated by the current flowing through the conductor portion 23 passes through the long side surface 4 a of the semiconductor package 4. . Thereby, the semiconductor package housing 3 described above is formed.

  Then, the current sensor 1 is manufactured by assembling the semiconductor package housing 3 and the semiconductor package 4 separately manufactured as described above. That is, the end of the semiconductor package 4 opposite to the connection terminal 44 is formed in the housing space 31 in a state where the convex portions 45, 45 of the semiconductor package 4 are aligned with the grooves 32, 32 of the housing space 31 of the semiconductor package housing 3. insert. At this time, since the convex portions 45 and 45 are guided into the grooves 32 and 32, the semiconductor package 4 is smoothly inserted into the housing space 31 of the semiconductor package housing 3. When the end of the semiconductor package 4 opposite to the connection terminal 44 is inserted to a position where it abuts against the inner bottom surface of the housing space 31 of the semiconductor package housing 3, the convex portions 45, 45 of the semiconductor package 4 are placed in the housing space 31. The semiconductor package 4 is fixed to the semiconductor package housing 3 and is prevented from falling off. At this insertion position, the connection terminal 44 of the semiconductor package 4 is surrounded by the inner side surface 31a of the accommodation space 31, and a part of the inner side surface 31a of the accommodation space 31 functions as a connector housing. In addition, the Hall element 41 is located inside the conductor portion 23 of the bus bar 2. This completes the manufacture of the current sensor 1.

  Next, the operation of the current sensor 1 will be described. As described above, the current sensor 1 is provided on the electric circuit connected to the battery via the first connection portion 21 and the second connection portion 22, and the connection terminal 44 is connected to a connection terminal of an external device (not shown). Used in the state.

  As shown in FIG. 1, when a current I flows through the bus bar 2, a magnetic field MF is formed around the conductor portion 23 of the bus bar 2 based on the right-hand rule. At this time, the magnetic flux is concentrated inside the conductor portion 23 of the bus bar 2. That is, since the direction of the magnetic field is the same inside the conductor portion 23, the magnetic field becomes dense and the magnetic field is strengthened. Since the Hall element 41 is arranged in the conductor portion 23 where the magnetic flux is concentrated in this way, the magnetic flux density that passes vertically through the Hall element 41 (more precisely, the long side surface 41a), that is, the magnetic field strength is high. Sufficiently secured, the current flowing through the bus bar 2 can be detected magnetically. That is, the magnetic field generated by the current is converted into a voltage by the Hall element 41 and detected.

  The hall element 41 outputs a voltage corresponding to the magnetic field strength to the processing circuit 43. The thermistor 42 detects the temperature of the bus bar 2 and outputs a voltage corresponding to the temperature to the processing circuit 43. Precisely, Joule heat generated by current flowing through the bus bar 2 is transmitted to the thermistor 42 via the semiconductor package housing 3 and the semiconductor package 4, and the thermistor 42 detects the temperature. By detecting the temperature of the bus bar 2, abnormal heat generation of the battery connected to the bus bar 2 can be detected. The processing circuit 43 calculates the output value of the Hall element 41 and the output value of the thermistor 42 and outputs them to a control device or the like of an external device (not shown) via a connection terminal (lead frame) 44.

As described above, according to the embodiment described above, the following effects can be obtained.
(1) Since the semiconductor package 4 is formed by accommodating the Hall element 41 as the magnetic detection element and the processing circuit 43 as the arithmetic device, the magnetic detection element and the arithmetic device provided on the substrate as in the prior art Compared to those arranged separately, the size can be reduced. The semiconductor package 4 is housed in the housing space 31 of the semiconductor package housing 3 so that the Hall element 41 is positioned inside the conductor portion 23 of the bus bar 2. However, the magnetic detection element does not shift and the detection accuracy can be stabilized. When the manufactured current sensor 1 is inspected and the predetermined detection accuracy cannot be obtained due to the Hall element 41 or the like housed in the semiconductor package, the semiconductor package housing 3 is used again for the semiconductor. Since only the package 4 can be exchanged, material waste can be reduced. Further, the Hall element 41 and the like are molded in the semiconductor package 4, and the bus bar 2 is molded in the semiconductor package housing 3, which is waterproof and dustproof.

  (2) Since the semiconductor package 4 and the semiconductor package container 3 are partly elastically engaged and fixed to each other, that is, by snap fitting, they can be easily assembled.

  (3) When the semiconductor package 4 is inserted into the housing space 31 of the semiconductor package housing 3, the short side surface of the semiconductor package 4 is formed in the grooves 32 and 32 formed in the inner surface 31 a of the housing space 31 of the semiconductor package housing 3. Since the convex portions 45, 45 formed on 4 b, 4 b are guided, the semiconductor package 4 can be easily assembled in the housing space 31 of the semiconductor package housing 3.

  (4) Since the housing space 31 of the semiconductor package housing 3 is also used as a connector housing, the connection terminal 44 can be protected and the connection terminal of an external device can be guided to the connection terminal 44 at the time of connection. An increase in the formation process can be suppressed without forming the housing separately.

(5) Since the connection terminal 44 of the semiconductor package 4 is a connector terminal, connection to an external substrate or the like is not required as in the prior art.
(6) By providing the first connection part 21 and the second connection part 22 as attachment parts at both ends of the bus bar 2, the current sensor 1 can be attached to the electric path integrally with the bus bar 2.

(7) Although the vehicle battery and its electric circuit may be exposed to rainwater, the current sensor 1 of the present embodiment is waterproof and dustproof, so that durability can be improved.
In addition, the said embodiment can be implemented with the following forms which changed this suitably.

-In above-mentioned embodiment, although the current sensor 1 was applied to the electric circuit connected to the battery of a vehicle, you may apply not only to the electric circuit connected to the battery of a vehicle but to another electric circuit.
In the above embodiment, the bus bar 2 is formed of a copper plate. However, the bus bar 2 may be formed of another metal plate such as aluminum.

In the above embodiment, the Hall element 41, the thermistor 42, and the processing circuit 43 are accommodated in the semiconductor package 4. However, other necessary circuits may be accommodated.
In the above embodiment, the thermistor 42 is housed in the semiconductor package 4. However, if temperature detection is not necessary, the omitted configuration may be adopted.

  In the above embodiment, the connector housing is formed as the accommodating space 31 when the bus bar 2 is molded. However, when the semiconductor package 4 is molded, a portion surrounding the connection terminal 44 is formed as the connector housing. Good. That is, the connection terminal 44 is exposed from the semiconductor package housing 3.

In the above embodiment, the connection terminal 44 of the hall element 41 is covered with the connector housing, but the connector housing may be omitted.
In the above embodiment, the Hall element 41 is used as the magnetic detection element. However, the magnetic detection element is not limited to the Hall element 41 and may be a GMR (Giant Magneto Resistive) element or the like.

  In the above embodiment, the grooves 32, 32 are formed in the housing space 31 of the semiconductor package housing 3, and the convex portions 45, 45 are formed in the semiconductor package 4, so that the semiconductor package 4 is mounted on the semiconductor package housing 3. Although it is guided to the accommodation space 31, a groove may be formed in the semiconductor package 4 and a convex portion may be formed in the semiconductor package housing 3.

-Moreover, you may abbreviate | omit the said groove | channel and convex part which are the structures which guide the semiconductor package 4 to the accommodation space 31 of the semiconductor package container 3. FIG.
In the above embodiment, the recesses 33 and 33 are formed in the housing space 31 of the semiconductor package housing 3, and the protrusions 45 and 45 are formed in the semiconductor package 4, so that the semiconductor package 4 is mounted on the semiconductor package housing 3. Although the snap fit fixed in the state accommodated in the accommodation space 31 was employ | adopted, the structure which abbreviate | omitted the snap fit may be employ | adopted. For example, the semiconductor package 4 may be inserted and fixed in the housing space 31 of the semiconductor package housing 3 by press fitting or the like.

  In the above configuration, the semiconductor package 4 may be fixed to the semiconductor package housing 3 with a room temperature curing adhesive. For example, as shown in FIG. 4, a room temperature curable adhesive 50 may be applied to the upper surface 4 c of the semiconductor package 4, and the semiconductor package 4 may be inserted into the semiconductor package housing 3 and fixed.

The transmission perspective view which shows the structure of a current sensor. AA sectional drawing of a current sensor. (A) The bottom view of a semiconductor package container, (b) The bottom view of a semiconductor package. The perspective view which shows a semiconductor package container and a semiconductor package.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Current sensor, 2 ... Bus bar, 3 ... Semiconductor package container, 4 ... Semiconductor package, 4a ... Long side surface, 4b ... Short side surface, 4c ... Upper surface, 21 ... 1st connection part, 21a ... 1st connection hole, 22 2nd connection part, 22a ... 2nd connection hole, 23 ... Conductor part, 31 ... Housing space, 31a ... Inner side surface, 32 ... Groove, 33 ... Recessed part, 41 ... Hall element, 42 ... Thermistor, 43 ... Processing circuit, 44 ... connecting terminal, 45 ... convex, 50 ... adhesive, I ... current, MF ... magnetic field.

Claims (6)

In a current sensor comprising a bus bar formed of a conductor and having a U-shaped conductor portion and a magnetic detection element that magnetically detects a current flowing through the bus bar,
A semiconductor package containing the magnetic detection element, a processing circuit for processing an output from the magnetic detection element, and a connection terminal between the processing circuit and the outside is formed by molding with a resin material,
A semiconductor package housing body is formed by molding with a resin material in which both end portions of the bus bar are exposed and a housing space for housing the semiconductor package is provided so that the magnetic detection element is located inside the conductor portion. ,
The current sensor, wherein the semiconductor package is housed in a housing space of the semiconductor package housing body. The current sensor according to claim 1.
A part of the semiconductor package and the semiconductor package container are elastically engaged and fixed to each other. The current sensor according to claim 2,
A convex portion is formed on one of the inner side surface of the housing space of the semiconductor package container and the outer side surface of the semiconductor package, and a concave portion is formed at a position facing these other convex portions, A current sensor characterized by being fixed by fitting a convex part into the concave part. In the current sensor according to any one of claims 1 to 3,
Grooves for guiding the semiconductor package to the housing space of the semiconductor package housing are formed on either the inner surface of the housing space of the semiconductor package housing or the outer surface of the semiconductor package. The current sensor is characterized in that a convex portion guided in the groove is formed on the other side. In the current sensor according to any one of claims 1 to 4,
The current sensor, wherein the housing space of the semiconductor package housing is a connector housing that surrounds the connection terminals of the semiconductor package. In the current sensor according to any one of claims 1 to 5,
The current sensor, wherein the semiconductor package and the semiconductor package container are fixed by a room temperature curing adhesive.

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