JP2014163925A - Current sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a substrate mounting type current sensor capable of achieving a GND connection of a core easily at low cost and high in reliability and excellent in assemblability.SOLUTION: The current sensor has an annular magnetic laminate core formed with at least one GND connection hole laminated by pressing a magnetic steel plate into an annular shape having a gap, and one of metal pins formed into a rod-like shape is press-fitted into the GND connection hole. When the annular magnetic laminate core is assembled into a case, the other of the metal pins is configured to project to the outside from a through hole provided in the case, and can be electrically connected to the GND of a mother board mounted with the current sensor. Further, a fixing piece for pressing and fixing an input/output terminal of a circuit board assembled into the case is integrally provided with the case. Furthermore, one end of a primary conductor formed into a U-shape is inserted into a primary conductor insertion hole of the current sensor main body, and a U shape intermediate side part and the other end are press-fitted to a conductor positioning recess part provided in the current sensor main body, and the primary conductor is configured to be fixed to the current sensor main body.

Description

  The present invention relates to a board-mounted type current sensor that detects current using a magnetoelectric transducer disposed in a gap provided in an annular magnetic laminated core.

  Some current sensors that detect the magnitude of current use a magnetoelectric transducer such as a Hall element. This type of current sensor has a magnetoelectric transducer placed in a gap in a part of the annular magnetic core. The magnetic flux generated in the gap by the detected current flowing through the primary conductor passing through the annular magnetic core is detected by the magnetoelectric conversion element, and amplified to a predetermined level by the amplifier circuit connected at the subsequent stage and output. It is comprised, and the magnitude | size of the electric current which flows into a primary conductor is measurable by detecting the magnetic flux density in a gap with a magnetoelectric conversion element.

This type of current sensor has a structure in which a magnetoelectric conversion element is arranged in a gap provided in an annular magnetic core that penetrates a primary conductor. Since the core and the magnetoelectric conversion element are close to each other, the potential of the primary conductor suddenly increases. Since the potential of the core is shaken by the electrostatic coupling between the primary conductor and the core and noise is generated in the electric circuit, it is desirable to connect the core to GND.
In order to connect the core to the GND, a current sensor provided with a GND connection member formed of a metal plate has been proposed. (For example, see Patent Document 1)

  In addition, in a board-mounted type current sensor that is used by being mounted on the mother board of the device, a plurality of independent U-shaped primary conductors are arranged in parallel, and the mother board side on which the current sensor is mounted is arranged. By combining and connecting multiple conductors in parallel or in series in a pattern, together with supporting the mounting of the current sensor on the mother board, the ampere turn of the current to be measured that penetrates the annular magnetic core of the current sensor is made constant, and several types of A current sensor configured to measure the rated current with the same current sensor has been proposed. (For example, see Patent Document 2)

JP-A-8-194015 Special table 2002-508846

In the conventional example disclosed in Patent Document 1, a case 103 for holding a circuit board 105 and an annular magnetic core 101 around which a primary conductor 102 for applying a current to be measured is wound as shown in FIGS. A bobbin portion 109 partially insulated by an insulating resin, and the case 103 and the bobbin portion 109 are integrally formed on the annular magnetic core 101 so that the case 103 covers the periphery of the annular magnetic core 101 with an insulating resin. Is formed.
Note that both ends 102 a and 102 b of the primary conductor wound around the bobbin portion 109 are inserted into insertion holes 106 a and 106 b provided in the bottom cover 106 and fixed in position.

  Further, a partition wall 111 is provided between the bobbin portion 109 and the circuit board 105, and a shield plate 104 made of a metal plate is disposed on the circuit board 105 side of the partition wall 111. A pair of first and second projecting pieces 104 a and 104 b extending from the core 101 are in contact with the core 101, and are integrally formed and fixed to the annular magnetic core 101.

Further, as shown in FIG. 6, the third protrusion 104 c of the shield plate 104 is bent into an L shape and is electrically connected to the GND of the input / output terminal 108 of the circuit board 105.
Therefore, the core 101 is connected to the GND via the shield plate 104.
The circuit board 105 is inserted along the first guide part 110 a and the second guide part 110 b provided in the case 101, and is held by the case 101 by the board holding part 110.

  The current sensor configured as described above has a case for holding a circuit board, and a bobbin portion in which a part of an annular magnetic core around which a primary conductor is wound is insulated by an insulating resin, and the case and bobbin are provided on the annular magnetic core. Since the portion and the shield plate are formed integrally, there is an advantage that not only the shape is reduced, but also a current sensor that is resistant to external electromagnetic noise and inexpensive can be obtained.

  However, when the shield plate and the annular magnetic core are integrally molded, the resin molding conditions must be managed so that they can maintain electrical continuity with each other, and after the circuit board is incorporated into the case, the shield Bending the protrusions of the board into an L shape and electrically connecting them to the GND terminal of the circuit board by soldering, etc., or inserting both ends of the primary conductor into the insertion holes in the bottom lid to fix the position, etc. There is a problem that it takes.

  Although the method for holding the circuit board in the case is not specified, it is necessary to fix the circuit board to the case with an adhesive after inserting the circuit board into the case, which increases the assembly lead time and costs. After the current sensor is mounted on the mother board of the device, external force is applied to the input / output terminals mounted on the circuit board due to vibration, etc., and the connection between the circuit board and the input / output terminals may cause solder cracks due to stress, etc. There are problems such as causing problems.

  Next, in another conventional example disclosed in Patent Document 2, a plurality of primary conductors 219 obtained by punching a metal plate as shown in FIG. 7 and FIG. Independently integrally molded, internal components are assembled and fixed in the case 216 so that the primary conductor 219 penetrates the annular magnetic core 214, and then both ends of the primary conductor 219 are bent at right angles in the same direction. It is molded into the shape of

  The current sensor configured as described above has an advantage that it can be easily assembled and reduced in size because a plurality of primary conductors are fixed to a predetermined position by integral molding with the case.

  However, since a plurality of primary conductors are integrally formed with the case, the cost of the case is increased, and further, it is difficult to obtain a predetermined terminal pitch by bending both ends of the primary conductor into a U-shape.

  SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems, and is to provide a board-mount type current sensor that has a highly reliable core GND connection structure, is easy to assemble and is inexpensive. .

  A current sensor according to the present invention includes an annular magnetic core provided with a gap in a part thereof, a magnetoelectric conversion element arranged in the gap, and an amplification circuit that amplifies and outputs an output of the magnetoelectric conversion element to a predetermined level Circuit board mounted with components such as I / O terminals and the like, and a board mounted type current sensor configured by incorporating a primary conductor for applying a current to be measured into a case, the annular magnetic core has a gap between magnetic steel plates. A ring-shaped magnetic core having at least one GND connection hole, which is press-processed into a ring shape having a ring shape, and one of metal pins formed in a rod shape is press-fitted into the GND connection hole, When the annular magnetic core is incorporated into the base plate, the other metal pin protrudes outward from the through hole provided in the case, and the GND of the mother board on which the current sensor is mounted And it can be electrically connected to the turn.

  In addition, a fixed piece that presses and fixes the input / output terminal mounted on the circuit board is formed integrally with the case via the hinge part, and after inserting the circuit board along the board guide part provided on the case, The hinge part is bent and a fixing piece is fitted into a recess provided in the case to press and fix the input / output terminal to the case from above, and a circuit board holder provided on the top of the cover with a cover attached to the case is attached to the circuit board. The structure is fixed to the case by pressing.

  Furthermore, the elongated hole-shaped primary conductor insertion hole provided in the approximate center of the case is formed with a wide end portion where one end is wider than the primary conductor diameter, and a narrow end portion where the other end is substantially zero in clearance with the primary conductor diameter. After attaching the cover to the case, one end of the primary conductor formed by round copper wire in a U shape is inserted into the wide end portion of the primary conductor insertion hole, and the middle side of the U shape is Press fit into the Y direction conductor positioning recess provided on the upper surface of the cover, then slide the primary conductor toward the center of the body, and press fit and fix the other end of the primary conductor in the Z direction conductor positioning recess provided on the outer wall of the front of the case. .

  According to the board-mounted type current sensor of the present invention, the GND connection structure of the annular magnetic laminated core can be easily realized, and a current sensor with high connection reliability, easy assembly, and low cost can be obtained.

  Furthermore, the circuit board and the input / output terminal can be securely fixed to the case in a short time, and an inexpensive current sensor with high connection reliability between the circuit board and the input / output terminal and a short assembly lead time can be obtained.

  Furthermore, it is possible to obtain a current sensor that has a small variation in terminal pitch of a plurality of primary conductors that are incorporated, and that is easy and inexpensive to incorporate the primary conductors.

It is a perspective view which shows the assembly structure of the current sensor of this invention. It is a perspective view which shows the assembly state of the current sensor of this invention. Fig.2 (a) is a perspective view which shows before the case fitting of a fixing piece. FIG. 2B is a perspective view showing a state in which the hinge portion is bent, the fixing piece is fitted into the case, and the input / output terminals are fixed to the case. Furthermore, FIG.2 (c) is a front view which shows the shape of a primary conductor insertion hole. It is a perspective view which shows the assembly state of the current sensor of this invention. FIG. 3 (a) shows a state where one end of the primary conductor is inserted into the wide end portion of the primary conductor insertion hole, the primary conductor is fitted into the Y-direction conductor positioning recess, and press-fitted into the Z-direction conductor positioning recess provided on the front wall of the case. It is a perspective view which shows the state of. FIG. 3B is a perspective view showing a state in which the primary conductor is fixed to the current sensor body by being press-fitted into the Z-direction conductor positioning recess provided on the outer front wall of the case. It is a perspective view which shows the assembly structure of the current sensor which concerns on the device of patent document 1. FIG. It is a top surface sectional view showing the current sensor concerning the device of patent documents 1. It is side surface sectional drawing which shows the current sensor which concerns on the device of patent document 1. It is a front view which shows the current sensor which concerns on the device of patent document 2. FIG. It is side surface sectional drawing which shows the current sensor which concerns on the device of patent document 2.

Hereinafter, embodiments of the present invention will be described with reference to FIGS.
1 to 3, reference numeral 1 denotes a case, 2 denotes a circuit board, on which components such as a magnetoelectric conversion element 3 and a signal amplifier 4 and an input / output terminal 5 for outputting driving power and signals of the circuit are mounted.
Reference numeral 6 denotes an annular magnetic laminated core, and a gap 7 is provided in a part thereof. An output signal of the magnetoelectric conversion element 3 disposed in the gap is amplified to a predetermined level by the signal amplifier 4 of the circuit board 2. And output from the input / output terminal 5.
A metal pin 9 formed in a rod shape is press-fitted and fixed in a GND connection hole 8 provided in the annular magnetic laminated core 6.
Note that it is desirable to use a spring pin instead of the metal pin 9 because the contact stability can be further improved.
The primary conductor 10 to which the current to be measured is applied is obtained by processing a round copper wire into a U shape, and one end 10a and the other end 10b of the U shape are formed in substantially the same shape with the middle side 10c as a boundary. ing.

  First, after inserting the circuit board 2 along the guide portion 12 of the case 1 so that the input / output terminal 5 of the circuit board 2 penetrates into the input / output terminal hole 11 provided in the case 1, Fixing convex portions 15 provided at both ends of a fixing piece 14 formed integrally with the case 1 are fitted into fixing concave portions 16 provided in the case 1 by bending the hinge portion 13 so that the fixing piece 14 is the input / output terminal. 5 is pressed and fixed to the case 1 from above.

  The magnetoelectric transducer 3 of the circuit board 2 incorporated in the case 1 is positioned in the gap 7 of the annular magnetic laminated core 6 in which the metal pin 9 is press-fitted and fixed in the GND connection hole 8 in advance. The annular magnetic laminated core 6 is inserted into the case 1 so that the metal pin 9 protrudes through the through hole 17 provided in the same direction as the input / output terminal hole 11 of the case 1.

Next, the cover 18 is attached to the case 1, and the board presser 19 provided on the top surface of the cover 18 presses the assembled circuit board 2 and is fixed to the case 1.
Furthermore, a Y-direction conductor positioning recess provided in the cover 18 by inserting one end 10 a of the primary conductor 10 processed into a U-shape into the wide end portion 23 of the primary conductor insertion hole 20 provided in the approximate center of the case 1. 21. The middle side 10c of the primary conductor 10 is press-fitted into 21, and then the primary conductor 10 is slid toward the center of the current sensor body 30, and the other end 10b of the primary conductor 10 is positioned on the front outer wall of the case 1 in the Z direction conductor positioning. The primary conductor 10 is fixed to the current sensor body 30 by being press-fitted into the recess 22.
The primary conductor insertion hole 20 is formed in the shape of a long hole having a wide end portion 23 whose one end is wider than the primary conductor diameter and a narrow end portion 24 whose other end is substantially zero in clearance with the primary conductor diameter. When the other end 10 b is press-fitted into the directional conductor positioning recess 22, the one end 10 a inserted into the wide end portion 23 of the primary conductor insertion hole 20 slides to the narrow end portion 24 and is fixed to the current sensor body 30.

As described above, according to the current sensor of the present invention, an inexpensive circuit board mounting type current that is less susceptible to external force applied to the input / output terminals, has a highly reliable core GND connection structure, and has excellent assemblability. A sensor can be obtained.
In addition, it is possible to increase or decrease the number of turns of the primary conductor according to the measured current value by fixing a plurality of primary conductors in the current sensor body and connecting the primary conductors in parallel or in series with the mother board side wiring mounted. As is well known.

DESCRIPTION OF SYMBOLS 1 Case, 2 Circuit board, 3 Magnetoelectric conversion element, 4 Signal amplifier, 5 Input / output terminal, 6 Cyclic magnetic laminated core, 7 Gap, 8 GND connection hole, 9 Metal pin, 10 Primary conductor, 10a One end, 10b etc. End, 10c Middle side, 11 Input / output terminal hole, 12 Guide part, 13 Hinge part, 14 Fixing piece, 15 Fixing convex part, 16 Fixing concave part, 17 Through hole, 18 Cover, 19 Substrate presser, 20 Primary conductor insertion Hole, 21 Y-direction conductor positioning recess, 22 Z-direction conductor positioning recess, 23 Wide end, 24 Narrow end, 30 Current sensor body

Claims (5)

  A circular magnetic core having a gap in part, a circuit board on which magnetoelectric transducers and other circuit components and input / output terminals arranged in the gap are mounted, and a conductive metal material having a round cross-sectional shape are copied. In a board mounting type current sensor in which a primary conductor formed in a U-shape is incorporated in a case and a cover is attached, a core GND connection member is provided in the annular magnetic core, and the annular magnetic core is provided in the case Board mounting type current, wherein the core GND connection member protrudes from a through hole provided in the case and is electrically connected to the GND of the mother board on which the current sensor is mounted. Sensor.   The annular magnetic core is an annular magnetic laminated core having at least one GND connection hole formed by pressing and laminating magnetic steel plates into a ring shape having a gap, and the core GND connection member is A through hole provided in the case when the annular magnetic laminated core is assembled into the case, which is made of a metal pin formed into a rod shape, and one of the metal pins is press-fitted into the GND connection hole of the annular magnetic laminated core The board-mounted type current sensor according to claim 1, wherein the other metal pin protrudes outward from the outside.   The board-mounted type current sensor according to claim 2, wherein the metal pin is a spring pin obtained by winding a thin metal plate into a cylindrical shape.   The fixing piece for pressing the input / output terminal mounted on the circuit board and fixing the input / output terminal to the case after the circuit board is inserted into the case is formed integrally with the case via a hinge portion. Item 4. The board-mounted type current sensor according to Item 3.   The primary conductor insertion hole provided in the substantially central opening of the case is formed in the shape of a long hole with a wide end portion where one end is wider than the primary conductor diameter and a narrow end portion where the other end is substantially zero in clearance with the primary conductor diameter. One end of a U-shaped primary conductor is inserted into the wide end portion of the primary conductor insertion hole after the cover is attached to the case, and the U-shape is positioned in the Y-direction conductor positioning recess provided on the cover. Press the center side of the wire, then slide the primary conductor toward the center of the current sensor body, press the other end of the primary conductor into the Z-direction conductor positioning recess provided on the outer wall of the case front, and the primary conductor is the current sensor body The board mounted type current sensor according to any one of claims 1 to 4, wherein the primary conductor insertion hole and the conductor positioning recess are formed so as to be fixed to each other.

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