JP4891217B2 - Current sensor - Google Patents

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 conductors arranged oppositely (current flowing in the bus bar) is amplified at the intermediate position of the conductors, so that even if no core is provided, the magnetic sensor Current detection based on the detection signal becomes possible.
JP 2002-243768 A JP 2007-218729 A

  By the way, in the current sensor described in Patent Document 2, the package containing the magnetic detection elements constituting the magnetic sensor is provided on a substrate on which a control device and the like are provided. This substrate is provided so as to protrude greatly to the side of the bus bar, which leads to an increase in the size of the current sensor. Further, 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.

In the following, means for achieving the above object and its operational 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 in which a magnetic detection element, a processing circuit for processing an output from the magnetic detection element, and a connection terminal to the outside are formed by molding with a resin material is provided inside the conductor portion. The gist of the present invention is that the bus bar and the semiconductor package are integrally formed by molding with a resin material so that both ends of the bus bar are exposed in a state where they are positioned.

  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. In addition, since the bus bar and the semiconductor package are integrally formed at the manufacturing stage so that the magnetic detection element is positioned on the conductor portion of the bus bar, the magnetic detection element is shifted with respect to the bus bar when assembled to the bus bar as in the conventional case. In this case, the detection accuracy can be stabilized. Further, the magnetic detection element or the like is molded in a semiconductor package, and the bus bar and the semiconductor package are further molded, and is waterproof.

  According to a second aspect of the present invention, the gist of the current sensor according to the first aspect is that a connector housing surrounding the connection terminals of the semiconductor package is formed by the molding.

  According to this configuration, since the connector housing is formed by molding, the connection terminals of the semiconductor package are protected, and positioning is facilitated when connecting the external terminals. Further, since the terminal of the semiconductor package is a connector terminal, connection to an external substrate or the like is unnecessary as in the prior art. The connector housing may be formed when the semiconductor package is molded, or may be formed when the bus bar and the semiconductor package are integrally molded.

  The gist of the invention described in claim 3 is that, in the current sensor according to claim 1 or 2, the semiconductor package further includes temperature detecting means for detecting the temperature of the bus bar.

According to this configuration, since the temperature detecting means is provided in the semiconductor package, the temperature of the bus bar can be detected and the size can be reduced as compared with a separately provided one.
The gist of the invention described in claim 4 is that the bus bar of the current sensor according to any one of claims 1 to 3 is applied to an electric circuit connected to a battery of a vehicle.

  According to this configuration, the bus bar is applied to the electric circuit connected to the vehicle battery, that is, the current sensor is applied to the current detection of the electric circuit connected to the vehicle battery. Although the vehicle battery and its electric circuit may be exposed to rain water, the current sensor of the present invention is waterproof, so that it is particularly effective when applied to an electric circuit connected to the vehicle battery.

  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 connected to a battery of a vehicle that is a current detection target is a strip-shaped metal plate (a copper plate in this embodiment) as a conductor. A bus bar 2 that is plastically deformed in a letter shape, and a semiconductor package 3 in which a magnetic detection element that magnetically detects a current flowing through the bus bar 2 is accommodated. The bus bar 2 and the semiconductor package 3 are covered with a resin housing 4 having insulating properties.

  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 part 21 and the second connection part 22 protrude outside the housing 4 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 3 includes a Hall element 31 as a magnetic detection element, a thermistor 32 as temperature detection means for detecting the temperature of the bus bar 2, and outputs from the Hall element 31 and the thermistor 32. The processing circuit 33 to be processed is mounted on the lead frame with a conductive paste, and is molded into a rectangular parallelepiped shape with an insulating resin material. A part of the lead frame protrudes from the mold portion to the outside as a connection terminal 34 to the outside. The Hall element 31 is provided with a magnetosensitive axis capable of detecting a magnetic field perpendicular to the long side surface 3a of the semiconductor package 3, so that the semiconductor package 3 is generated by the current I flowing through the bus bar 2, as shown in FIG. The magnetic flux to be transmitted passes vertically through the long side surface 31 a of the Hall element 31.

  As shown in FIG. 2, the housing 4 is integrally formed by molding with a resin material having insulating properties, and protrudes from the outer surface of the housing 4 and the main body housing 41 covering the conductor portion 23 of the bus bar 2 and the semiconductor package 3. The connector housing 42 covers the connecting terminal 34. In other words, the connection terminal 34 of the semiconductor package 3 is surrounded by the connector housing 42 and exposed. That is, the connection terminal 34 of the semiconductor package 3 is a connector terminal. In the current sensor 1, a bus bar 2 and a semiconductor package 3 are integrally formed by a housing 4.

Next, a method for manufacturing the current sensor 1 will be described with reference to FIGS.
First, the Hall element 31, the thermistor 32, and the processing circuit 33 are mounted on a lead frame on which an external connection terminal 34 is formed using a conductive paste. The Hall element 31, the thermistor 32, and the processing circuit 33 mounted on the lead frame are molded into a rectangular parallelepiped shape so that the connection terminal 34 protrudes. Thereby, the semiconductor package 3 is formed.

  Then, as shown in FIG. 3, the semiconductor package 3 is placed in the U-shaped conductor portion 23 of the bus bar 2 so that the magnetic flux generated by the current flowing through the conductor portion 23 passes through the long side surface 3 a of the semiconductor package 3. Deploy. In a state where the semiconductor package 3 is disposed on the conductor portion 23 of the bus bar 2, the bus bar 2 and the semiconductor package 3 are molded. As a result, as shown in FIG. 4, the housing 4 including the main body housing 41 and the connector housing 42 is formed. This completes the manufacture of the current sensor 1.

Next, the operation of the current sensor 1 described above will be described.
As shown in FIG. 1, when a current I flows through the bus bar 2, a magnetic field MF is formed in the conductor portion 23 of the bus bar 2. Then, the Hall element 31 outputs a voltage corresponding to the magnetic field strength to the processing circuit 33. The thermistor 32 detects the temperature of the bus bar 2 and outputs a voltage corresponding to the temperature to the processing circuit 33. Precisely, Joule heat generated by current flowing through the bus bar 2 is transmitted to the thermistor 32 through the housing 4 and the semiconductor package 3, and the thermistor 32 detects the temperature. By detecting the temperature of the bus bar 2, the battery connected to the bus bar 2 can detect abnormal heat generation or the like. The processing circuit 33 calculates the output value of the Hall element 31 and the output value of the thermistor 32 and outputs them to a control device or the like of an external device (not shown) connected to the connection terminal 34 via the connection terminal (lead frame) 34.

  At this time, the magnetic flux is concentrated on 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 31 is arranged in the conductor portion 23 where the magnetic flux concentrates in this way, the magnetic flux density that passes vertically through the Hall element 31 (more precisely, the long side surface 31a), 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 31 and detected.

As described above, according to the embodiment described above, the following effects can be obtained.
(1) Since the semiconductor package 3 is formed by accommodating the Hall element 31 as a magnetic detection element, the processing circuit 33 as an arithmetic unit, and the like, the magnetic detection element and the arithmetic unit provided on the substrate as in the past are provided. Compared to those arranged separately, the size can be reduced. In addition, since the bus bar 2 and the semiconductor package 3 are integrally formed at the manufacturing stage so that the Hall element 31 is positioned on the conductor portion 23 of the bus bar 2, when the bus bar 2 is assembled to the bus bar as in the related art, the magnetic force is applied to the bus bar. The detection element is not displaced, and the detection accuracy can be stabilized. Further, the Hall element 31 and the like are molded in the semiconductor package 3, and the bus bar 2 and the semiconductor package 3 are further molded, which is waterproof.

  (2) Since the connector housing 42 is formed by molding, the connection terminals 34 of the semiconductor package 3 are protected, and positioning is facilitated when connecting external terminals. Further, since the terminal of the semiconductor package is a connector terminal, connection to an external substrate or the like is unnecessary as in the prior art.

  (3) Since the thermistor 32 as temperature detecting means is provided in the semiconductor package 3, the temperature of the bus bar 2 can be detected, and the size can be reduced as compared with the separately provided one.

(4) Although the battery of the vehicle and its electric circuit may be exposed to rainwater, the current sensor 1 of the present embodiment is waterproof, so that durability can be improved.
(5) 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.

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 31, the thermistor 32, and the processing circuit 33 are accommodated in the semiconductor package 3, but other necessary circuits may be accommodated.

In the above embodiment, the thermistor 32 is housed in the semiconductor package 3 as temperature detection means. However, if temperature detection is not required, a configuration in which the temperature detection means is omitted may be employed.
In the above embodiment, the connector housing 42 is formed when the bus bar 2 and the semiconductor package 3 are integrally molded. However, the connector housing 42 may be formed when the semiconductor package 3 is molded.

In the above embodiment, the connection terminal 34 of the hall element 31 is covered with the connector housing 42, but the connector housing 42 may be omitted.
In the above embodiment, the Hall element 31 is used as the magnetic detection element. However, the magnetic detection element is not limited to the Hall element 31 and may be a GMR (Giant Magneto Resistive) element or the like.

The transmission perspective view which shows the structure of a current sensor. AA sectional drawing of a current sensor. The perspective view which shows a bus-bar and a semiconductor package. The perspective view which shows the external appearance of a current sensor.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Current sensor, 2 ... Bus bar, 3 ... Semiconductor package, 3a ... Long side surface, 4 ... Housing, 21 ... 1st connection part, 21a ... 1st connection hole, 22 ... 2nd connection part, 22a ... 2nd connection hole , 23 ... Conductor part, 31 ... Hall element, 32 ... Thermistor, 33 ... Processing circuit, 34 ... Connection terminal, 41 ... Main body housing, 42 ... Connector housing, I ... Current, MF ... Magnetic field.

Claims (4)

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 in which the magnetic detection element, a processing circuit for processing the output from the magnetic detection element, and a connection terminal to the outside are formed by molding with a resin material is detected inside the conductor portion. The current bar, wherein the bus bar and the semiconductor package are integrally formed by molding with a resin material so that both ends of the bus bar are exposed in a state where the elements are disposed. The current sensor according to claim 1, wherein a connector housing that surrounds a connection terminal of the semiconductor package is formed by the molding. The current sensor according to claim 1, wherein temperature detection means for detecting a temperature of the bus bar is housed in the semiconductor package. The current sensor according to any one of claims 1 to 3, wherein the bus bar is applied to an electric circuit connected to a battery of a vehicle.

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