JP7087880B2 - Reactor - Google Patents

Description

The technique disclosed herein relates to a reactor in which a coil and a cooling plate face each other with a heat dissipation sheet in between.

A reactor in which a coil and a cooling plate face each other with a heat dissipation sheet sandwiched between them is known (for example, Patent Documents 1 and 2). In the reactor of Patent Document 1, the surface of the cooling plate opposite to the coil facing surface faces the refrigerant flow path, and fins are provided on that surface. In the reactor of Patent Document 2, a groove is provided on the surface of the cooling plate facing the coil so as to face the winding of the coil. Fins and grooves are provided to increase the cooling efficiency of the coil.

Japanese Unexamined Patent Publication No. 2017-174884 JP-A-2015-201491

The present specification provides a reactor having a better cooling efficiency of the coil than before.

The reactor disclosed herein includes a coil around which the windings are wound, a heat dissipation sheet, and a cooling plate. The heat dissipation sheet is in contact with the side surface of the coil. The cooling plate faces the coil with the heat radiation sheet interposed therebetween, and has a plurality of fins on the surface opposite to the surface facing the coil. Each fin is arranged so as to be parallel to the winding of the coil and to face the winding. Since the reactor disclosed herein is provided with fins facing the windings, the distance between the windings and the fins is shortened. Therefore, heat is easily transferred from the winding to the fins, and the cooling efficiency of the coil is improved.

The reactor disclosed herein may have the following characteristics: A groove is provided on the surface of the cooling plate facing the coil so as to face the winding. The surface of the groove and the surface of the winding facing the groove are substantially parallel. When the surface of the groove and the winding face each other in a narrow gap over a wide range, the heat transfer efficiency from the winding to the groove is improved.

The reactor disclosed herein may further have the following characteristics: Here, the winding of the coil is one, but for convenience of explanation, the windings adjacent to each other in the pitch direction are referred to as a first winding and a second winding. The fin facing the first winding is referred to as a first fin, and the fin facing the second winding is referred to as a second fin. In the cross section passing through the axis of the coil, the inclination is 45 degrees with respect to the radial direction of the coil, starting from the boundary point where the distance between the first winding and the surface of the cooling plate facing the first winding in the axial direction begins to widen. The straight line extending toward the second fin is called the first straight line. Starting from the boundary point on the first winding side of the second winding (the point where the distance between the second winding and the surface of the cooling plate begins to widen), the inclination is 45 degrees with respect to the radial direction of the coil toward the first fin. The extending straight line is called a second straight line. It is preferable that the first straight line and the second straight line are configured to intersect with each other on the outside of the cooling plate.

If the condition that the first straight line and the second straight line intersect on the outside of the cooling plate is satisfied, it is possible to prevent the cooling plates from becoming locally hot due to the heat of the adjacent windings interfering with each other. The grounds for the above conditions will be described in the detailed description of the invention.

In the reactor disclosed in the present specification, it is preferable that the surface of the groove of the cooling plate is further provided with fine irregularities. The heat dissipation sheet gets into the fine irregularities, and the heat transfer efficiency from the heat dissipation sheet to the cooling plate is further improved.

Details and further improvements to the techniques disclosed herein will be described in the "Modes for Carrying Out the Invention" section below.

It is sectional drawing of the reactor cut in the plane perpendicular to the coil axis. It is sectional drawing of the reactor cut in the plane including the coil axis. It is an enlarged view of the range of the broken line III of FIG. It is an enlarged view of the range of the broken line IV of FIG. It is an enlarged sectional view which shows the 1st modification of a cooling plate. It is an enlarged sectional view which shows the 2nd modification of a cooling plate.

Reactor 2 of the embodiment will be described with reference to the drawings. 1 and 2 show a cross-sectional view of the reactor 2. FIG. 1 is a cross-sectional view of the reactor 2 cut in a plane perpendicular to the coil axis CL. FIG. 2 is a cross-sectional view of the reactor 2 cut in a plane including the coil axis CL. The reactor 2 is used, for example, in a chopper type voltage converter. Since the reactor 2 through which a large current flows has a large amount of heat generated by the coil 3, it is provided with a cooler 8 for cooling the coil.

The reactor 2 includes a core 12, a coil 3, and a cooler 8. The core 12 is made by solidifying magnetic powder with a resin. The core 12 has a quadrangular prism shape. The coil 3 is a wound winding 4. The lead wires at both ends of the coil 3 are not shown. The core 12 is inserted through the coil 3. The coil 3 wound around the quadrangular prism-shaped core 12 also has a quadrangular prism shape. Therefore, the coil 3 has four flat sides. The assembly of the coil 3 and the core 12 is covered with a resin cover 9 except for the lower surface. The cooler 8 is fixed to the lower surface of the assembly, i.e., to the lower side surface of the coil 3. The resin cover 9 is fixed to the cooler 8 with bolts 91.

The upper plate of the cooler 8 is referred to as a cooling plate 5. The coil 3 faces the cooling plate 5 with the heat radiation sheet 7 interposed therebetween. The heat radiating sheet 7 is made of, for example, silicon rubber having an insulating property and a high heat transmitting property. The heat radiating sheet 7 is sandwiched between the metal coil 3 and the cooling plate 5, and assists heat transfer between the two.

For convenience of explanation, the surface of the cooling plate 5 facing the coil 3 is referred to as a front surface 5a, and the surface opposite to the front surface 5a is referred to as a back surface 5b. The inside of the cooler 8 is a refrigerant flow path Ch, and the back surface 5b of the cooling plate 5 faces the refrigerant flow path Ch. A plurality of thin plate-shaped fins 6 are provided on the back surface 5b. The plate-shaped fins 6 are arranged so that their longitudinal directions are orthogonal to the coil axis CL. In other words, the plurality of fins 6 are arranged so as to be parallel to the winding 4. Further, each fin 6 is arranged so as to face each winding 4. In other words, the distance between the adjacent fins 6 is the same as the pitch distance of the winding 4, and the fins 6 are arranged so as to be located directly below the winding 4. By arranging the fin 6 directly under the winding 4, the distance between the winding 4 and the fin 6 becomes the shortest, and the heat transfer efficiency from the winding 4 (coil 3) to the fin 6 is enhanced. By providing the fins 6 directly below the winding 4, the cooling performance for the coil 3 is improved.

Grooves are provided on the front surface 5a and the back surface 5b of the cooling plate 5, but the grooves are not shown in FIGS. 1 and 2. The groove provided in the cooling plate 5 will be described with reference to FIGS. 3 and 4. FIG. 3 is an enlarged view of the range of the broken line III in FIG. In FIG. 3, the illustration of the core 12 is omitted. The cross section of the winding 4 is circular.

A plurality of grooves 13 are provided on the front surface 5a of the cooling plate 5. The groove 13 extends in the extending direction of the winding 4, that is, in the direction orthogonal to the coil axis CL (see FIG. 2) (Y direction in the drawing). The groove 13 has an arcuate cross-sectional shape orthogonal to the extending direction (Y direction in the drawing), and its radius is substantially the same as the radius of the cross-section of the winding 4. In other words, the groove 13 is provided so that its surface is substantially parallel to the surface of the winding 4. Therefore, the surface of the groove 13 and the winding 4 keep a constant distance d over the groove width W. Since the surface of the groove 13 and the surface of the winding 4 face each other over the groove width W at a short distance d, the heat transfer efficiency from the winding 4 (coil 3) to the cooling plate 5 becomes high. A heat dissipation sheet 7 is sandwiched between the surface of the groove 13 and the winding 4.

A groove 14 is also provided on the back surface 5b of the cooling plate 5. The groove 14 also extends in a direction (Y direction in the drawing) orthogonal to the coil axis CL (see FIG. 2). The role of the groove 14 will be described with reference to FIG.

FIG. 4 is an enlarged view of the range of the broken line IV of FIG. In FIG. 4, the heat dissipation sheet 7 is not shown for the sake of understanding. The coil 3 is composed of one winding 4, but for convenience of explanation, the winding on the left side of the figure is referred to as a first winding 4a, and the winding on the right side of the figure is referred to as a second winding 4b. The first winding 4a and the second winding 4b include the coil axis CL (see FIGS. 1 and 2), and the reactor 2 is cut in a plane orthogonal to the extending direction of the fin 6 (FIG. 4). Corresponds to adjacent windings in the pitch direction. When the entire winding including the first winding 4a and the second winding 4b is shown, it is referred to as winding 4.

The groove facing the first winding 4a is referred to as a first groove 13a, and the groove facing the second winding 4b is referred to as a second groove 13b. Further, the fin facing the first winding 4a is referred to as a first fin 6a, and the fin facing the second winding 4b is referred to as a second fin 6b.

The point Pa in FIG. 4 corresponds to the end of the first groove 13a facing the first winding 4a in the pitch direction (X direction in the drawing). In other words, the point Pa corresponds to the boundary point where the distance between the first winding 4a and the front surface 5a of the cooling plate 5 begins to increase. The point Pa is hereinafter referred to as a boundary point Pa. The point Pb corresponds to the end of the second groove 13b facing the second winding 4b in the pitch direction (X direction in the figure). The point Pb corresponds to a boundary point where the distance between the second winding 4b and the front surface 5a of the cooling plate 5 begins to widen on the side of the first winding 4a. The point Pb is also referred to as a boundary point Pb below.

The straight line Ra (Rb) in FIG. 4 is a straight line in the radial direction of the coil 3 and passes through the boundary point Pa (Pb). The first straight line La in the figure is a straight line that passes through the boundary point Pa and extends toward the adjacent second fin 6b at an inclination of 45 degrees with respect to the coil radial direction (straight line Ra). The second straight line Lb is a straight line that passes through the boundary point Pb and extends toward the adjacent first fin 6a at an inclination of 45 degrees with respect to the coil radial direction (straight line Rb). By providing the groove 14, the intersection Px of the first straight line La and the second straight line Lb is located outside the cooling plate 5. When such a condition is satisfied, the heat transfer efficiency from the winding wire 4 (coil 3) to the cooling plate 5 is improved. The reason will be explained below.

In the cross section (FIG. 4) passing through the coil axis CL (see FIG. 2), the heat of the first winding 4a (second winding 4b) spreads radially from the first winding 4a (second winding 4b). As described above, the heat of the first winding 4a (second winding 4b) is well transferred to the surface of the first groove 13a (second groove 13b) having a short distance. Since the windings 4a and 4b and the cooling plate 5 are separated from each other between the boundary point Pa and the boundary point Pb, it is relatively difficult for heat to be transferred to the cooling plate 5 during this period. At the boundary points Pa and Pb, the direction in which heat is well transferred is up to an angle of 45 degrees with respect to the Z direction in the figure.

A large amount of heat is transferred from the first winding 4a to the cooling plate 5 on the left side of the first straight line La. On the right side of the first straight line La, the amount of heat transferred from the first winding 4a to the cooling plate 5 is relatively small. Similarly, much heat is transferred from the second winding 4b to the cooling plate 5 on the right side of the second straight line Lb. On the left side of the second straight line Lb, the amount of heat transferred from the second winding 4b to the cooling plate 5 is relatively small. The thick arrow line superimposed on the first straight line La and the second straight line Lb indicates the heat transfer direction. When the groove 14 is not provided, the intersection Px of the first straight line La and the second straight line Lb is located inside the cooling plate 5. In that case, the heat radiated from the first winding 4a and the heat radiated from the second winding 4b interfere with each other in the vicinity of the intersection Px. As a result, the temperature in the vicinity of the intersection Px inside the cooling plate 5 rises locally. When the temperature of the cooling plate 5 rises locally at a position away from the first fins 6a and the second fins 6b, the efficiency of heat dissipation through the first fins 6a and the second fins 6b decreases. On the contrary, when the intersection Px of the first straight line La and the second straight line Lb is located outside the cooling plate 5, the heat from the first winding 4a and the heat from the second winding 4b inside the cooling plate 5 No interference occurs, and the local temperature rise of the cooling plate 5 is suppressed. As a result, the heat dissipation efficiency does not decrease. As described above, the cooling efficiency of the winding 4 (that is, the coil 3) is improved by providing the groove 14 so that the intersection Px of the first straight line La and the second straight line Lb is located outside the cooling plate 5. ..

(First Modification Example) The cooling plate 105 of the first modification will be described with reference to FIG. The overall structure of the reactor is the same as in Reactor 2 of the example. The cross section of FIG. 5 corresponds to the cross section of FIG. However, in FIG. 5, the heat dissipation sheet 7 is also shown. Like the cooling plate 5, the cooling plate 105 is provided with a groove 13 on the front surface 105a and a groove 14 on the back surface 105b. The grooves 13 and 14 of the cooling plate 105 have the same effect as the grooves 13 and 14 of the cooling plate 5 of the reactor 2 of the embodiment.

The cooling plate 5 has fine irregularities 115 on the front surface 105a. The contact area between the front surface 105a and the heat radiating sheet 7 increases as the heat radiating sheet 7 enters the gaps of fine irregularities. As a result, the heat transfer efficiency from the heat radiating sheet 7 to the cooling plate 105 is enhanced.

(Second Modification Example) The cooling plate 205 of the second modification will be described with reference to FIG. The overall structure of the reactor is the same as in Reactor 2 of the example. The cross section of FIG. 6 corresponds to the cross section of FIG. Like the cooling plate 5, the cooling plate 205 is provided with a groove 13 on the front surface 205a and a groove 214 on the back surface 205b. The grooves 13 and 214 of the cooling plate 205 have the same effect as the grooves 13 and 14 of the cooling plate 5 of the reactor 2 of the embodiment.

The cooling plate 5 has a plurality of fins 206 on the back surface 105b. Each fin 206 faces winding 4. As shown in FIG. 6, the cross-sectional shape of the fin 206 (the shape of the cross section orthogonal to the longitudinal direction of the fin) is corrugated, and the base of the fin 206 and the edge of the groove 214 are smoothly continuous. The fins of the reactor cooling plate disclosed herein may have a shape having a curved cross section as shown in FIG.

Although specific examples of the present invention have been described in detail above, these are merely examples and do not limit the scope of claims. The techniques described in the claims include various modifications and modifications of the specific examples exemplified above. The technical elements described herein or in the drawings exhibit their technical usefulness alone or in various combinations, and are not limited to the combinations described in the claims at the time of filing. In addition, the techniques exemplified in the present specification or the drawings can achieve a plurality of purposes at the same time, and achieving one of the purposes itself has technical usefulness.

2: Reactor 3: Coil 4, 4a, 4b: Winding 5, 105, 205: Cooling plate 5a, 105a, 205a: Front surface 5b, 105b, 205b: Back surface 6, 6a, 6b, 206: Fin 7: Heat dissipation sheet 8: Cooler 9: Resin cover 12: Core 13, 13a, 13b, 14, 214: Groove 115: Concavo-convex

Claims (4)

With the coil around which the winding is wound,
The heat dissipation sheet in contact with the side surface of the coil and
A cooling plate that faces the coil with the heat radiation sheet sandwiched between them and has a plurality of fins on the opposite side of the surface facing the coil.
Equipped with
A reactor in which each of the fins is arranged to be parallel to the winding and is arranged to face each of the windings. A groove is provided on the surface of the cooling plate facing the coil so as to face the winding.
The reactor according to claim 1, wherein the surface of the groove and the surface of the winding are substantially parallel to each other. The first and second windings adjacent to each other in the pitch direction,
The first fin facing the first winding and
The second fin facing the second winding and
Equipped with
In the cross section passing through the axis of the coil, with respect to the radial direction of the coil, starting from the boundary point where the distance between the first winding and the surface of the cooling plate facing the first winding in the axial direction begins to widen. The first straight line extending toward the second fin at an inclination of 45 degrees and the boundary point on the first winding side of the second winding are the starting points, and the inclination is 45 degrees with respect to the radial direction. The reactor according to claim 2, wherein a second straight line extending toward the first fin intersects the outside of the cooling plate. The reactor according to claim 2 or 3, wherein the surface of the groove is provided with fine irregularities.

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