JP2015064278A - Current sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a current sensor capable of securing a core to a case without being subjected to stresses from the surrounding and also capable of efficiently eliminating induction noise and radiation noise.SOLUTION: Provided is a current sensor 1 created by accommodating a core 3 made of magnetic metal in a case 2 of insulating properties and disposing a hall element in a notch 3a of the core 3, wherein a core-fixing plate 4 of non-magnetic properties is secured to the core 3 by spot-welding or caulking so as to allow electrical continuity and the core-fixing plate 4 is fastened to the case 2, the core-fixing plate 4 being further connected, for grounding, to GND (ground) of a circuit board 5. Furthermore, a fixing tab 4B penetrating a hollow part 3b of the core 3 is formed, by bending, on the core-fixing plate 4 as an integral body, and the fixing tab 4B is inserted through a slit 2a formed in the case 2, whereby the core 3 and the core-fixing plate 4 secured thereto are secured to the case 2.

Description

  The present invention relates to a current sensor that detects the magnitude of a current by amplifying a magnetic field generated by a current with a core and detecting it with a Hall element.

  The current sensor is used, for example, to constantly monitor the remaining amount of a battery mounted on the vehicle. Such a current sensor is configured by accommodating a magnetic metal core inside a case made of insulating resin, and arranging a Hall element in a notch portion of the core, such as a bus bar penetrating the core. A magnetic field generated by a flowing current is detected by the core and converted into a voltage by the Hall element.

  In such a current sensor, there are a method of fixing the core to the case by a method of integrating the core into the case by insert molding and a method of fixing the core by potting with a urethane resin or the like. Further, as a method of grounding the core, a method of connecting the core to the GND (ground) of the circuit board using a copper tape has been used.

  By the way, regarding the current sensor, for example, Patent Document 1 proposes a configuration in which stress generated in the core due to the expansion and contraction of the case is relieved to easily and reliably prevent the deformation of the core. Specifically, a nonmagnetic metal plate is disposed along the inner surface of the wall portion of the insulating case, and a magnetic core is disposed on the metal plate so as to overlap the wall portion and the core. By interposing a metal plate and bonding and fixing the wall portion and the metal plate and the metal plate and the core with a molding agent filled in the case, the expansion and contraction of the wall portion is absorbed by the metal plate. The stress load on the core is relaxed.

  Patent Document 2 proposes a current sensor with improved assembly workability. Specifically, it has a side part provided alongside the ground terminal and a through hole provided in the side part and connected to the hole of the ground terminal, and is fixed through the hole of the ground terminal and the through hole. In a current sensor fixed to a grounding member together with the grounding terminal by a member, a configuration is proposed in which a locking part for locking the side part to the grounding terminal is provided so that the hole of the grounding terminal and the through hole are continuous. ing.

JP 2012-037351 A JP 2008-070173 A

  However, the configuration of the current sensor proposed in Patent Document 1 only has a function of relieving stress from the core molding agent via the metal plate, and the metal plate itself is a function of fixing the core alone. Does not have.

  Further, the current sensor proposed in Patent Document 2 has only a function of returning the current flowing from the positive terminal of the battery to the negative terminal (ground terminal) of the battery through the ground. Does not have a function to remove noise.

  By the way, as a method of fixing the core to the case in the current sensor, when using a method in which the core is integrated into the case by insert molding, stress is applied to the entire core due to stress at the time of insert molding, and the core is deformed. There exists a problem that the characteristic of a current sensor deteriorates remarkably. In order to solve such a problem, it is necessary to increase the size of the core to mitigate the influence of stress on the core. However, there arises a problem that the core is enlarged and the weight is increased.

  In addition, when adopting a method of potting and fixing the core with urethane resin or the like, there is a problem that a potting resin injection facility is required and maintenance costs are also generated. Even in this method, it is impossible to completely reduce the stress of the potting portion, and there is a problem that some deterioration in characteristics cannot be avoided due to the change in the gap (core gap) of the core notch due to the stress. There is also.

  Furthermore, when a method of connecting the core to the GND (ground) of the circuit board with a copper tape as a conventional grounding method of the core is employed, whether or not the copper tape is securely attached to the core and the circuit board. There was a problem that a lot of man-hours were required to attach the copper tape.

  The present invention has been made in view of the above problems, and the object of the present invention is that the core can be fixed to the case without receiving stress from the surroundings, and induction noise and radiation noise can be efficiently removed. An object of the present invention is to provide a current sensor capable of

  In order to achieve the above object, a first aspect of the present invention provides a current sensor in which a magnetic metal core is accommodated in an insulating case, and a Hall element is disposed in the notch of the core. The core fixing plate is fixed to the core so as to be electrically conductive by spot welding or caulking, the core fixing plate is fastened to the case, and the core fixing plate is connected to the GND (ground) of the circuit board. It is characterized by being connected to and grounded.

  According to a second aspect of the present invention, in the first aspect of the present invention, a fixing tab penetrating the hollow portion of the core is integrally formed on the core fixing plate, and the fixing tab is formed in the case. The core and the core fixing plate fixed to the core are fixed to the case through the formed slit.

  According to a third aspect of the present invention, in the first or second aspect of the invention, the core is connected to the ground of the circuit board by grounding the core fixing plate and the circuit board together with a screw, and grounded. It is characterized by that.

  According to the first aspect of the present invention, the core is fixed to the case by fastening the core fixing plate fixed to the core by spot welding or caulking without filling the potting agent. The core can be fixed to the case without receiving stress from the surroundings. For this reason, deformation of the core can be prevented, the gap (core gap) of the notch portion of the core can be kept constant, and deterioration of the characteristics of the current sensor can be prevented, and the current can always be detected with high accuracy.

  In addition, since the grounding of the core by the conventional copper tape is abolished and the core is connected to the ground (GND) of the circuit board via the fixing plate, the core can be reliably grounded. Man-hours required for grounding can be reduced, and induction noise and radiation noise can be efficiently removed by reliable grounding of the core.

  According to the second aspect of the present invention, the fixing tab formed integrally with the core fixing plate is passed through the hollow portion of the core and passed through the slit of the case, thereby fixing the core and the core fixing fixed thereto. Since the working plate is fixed to the case, the core can be positioned and securely fixed to the case.

  According to the invention described in claim 3, since the core is connected to the GND of the circuit board by grounding the core fixing plate and the circuit board together with screws, it is grounded by the conventional copper tape. In comparison, the core can be securely grounded, and can be easily grounded, thereby reducing the number of man-hours required for grounding.

It is a front view of the current sensor concerning the present invention. It is a perspective view which shows the state before fixation of the core and core fixing plate of the current sensor which concerns on this invention. It is a perspective view which shows the fixed state of the core of the current sensor which concerns on this invention, and a plate for core fixation. It is a rear view of the case of the current sensor according to the present invention. It is a perspective view which shows the grounding structure to the circuit board of the core in the current sensor which concerns on this invention.

  Embodiments of the present invention will be described below with reference to the accompanying drawings.

  1 is a front view of a current sensor according to the present invention, FIG. 2 is a perspective view showing a state before the core of the current sensor and the core fixing plate are fixed, and FIG. 3 is a diagram of the core of the current sensor and the core fixing plate. FIG. 4 is a rear view of the case of the current sensor, and FIG. 5 is a perspective view showing a grounding structure of the core to the circuit board in the current sensor.

  As shown in FIG. 1, the current sensor 1 according to the present invention houses a magnetic metal core 3 shown in FIG. 2 inside a case 2 made of insulating resin, and is not shown in a notch 3 a of the core 3. A hall element is arranged, and a magnetic field generated by a current flowing through a bus bar (not shown) penetrating the core 3 is detected by the core 3 and converted into a voltage by the hall element. It is to detect.

  Here, as shown in FIG. 2, the core 3 is formed into a rectangular discontinuous ring in which the cutout portion 3a is formed in part, and is configured by laminating a plurality of thin magnetic metal plates. ing. In this embodiment, the core fixing plate 4 made of a nonmagnetic metal is spot-welded or caulked at the six points a shown in FIG. 2 on the front surface (front surface in FIG. 2) of the core 3. It is fixed as shown in FIG.

  The core fixing plate 4 has a shape along the front shape of the core 3, that is, a main body portion 4A having a rectangular discontinuous shape in which a notch portion 4a is formed in part, and a rectangular opening 4b of the main body portion 4A. It is provided with an elongated fixing tab 4B that is integrally bent at a right angle from the upper side to the back side. Here, a circular screw hole 4c is formed at the upper center of the body portion 4A of the core fixing plate 4, and a similar screw hole 4d is also formed at the tip of the fixing tab 4B.

  Thus, as shown in FIG. 3, the core fixing plate 4 has the fixing tab 4 </ b> B penetrated through the hollow portion 3 b of the core 3 and the main body portion 4 </ b> A is in close contact with the front surface of the core 3. It is fixed to the front surface of the core 3 by spot welding or caulking at 6 points a.

  By the way, as shown in FIG. 4, the case 2 is provided with a slit 2a that is elongated in the lateral direction. As shown in FIG. 3, the core 3 is fixed to the core 3 by spot welding or caulking. 1, the fixing tab 4B of the core fixing plate 4 is inserted from the front side into the slit 2a of the case 2 as shown in FIG. 1, and is inserted into the screw hole 4c formed in the main body 4A of the core fixing plate 4. The core 3 is fixed to the case 2 by fastening the core fixing plate 4 to the case 2 with the screws.

  Then, as shown in FIG. 5, the circuit board 5 is overlaid on the fixing tab 4B of the core fixing plate 4, and the screw inserted into the screw hole 4d (see FIGS. 2 and 3) formed in the fixing tab 4B. 6, the fixing tab 4B and the circuit board 5 are fastened together to connect the core 3 to the GND (ground) of the circuit board 5 and ground it.

  As described above, in this embodiment, the core 3 is fixed to the case 2 by fastening the core fixing plate 4 fixed to the core 3 by spot welding or caulking to the case 2 with screws without filling with a potting agent. Since the core 3 is fixed, the core 3 can be fixed to the case 2 without receiving stress from the surroundings. For this reason, the deformation of the core 3 can be prevented, the gap (core gap) of the notch 3a of the core 3 can be kept constant, and the deterioration of the characteristics of the current sensor 1 can be prevented, and the current is always detected with high accuracy. be able to.

  In the present embodiment, the fixing tab 4B formed integrally with the core fixing plate 4 is passed through the hollow portion 3b of the core 3 and passed through the slit 2a of the case 2, whereby the core 3 and the core 3 Since the fixed core fixing plate 4 is fixed to the case 2, the core 3 can be positioned and fixed securely to the case 2.

  In the present embodiment, the grounding of the core 3 using the conventional copper tape is eliminated, and the core 3 is connected to the GND of the circuit board 5 by fastening the core fixing plate 4 and the circuit board 5 together with the screws 6. Therefore, the core 3 can be reliably grounded and can be grounded easily, and the number of man-hours required for grounding can be reduced as compared with the conventional grounding using copper tape. In addition, there is an effect that induction noise and radiation noise can be efficiently removed by reliable grounding of the core 3.

DESCRIPTION OF SYMBOLS 1 Current sensor 2 Case 2a Case slit 3 Core 3a Core notch 3b Core hollow 4 Core fixing plate 4A Core fixing plate main body 4B Core fixing plate fixing tab 4a Core fixing plate notch 4b Core fixing plate opening 4c, 4d Screw hole in core fixing plate 5 Circuit board 6 Screw

Claims (3)

In a current sensor comprising a magnetic metal core housed in an insulating case, and a hall element disposed in the notch of the core,
A non-magnetic core fixing plate is fixed to the core so as to be electrically conductive by spot welding or caulking, the core fixing plate is fastened to the case, and the core fixing plate is connected to the GND ( A current sensor characterized in that it is connected to ground and grounded.   The core fixing plate is integrally formed with a fixing tab penetrating the hollow portion of the core, and the fixing tab is passed through a slit formed in the case to fix the core and the core fixed thereto. The current sensor according to claim 1, wherein a fixing plate is fixed to the case. 3. The current sensor according to claim 1, wherein the core is connected to the ground of the circuit board by grounding the core fixing plate and the circuit board together with a screw, and grounded. 4.

Images