JP3619457B2 - Smoothing coil for large current smoothing - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a smoothing coil for smoothing a large current.
[0002]
[Prior art and problems to be solved by the invention]
Vehicle DC-DC converters and rectifier circuits have a large space limitation, and switching elements constituting these circuits and smoothing coils (choke coils) that smooth the intermittent current of these switching elements are arranged in close proximity. Therefore, there is a demand for downsizing the apparatus.
[0003]
However, in a DC-DC converter for a vehicle, it is often necessary to process a large current, and as a result, in order to prevent the heat generated by the smoothing coil from adversely affecting the switching elements arranged in proximity, circuit reliability is improved. There was a problem that damages.
[0004]
In addition, a magnetic core (hereinafter referred to as a core) used in a smooth coil is usually provided with a gap in order to prevent its magnetic saturation. In order to radiate electromagnetic noise to the outside, a switching element or a semiconductor element is used. It was necessary to keep it away and prevent its malfunction.
[0005]
However, in a smoothing coil for smoothing a large current used for a DC-DC converter for a vehicle or the like, downsizing of an electronic circuit device is required due to restrictions on main space. It was not easy to secure a sufficient distance between them.
[0006]
Furthermore, due to the influence of the magnetic vibration of the core accompanying the periodic coil current change and the leakage magnetic field acting on the coil, the coil fitted to the core may vibrate and coil chatter noise may occur. This chatter noise can be prevented if the coil is integrated with the core with mold resin, etc.
Coil overheating and resin degradation became a problem due to the significant deterioration of coil heat dissipation performance.
[0007]
The present invention has been made in view of the above problems, and its object is to provide a smoothing coil for smoothing large currents that can be integrated at high density while suppressing an increase in adverse effects due to electromagnetic noise and heat with a simple configuration. It is said.
[0008]
[Means for Solving the Problems]
The smoothing coil for smoothing a large current according to claim 1 is formed by winding a core having a closed magnetic path formed by butting a plurality of partial cores formed of a high permeability magnetic material and a flat rectangular conductor wire around the core. A flat rectangular conductor wire coil, a metal heat radiating plate having a flat heat transfer heat absorbing surface that is in close contact with the flat main surface of the rectangular conductor wire coil, and the core via the rectangular conductor wire coil. And a fixing member that presses the rectangular conductor wire coil against the heat transfer heat absorption surface of the heat radiating plate by pressing it toward the heat transfer heat absorption surface of the heat radiation plate .
[0009]
That is, in the present invention, since the flat conductor wire coil is sandwiched between the core and the metal heat sink, the heat generated by the resistance loss of the coil through which a large current flows can be obtained even when the pre-formed coil is fitted to the core. Heat transfer and cooling are performed satisfactorily by both the metal heat sink and the core which are in close contact with the flat surface of the conductor wire coil, and the heat is dissipated well through the metal heat sink and the core.
[0010]
For this reason, the coil does not become high temperature, the resistance value can be reduced, and it is possible to prevent the semiconductor elements in the vicinity of the coil from being adversely affected by heat transfer, convection, and radiation. In addition, the heat radiation effect is much higher in the metal heat radiating plate that has no self-heating than the core and has a much better thermal conductivity than the core.
[0011]
Even when a gap core is used for preventing magnetic saturation in the core, the metal heat radiating plate extending in the vicinity of the gap exhibits an electromagnetic shielding effect, and electromagnetic noise can be reduced well. As a result, even when a smoothing coil for smoothing a large current is used, high-density mounting is possible, and the device accommodation space can be reduced.
[0012]
Furthermore, in the present invention, since the coil is strongly clamped between the core and the metal heat sink, even when the molded coil is fitted to the core, chatter noise is almost completely prevented without fixing the coil to the core with resin. Can do.
[0013]
According to the second aspect of the present invention, in the smoothing coil for smoothing a large current according to the first aspect, the flat conductor wire coil is formed of a molded coil that is previously molded and fitted into the core. Yes.
[0014]
According to this configuration, since the pre-formed molded coil can be easily fitted to the flat plate portion of the core, the mounting operation can be simplified. In addition, it is possible to satisfactorily reduce heat dissipation reduction and chatter noise that are likely to occur in the formed coil by the clamping pressure.
[0015]
According to the configuration of claim 3, in the smoothing coil for smoothing a large current according to claim 2, the molded coil is formed in a spiral shape in advance, and all the turn portions are the heat transfer heat absorption of the heat radiating plate. It is characterized by comprising a single-layer wound coil in close contact with the surface.
[0016]
According to this configuration, cooling of the formed coil and reduction of chatter noise are further improved.
[0017]
According to the configuration of claim 4, in the smoothing coil for smoothing a large current according to any one of claims 1 to 3, the fixing member is fixed to the heat radiating plate at both ends and the core is connected to the core. It consists of a substantially U-shaped leaf spring member that urges toward the heat radiating plate.
[0018]
According to this configuration, the above clamping pressure can be realized with a simple configuration.
[0019]
According to the configuration of claim 5, in the smoothing coil for smoothing a large current according to any one of claims 1 to 3, the fixing member is fastened to the heat radiating plate at both ends, and the core is the core at the center. It consists of the 2nd heat sink urged | biased toward the said heat sink.
[0020]
According to this structure, since a pair of metal heat sink is arrange | positioned on both sides of a core and a coil, a 2nd heat sink can serve as a fixing member, and it improves cooling performance, suppressing the increase in a number of parts. Can do. In addition, the electromagnetic shielding effect can be further improved.
[0021]
DETAILED DESCRIPTION OF THE INVENTION
The preferred embodiments of the smoothing coil for smoothing a large current according to the present invention will be described in detail with reference to the following examples.
[0022]
(Example 1)
A smoothing coil for smoothing a large current according to the first embodiment will be described below with reference to FIG. FIG. 1 is a side view of the smoothing coil.
[0023]
This smooth coil has a ferrite core 1, a coil 2, a heat radiating plate 3, a leaf spring member 4, and a heat conductive sheet 5.
[0024]
The core 1 includes a U-shaped U-shaped core 11 and an I-shaped I-shaped core 12. The U-shaped core 11 has a flat central plate portion and a pair of leg portions that project from both ends of the central plate portion in the same direction at right angles to the central plate portion. The I-shaped core 12 has a flat plate shape that extends in parallel with the central plate portion of the U-shaped core 11 and has both end portions in close contact with both leg portions of the U-shaped core 11. Although not shown, one end surface of one leg of the U-shaped core 11 is partially cut away to form a stepped portion, and the remaining portion is in close contact with the I-shaped core 12. A gap between the stepped portion and the surface of the I-shaped core 12 forms a magnetic saturation prevention gap of the core 1. Therefore, at a low current, the core 1 does not saturate and has a large inductance, and when the current increases, the tip of the leg portion of the U-shaped core 11 adjacent to the stepped portion is magnetically saturated, and the magnetic flux flows through this gap. However, the magnetic saturation of the core is suppressed.
[0025]
The coil 2 is a single-layer wound coil in which a flat conductor wire made of a resin-coated flat copper plate is spirally formed in advance, and is fitted to the I-shaped core 12. Each turn part of the coil 2 is in close contact with the flat surface of the I-shaped core 12 and the flat surface of the heat sink 3 via a heat conductive sheet (silicon resin sheet) 5. Instead of the heat conductive sheet 5, heat conductive grease may be employed.
[0026]
The heat sink 3 is made of a flat aluminum flat plate, and is fastened or soldered to a circuit board (not shown). In addition, the metal case that accommodates the circuit board can also serve as the heat sink 3.
[0027]
The leaf spring member 4 is formed by bending a leaf spring, both ends thereof are fastened to the heat radiating plate 3, and the central curved portion presses the coil 2 against the surface of the heat radiating plate 3 through the U-shaped core portion 11 and the I-shaped core 12. ing.
[0028]
The smoothing coil for smoothing a large current according to this embodiment described above performs heat dissipation, chattering prevention, and electromagnetic noise radiation reduction of the coil 2 already described.
[0029]
(Example 2)
Another embodiment will be described below with reference to FIG.
[0030]
This smooth coil employs a square-shaped core 1 in which a pair of L-shaped cores 13 having the same shape is combined instead of the combination of the U-shaped core 11 and the I-shaped core 12 in the first embodiment. Thereby, the number of parts can be reduced. Moreover, the coil 2 shape | molded previously can be fitted to both the L-shaped cores 13, and the core 1 can be reduced in size.
[0031]
Moreover, the 2nd heat sink 6 is used instead of the leaf | plate spring member 4 used for FIG. The second heat radiating plate 6 is formed in a substantially U shape by aluminum die casting, and both ends are fastened to the heat radiating plate 3 that forms the bottom plate portion of the metal case, and sandwiches the core 1 and the coil 2 together with the heat radiating plate 3. ing.
61 is a cooling fin protruding from the upper surface of the second heat radiating plate 6.
[0032]
If it does in this way, each turn of the coil 2 fitted by the upper L-shaped core 13 will closely_contact | adhere to the 2nd heat sink 6, and each turn of the coil 2 fitted by the lower L-shaped core 13 Since it adheres closely to the heat radiating plate 3, a good coil heat radiation effect, electromagnetic shielding effect, and coil chatter noise reduction effect can be achieved. Other details are the same as those in the first embodiment.
The heat conductive sheet 5 is not shown.
[0033]
(Example 3)
Another embodiment will be described below with reference to FIGS.
[0034]
This smooth coil is obtained by extending a pair of leg portions of the U-shaped core 11 of the first embodiment and fitting a pre-formed coil 2 on these leg portions.
[0035]
Thereby, the number of parts can be reduced. Also, by disposing the radiator plate 3 and the second radiator plate 6 with the core 1 and the coil 2 interposed therebetween, and fastening the radiator plate 3 and the second radiator plate 6 with the metal spacer 7 interposed therebetween, The coil 2 is pressed against the heat radiating plate 3 and the second heat radiating plate 6. Thereby, the core 1 can be reduced in size and the coil heat radiation effect, the electromagnetic shielding effect, and the coil chatter noise reduction effect can be improved. Other details are the same as those in the first embodiment. Further, the leaf spring member 4 used in FIG. 1 can be omitted. As in FIG. 2, the spacer 7 may be integrated with the heat sink 3 or the second heat sink 6.
[0036]
(Example 4)
Another embodiment will be described below with reference to FIG.
[0037]
This smoothing coil employs the second heat radiation plate 6 and the spacer 7 shown in FIGS. 3 and 4 in the first embodiment shown in FIG. Thereby, the coil heat dissipation effect and the electromagnetic shielding effect can be improved.
[0038]
(Example 5)
Another embodiment will be described below with reference to FIG.
[0039]
This smoothing coil employs an E-shaped E-shaped core 14 instead of the U-shaped core 11 in the third embodiment shown in FIG. The E-shaped core 14 has three leg portions 141, 142, and 143 that project from the central plate portion 140 at a right angle in the same direction.
[0040]
The coil 2 is fitted to the leg portions 141 and 143 on both sides forming a parallel magnetic path in a closed magnetic circuit formed by the core 1. Of course, it may be fitted to the center leg 142. In this embodiment, the magnetic path cross-sectional areas of the respective leg portions 141 to 143 are equally shown, but actually, the magnetic path cross-sectional area of the central leg portion 142 is substantially the same as the magnetic path cross-sectional area of the other leg portions. Are equally formed.
[0041]
In the smoothing coil for smoothing a large current described in each of the embodiments described above, the coil temperature can be lowered as compared with the prior art, so that an increase in the electrical resistance can be suppressed and the efficiency can be improved.
[Brief description of the drawings]
FIG. 1 is a side sectional view of a smoothing coil according to a first embodiment.
FIG. 2 is a side sectional view of a smoothing coil according to a second embodiment.
FIG. 3 is a plan view of a core and a coil of a smoothing coil according to a third embodiment.
FIG. 4 is a side sectional view of a smoothing coil according to a third embodiment.
FIG. 5 is a side sectional view of a smoothing coil according to a fourth embodiment.
6 is a sectional side view of a smoothing coil according to Embodiment 5. FIG.
[Explanation of symbols]
1 Core 2 Coil 3 Heat sink 4 Leaf spring member (fixing member)
5 Thermal conductive sheet 6 Second heat sink (heat sink, fixing member)

Claims (5)

A core having a closed magnetic path constituted by butting a plurality of partial cores formed of a high permeability magnetic material;
A flat conductor wire coil formed by winding a flat rectangular conductor wire around the core;
A metal heat dissipating plate having a flat heat transfer heat absorbing surface that is in close contact with the flat main surface of the flat conductor wire coil;
A fixing member that presses the rectangular conductor wire coil against the heat transfer heat absorption surface of the heat dissipation plate by pressing the core toward the heat transfer heat absorption surface of the heat dissipation plate via the rectangular conductor wire coil ;
A smoothing coil for smoothing a large current. The smoothing coil for smoothing a large current according to claim 1,
The flat rectangular conductor wire coil is a smooth coil for smoothing a large current, which is formed of a molded coil that is molded in advance and fitted into the core. The smoothing coil for smoothing a large current according to claim 2,
The smoothing coil for smoothing a large current, wherein the forming coil is formed of a single-layer winding coil that is preliminarily formed in a spiral shape and all turn portions are in close contact with the heat transfer heat absorption surface of the heat radiating plate. The smoothing coil for smoothing a large current according to any one of claims 1 to 4,
The fixing member has a substantially U-shaped leaf spring member whose both ends are fixed to the heat radiating plate and whose central portion urges the core toward the heat radiating plate. Smooth coil. The smoothing coil for smoothing a large current according to any one of claims 1 to 4,
A smoothing coil for smoothing a large current, characterized in that the fixing member comprises a second heat radiating plate having both ends fastened to the heat radiating plate and a central portion urging the core toward the heat radiating plate.

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