JP2016063041A - choke coil - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a choke coil capable of efficiently radiating heat generated by a hysteresis loss in a magnetic substance core.SOLUTION: A magnetic substance core 20 penetrated by a bus bar 30 is divided into a first core 20a and a second core 20b. End surfaces of divided first and second cores 20a, 20b hold first heat radiation parts 51a, 52a of heat radiation parts 51, 52 therebetween. The heat radiation parts 51, 52 include second heat radiation parts 51b, 52b which are provided extending from the first heat radiation parts 51a, 52a to the outside. The heat radiation parts 51, 52 radiate heat generated in the magnetic substance core 20.SELECTED DRAWING: Figure 3

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, there are cases in which noise at the operating frequency of an electronic device or its harmonic frequency is mixed in an output voltage or output signal output from a switching power supply or other electronic device. This noise may be superimposed on the output voltage or the like and transmitted to an external electronic device, which may 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.

  Depending on the switching power supply and the like, a large current may flow as an output voltage or an output signal. In this case, the output path may be constituted by a bus bar. In patent document 1, the bus bar assembly is illustrated about the choke coil in the case of providing a bus bar. A bus bar penetrates the hollow portion of the core to form a choke coil, which is covered with a conductive case.

  Here, the core has an intrinsic iron loss as a loss resulting from the physical properties of the constituent materials. Among the iron losses, the hysteresis loss is a loss generated with a change in 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. If noise is superimposed on a large current flowing through the bus bar, the magnetic field of the core may change significantly, resulting in a large hysteresis loss. This hysteresis loss is converted into 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 comes into contact with the core.

JP 2014-030331 A

  In Patent Document 1, heat generated in the core is radiated to the outside through the case. However, since it is the outer surface of the core that is in contact with the case, it is possible that the heat generated inside the core cannot be efficiently dissipated. Moreover, since the core is covered with the case, there is a possibility that heat may be generated inside the case.

  As a result of insufficient heat dissipation from the core and an increase in the core temperature due to heat storage in the core, the magnetic permeability of the core fluctuates, leading to a decrease or fluctuation in the inductance characteristics of the choke coil, and EMC noise countermeasures are inadequate. There is a risk of becoming unstable and insufficient.

  The technology disclosed in the present application has been proposed in view of the above-described problems, and an object thereof is to provide a choke coil that can efficiently dissipate heat generated by hysteresis loss in a magnetic core. To do.

  A choke coil according to a technique disclosed in the present application includes a bus bar, a magnetic core, and a heat radiating portion. The magnetic core surrounds the bus bar to form a choke coil, and has a gap in the magnetic path of the core. The heat dissipating part is molded of a material having good heat conduction and a small magnetic permeability as compared with the magnetic core. One end contacts the magnetic core in the gap, and the other end extends outward from the gap.

  The alternating magnetic field passing through 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 hysteresis loss is generated as heat in the magnetic core. The heat generated by the core in response to the hysteresis loss is radiated by the heat radiating part in contact with the gap of the magnetic core, and the heat of the magnetic core is radiated. In this case, since the heat radiating portion is in contact with the gap of the magnetic core, heat can be efficiently radiated 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 radiating portion is in planar contact with the opposing surface of the gap. Thereby, the area which a thermal radiation part contacts a magnetic body core can be enlarged, and the thermal radiation from a magnetic body core can be performed still more efficiently. Further, when the magnetic core has a halved structure that is divided into two along the axial direction of the bus bar, when the choke coil is formed, one end of the heat radiating portion serves as a spacer for forming a gap. do. A gap can be formed by contacting the opposing surface of the gap in a planar manner.

  Furthermore, it is preferable that the other end of the heat radiating portion is connected to a member having good heat conduction. Thereby, the heat propagated from the magnetic core to the heat radiating portion can be further radiated outward.

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

  Further, it is preferable that the magnetic core has an inner side surface close to or in contact with the bus bar, a capacitive element is interposed in a path reaching the other end of the heat radiating portion, and the other end of the heat radiating portion is connected to a reference potential. Even when the magnetic core is electrically connected to the bus bar when the magnetic core is close to or in contact with the bus bar, the magnetic core is not electrically connected to the reference potential via the heat radiating portion. As a result, the bus bar is not short-circuited with the reference potential. Further, according to this configuration, since 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, the LC filter is connected to the terminal of the bus bar. Become. Noise filtering effects such as EMC noise countermeasures for bus bars can be enhanced.

  According to the choke coil according to the technique disclosed in the present application, it is possible to efficiently dissipate heat generated by the magnetic core due to hysteresis loss.

As an application example of the choke coil 1 of the first embodiment, it is a circuit diagram in the case of being connected to an output terminal of a switching power supply 5. FIG. It is an exploded perspective view of choke coil 1 of a 1st embodiment. It is a perspective view of the state which assembled choke coil 1 of a 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 part 53, 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 of the first embodiment according to the present application. This is a case where 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 in-vehicle power supply. This is a step-down switching power supply that steps down a voltage value from a main battery (not shown) that supplies a drive system power supply voltage VIN in a hybrid vehicle or an electric vehicle and supplies power to an auxiliary battery (not shown). The auxiliary battery supplies power supply voltage to in-vehicle electrical equipment such as audio equipment, air conditioner equipment, and lighting equipment.

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

  On / off control of the power transistor T is repeated at a predetermined switching frequency f by the switching signal SW applied to the gate terminal of the power transistor T. 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 accumulated electromagnetic energy is discharged 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. Thereby, 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 corresponding to the load current alternately flows through the power supply voltage VIN and the ground potential GND at a predetermined switching frequency f. In addition, the voltage value at the connection point X alternately varies 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 at the connection point X. As a result, at the original output terminal X1, which is a connection point between the coil L0 and the output capacitor C0, voltage fluctuations of the power supply voltage VIN and the ground potential GND that are alternately repeated at the connection point X are smoothed, and voltage fluctuations corresponding to the ripple voltage. Is output.

  Here, the original output voltage includes current fluctuation that alternately flows between the power supply voltage VIN and the ground potential GND, voltage fluctuation of the connection point X that alternately changes between the power supply voltage VIN and the ground potential GND, and other circuit operations. There may be a case where noise having a predetermined frequency band is mixed due to current fluctuations or voltage fluctuations. For example, current fluctuations in the power supply voltage VIN and the ground potential GND are unexpected voltage fluctuations in the power supply voltage VIN and the ground potential GND according to the back electromotive force due to parasitic inductive components interposed in the wiring path of the power supply voltage VIN and the ground potential GND. May cause harmonic noise. Further, the voltage fluctuation at the connection point X may cause unexpected harmonic noise to the circuit element at the coupling destination in accordance with the capacitive coupling due to the parasitic capacitance component interposed between the circuit elements or between the wirings.

  The switching frequency f in the switching power supply 5 is determined according to the output power rating, the specifications and ratings of each component, and the like. For example, an in-vehicle switching power supply can be operated at several hundred kHz. For this reason, noise of the switching frequency f and its harmonic frequency may be mixed in the original output voltage. This noise may overlap with the frequency band (around 500 to 1700 kHz) of the in-vehicle AM radio, which may cause so-called radio noise. Considering noise caused by various other circuit operations, the noise band to be reduced is hundreds of tens of kiloHz to several megaHz. For example, the choke coil 1 having a characteristic of reducing a noise band of 150 kHz to 5 MHz is provided.

  Next, the shape and structure of the choke coil 1 according to the first embodiment will be described with reference to 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 resin is omitted.

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

  The heat radiating portions 51 and 52 are formed of a metal member or other member having good thermal conductivity. The shape has a mirror-symmetrical relationship with each other across the axis. Each of the L-shaped and inverted L-shaped flat plate members is bent so that the directions of the flat plate surfaces on both sides are substantially orthogonal with the L-shaped and inverted L-shaped bent portions as boundaries. The rectangular flat plate surface portion from the L-shaped and inverted L-shaped starting end to the bent portion is the first heat radiating portion 51a, 52a, and the rectangular flat plate surface from the bent portion to the L-shaped and inverted L-shaped terminal ends The part is the 2nd thermal radiation parts 51b and 52b. A through-hole through which a fastening member such as a screw is inserted is opened at the tip (L-shaped and inverted L-shaped end) of the second heat radiation portions 51b and 52b. Moreover, it has a relative permeability smaller than that of the magnetic core 20. As the material, for example, a metal material such as copper or aluminum can be considered. 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 about 5000 general ferrites. The thermal conductivity is 398 (W / mK) for copper and 236 (W / mK) for aluminum. Since the thermal conductivity of general ferrite is considered to be about 5 (W / mK), the thermal conductivity can be made better than that of ferrite.

  The bus bar 30 has a cylindrical bar shape, and is formed of a metal material such as copper or chrome molybdenum steel, for example. The bus bar 30 penetrates the hollow through hole of the magnetic core 20 in the axial direction. That is, the rectangular divided end faces of the first and second cores 20a and 20b are opposed to each other so as to be surrounded by the first and second cores 20a and 20b. The choke coil 1 is formed with the bus bar 30 penetrating through the through hole of the magnetic core 20.

  The pedestal portion 40 is a cylindrical metal member having a through-hole into which a fastening member such as a screw is inserted, and heat radiating portions 51 and 52 to be described later are fixed thereto. The pedestal portion 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 portion 40 with a fastening member such as a screw.

  When the heat dissipating parts 51 and 52 oppose the rectangular divided end faces of the first and second cores 20a and 20b, the first heat dissipating parts 51a and 52a are sandwiched between the end faces. At this time, the first heat radiating portions 51a and 52a are sandwiched between the first and second cores 20a and 20b in contact with the entire rectangular divided end surfaces. Moreover, the 2nd heat radiating part 51b, 52b of the heat radiating part 51, 52 is arrange | positioned in the position where a through-hole overlaps the through hole of each base part 40, and is fixed to the base part 40 by welding etc. FIG.

  The magnetic core 20, the bus bar 30, the pedestal portion 40, and the heat radiating portions 51 and 52 are molded with a resin material (not shown) in a state where the relative positional relationship is maintained, and have the relative positional relationship 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 portion 51a, 52a of the heat radiating portion 51, 52 is sandwiched between the first and second cores 20a, 20b to form the magnetic core 20. The bus bar 30 is configured to pass through the through hole of the magnetic core 20. The magnetic core 20 is molded and formed with the bus bar 30 penetrating through the through hole of the magnetic core 20.

  The flange portion has a shape having a rectangular expansion substantially parallel to the side surface of the metal casing that is substantially orthogonal to the axial direction of the bus bar 30 and in which the switching power supply 5 is accommodated. The through holes of the pedestal part 40 are aligned and fixed to the through holes of the second heat radiating parts 51b and 52b of the heat radiating parts 51 and 52, and further, the whole is molded. 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 a fastening member such as a screw. Attached to the outer surface of the body. Thereby, the heat radiating portions 51 and 52 are connected to the metal casing via the pedestal portion 40. In addition to the heat radiating portions 51 and 52, the pedestal portion 40 and the metal casing are also metal materials having good heat conductivity, so that the heat conductivity of the heat radiating portions 51 and 52 can be maintained well. Further, since the pedestal portion 40 is electrically connected to a metal casing having the ground potential GND, the heat radiation 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 inner end (the right side in FIG. 3) of the bus bar 30 is connected to the original output terminal X1, and the outer end (the left side in FIG. 3) is the output terminal VO.

  The magnetic core 20 is configured by opposing the split end surfaces of the first and second cores 20a and 20b. The first heat dissipating parts 51a and 52a of the heat dissipating parts 51 and 52 are inserted between the divided end faces 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 member such as copper or aluminum constituting the heat radiating portions 51 and 52 has a relative permeability smaller than that of ferrite and is comparable to the relative permeability of air. Therefore, the gap obtained by inserting the first heat radiating portions 51a and 52a is equivalent to a general air gap, and has the same effect as adjusting the magnetic resistance and preventing magnetic saturation by inserting a general air gap. Can be obtained.

  Further, the first heat radiating portions 51a, 52a of the heat radiating portions 51, 52 are brought into contact with the entire surfaces of the divided end surfaces of the first and second cores 20a, 20b to sandwich the first heat radiating portions 51a, 52a in a hollow cylindrical shape. The magnetic core 20 can be uniformly contacted in the thickness direction from the outer diameter end to the inner diameter end. Moreover, the thermal radiation parts 51 and 52 are connected to the metal housing | casing via the base part 40, and all of these members have favorable heat conductivity. Accordingly, heat generated due to energy loss due to hysteresis loss or the like generated in the magnetic core 20 can be efficiently radiated from any position in the thickness direction from the outer diameter end to the inner diameter end of the magnetic core 20.

  Moreover, the 1st thermal radiation part 51a, 52a of the thermal radiation part 51, 52 can be made to contact with both the division | segmentation end surfaces of the 1st and 2nd cores 20a, 20b divided in half. Since the first heat dissipating parts 51a and 52a of the heat dissipating parts 51 and 52 are provided for each half circumference in the circumferential direction of the magnetic core 20, heat can be evenly dissipated 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 arranged evenly in both the radial direction and the circumferential direction so that the heat radiation from the magnetic core 20 is evenly distributed. It can be done efficiently.

  Further, the heat radiating portions 51 and 52 are connected to the metal casing via the pedestal portion 40. The pedestal portion 40 and the metal casing are both made of a metal member having good electrical conductivity, and also have good thermal conductivity. Therefore, the pedestal 40 and the metal housing can achieve the same effects as the heat dissipating fins that reduce the heat resistance of the heat dissipating parts 51 and 52 and improve the heat dissipating property. Good heat dissipation characteristics can be obtained.

  FIG. 4 is a diagram showing a second embodiment. For convenience of explanation, the bus bar 30 is omitted. In 2nd Embodiment, it replaces with the thermal radiation parts 51 and 52 of 1st Embodiment, and is equipped with the thermal radiation parts 53 and 54. FIG. In the first embodiment, the first heat radiating portions 51a and 52a have a rectangular shape that contacts the entire divided end surfaces of the first and second cores 20a and 20b, whereas the first heat radiating portion 53a in the second embodiment. , 54a has a U-shaped shape. Thereby, it contacts only in the both ends of the axial direction of the division | segmentation end surface of the 1st and 2nd core 20a, 20b.

  Depending on the electrical resistance of the heat radiating portions 53 and 54, when the alternating magnetic flux penetrating the magnetic core 20 due to noise passes through 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 change. Accordingly, an eddy current may be generated in the first heat radiation portions 53a and 54a. In particular, when the heat dissipating parts 53 and 54 are members having good electrical conductivity, eddy currents are remarkably generated in the part facing the gap. The eddy current itself causes heat generation as an eddy current loss, and as a result of preventing the change of magnetic flux, there is a possibility that the absorption of noise by the choke coil 1 is offset. Therefore, by making the first heat radiating parts 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 parts 53a and 54a is reduced, and the heat radiating part 53 , 54 is limited to a part of the opposing surface of the gap, thereby limiting the area through which the magnetic flux penetrates. Thereby, generation | occurrence | production of an eddy current can be suppressed, the heat_generation | fever resulting from an eddy current loss can be suppressed, and it becomes possible to further improve a noise removal characteristic.

  Further, 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 dissipating parts 53a and 54a are U-shaped 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 placed at two locations. The gap can be formed stably.

  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 according to the present application. In 3rd Embodiment, the magnetic body core 21 and the thermal radiation parts 55 and 56 differ from 1st 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 approaches or contacts the bus bar 30. The heat radiating portions 55 and 56 are configured to mount the chip capacitor 60 by dividing the second heat radiating portions 51b and 52b of the heat radiating portions 51 and 52 of the first embodiment. Each of the second heat radiation portions 51b and 52b of the first embodiment is divided into three parts in the direction toward the tip, and the first member 55b1 and 56b1, the second member 55b2 and 56b2, and the third member 55b3 and 56b3. It is configured. Here, each of the second members 55b2 and 56b2 is divided into two so as to be juxtaposed in the direction toward the tip. Slits A are respectively 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 and the third members 55b3 and 56b3, two chip capacitors 60 connected in parallel across the slits A are mounted in series.

  Since the magnetic core 21 has a smaller inner diameter and a larger thickness and a larger volume than the magnetic core 20, an allowable magnetic field until magnetic saturation is increased. Thereby, the noise energy that can be removed by the choke coil can be further increased, and the noise removal characteristics can be improved.

  Since the magnetic core 21 is close 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 55 a and 56 a are in contact with the magnetic core 21. For this reason, if the heat radiating portions 55 and 56 are good electrical 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. Further, since the magnetic core 21 is close to or in contact with the bus bar 30, the end portions of the first heat radiating portions 55a and 56a of the heat radiating portions 55 and 56 may be in direct contact with and electrically connected to the bus bar 30. 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, the short circuit between the potential of the bus bar 30 and the ground potential GND in the heat dissipation portions 55 and 56. There is no fear of occurrence.

Further, the chip capacitor 60 connected between the first heat radiating portions 55a and 56a of the heat radiating portions 55 and 56 and the third members 55b3 and 56b3 reaches the ground potential GND from the magnetic core 21 through which the bus bar 30 passes. It is inserted in the route. Electrically, it is connected between the choke coil and the ground potential GND. For this reason, an LC filter is constituted by the choke coil and the chip capacitor 60, and the noise removal characteristics can be further improved.
Further, 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 by high frequency.

  By the way, when a large current flows through the bus bar 30, heat loss due to so-called copper loss may occur. When the magnetic core 21 is brought close to or in contact with the bus bar 30, heat generated in the bus bar 30 is radiated from the magnetic core 21 via the heat radiating portions 55 and 56 or directly via the heat radiating portions 55 and 56. can do.

  According to the third embodiment, the magnetic core 21 has a smaller inner diameter and a thickness of the magnetic core 21 is increased, so that the magnetic field allowed for the magnetic core 21 is increased and the noise removal capability as a choke coil is improved. Can be achieved. Further, similarly to the case of the first embodiment, heat generated by the hysteresis loss in the magnetic core 21 can be efficiently radiated by the heat radiating portions 55 and 56. In addition, the heat radiating portions 55 and 56 can radiate heat generated by copper loss in the bus bar 30. Furthermore, the 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 and 56. In addition, the short circuit of the bus bar 30 to the ground potential GND due to the proximity or contact between the bus bar 30 and the magnetic core 21 and the first heat radiating portions 55a and 56a of the heat radiating portions 55 and 56 due to the interposition of the chip capacitor 60. Can be prevented.

  Here, the core gap is an example of a gap. The ground potential GND is an example of a reference potential. The first heat radiation portions 51a, 52a, 53a, 54a, 55a, and 56a of the heat radiation portions 51, 52, 53, 54, 55, and 56 are an example of one end of the heat radiation 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 ends of the heat radiating portions. It is. The chip capacitor 60 is an example of a capacitive element.

  It goes without saying that the present application is not limited to the above-described embodiment, and various improvements and changes can be made without departing from the spirit of the present application.

  For example, in the first embodiment, the magnetic core 20 is radiated by the heat radiating portions 51 and 52 sandwiched between the divided end surfaces of the first and second cores 20a and 20b divided into two along the axial direction of the bus bar 30. The configuration to be performed has been described. However, the present application is not limited to this. The heat radiation part should just be provided in any one among the two opposing surfaces which a division | segmentation end surface opposes. Further, the magnetic core may be divided into three or more in the axial direction, and may be configured to be sandwiched between at least one of the opposed divided end surfaces. By increasing the number of divisions in the axial direction of the magnetic core and providing a large number of heat radiation portions sandwiched between the divided surfaces, heat generated in the magnetic core can be radiated more evenly. Moreover, since the space | interval between division | segmentation end surfaces becomes narrow, heat dissipation efficiency can further be improved.

  In the first embodiment, the first heat radiating portions 51a and 52a of the heat radiating portions 51 and 52 are in contact with the entire surface of the divided end surface of the magnetic core 20, and in the second embodiment, the first heat radiating portions 53 and 54 have a first heat radiating. Although the parts 53a and 54a have been described as being in contact with both ends of the divided end face, the present application is not limited to this. Furthermore, it can also be set as the structure which increased the contact area. For example, it can also be set as the structure which makes at least one part of a 2nd thermal radiation part contact the outer surface of a magnetic body core. The heat radiation efficiency can be further increased 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 in 1st Embodiment, this application is not limited to this. For example, ceramics can be considered as a material having a good thermal conductivity and a magnetic permeability smaller than that of the magnetic core and having a high electric resistance. The generation of eddy current can be suppressed with ceramics having high electrical resistance.

  Moreover, although 1st Embodiment demonstrated the shape of the thermal radiation parts 51 and 52 as a flat member, this application is not limited to this. The second heat radiating portions 51b and 52b may be members having a shape that increases the surface area, such as heat radiating fins. When molding, the heat radiation efficiency can be improved by exposing structural parts such as heat radiation fins.

  Moreover, although 3rd Embodiment demonstrated LC filter being comprised, this application is not limited to this. It is good also as a structure provided with 2 sets of thermal radiation parts with which the chip capacitor was mounted. That is, the first heat radiating portion is a rectangular flat plate surface that is in contact with the end portion on the pedestal portion 40 side (the front side in FIG. 5) instead of the entire divided end surfaces of the first and second cores 21a and 21b. Let the heat dissipating part be the first heat dissipating part. In addition to this, a second heat radiating portion is provided. The second heat radiating portion is a rectangular flat plate surface in which the rectangular flat plate surface of the first heat radiating portion is in contact with the end portion on the opposite side of the pedestal portion 40 (the back side in the drawing of FIG. 5). Thereby, a π-type filter can be configured while maintaining heat dissipation characteristics.

DESCRIPTION OF SYMBOLS 1 Choke coil 5 Switching power supply 20, 21 Magnetic body core 20a 1st core 20b 2nd core 30 Bus bar 40 Base part 51, 52, 53, 54, 55, 56 Radiating part 51a, 52a, 53a, 54a, 55a, 56a 1 heat radiation part 51b, 52b 2nd heat radiation part 55b1, 56b1 1st member 55b2, 56b2 2nd member 55b3, 56b3 3rd member 60 Chip capacitor

Claims (5)

A bus bar,
A magnetic core surrounding the bus bar and having a gap in the magnetic path;
A material having good heat conduction and a low magnetic permeability as compared with the magnetic core, one end of which is in contact with the magnetic core in the gap, and the other end of which is extended outward from the gap. Provided choke coil.   2. The choke coil according to claim 1, wherein one end of the heat radiating portion is in planar contact with an opposing surface of the gap.   The choke coil according to claim 1 or 2, wherein the other end of the heat radiating portion is connected to a member having good heat conduction.   4. The choke coil according to claim 1, wherein one end of the heat dissipating part is in contact with a part of an opposing surface of the gap. The magnetic core has an inner side surface close to or in contact with the bus bar,
Comprising a capacitive element interposed in the path leading to the other end of the heat dissipating part,
The choke coil according to any one of claims 1 to 4, wherein the other end of the heat radiating portion is connected to a reference potential.

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