JP2010225963A - Reactor - Google Patents

Abstract

The present invention provides a reactor capable of preventing separation and a gap from being generated between an exterior resin and a component to be included.
A reactor (1) includes a coil (11), and a core (12) having a winding part in which the coil (11) is disposed and an exposed part that is exposed without the coil (11) being disposed. The resin mold body 10 is made of a first mold resin that holds the shape of the coil 11, and the second mold resin covers the outer periphery of the resin mold body 10 and the exposed portion (end core 12e) of the core 12. An exterior mold body 20. The resin mold body 10 and the exterior mold body 20 are each molded at a temperature higher than the use temperature of the reactor, and the thermal expansion coefficients of the core 12, the first mold resin, and the second mold resin at the molding temperature. _Where α _c , α _p1 , and α _p2 are satisfied, α _c <α _p2 and α _p1 ≦ α _p2 are satisfied.
[Selection] Figure 1

Description

  The present invention relates to a reactor used for a DC-DC converter for an electric vehicle such as a hybrid vehicle. In particular, the present invention relates to a reactor that can prevent peeling or a gap from being generated between an exterior resin and a component to be included.

  An electric vehicle such as a hybrid vehicle is equipped with a DC-DC converter that raises and lowers a DC voltage, and a reactor is one of the parts of this converter. Conventionally, a typical reactor has a structure in which an assembly in which a coil is arranged on an annular core is housed in a case, and the case is filled with resin and sealed (for example, Patent Document 1). reference).

  The reactor described in Patent Document 1 includes a track-shaped core, a coil disposed in the core, a middle case that houses a combination of the core and the coil, and a case that houses the whole. In this reactor, the straight portion of the core where the coil is disposed is covered with the inner bobbin, and the coil is wound around the outer side of the inner bobbin. The reactor has outer bobbins attached to both ends of the coil, and both ends of the coil are sandwiched between the outer bobbins. Furthermore, since this reactor dissipates the heat generated in the reactor by energizing the coil, the case is used with the case installed on the heat sink.

JP 2008-28290 A

  However, the conventional reactor described above has a problem that the number of parts is large and assembly workability is poor.

  Normally, a coil serving as a reactor part is acted on by a springback, and a relatively large space is formed between winding turns. In this state, since the coil expands and contracts, it is difficult to handle the coil, resulting in deterioration in assembling workability. In order to reduce the size of the reactor, it is desired to compress the coil to reduce the space between the winding turns. Therefore, Patent Document 1 proposes a method of holding the coil in a compressed state by sandwiching both ends of the coil with outer bobbins and storing the coil in an inner case. However, with this method, the number of parts and the assembly process are large, and the assembly workability is poor.

  Furthermore, the conventional reactor stored in the case has a problem that it is difficult to reduce the size and weight.

  In recent years, miniaturization and weight reduction are strongly desired for in-vehicle parts such as hybrid vehicles. Therefore, it is conceivable to omit the case. However, if the case is simply omitted, the core and coil are exposed, and cannot be protected from the external environment such as moisture and dust, and mechanical stress such as impact. . Therefore, in order to meet such a demand, it is conceivable to omit the case and cover the combination of the core and the coil with an exterior resin, for example.

  However, as a result of intensive studies by the inventor, the reactor in which the resin is directly molded on the outer periphery of the combination of the core and the coil to form the exterior resin, the heat in the operating temperature range (for example, −40 to 150 ° C.) When the cycle was repeatedly loaded, a problem was found in which peeling or a gap occurred between the exterior resin and the part to be included.

  The present invention has been made in view of the above circumstances, and one of its purposes is to provide a reactor that can prevent peeling or gaps between an exterior resin and a component to be included. There is to do.

The reactor of this invention is provided with the core which has the coil formed by winding a coil | winding helically, the winding part by which this coil is arrange | positioned, and the exposed part which is exposed without arrange | positioning a coil. Moreover, the resin mold body which consists of 1st mold resin which hold | maintains the shape of a coil, and the exterior mold body which consists of 2nd mold resin which covers the outer periphery of the resin mold body and the exposed part of a core are provided. The resin mold body and the exterior mold body are each molded at a temperature higher than the operating temperature of the reactor, and the thermal expansion coefficients of the core, the first mold resin, and the second mold resin at the molding temperature are respectively α. _{When c 1} , α _p1 , and α _p2 are satisfied, α _c <α _p2 and α _p1 ≦ α _p2 are satisfied.

  In the reactor of the present invention, since the resin mold body is a molded body that maintains the shape of the coil, handling of the coil is facilitated and the assembly workability of the reactor is excellent. In the reactor of the present invention, since the resin mold body can also function as the bobbin (inner bobbin, outer bobbin and inner case) of the conventional reactor, the number of parts and the assembly process can be reduced. Excellent assembly workability. Furthermore, the reactor of the present invention is configured to include an exterior mold body, so that the core and the coil (resin mold body) can be removed from the external environment and mechanical stress while reducing the size and weight of the reactor by omitting the case. Can be protected.

  The reactor of the present invention also has the following effects.

  Using the first mold resin and the second mold resin whose thermal expansion coefficient satisfies the above relationship, the resin mold body and the exterior mold at a temperature higher than the reactor operating temperature (the maximum operating temperature, for example, 150 ° C.) Shape the body. In this case, the outer mold body tends to shrink more than the core and the resin mold body in the operating temperature range of the reactor (for example, 150 ° C. or less). Therefore, the state in which the exterior mold body is in close contact with the core and the resin mold body can be maintained, and peeling between the exterior mold body and the core (exposed portion) or between the exterior mold body and the resin mold body can be performed. Generation of a gap can be prevented.

  On the other hand, when the relationship between the thermal expansion coefficients is reversed, the core and the resin mold body tend to shrink more with respect to the exterior mold body as the reactor moves to the lower temperature side of the use temperature range. Therefore, when the thermal cycle in the operating temperature range is repeatedly applied to the reactor, the exterior mold body cannot follow the shrinkage deformation of the core and the resin mold body, and the space between the exterior mold body and the core (exposed part). Alternatively, peeling or a gap may occur between the exterior mold body and the resin mold body.

The resin molded body may be a molded body that maintains the shape of the coil and further integrates the coil and the winding portion of the core. Further, from the viewpoint of preventing the occurrence of peeling or gaps between the resin mold body and the core (winding part), the relationship of the thermal expansion coefficient preferably satisfies α _c <α _p1 ≦ α _p2 , Preferably, α _c <α _p1 <α _p2 .

  In a more preferred embodiment of the present invention, the first mold resin contains a ceramic filler.

  Since the resin mold body has a coil disposed therein, and this coil generates heat and becomes high temperature, it is preferably excellent in thermal conductivity. Therefore, the thermal conductivity of the resin mold body can be improved when the first mold resin contains a ceramic filler.

  A more preferable embodiment of the present invention is a configuration in which the second mold resin contains a glass fiber filler.

  The exterior mold body is intended to protect the core and coil (resin mold body) from the external environment and mechanical stress, and therefore preferably has excellent mechanical strength. Then, the mechanical strength of an exterior mold body can be improved because the 2nd mold resin contains the filler of glass fiber.

In the reactor of the present invention, the relationship between the thermal expansion coefficients satisfies α _c <α _p2 and α _p1 ≦ α _p2 , so that the outer resin (outer mold body) and the components (core and resin mold body) to be included are between It is possible to prevent peeling and gaps from occurring.

1 is a schematic perspective view showing a reactor according to Embodiment 1. FIG. It is a schematic perspective view which shows the resin mold body with which the reactor which concerns on Embodiment 1 is equipped. It is the schematic for demonstrating the resin mold body with which the reactor which concerns on Embodiment 1 is equipped, (A) is a perspective view which shows the state before resin mold, (B) is a disassembled perspective view of the winding part of a core FIG. It is explanatory drawing which shows the shaping | molding method of the resin mold body with which the reactor which concerns on Embodiment 1 is equipped.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. Moreover, the same code | symbol is attached | subjected to the same member in the figure.

(Embodiment 1)
With reference to FIGS. 1-3, the reactor 1 which concerns on Embodiment 1 is demonstrated. In FIG. 1, for ease of explanation, a part of the outer mold body 20 is cut away so that the core (exposed portion 12 e) and the resin mold body 10 existing inside the outer mold body 20 can be seen. .

  The reactor 1 includes a coil 11, a core 12 having a winding part 12c where the coil 11 is arranged, and an exposed part 12e where the coil 11 is exposed without being arranged (see FIGS. 1 and 2). Further, a resin mold body 10 that integrally holds the coil 11 and the core winding portion 12c, and an exterior mold body 20 that covers the outer periphery of the resin mold body 10 and the exposed portion 12e of the core are provided. The reactor 1 is used by inserting a fixing bracket (for example, a bolt) through an insertion hole 20h formed in the exterior mold body 20 and installing it in a heat dissipation mechanism such as a heat sink. Hereinafter, each configuration will be described in more detail.

  The coil 11 is formed by edgewise winding a rectangular winding. As shown in FIG. 3A, the coil 11 is composed of a pair of coil elements 11a and 11b whose axial directions are parallel, and both the coil elements 11a and 11b are formed of one winding. Specifically, on one end side in the axial direction of the coil 11, the start end 11s and the end end 11e of the winding are drawn upward, and on the other end side in the axial direction of the coil 11, the winding is bent in a U shape to form the bent portion 11u. By providing, both the coil elements 11a and 11b are formed by one winding.

  An intermediate core (winding portion 12c) is disposed on the inner circumference of each of the coil elements 11a and 11b. As shown in FIG. 3B, the intermediate core 12c is formed in a rectangular parallelepiped shape by integrating a plurality of core pieces 120 and a gap material g interposed between the core pieces 120 with an adhesive. The core piece 120 is made of a magnetic material, and may be composed of a laminated body in which silicon steel plates are laminated, or a compacted body in which the surface of a soft magnetic powder such as iron powder is coated with an insulating coating and the powder is pressure-molded. it can. The gap material g is made of a nonmagnetic material and can be formed of a ceramic plate material such as glass epoxy resin or alumina.

  The resin mold body 10 is a resin (first mold resin) between the coil 11 and the intermediate core 12c in a state where the intermediate core 12c is disposed on the inner periphery of each of the coil elements 11a and 11b (see FIG. 3A). And are integrally molded (see FIG. 2). Here, both the end surfaces of the intermediate core 12c, the winding start and end ends 11s, the top surfaces of the coil elements 11a and 11b, and a part of the side surface where the coil elements do not face each other are exposed. The resin mold body 10 is filled with resin between the winding turns of the coil 11, and is formed so that the resin covers a part of the outer peripheral surface of each coil element 11a, 11b. Resin is filled between the inner peripheral surface of each of the coil elements 11a and 11b and the intermediate core 12c so as not to be in direct contact with 12c.

  In addition to the function of holding the coil 11 and the intermediate core 12c integrally, the resin mold body 10 also has a function of holding the shape of the coil 11. Specifically, resin is filled between winding turns of the coil 11, and the resin 11 is formed so as to continue from one end side to the other end side of the coil 11, thereby fixing the shape of the coil 11. ing. Further, when the resin mold body 10 is formed in a state where the coil 11 is compressed, the coil 11 is held in a compressed state, so that the reactor can be downsized. Such a resin mold body 10 facilitates handling of the coil, and contributes to the reduction in the number of reactor parts and the assembly process.

  A specific example of the method for manufacturing the resin mold body 10 will be described with reference to FIG. When the coil 11 and the intermediate core 12c are integrally molded with resin, as shown in FIG. 3A, the intermediate core 12c with the gap material g interposed between the core pieces 120 is included in the coil elements 11a and 11b. It is inserted into the circumference and placed in the mold 50 in that state.

  The mold 50 is a pair of split molds that are opened and closed, and includes a first mold 51 and a second mold 52. The first mold 51 located in the lower part includes an end plate 51A located on the other end side (bent portion side) of the coil 11 and a side wall 51B covering the periphery of the coil 11. On the other hand, the second mold 52 located in the upper part includes an end plate 52A located on one end side (start end / end end side) of the coil 11. By arranging the coil 11 and the intermediate core 12c with the bent portion side of the coil 11 facing down in the mold 50, the axial direction of the coil 11 becomes the vertical direction, and the stacking direction of the core piece and the gap material is also Since the core piece and the gap material are not integrated with the adhesive, the core piece and the gap material can be easily arranged at predetermined positions in the mold 50 because the core piece and the gap material are not integrated. In particular, by arranging the coil 11 and the intermediate core 12c in the mold 50 so that the axial direction of the coil 11 is the vertical direction, the coil 11 and the intermediate core 12c are arranged so that the axial direction of the coil 11 is horizontal. Is easier to arrange the coil 11 and the intermediate core 12c coaxially than in the mold 50.

  In such a mold 50, the coil 11 and the intermediate core 12c are respectively positioned and arranged coaxially. In the resin mold body 10 shown in FIG. 2, a portion where the coil 11 is exposed is a portion where the mold 50 and the coil 11 are brought into contact with each other so that the mold 50 supports the coil 11. If there is a possibility that the space between the coil elements 11a and 11b may be reduced by coming into contact with the mold 50, an appropriate pin (not shown) is disposed between the coil elements 11a and 11b. , 11b may be maintained. A predetermined space is formed between the other outer peripheral surface region of the coil 11 and the mold 50. On the other hand, the intermediate core 12c is positioned in the mold 50 with its lower end in contact with the first mold 51.

  The first and second molds 51 and 52 include a plurality of rod-like bodies 53 that can be moved back and forth in the mold 50 by a drive mechanism (not shown), and these rod-like bodies 53 press the end faces of the coil elements 11a and 11b. Thus, the coil 11 can be compressed. The rod-like body 53 is made as thin as possible in order to reduce the number of places where the coil 11 is not covered with resin, but has sufficient strength and heat resistance to compress the coil 11. At the stage where the coil 11 is placed in the mold 50, the coil 11 is not yet compressed, and a gap is formed between the winding turns.

  Next, the mold 50 is closed, and the rod-shaped body 53 is advanced into the mold 50 to hold the coil 11 in a predetermined shape. At this time, the coil 11 may be compressed until the windings adjacent to each other in the axial direction of the coil 11 are in contact with each other so that the gap between the winding turns is eliminated as much as possible.

  Thereafter, a first mold resin is injected into the mold 50 from a resin injection port (not shown). The resin injection port is positioned substantially in the middle of the end plate 52A of the second mold, that is, between the coil elements 11a and 11b. Further, the rod-like body 53 may be retracted from the mold 50 as long as the resin is cured to some extent and the coil 11 is maintained in a predetermined shape.

  Then, after the resin is cured and a resin mold body is formed, the mold 50 is opened and the part is taken out from the mold 50. The plurality of small holes formed at the place pressed by the rod-like body 53 may be filled with an appropriate insulating material or the like, or may be left as it is.

  In the above manufacturing method example, the case where the coil 11 and the intermediate core 12c are integrally molded with resin has been described. For example, after the coil 11 is molded with resin, the intermediate core 12c is placed on the inner periphery of the coil elements 11a and 11b. It can also be manufactured by insertion.

  Even in this case, the above-described mold 50 can be used. Specifically, the core is placed in the mold 50 at the position where the intermediate core 12c of the coil elements 11a and 11b is inserted, and the coil 11 is molded with resin to produce a molded body. Thereafter, in another step, the intermediate core 12c is inserted into the core insertion hole formed by the core of the molded body. In this case, even if a gap is formed between the inner peripheral surface of the core insertion hole and the inserted intermediate core, the second mold resin enters the gap in the molding process of the exterior mold body to be described later. Sometimes.

  End cores (exposed portions 12e) are respectively disposed at both ends of the resin mold body 10, and the core 12 is configured in an annular shape by connecting the end portions of the intermediate core 12c via the end core 12e. ing. Here, the intermediate core 12c and the end core 12e are connected using an adhesive. The end core 12e is made of a magnetic material and can be made of the same material as the above-described core piece. In such a combination of the core 12 and the coil 11 (combination of the end core 12e and the resin mold body 10), a closed magnetic circuit is formed in the core 12 by supplying current to the coil 11. Will be.

  The outer mold body 20 is molded with a resin (second mold resin) so as to cover the outer periphery of the end core 12e and the resin mold body 10 in a state where the end core 12e and the resin mold body 10 are combined. Is formed. Here, it is formed so that the lower surface of the end core 12e and the lower surface of the resin mold body 10 located on the installation location side where the reactor 1 is installed are exposed. By providing such an exterior mold body 20, it is possible to protect the end core 12e and the resin mold body 10 from the external environment and mechanical stress while omitting the case and reducing the size and weight of the reactor.

The resin mold body 10 and the exterior mold body 20 are each molded at a temperature higher than the use temperature of the reactor. Therefore, as the first requirement, it is necessary to select a resin that is cured or solidified at a temperature higher than the use temperature of the reactor as the first mold resin and the second mold resin. Further, in the operating temperature range of the reactor, as a second requirement, at least the thermal expansion coefficient of the outer mold body 20 can be maintained so that the outer mold body 20 can be kept in close contact with the core 12 (end core 12e) and the resin mold body 10. The relationship needs to satisfy α _c <α _p2 and α _p1 ≦ α _p2 . Note that α _c , α _p1, and α _p2 are thermal expansion coefficients at the molding temperatures of the core, the first mold resin, and the second mold resin, respectively.

The first mold resin and the second mold resin are not particularly limited as long as the above requirements are satisfied, and for example, a thermosetting resin that satisfies such requirements can be used. For example, a phenol resin, an unsaturated polyester resin, an epoxy resin, etc. are mentioned. The general molding (curing) temperature of the resins listed here and the coefficient of thermal expansion at that temperature are 150 to 200 ° C. and 15 × 10 ^{−6 to} 35 × 10 ⁻⁶ / K for phenol resin, unsaturated polyester resin 150 to 200 ° C. and 5 × 10 ⁻⁶ to 30 × 10 ⁻⁶ / K, and epoxy resin is 140 to 190 ° C. and 5 × 10 ^{−6 to} 100 × 10 ⁻⁶ / K. Further, the thermal expansion coefficient at 150 to 200 ° C. of the core is 12 × 10 ⁻⁶ to 15 × 10 ⁻⁶ / K in the case of the laminated body of silicon steel plates, and 10 × 10 ^{−6 in} the case of the compacted body of soft magnetic powder. ~ 12 × 10 ⁻⁶ / K.

  The first mold resin and the second mold resin may be the same type or different types. Moreover, you may mix fillers, such as ceramics or glass fiber, in each resin. Examples of the ceramic filler include alumina, aluminum nitride, boron nitride, silicon nitride, silicon carbide, zircon, and mullite. A resin containing a ceramic filler is excellent in thermal conductivity. Therefore, it is preferable that the first mold resin constituting the resin mold body 10 in which the coil 11 that generates heat when energized is disposed contains a ceramic filler. In addition, a resin containing a glass fiber filler is excellent in mechanical strength. Therefore, the second mold resin constituting the exterior mold body 20 that protects the end core 12e and the resin mold body 10 preferably contains a glass fiber filler. Thus, the coefficient of thermal expansion of the first mold resin and the second mold resin can be adjusted by changing the type of resin and the material or content of the filler.

Example 1
A reactor 1 including the core 12, the resin mold body 10, and the exterior mold body 20 shown below was manufactured, and a thermal cycle test was performed on the reactor to evaluate the reactor.

The resin mold body 10 was molded using unsaturated polyethylene containing an alumina filler. The molding conditions were a molding temperature of 170 ° C., and the thermal expansion coefficient α _p1 of the resin at the molding temperature was 13 × 10 ⁻⁶ / K.

The exterior mold body 20 was molded using unsaturated polyethylene containing a glass fiber filler. The molding conditions were a molding temperature of 170 ° C., and the thermal expansion coefficient α _p2 of the resin at the molding temperature was 19 × 10 ⁻⁶ / K.

The core 12 (core piece 120, end core 12e) was formed using a compacted body of soft magnetic powder. The thermal expansion coefficient α _c of the core at the above molding temperature was 12 × 10 ⁻⁶ / K.

  The thermal cycle test was conducted up to 100 cycles in the temperature range of -40 to 150 ° C. assuming an actual use environment. As a result, no separation was observed between the exterior mold body 20 and the exposed portion of the core 12 and the resin mold body 10. Further, no separation was observed between the resin mold body 10 and the winding portion of the core 12.

  Note that the present invention is not limited to the above-described embodiment, and can be modified as appropriate without departing from the gist of the present invention. For example, you may change suitably the kind of 1st mold resin and 2nd mold resin, and the material of a filler.

  The reactor of the present invention can be suitably used for, for example, a DC-DC converter for an electric vehicle such as a hybrid vehicle.

1 Reactor
10 Resin mold body
11 Coil 11a, 11b Coil element
11s Start 11e End 11u Bend
12 core 12c winding part (intermediate core) 12e exposed part (end core)
120 Core piece g Gap material
20 Exterior mold body 20h Insertion hole
50 molds
51 First mold 51A End plate 51B Side wall
52 Second mold 52A End plate
53 Rod

Claims (4)

A reactor comprising: a coil formed by spirally winding a winding; a core having a winding part in which the coil is arranged; and an exposed part that is exposed without the coil being arranged;
A resin mold body made of a first mold resin that retains the shape of the coil;
An exterior mold body made of a second mold resin covering the outer periphery of the resin mold body and the exposed portion of the core,
Each of the resin mold body and the exterior mold body is molded at a temperature higher than the use temperature of the reactor,
A reactor satisfying the following relationship when the thermal expansion coefficients of the core, the first mold resin, and the second mold resin at molding temperatures are α _c , α _p1 , and α _p2 , respectively.
α _c <α _p2 and α _p1 ≦ α _p2 The reactor according to claim 1, wherein the relationship between the thermal expansion coefficients satisfies α _c <α _p1 ≦ α _p2 .   The reactor according to claim 1, wherein the first mold resin contains a ceramic filler.   The reactor according to any one of claims 1 to 3, wherein the second mold resin contains a glass fiber filler.

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