JP4453444B2 - Common mode choke coil - Google Patents

Description

  The present invention relates to a common mode choke coil.

  Conventionally, as a common mode choke coil for preventing the passage of noise having the same phase, for example, the one described in Patent Document 1 is known. As shown in FIG. 8, the common mode choke coil 31 includes a magnetic core 50 composed of two core members 50 a and 50 b having a U-shape, and two bobbins 32 and 42.

  Each of the bobbins 32 and 42 has cylindrical body portions 33 and 43 and flange portions 34, 35, 44, and 45 provided on the cylindrical body portions 33 and 43. The bobbins 32 and 42 are disposed so that the cylindrical body portions 33 and 43 are parallel to each other. Each of the windings 37 and 47 is wound around the outer periphery of the cylindrical body portions 33 and 43 of the bobbins 32 and 42. The leg portions 52a and 52b of the core members 50a and 50b are inserted into the holes 33a and 43a of the cylindrical body portions 33 and 43 of the bobbins 32 and 42, respectively. The core members 50a and 50b have a common-mode closed magnetic circuit in which the tip surfaces of both leg portions 52a and 52b abut each other in the holes 33a and 43a.

  By the way, generally, since the common mode choke coil has a slight amount of normal mode leakage inductance component, it also has an effect of removing normal mode noise. However, when a strong normal mode noise in addition to the common mode noise flows in the signal (power supply) line, it is necessary to take measures against the noise by using both the common mode choke coil and the normal mode choke coil. Further, in the case of a common mode choke coil having a relatively large leakage inductance component in the normal mode, the leakage magnetic flux may adversely affect the peripheral circuit. Therefore, it is necessary to provide a magnetic shield material on the outer periphery of the common mode choke coil. . Therefore, as a countermeasure against these, as shown in FIGS. 8 and 9, a magnetic member 80 for forming a normal mode magnetic path is provided between two adjacent bobbins 32 and 42 of the common mode choke coil 31. is doing.

  In the common mode choke coil 31 having the above configuration, when a common mode (in-phase) noise current flows through the windings 37 and 47, magnetic fluxes are generated in the same direction in the magnetic core 50 by the windings 37 and 47, respectively. This magnetic flux is consumed while circulating in the magnetic core 50. On the other hand, by providing the magnetic member 80, the effective magnetic permeability of the magnetic path in the normal mode is increased, and the magnetic flux is concentrated on the magnetic path (the magnetic member 80 and the core members 50a and 50b) having a large effective magnetic permeability. Therefore, the common mode choke coil 31 can be obtained which has a large normal mode inductance component and can remove strong normal mode noise.

  However, when such a common mode choke coil 31 is manufactured, the core members 50a and 50b and the magnetic member 80 have a dimensional deviation. Therefore, a gap for absorbing the deviation is required between the core members 50a and 50b and the magnetic member 80, and the position of the magnetic member 80 varies. Therefore, when the entire coil 31 is finally fixed with an adhesive (varnish), the relative positional relationship between the core members 50a and 50b and the magnetic member 80 varies, and the effective permeability of the normal mode magnetic path changes. Normal mode inductance varies. More specifically, as indicated by the solid line in FIGS. 8 and 9, when the magnetic member 80 is located at the same distance from the magnetic core 50, the normal mode inductance is maximized. Then, as indicated by a dotted line 80 ′, when the magnetic member 80 is positioned at one side of the magnetic core 50, the normal mode inductance is minimized.

When the normal mode inductance is reduced, the noise removal effect is weakened. Conversely, when the normal mode inductance is increased, the magnetic core 50 is likely to be magnetically saturated by the normal mode magnetic flux.
Japanese Patent Laid-Open No. 2003-224012

  Accordingly, an object of the present invention is to provide a common mode choke coil that can suppress variations in the relative positional relationship between a magnetic core and a magnetic member and reduce variations in normal mode inductance.

In order to achieve the above object, a common mode choke coil according to the present invention includes:
(A) two or more bobbins having a cylindrical body;
(B) a winding wound around each cylindrical body of the bobbin;
(C) a magnetic core that has a leg inserted through a hole in the cylindrical body and forms a common-mode closed magnetic path;
(D) a magnetic member for forming a normal mode magnetic path disposed between two adjacent bobbins;
(E) In at least one of the locations where the magnetic core and the magnetic member are in contact with each other, either the inner peripheral surface of the magnetic core or the outer peripheral surface of the magnetic member may Provide a taper-shaped protrusion for positioning,
(F) The tip of the protrusion is crushed by being pressed against the outer peripheral surface of the magnetic member or the inner peripheral surface of the magnetic core;
It is characterized by.

  According to the present invention, the protrusion reduces the variation in relative position between the magnetic core and the magnetic member, makes the effective permeability of the normal mode magnetic path substantially constant, and suppresses the variation in normal mode inductance. As a result, it is possible to obtain a common mode choke coil that is hardly magnetically saturated and has an excellent noise removal effect.

  Hereinafter, embodiments of a common mode choke coil according to the present invention will be described with reference to the accompanying drawings.

  The external appearance of the common mode choke coil is shown in FIG. 1, a front view thereof is shown in FIG. 2, and a horizontal sectional view is shown in FIG. The common mode choke coil 11 includes a magnetic body core 50 including two U-shaped core members 50 a and 50 b, two bobbins 32 and 42, the magnetic member 1, and a fastener 60.

  Each of the bobbins 32 and 42 includes cylindrical body portions 33 and 43 and flange portions 34, 35, 44, and 45 provided at both ends of the cylindrical body portions 33 and 43. Lead terminals 54a, 54b, 55a, and 55b are implanted in the flange portions 34, 35, 44, and 45, respectively. The bobbins 32 and 42 are disposed so that the cylindrical body portions 33 and 43 are parallel to each other. The bobbins 32 and 42 are made of resin or the like.

  Each of the windings 37 and 47 is wound in a single layer around the outer periphery of the cylindrical body portions 33 and 43 of the bobbins 32 and 42. The windings 37 and 47 have the same number of turns. Both ends of the winding 37 are electrically connected to lead terminals 54a and 54b provided on the bobbin 32, respectively. Similarly, both ends of the winding 47 are electrically connected to lead terminals 55a and 55b provided on the bobbin 42, respectively.

  Each of the core members 50a and 50b constituting the magnetic core 50 has arm portions 51a and 51b and leg portions 52a and 52b extending in a right angle direction from both ends of the arm portions 51a and 51b. Yes. The leg portions 52a and 52b (the cross-sectional shape is rectangular) of the core members 50a and 50b are inserted into the holes 33a and 43a (the cross-sectional shape is rectangular) of the cylindrical body portions 33 and 43 of the bobbins 32 and 42, respectively. Has been. The core members 50a and 50b have a common mode closed magnetic circuit in which the front end surfaces of both leg portions 52a and 52b collide with each other in the holes 33a and 43a.

  Rail-like projections 33b and 43b for forming a space gap are provided on the four inner wall surfaces of the holes 33a and 43a of the cylindrical body portions 33 and 43 of the bobbins 32 and 42, respectively. Tapers are formed at both ends of the rail-shaped protrusions 33b and 43b so that the leg portions 52a and 52b of the core members 50a and 50b can be easily inserted. The rail-shaped protrusions 33b and 43b form a space gap G1 having a predetermined size between the outer peripheral surfaces 52aa and 52ba of the leg portions 52a and 52b of the core members 50a and 50b and the inner wall surfaces of the holes 33a and 43a. Yes. The contact surface between the rail-shaped protrusions 33b and 43b and the core members 50a and 50b is preferably a flat surface from the surface for holding the core members 50a and 50b, and from the viewpoint of reducing stray capacitance as much as possible. Since it is better for the contact area to be smaller, the contact surface is preferably like an R surface.

  Further, as shown in FIG. 3, the arm portions 51 a and 51 b of the core members 50 a and 50 b run in parallel with the flange portions 34, 35, 44 and 45 of the bobbins 32 and 42. Convex spacers 36 and 46 for forming a space gap are provided on the surfaces 33c, 33d, 43c and 43d of the holes 33a and 43a of the bobbins 32 and 42, respectively. The convex spacers 36 and 46 have a taper so that the leg portions 52a and 52b of the core members 50a and 50b can be easily inserted into the holes 33a and 43a.

  In the common mode choke coil 11, the stray capacitance C decreases as the size of the space gap G1 increases. However, as the space gap G1 is increased, the component size is also increased. Therefore, it is necessary to determine the size range of the space gap G1 that can efficiently reduce the stray capacitance. The dimension range of the space gap G1 that can efficiently reduce the stray capacitance C is G1 = 0.3 to 1.5 mm. More preferably, G1 = 0.5 to 1.0 mm. The lower limit of the dimensional range of the space gap G1 was determined for reasons of electrical characteristics (insertion loss characteristics) of the common mode choke coil 11. On the other hand, the upper limit of the dimensional range of the space gap G1 can obtain a smaller component size and a large inductance value (when the component size is determined, basically, the smaller the space gap, the more winding space increases. Therefore, the inductance value can be increased).

  As the material of the core members 50a and 50b, Mn—Zn ferrite or Ni—Zn ferrite is used. In particular, since Mn—Zn ferrite has a high magnetic permeability, a large inductance value of several mH to several hundred mH can be obtained even if the number of turns of the windings 37 and 47 is relatively small. Incidentally, in order to suppress a noise voltage from a low frequency band (several KHz), an inductance value of several mH to several hundred mH is required.

  A magnetic member 1 having a relative permeability of 1 or more (for example, 2 to several tens) is disposed between the two adjacent bobbins 32 and 42. The magnetic member 1 is made of, for example, an insulating resin material containing magnetic powder in which 80 to 90 wt% of Ni—Zn-based or Mn—Zn-based ferrite and a polyphenylene sulfide-based thermoplastic resin are kneaded. Since the insulating resin material containing magnetic powder is easy to process and itself has an insulating property, it is not necessary to sandwich an insulating spacer between the core members 50a and 50b.

  By providing the magnetic member 1, the effective permeability of the magnetic path in the normal mode is increased, and the magnetic flux φ is concentrated on the magnetic path (the magnetic member 1 and the core members 50a and 50b) having a large effective permeability. For this reason, the common mode choke coil 11 is obtained in which the normal mode inductance component is increased and strong normal mode noise can be removed.

  Here, the value of the normal mode inductance component is determined by the contact area and gap between the core members 50a and 50b and the magnetic member 1, the relative permeability of the magnetic member 1, and the like. When the normal mode inductance component is increased by the common mode choke coil 11, the core members 50a and 50b are easily saturated. Therefore, the characteristics (saturation characteristics and relative permeability, etc.) of the core members 50a and 50b to be used and their common The current flowing through the mode choke coil 11 determines how much the normal mode inductance component can be increased. That is, it is necessary to increase the normal mode inductance component using the magnetic member 1 so that the core members 50a and 50b are not saturated within the guaranteed use range of the common mode choke coil 11.

  As shown in FIG. 4, a protrusion 2 having a height H and a width W is provided at a contact portion of the magnetic member 1 with the core members 50 a and 50 b. When assembling the magnetic member 1 and the core members 50a and 50b, as shown in FIG. 5, the tip of the protrusion 2 is pressed and crushed, and a certain distance is secured between the magnetic member 1 and the core members 50a and 50b. Is done. Since the protrusion 2 is formed by resin molding, the pressing force applied to the core members 50a and 50b increases with the deformation of the protrusion 2 by making the shape of the protrusion 2 tapered. Therefore, by controlling the fitting force of the core members 50a and 50b, a certain distance can be secured between the magnetic member 1 and the core members 50a and 50b.

  Further, as shown in FIGS. 1 and 2, a U-shaped stopper 60 is fitted between the bobbins 32 and 42 in order to firmly contact the abutting surfaces of the core members 50a and 50b.

  The parts 1, 32, 42, 50a, 50b, 60 are made of adhesive or varnish (not shown) between the bobbins 32, 42 and the core members 50a, 50b, and between the core members 50a, 50b and the magnetic member 1. Apply and fix between. Note that adhesive or varnish generates a large stray capacitance C when it enters the gap between adjacent winding portions of the winding 37 (or 47), so care must be taken not to enter it.

  In the common mode choke coil 11 having the above configuration, when a common mode (in-phase) noise current flows through the windings 37 and 47, magnetic fluxes are generated in the same direction in the magnetic core 50 by the windings 37 and 47, respectively. This magnetic flux is consumed while circulating in the magnetic core 50. On the other hand, by providing the magnetic member 1, the effective magnetic permeability of the magnetic path in the normal mode is increased, and the magnetic flux φ is concentrated on the magnetic path (the magnetic member 1 and the core members 50a and 50b) having a large effective magnetic permeability. For this reason, the common mode choke coil 11 is obtained in which the normal mode inductance component is increased and strong normal mode noise can be removed.

  Further, at two locations where the magnetic core 50 and the magnetic member 1 are in contact with each other, protrusions 2 for relative positioning of the magnetic core 50 and the magnetic member 1 are provided on the outer peripheral surface of the magnetic member 1. Therefore, the protrusion 2 reduces the variation in the relative position of the magnetic core 50 and the magnetic member 1, makes the effective permeability of the normal mode magnetic path substantially constant, and suppresses the variation in the normal mode inductance. As a result, it is possible to obtain the common mode choke coil 11 which is hardly magnetically saturated and has an excellent noise removal effect.

  More specifically, Table 1 shows the results of measuring the normal mode inductance of the common mode choke coil 11 with the height H of the protrusion 2 being 0.5 mm and the width W being 0.25 mm.

  From Table 1, the variation of the normal mode inductance of this example was about 1.0% (= {(511-506) / 506} × 100). On the other hand, the normal mode inductance of the conventional common mode choke coil 31 shown in FIGS. 8 and 9 is such that when the magnetic member 80 is located at an equal distance from the magnetic core 50, the magnetic member 80 and the magnetic core When designed so that the gap with respect to 50 is about 0.5 mm, a variation of about 2.4% (= {(512-500) / 500} × 100) may occur.

  As described above, the common mode choke coil 11 stabilizes the positional relationship between the magnetic member 1 and the magnetic core 50, and arranges the magnetic member 1 at an equal distance from the magnetic core 50. Inductance can be maximized stably. That is, the magnetic member 1 can be minimized (in particular, the width of the magnetic member 1), and the material cost can be suppressed.

  Further, as shown in FIG. 6, even in the common mode choke coil 11 using the magnetic member 1A provided with the protrusion 2 only on one side, the positional relationship between the magnetic member 1A and the magnetic core 50 is similarly stabilized, Normal mode inductance can be made constant. When the magnetic member 1A and the magnetic core 50 are assembled, the protrusion 2 is crushed as much as necessary, and the magnetic member 1A on the side without the protrusion 2 and the magnetic core 50 are always in close contact as shown in FIG. More specifically, Table 2 shows the results of measuring the normal mode inductance of the common mode choke coil 11 with the height H of the protrusion 2 of the magnetic member 1A being 1.0 mm and the width W being 0.5 mm.

  From Table 2, the variation of the normal mode inductance of this example was 1.0% (= {(505-500) / 500} × 100).

  In addition, this invention is not limited to the said Example, It can change variously within the range of the summary. For example, the protrusions for relative positioning of the magnetic core 50 and the magnetic member 1 are not necessarily provided on the outer peripheral surface of the magnetic member 1, and the magnetic core 50 (the arm portions 51 a of the core members 50 a and 50 b, 51b) may be provided on the inner peripheral surfaces 51aa and 51bb.

  Alternatively, a square-shaped integral core may be used as the magnetic core, and a bobbin having a gear structure divided into two or more may be used as the bobbin. Moreover, although the said Example demonstrated the thing of two lines which has two windings, the thing of three lines or more which has three or more windings may be sufficient.

  Moreover, you may use the ferrite material by which the surface is coat | covered with insulating resin instead of the insulating resin material containing magnetic powder as a magnetic member. This ferrite material (made of Ni—Zn-based or Mn—Zn-based material) also has the same effects as the magnetic resin-containing insulating resin material. The shape of these magnetic members is arbitrary, and may be an “E” shape, a “T” shape, or a rectangular shape.

1 is an external perspective view showing an embodiment of a common mode choke coil according to the present invention. The front view of the common mode choke coil shown in FIG. The horizontal sectional view of the common mode choke coil shown in FIG. The side view of the magnetic member shown in FIG. FIG. 5 is a vertical sectional view taken along the line V-V in FIG. 3. The side view which shows the modification of the magnetic member shown in FIG. FIG. 7 is a vertical sectional view showing a contact state between a magnetic member and a magnetic core shown in FIG. 6. The horizontal sectional view which shows the conventional common mode choke coil. FIG. 9 is a vertical sectional view of IX-IX in FIG. 8.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1,1A ... Magnetic member 2 ... Protrusion 11 ... Common mode choke coil 32, 42 ... Bobbin 33, 43 ... Cylindrical trunk part 33a, 43a ... Hole 37, 47 ... Winding 50 ... Magnetic body core 51a, 51b ... Arm part 52a, 52b ... Legs

Claims (1)

Two or more bobbins having a cylindrical body;
A winding wound around each cylindrical body of the bobbin;
Legs are inserted through the holes of the cylindrical body, and a magnetic core that forms a common mode closed magnetic path;
A magnetic member for forming a normal mode magnetic path disposed between two adjacent bobbins;
At least one of the locations where the magnetic core and the magnetic member are in contact with each other, either the inner peripheral surface of the magnetic core or the outer peripheral surface of the magnetic member, the magnetic core and the magnetic member Provided with a taper-shaped projection for relative positioning,
The tip of the protrusion is crushed by being pressed against the outer peripheral surface of the magnetic member or the inner peripheral surface of the magnetic core;
A common mode choke coil.

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