JP6508694B2 - choke coil - Google Patents

Description

  The technology disclosed in the present application relates to a choke coil, and more particularly to a choke coil formed by inserting a magnetic core in a path through which a large current flows.

  Conventionally, noise in the operating frequency of an electronic device or the like or its harmonic frequency may be mixed in an output voltage or an output signal output from a switching power supply or another electronic device. This noise may be superimposed on the output voltage or the like and may be propagated to an external electronic device to have an adverse effect. In order to reduce such noise, a choke coil or the like is generally provided in an output path such as an output voltage.

  Now, depending on the switching power supply, a large current may flow as an output voltage or an output signal. In this case, the output path may be configured by a bus bar. Patent Document 1 exemplifies a bus bar assembly for a choke coil provided with a bus bar. The bus bar passes through the hollow portion of the core to form a choke coil, which is covered with a conductive case.

  Here, the core has an inherent iron loss as a loss due to the physical properties of the constituent material. Of the iron loss, the hysteresis loss is a loss that occurs with the change of the alternating magnetic field. The change of the alternating magnetic field occurs according to the magnitude of the current related to the noise mixed in the bus bar and the frequency band of the noise. When noise is superimposed on the large current flowing through the bus bar, the magnetic field of the core may be largely changed to cause a large hysteresis loss. The hysteresis loss is converted to heat energy and the core generates heat. Patent Document 1 describes that the heat of the core is dissipated through the case when a part of the inner surface of the case contacts the core.

JP, 2014-030331, A

  In Patent Document 1, the heat generated in the core is dissipated to the outside through a case. However, since it is the outer surface of the core that is in contact with the case, it is conceivable that the heat generated inside the core can not be dissipated efficiently. In addition, since the core is covered by the case, there is also a possibility that heat may get inside the case.

  As a result of insufficient heat radiation of the core and temperature rise of the core due to heat accumulation in the core, the permeability of the core fluctuates, resulting in deterioration or fluctuation of the inductance characteristic of the choke coil, and the EMC noise countermeasure is not completed. There is a risk of becoming unstable and inadequate.

  The technique disclosed in the present application has been proposed in view of the above problems, and it is an object of the present invention to provide a choke coil capable of efficiently radiating heat generated by hysteresis loss in a magnetic substance core. Do.

A choke coil according to a technology disclosed in the present application includes a bus bar, a magnetic core, a heat radiating portion, and a pedestal portion . The magnetic core surrounds the bus bar to form a choke coil, and the magnetic path of the core has a gap. The heat dissipating part is made of a material that has a good heat conductivity and a small permeability compared to the magnetic core. One end is in contact with the magnetic core at the gap, and the other end extends outward from the gap. The pedestal portion has good thermal conductivity and has a through hole, and the through hole is aligned with the through hole opened at the other end of the heat radiating portion and fixed to the heat radiating portion. Here, the heat dissipating portion includes a pair of members having a mirror symmetry relationship with each other with the bus bar interposed therebetween, and each of the pair of members is L so that the flat plate surfaces are substantially orthogonal with the bending portion as a boundary. It is bent and formed in a letter or inverted L shape. The relative positions of the bus bar, the magnetic core, the heat radiating portion, and the pedestal are maintained, and both end surfaces of the pedestal are exposed substantially flush with the surface of the mold and molded with a resin material. Become.

  The alternating magnetic field penetrating the magnetic core changes according to the magnitude of the current related to the noise mixed in the bus bar and the frequency band of the noise, and a loss due to the hysteresis loss is generated as heat in the magnetic core. The heat generated by the core in response to the hysteresis loss is dissipated by the heat dissipation portion in contact with the gap of the magnetic core, and the heat of the magnetic core is dissipated. In this case, since the heat radiating portion is in contact with the gap of the magnetic core, heat can be efficiently dissipated not only from the outer side of the magnetic core but also from the outer side to the inner side.

  Furthermore, it is preferable that one end of the heat dissipation portion be in plane contact with the opposing surface of the gap. As a result, the area of the heat radiating portion in contact with the magnetic core can be increased, and heat can be dissipated from the magnetic core more efficiently. When the magnetic core has a half structure in which the magnetic core is divided into two along the axial direction of the bus bar, one end of the heat dissipation portion serves as a spacer for forming a gap when forming the choke coil. do. A gap can be formed by planarly contacting the opposite surface of the gap.

  Furthermore, it is preferable that the other end of the heat dissipation part be connected to a member with good thermal conductivity. Thus, the heat transmitted from the magnetic core to the heat dissipation portion can be dissipated further outward.

  Furthermore, it is preferable that one end of the heat dissipation portion be in contact with a part of the opposing surface of the gap. When the magnetic core has a half structure in which the magnetic core is divided into two along the axial direction of the bus bar, one end of the heat dissipation portion serves as a spacer for forming a gap when forming the choke coil. . The gap can be formed by contacting part of the opposing surface of the gap.

Furthermore, the heat dissipating portion is a good electrical conductor, the magnetic core has an inner side surface close to or in contact with the bus bar, and a capacitive element is interposed in the path leading to the other end of the heat dissipating portion. It is preferable to be connected. Even when the magnetic core is electrically connected to the bus bar when the magnetic core is in proximity to or in contact with the bus bar, the magnetic core is not electrically connected to the reference potential via the heat dissipation portion. Thereby, the bus bar does not short circuit with the reference potential. Furthermore, according to this configuration, the capacitive element is connected between one end of the choke coil formed by the magnetic core surrounding the bus bar and the reference voltage, so that the LC filter is connected to the terminal of the bus bar Become. It is possible to enhance the filtering effect of noise such as EMC noise measures to the bus bar.

  According to the choke coil according to the technology disclosed in the present application, the heat generation of the magnetic core due to the hysteresis loss can be efficiently dissipated.

It is a circuit diagram at the time of connecting to the output terminal of the switching power supply 5 as an application example of the choke coil 1 of 1st Embodiment. It is a disassembled perspective view of choke coil 1 of a 1st embodiment. It is a perspective view of the state which assembled the choke coil 1 of 1st Embodiment. It is a figure which shows the positional relationship of the assembly | attachment of the magnetic body core 20 and the thermal radiation parts 53 and 54 about the choke coil of 2nd Embodiment. It is a perspective view which shows the choke coil of 3rd Embodiment.

  FIG. 1 shows an application example of the choke coil 1 according to the first embodiment of the present invention. In this case, the choke coil 1 is connected between the original output terminal X1 of the switching power supply 5 and the output terminal VO. The choke coil 1 reduces noise mixed in the output voltage output from the original output terminal X1. An output voltage with reduced noise is output from the output terminal VO.

  The switching power supply 5 is, for example, an on-vehicle power supply. It is a step-down switching power supply that supplies power to auxiliary battery (not shown) by stepping down a voltage value from a main battery (not shown) that supplies power supply voltage VIN of a drive system in a hybrid vehicle or electric vehicle. The accessory battery supplies power supply voltage to in-vehicle electrical equipment such as audio equipment, air conditioner equipment, lighting equipment and the like.

  Power is taken from a connection point X of a power transistor T and a diode D connected in series between the power supply voltage VIN and the ground potential GND. The diode D has a forward direction from the ground potential GND to the connection point X. The coil L0 is connected to the connection point X, and the other end is the original output terminal X1. Further, an output capacitor C0 is connected between the original output terminal X1 and the ground potential GND.

  By the switching signal SW applied to the gate terminal of the power transistor T, on / off control of the power transistor T is repeated at a predetermined switching frequency f. During the on period of the power transistor T, a current path is formed from the power supply voltage VIN to the coil L0, and electromagnetic energy is accumulated in the coil L0. The stored electromagnetic energy is released to the output side including the output capacitor C0 by the current from the diode D during the off period of the power transistor T. Thus, the original output voltage output from the original output terminal X1 is maintained at a predetermined voltage. In the switching power supply 5, in order to maintain the original output voltage at a predetermined voltage, a current according to the load current alternately flows to the power supply voltage VIN and the ground potential GND at a predetermined switching frequency f. In addition, the voltage value of the connection point X alternately fluctuates between the power supply voltage VIN and the ground potential GND.

  The coil L0 and the output capacitor C0 have a role of smoothing the voltage of the connection point X. Thereby, voltage fluctuation of power supply voltage VIN and ground potential GND alternately repeated at connection point X is smoothed at original output terminal X1 which is a connection point of coil L0 and output capacitor C0, and voltage fluctuation corresponding to ripple voltage An original output voltage having the

  Here, for the original output voltage, current fluctuation alternately flowing between the power supply voltage VIN and the ground potential GND, voltage fluctuation at the connection point X alternately changing between the power supply voltage VIN and the ground potential GND, and other circuit operations. Noise having a predetermined frequency band may be mixed in due to current fluctuation or voltage fluctuation caused by the noise. For example, current fluctuations of the power supply voltage VIN and the ground potential GND are unexpected voltage fluctuations on the power supply voltage VIN and the ground potential GND according to a back electromotive force due to a parasitic induction component interposed in the wiring path of the power supply voltage VIN May cause harmonic noise. In addition, the voltage fluctuation at the connection point X may cause unexpected harmonic noise to the circuit element of the coupling destination according to the capacitive coupling due to the parasitic capacitive component interposed between the circuit elements, the wiring, and the like.

  The switching frequency f in the switching power supply 5 is determined according to the power rating to be output, the specification or rating of each component, and the like. For example, in a switching power supply for vehicles, it is conceivable to operate at several hundred kHz. For this reason, noise of the switching frequency f or its harmonic frequency may be mixed into the original output voltage. This noise may overlap with the frequency band of the on-vehicle AM radio (about 500 to 1700 kHz), which may cause so-called radio noise. The noise band to be reduced is one hundred and several tens kilohertz to several megahertz, taking into consideration the noise caused by various other circuit operations. For example, the choke coil 1 having the characteristic of reducing the noise band of 150 kHz to 5 MHz is provided.

  Next, the shape and structure of the choke coil 1 of the first embodiment will be described based on FIGS. FIG. 2 is an exploded perspective view of the choke coil 1. FIG. 3 is a perspective view of the choke coil 1 in an assembled state. In FIG. 3, a mold member such as a resin is omitted.

  The magnetic core 20 is formed of, for example, a magnetic material such as ferrite. It has a hollow cylindrical shape having a through hole in the axial direction centering on the axis which is the through direction of the bus bar 30 described later. The magnetic core 20 is configured such that the split end faces of the half-shaped first core 20 a and the second core 20 b split into two along the axial direction are opposed to each other.

  The heat radiation parts 51 and 52 are formed of a metal member or another member having a good thermal conductivity. It is a shape which has mirror symmetry relation mutually on both sides of an axis. The L-shaped and inverted L-shaped flat plate members are bent so that the directions of the flat surfaces on both sides are substantially orthogonal to each other with the L-shaped and inverted L-shaped bent portions as boundaries. Rectangular flat surface portions from the start end to the L-shaped and inverted L-shaped portions are the first heat radiating portions 51a and 52a, and rectangular flat surfaces from the curved portion to the ends of the L-shaped and inverted L-shaped portions The portions are the second heat radiating portions 51b and 52b. Through holes through which fastening members such as screws are inserted are opened at the tips (ends of L-shaped and inverted L-shaped) of the second heat radiating portions 51 b and 52 b. Also, it has a relative permeability smaller than that of the magnetic core 20. As a material, metal materials, such as copper and aluminum, can be considered, for example. In the case of copper or aluminum, the relative permeability is about 1.0, and the relative permeability can be made smaller than that of a general ferrite of about 5000. The thermal conductivity is 398 (W / mK) for copper and 236 (W / mK) for aluminum. Since the thermal conductivity of a general ferrite is considered to be about 5 (W / mK), the thermal conductivity can be made better than that of the ferrite.

  The bus bar 30 has a cylindrical rod-like shape, and is formed of, for example, a metal material such as copper or chromium molybdenum steel. The bus bar 30 axially penetrates the hollow through hole of the magnetic core 20. That is, the rectangular divided end faces of the first and second cores 20a and 20b are opposed to each other to be arranged around the first and second cores 20a and 20b. The choke coil 1 is formed in a state where the bus bar 30 penetrates the through hole of the magnetic core 20.

  The pedestal portion 40 is a cylindrical metal member in which a through hole into which a fastening member such as a screw is inserted is opened, and the heat radiating portions 51 and 52 described later are fixed. The pedestal 40 is fastened to a metal casing or the like in which the switching power supply 5 is accommodated via a through hole of the pedestal 40 such as a fastening member such as a screw.

  When the heat radiating parts 51 and 52 oppose the rectangular divided end faces of the first and second cores 20a and 20b, the first heat radiating parts 51a and 52a are sandwiched between the end faces. At this time, the first heat radiating portions 51a and 52a are sandwiched in contact with the entire surfaces of the rectangular divided end faces of the first and second cores 20a and 20b. The second heat radiating portions 51b and 52b of the heat radiating portions 51 and 52 are disposed at positions where the through holes overlap the through holes of the respective pedestals 40, and are fixed to the pedestals 40 by welding or the like.

  The magnetic core 20, the bus bar 30, the pedestal portion 40, and the heat radiating portions 51, 52 are molded with a resin material (not shown) in a relative positional relationship as shown in FIG. It is fixed (choke coil 1). Here, as the resin material, for example, a thermoplastic resin such as PBT (Polybutylene terephthalate) and a thermosetting resin such as epoxy are used.

  The molded choke coil 1 is composed of two parts, a core part and a flange part. The core portion has a shape along the axial direction of the bus bar 30, and the first heat radiating portions 51a and 52a of the heat radiating portions 51 and 52 are sandwiched between the first and second cores 20a and 20b to form the magnetic core 20, The bus bar 30 penetrates the through hole of the magnetic core 20. The bus bar 30 is molded and configured to penetrate through the through hole of the magnetic core 20.

  The flange portion has a rectangular shape that is substantially orthogonal to the axial direction of the bus bar 30 and substantially parallel to the side surface of the metal casing in which the switching power supply 5 is housed. The through holes of the pedestal portion 40 are aligned with and fixed to the through holes of the second heat radiating portions 51 b and 52 b of the heat radiating portions 51 and 52, and further, the whole is molded and configured. Both end surfaces of the pedestal portion 40 are molded substantially flush with both end surfaces of the flange portion and exposed from the end surface of the flange portion, and are fastened to the metal casing by fastening members such as screws and the flange portion is a metal casing Attached to the outside of the body. Thus, the heat radiating portions 51 and 52 are connected to the metal casing via the pedestal portion 40. In addition to the heat dissipation portions 51 and 52, the pedestal portion 40 and the metal casing are also metal materials having good thermal conductivity, so the heat conductivity of the heat dissipation portions 51 and 52 can be maintained well. Further, since the pedestal portion 40 is electrically connected to the metal casing which is the ground potential GND, the heat radiating portions 51 and 52 are set to the ground potential GND via the pedestal portion 40.

  Here, the bus bar 30 is an output voltage path connecting the original output terminal X1 and the output terminal VO shown in FIG. The inward end (right side in the drawing of FIG. 3) of the bus bar 30 is connected to the original output terminal X1, and the outward end (left side in the drawing of FIG. 3) is the output terminal VO.

  The magnetic core 20 is configured by causing divided end faces of the first and second cores 20a and 20b to face each other. The first heat radiating portions 51a and 52a of the heat radiating portions 51 and 52 are inserted between the divided end surfaces of the first and second cores 20a and 20b. Thereby, a so-called core gap (hereinafter, abbreviated as a gap) is formed. In this case, the metal members such as copper and aluminum constituting the heat radiating portions 51 and 52 have a relative permeability smaller than that of the ferrite and have the same degree as the relative permeability of air. Therefore, the gap obtained by inserting the first heat radiating portion 51a, 52a becomes equivalent to a general air gap, and the effect equivalent to the adjustment of the magnetic resistance and the prevention of magnetic saturation by the general insertion of the air gap You can get it.

  Further, the first heat radiating portions 51a, 52a are formed into a hollow cylindrical shape by bringing the first heat radiating portions 51a, 52a of the heat radiating portions 51, 52 into contact with and sandwiching the entire end faces of the first and second cores 20a, 20b. The magnetic material core 20 can be uniformly contacted in the thickness direction from the outer diameter end to the inner diameter end. Further, the heat radiating portions 51 and 52 are connected to the metal casing via the pedestal portion 40, and all of these members have good thermal conductivity. As a result, heat generation due to energy loss due to hysteresis loss or the like generated in the magnetic core 20 can be efficiently dissipated from any position in the thickness direction of the outer diameter end to the inner diameter end of the magnetic core 20.

  In addition, the first heat radiating portions 51a and 52a of the heat radiating portions 51 and 52 can be brought into contact with both divided end faces of the first and second cores 20a and 20b which are divided in half. Since the first heat radiating portions 51a and 52a of the heat radiating portions 51 and 52 are provided for each half circumference of the magnetic core 20 in the circumferential direction, the heat can be dissipated uniformly in the circumferential direction. Even if the thermal conductivity of the magnetic core 20 is not good, the first heat radiating portions 51a and 52a are equally disposed in any direction of the radial direction and the circumferential direction to evenly radiate the heat from the magnetic core 20. It can be done efficiently.

  Furthermore, the heat radiating portions 51 and 52 are connected to the metal casing via the pedestal portion 40. Each of the pedestal portion 40 and the metal casing is formed of a metal member having good electrical conductivity, and also has good thermal conductivity. Therefore, the pedestal portion 40 and the metal casing can achieve the same function and effect as the heat dissipating fins for reducing the heat resistance of the heat dissipating portions 51 and 52 to improve the heat dissipating performance. Good heat dissipation characteristics can be obtained.

  FIG. 4 is a diagram showing a second embodiment. The bus bar 30 is omitted for convenience of explanation. In the second embodiment, the heat radiating portions 53 and 54 are provided instead of the heat radiating portions 51 and 52 of the first embodiment. In the first embodiment, the first heat radiating portions 51a and 52a have a rectangular shape in contact with the entire surfaces of the divided end faces of the first and second cores 20a and 20b. , 54a has a U-shaped shape. Thereby, it contacts only in the both ends of the direction of an axis of the division end face of the 1st and 2nd cores 20a and 20b.

  Depending on the electrical resistance of the heat radiating portions 53 and 54, if the alternating magnetic flux penetrating the magnetic core 20 due to noise penetrates the first heat radiating portions 53a and 54a of the heat radiating portions 53 and 54, the magnitude and direction of the alternating magnetic flux changes In response to this, eddy currents may be generated in the first heat radiating portions 53a and 54a. In particular, in the case where the heat radiation parts 53 and 54 are members having good electrical conductivity, eddy currents are generated notably in the part facing the gap. The eddy current itself causes heat generation as an eddy current loss, and as a result of preventing a change in magnetic flux, there is also a possibility that the absorption of noise by the choke coil 1 may be offset. Therefore, by making the first heat radiating portions 53a and 54a U-shaped, the facing area between the divided end faces of the first and second cores 20a and 20b and the first heat radiating portions 53a and 54a is reduced. , 54 is limited to a part of the facing surface of the gap to limit the area through which the magnetic flux penetrates. As a result, it is possible to suppress the generation of the eddy current, to suppress the heat generation due to the eddy current loss, and to further improve the noise removal characteristic.

  The first heat radiating portions 53 a and 54 a also have a function as a spacer for stably securing the gap of the magnetic core 20. Since the first heat radiating parts 53a and 54a have a U-shaped shape and are opposed at both ends of the divided end faces of the first and second cores 20a and 20b, the first and second cores 20a and 20b are at two places. It can be supported and the gap can be formed stably.

  In the third embodiment according to the present application, FIG. 5 shows a case where an LC filter in which a capacitive element is added to a choke coil is configured. In the third embodiment, the magnetic core 21 and the heat radiating portions 55, 56 are different from those in the first embodiment. The magnetic core 21 has a shape in which the diameter of the hollow portion of the magnetic core 20 is reduced. When the bus bar 30 is inserted into the hollow portion, the inner diameter side surface of the magnetic core 21 is in proximity to or in contact with the bus bar 30. The heat radiating parts 55 and 56 are configured to divide the second heat radiating parts 51 b and 52 b of the heat radiating parts 51 and 52 of the first embodiment and to mount the chip capacitor 60. The second heat radiating portions 51b and 52b of the first embodiment are each divided into three in a direction toward the tip, and the first members 55b1 and 56b1, the second members 55b2 and 56b2, and the third members 55b3 and 56b3. It is configured. Here, the second members 55b2 and 56b2 are each divided into two so as to be juxtaposed in the direction toward the tip. Slits A are provided between the first members 55b1 and 56b1 and the second members 55b2 and 56b2, and between the second members 55b2 and 56b2 and the third members 55b3 and 56b3. The relative position is fixed by the material. Between the first members 55b1 and 56b1 to the third members 55b3 and 56b3, two chip capacitors 60 connected in parallel across the respective slits A are mounted in series.

  The inner diameter of the magnetic core 21 is smaller than that of the magnetic core 20, the thickness is increased, and the volume is increased. Therefore, the allowable magnetic field until the magnetic saturation is increased. As a result, noise energy that can be removed by the choke coil can be further increased, and noise removal characteristics can be improved.

  Since the magnetic core 21 is in close proximity to or in contact with the bus bar 30, the bus bar 30 may be electrically connected to the magnetic core 21. Here, in the heat radiating portions 55 and 56, the first heat radiating portions 55a and 56a are in contact with the magnetic core 21. Therefore, when the heat radiating portions 55 and 56 are good conductors, the bus bar 30 and the first heat radiating portions 55 a and 56 a of the heat radiating portions 55 and 56 are electrically connected via the magnetic core 21. In addition, since the magnetic core 21 is in close proximity to or in contact with the bus bar 30, the end portions of the first heat radiating portions 55a, 56a of the heat radiating portions 55, 56 may be directly connected to the bus bar 30 for electrical connection. is there. However, in the heat radiating portions 55 and 56, the chip capacitor 60 is interposed between the first heat radiating portions 55a and 56a and the third members 55b3 and 56b3 of the second heat radiating portion. Therefore, even if the third members 55b3 and 56b3 fixed to the pedestal portion 40 are connected to the ground potential GND via the pedestal portion 40, in the heat radiating portions 55 and 56, a short circuit between the potential of the bus bar 30 and the ground potential GND There is no fear of

The chip capacitor 60 connected between the first heat radiating portions 55a and 56a of the heat radiating portions 55 and 56 to the third members 55b3 and 56b3 extends from the magnetic core 21 through which the bus bar 30 penetrates to the ground potential GND. It is inserted in the route. Electrically, it is connected between the choke coil and the ground potential GND. Therefore, the LC filter is configured by the choke coil and the chip capacitor 60, and the noise removal characteristic can be further improved.
In addition, even if the bus bar 30 and the heat radiating portions 55 and 56 are not in direct contact with each other, the function of the LC filter can be obtained by capacitive coupling with high frequency.

  By the way, when a large current flows in the bus bar 30, a heat loss due to so-called copper loss may occur. By causing the magnetic core 21 to be close to or in contact with the bus bar 30, the heat generated by the bus bar 30 is dissipated from the magnetic core 21 through the heat dissipation portions 55, 56 or directly through the heat dissipation portions 55, 56. can do.

  According to the third embodiment, the inner diameter of the magnetic core 21 is reduced and the thickness of the magnetic core 21 is increased, so that the magnetic field permitted to the magnetic core 21 is increased, and the noise removing capability as a choke coil is improved. Can be Further, as in the case of the first embodiment, the heat dissipation portions 55 and 56 can efficiently dissipate the heat generated by the hysteresis loss in the magnetic core 21. In addition, the heat sinks 55 and 56 can also dissipate heat generated by copper loss in the bus bar 30. Furthermore, an LC filter can be configured by interposing the chip capacitor 60 in the path from the magnetic core 21 to the ground potential GND in the heat radiating portions 55, 56. In addition, a short circuit to the ground potential GND of the bus bar 30 due to the proximity or contact between the bus bar 30 and the magnetic core 21 and the first heat radiating portions 55 a and 56 a of the heat radiating portions 55 and 56 by the interposition of the chip capacitor 60. It can be prevented.

  Here, the core gap is an example of the gap. The ground potential GND is an example of a reference potential. The first heat radiating portions 51a, 52a, 53a, 54a, 55a, 56a of the heat radiating portions 51, 52, 53, 54, 55, 56 are an example of one end of the heat radiating portion. The second heat radiating portions 51b, 52b, 53b, 54b of the heat radiating portions 51, 52, 53, 54 and the first members 55b1, 56b1 to 55b3, 56b3 of the heat radiating portions 55, 56 are examples of the other end of the heat radiating portions. It is. The chip capacitor 60 is an example of a capacitive element.

  It is needless to say that the present application is not limited to the above embodiment, and various improvements and changes can be made without departing from the scope of the present invention.

  For example, in the first embodiment, heat dissipation of the magnetic material core 20 is performed by the heat dissipation portions 51 and 52 sandwiched by the split end surfaces of the first and second cores 20a and 20b which are split into two along the axial direction of the bus bar 30 The configuration to be performed has been described. However, the present invention is not limited to this. The heat dissipating portion may be provided at least in any one of two opposing surfaces facing each other at the divided end surfaces. Also, the magnetic core may be configured to be divided into three or more in the axial direction, and be configured to be sandwiched between at least one of the opposing divided end faces. By increasing the number of divisions in the axial direction of the magnetic core and providing a large number of heat dissipation portions interposed between the divided surfaces, the heat generation in the magnetic core can be dissipated more evenly. Further, since the distance between the divided end faces is narrowed, the heat radiation efficiency can be further improved.

  Further, in the first embodiment, the first heat radiating portions 51a, 52a of the heat radiating portions 51, 52 contact the entire surface of the divided end face of the magnetic core 20, and in the second embodiment, the first heat radiation of the heat radiating portions 53, 54 Although the portions 53a and 54a are described as being in contact with both ends of the divided end face, the present invention is not limited to this. Further, the contact area may be increased. For example, at least a part of the second heat radiation portion may be in contact with the outer surface of the magnetic core. The heat radiation efficiency can be further enhanced by increasing the contact area.

  Moreover, although the case where metal materials, such as copper and aluminum, were used as a member of the thermal radiation parts 51 and 52 was demonstrated in 1st Embodiment, this application is not limited to this. As a material having a good thermal conductivity and a smaller magnetic permeability than the magnetic core and having a high electrical resistance, for example, ceramics can be considered. If the ceramic has a high electrical resistance, the generation of the eddy current can be suppressed.

  Moreover, in 1st Embodiment, although the shape of the thermal radiation parts 51 and 52 was demonstrated as a flat member, this invention is not limited to this. The second heat radiation parts 51 b and 52 b may be members having a shape such as a heat radiation fin that increases the surface area. At the time of molding, the heat radiation efficiency can be improved by exposing the structural portion such as the heat radiation fin.

  Although the third embodiment has described that the LC filter is configured, the present invention is not limited to this. It is good also as composition provided with two sets of heat dissipation parts in which a chip capacitor was mounted. That is, the first heat radiating portion is a rectangular flat surface that contacts the end of the pedestal 40 side (the front side of the paper surface of FIG. 5) rather than the entire surface of the divided end faces of the first and second cores 21a and 21b. The heat dissipating part is a first heat dissipating part. In addition to this, a second heat dissipation unit is provided. The second heat radiating portion is a rectangular flat surface in which the rectangular flat surface of the first heat radiating portion is in contact with the end portion on the opposite side (the rear side in the drawing of FIG. 5) of the pedestal 40. Thus, the π-type filter can be configured while maintaining the heat dissipation characteristics.

DESCRIPTION OF SYMBOLS 1 choke coil 5 switching power supply 20, 21 magnetic material core 20a 1st core 20b 2nd core 30 bus bar 40 pedestal part 51, 52, 53, 54, 55, 56 heat dissipation part 51a, 52a, 53a, 54a, 55a, 56a 1 Heat Dissipation Portion 51b, 52b Second Heat Dissipation Portion 55b1, 56b1 First Member 55b2, 56b2 Second Member 55b3, 56b3 Third Member 60 Chip Capacitor

Claims (5)

With the bus bar,
A magnetic core surrounding the bus bar and having a gap in a magnetic path;
A material having good thermal conductivity and small magnetic permeability compared to the magnetic core, one end of which is in contact with the magnetic core at the gap and the other end of which extends outward from the gap ;
A pedestal portion having good heat conductivity and having a through hole, the through hole being aligned with the through hole formed at the other end of the heat dissipation portion, and fixed to the heat dissipation portion ;
The heat dissipating unit is
A pair of members having a mirror symmetry relationship with each other with the bus bar interposed therebetween;
Each of the pair of members is formed by being bent in an L-shape or an inverted L-shape such that a flat plate surface is substantially orthogonal with a bending portion as a boundary,
The relative positions of the bus bar, the magnetic core, the heat radiating portion, and the pedestal are maintained, and both end surfaces of the pedestal are exposed substantially flush with the surface of the mold, and the resin choke coil ing is molded by the material.   2. The choke coil according to claim 1, wherein one end of the heat dissipating unit is in plane contact with the facing surface of the gap.   3. The choke coil according to claim 1, wherein the other end of the heat dissipating unit is connected to a member having good thermal conductivity.   The choke coil according to any one of claims 1 to 3, wherein one end of the heat radiating portion is in contact with a part of the facing surface of the gap. The heat dissipating unit is a good electrical conductor,
In the magnetic core, the inward side face approaches or contacts the bus bar,
And a capacitive element interposed in a path leading to the other end of the heat radiating portion,
The choke coil according to any one of claims 1 to 4, wherein the other end of the heat dissipation part is connected to a reference potential.

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