Coil device

Abstract

A coil portion (10) is fixed to a case (40) by a first resin (50) and a second resin (60). The first resin (50) and the second resin (60) are both disposed in an accommodation space (44). The second resin (60) is softer than the first resin (50). The first resin (50) seals the opening of an accommodation recess (42). The second resin (60) is disposed closer to the bottom side of the accommodation recess (42) than the first resin (50) in the accommodation space (44). At least part of the coil portion (10) is exposed from the first resin (50). Said part is covered by the second resin (60).

Description

Coil Device

[0001] The present invention relates to a coil device.

[0002] Among coil devices, which are devices having a coil, there is a coil device in which the coil portion is housed in a case. Regarding this type of technology, Patent Document 1 below discloses an antenna device (10) in which the coil portion, which is an integrated body (100) including a core (20) and a coil (50), is housed in a case (70). The integrated body (100) is fixed to the case (70) by a cured resin part (120) such as urethane rubber.

[0003] JP 2019-47382 A

[0004] However, there is room for improvement in the stability of the core when an external force is applied to the core. For example, because the expansion coefficient of resin is generally greater than that of the core, heat generated during use of the coil device can cause the resin surrounding the core to expand and deform, resulting in the resin exerting an external force on the core. In addition, external forces can be applied to the coil device or the housing housing the coil device from outside the coil device, such as when the coil device is dropped or when contact is made with other components. When an external force is applied to the core, the core may deform or break, causing the core's shape to become unstable. Furthermore, when an external force is applied to the core, various magnetic properties, such as the core's temperature characteristics, may change, preventing the coil device from achieving the desired characteristics. Meanwhile, coil devices often require the prevention of liquids, such as water, from entering the housing.

[0005] The present invention has been made in consideration of the above-mentioned problems, and provides a coil device that has improved stability in shape or magnetic properties while suppressing the intrusion of liquid into the inside of the case.

[0006] The coil device of the present invention has a core, a coil section including a winding section which is a conductive material formed in a spiral shape with the extension direction of the core as the helical axis and arranged around the core, and a case in which the coil section is housed, wherein the case has a bottomed recess which includes an accommodation space for accommodating the core and the winding section and which opens in an opening direction which is one of the extension directions, the coil section is fixed to the case by a first resin and a second resin which is softer than the first resin which are respectively arranged in the accommodation space, the first resin sealing the opening of the recess, the second resin being arranged closer to the bottom of the recess than the first resin in the accommodation space, and at least a portion of the coil section being exposed from the first resin and covered by the second resin.

[0007] According to the coil device of the present invention, because the second resin is softer than the first resin, the thermal stress imparted to the coil portion by the second resin when heat is applied to the coil device tends to be smaller than the thermal stress imparted to the coil portion by the first resin when heat is applied. Furthermore, because the second resin is softer than the first resin, the stress imparted to the coil portion by the second resin can be alleviated even when an external force is applied to the coil device or the housing from the outside. Therefore, deformation or damage of the coil portion due to the external force from the second resin is suppressed, and changes in the magnetic properties of the core are suppressed. Furthermore, according to the coil device of the present invention, the opening of the case is sealed by the first resin, which suppresses liquid from entering the inside of the case. This makes it possible to provide a coil device that improves the stability of the core's shape or magnetic properties and suppresses liquid from entering the inside of the case.

[0008] The above-mentioned objects, as well as other objects, features and advantages, will become more apparent from the preferred embodiments described below and the accompanying drawings.

[0009] 1A and 1B are perspective views of a coil device according to a first embodiment of the present invention; FIG. 1C is an exploded perspective view of a coil device according to the first embodiment; FIG. 1D is a cross-sectional view of a coil device taken along dashed line III in FIG. 1A, viewed in the direction of arrows III-III; FIG. 1E is a cross-sectional view of a coil device taken along dashed line IV in FIG. 1A, viewed in the direction of arrows IV-IV; FIG. 5A is a cross-sectional view of a coil device taken along dashed line Va in FIG. 4A, viewed in the direction of arrows Va-Va; FIG. 5B is a cross-sectional view of a coil device taken along dashed line Vb in FIG. 4A, viewed in the direction of arrows Vb-Vb; FIG. 6A is an enlarged perspective view of a front end portion of a bobbin; FIG. 6B is an enlarged view of a front end portion of the coil device in FIG. 4A; FIG. 7A is an enlarged view of an example of the boundary between the first resin and the second resin and its vicinity in FIG. 3; FIG. 7B is an enlarged view of another example of the boundary between the first resin and the second resin and its vicinity in FIG. 3; FIG. 7C is an enlarged view of yet another example of the boundary between the first resin and the second resin and its vicinity in FIG. 3; 8 is a cross-sectional view of a coil device taken along dashed dotted line III shown in Fig. 1, seen in the direction of arrow III-III, and is another example different from Fig. 3. 9 is a cross-sectional view of a coil device taken along dashed dotted line III shown in Fig. 1, seen in the direction of arrow III-III, and is another example different from Fig. 3 and Fig. 8. 10 is a cross-sectional view of a coil device according to a second embodiment of the present invention, corresponding to the cross-sectional view shown in Fig. 3.

[0010] The various components of the coil device of the present invention do not need to be independent entities, and it is acceptable for multiple components to be formed as a single member, for one component to be formed from multiple members, for one component to be part of another component, or for part of one component to overlap with part of another component, etc.

[0011] An embodiment of the present invention will be described below with reference to the drawings. In each drawing, corresponding components are designated by the same reference numerals, and redundant descriptions will be omitted where appropriate. In this embodiment, the front-rear, left-right, top-bottom directions will be defined as shown in the drawings. However, these definitions are provided for convenience in order to easily explain the relative relationships between the components, and do not limit the directions during manufacture or use of a product embodying the present invention. When a coil device is grounded to the surface of another component (a ground surface), the direction normal to the ground surface is referred to as the up-down direction. In the up-down direction, the direction closest to the ground surface is referred to as the down direction, and the direction opposite to the down direction is referred to as the up direction. In this embodiment, the front-rear direction corresponds to the extension direction of the core (which is also the direction of the helical axis). The left-right direction also corresponds to the width direction of the coil device. Furthermore, the term "plane" as used herein refers to a shape physically formed with a flat surface as the target, and of course, it does not necessarily have to be a perfect geometric plane.

[0012] <First embodiment> (Coil device) Fig. 1 is a perspective view showing an example of a coil device 1 according to a first embodiment of the present invention. Fig. 2 is an exploded perspective view of the coil device 1, in which the first resin 50 and the second resin 60 are omitted. Fig. 3 is a longitudinal cross-sectional view of the coil device 1.

[0013] First, an overview of the coil device 1 of this embodiment will be described. As shown in FIG. 2 , the coil device 1 includes a coil portion 10 and a case 40. The coil portion 10 includes a core 20 and a winding portion 30. The winding portion 30 is a conductive member formed in a spiral shape with the extension direction of the core 20 as its helical axis. The winding portion 30 is disposed around the core 20. The case 40 is a member that accommodates the coil portion 10. As shown in FIG. 3 , the case 40 is formed with a bottomed recess (accommodation recess 42). The accommodation recess 42 includes an accommodation space 44 that accommodates the core 20 and the winding portion 30. The accommodation recess 42 opens in an opening direction, which is one of the extension directions. The coil portion 10 is fixed to the case 40 by a first resin 50 and a second resin 60. Both the first resin 50 and the second resin 60 are disposed in the accommodation space 44. The second resin 60 is softer than the first resin 50. The first resin 50 also seals the opening of the accommodating recess 42. The second resin 60 is disposed closer to the bottom of the accommodating recess 42 than the first resin 50 in the accommodating space 44. At least a portion of the coil portion 10 (the second covering portion 12) is exposed from the first resin 50. The second covering portion 12 is also covered with the second resin 60. As described above, the expansion coefficient of resin is generally greater than that of the core. Therefore, the resin surrounding the core may expand and deform due to heat generated during use of the coil device, causing the resin to apply an external force to the core. Additionally, an external force may be applied from outside the coil device to the coil device or to a housing or the like housing the coil device is housed in due to an impact such as a drop or contact with another component. In particular, in the case of a rod-shaped core that is long in the longitudinal direction, such as the core 20 in this embodiment, when an external force is applied to a midpoint of the core 20 in the longitudinal direction, the core 20 may bend and deform, or the core 20 may crack at that midpoint. Specifically, when an external force is applied to the intermediate portion from a direction having a vertical component or a horizontal component, the intermediate portion is likely to be deformed or cracked.According to the above configuration, because the second resin 60 is softer than the first resin, the thermal stress imparted to the coil portion 10 by the second resin 60 when heat is applied tends to be smaller than the thermal stress imparted to the coil portion 10 by the first resin 50 when heat is applied to the coil device 1. Furthermore, because the second resin 60 is softer than the first resin 50, the stress imparted to the coil portion 10 by the second resin 60 can be alleviated even when an external force is applied to the coil device 1 or the housing housing the coil device 1. This prevents the coil portion 10 from being deformed or damaged by the external force from the second resin 60, or prevents the magnetic properties of the core 20 from changing. Furthermore, according to the coil device 1 of this embodiment, the opening of the case 40 is sealed by the first resin 50, thereby preventing liquid from penetrating into the case 40. This makes it possible to provide a coil device 1 in which the stability of the shape or magnetic properties of the core 20 is improved and liquid penetration into the case 40 is suppressed.

[0014] Next, the coil device 1 of this embodiment will be described in detail. The coil device 1 is a device including a coil (the coil section 10 in this embodiment). An example of the coil device 1 is an antenna device in which the coil section 10 is an antenna section. The coil device may also be a device including other coils such as an inductor or a transformer. The coil device 1 of this embodiment is used for security system operations, including locking and unlocking operations in vehicles such as automobiles or houses.

[0015] The coil portion 10 shown in FIG. 2 is a portion that functions as a coil. In this embodiment, the coil portion 10 includes a winding portion 30 and a core 20. The core 20 is formed of a magnetic material. In this embodiment, the core 20 is a member that extends in a predetermined extension direction (front-rear direction). More specifically, the core 20 in this embodiment is a rod-shaped member that is long in the front-rear direction. The core 20 may be fixed to a bobbin 70 (described later) with another member such as an adhesive.

[0016] The winding portion 30 shown in FIG. 2 is a conductive member formed in a spiral shape. An example of the conductive member is a metal such as copper. In this embodiment, the conductive member is a coil wire. However, instead, a plate-shaped metal member formed in a spiral shape may be used as the conductive member. The winding portion 30 is formed in a spiral shape with the extension direction (front-rear direction) of the core 20 as the spiral axis. The winding portion 30 is also disposed on the outer periphery of the core 20. In other words, the core 20 is disposed on the inner diameter side of the spiral shape of the winding portion 30. The winding portion 30 may be formed by winding a conductive member (coil wire) around the core 20, or may be formed by inserting the core 20 into the interior of a spirally formed conductive member (coil wire). In this embodiment, both ends (lead portions 34) of the coil wire are drawn out from the winding portion 30. More specifically, the lead-out portion 34 is drawn out to the front side from the winding portion 30 and is wound around and connected to a terminal (winding terminal 77) fixed to the bobbin 70. The winding terminal 77 is electrically connected to a connector portion 79, which will be described later.

[0017] The case 40 is a member that houses the coil portion 10. At least a portion, preferably the entire coil portion 10, is housed in the case 40. Housed in the case 40 means that at least a portion of the coil portion 10 is disposed in a housing recess 42 (described later). In other words, housed in the case 40 means that at least a portion of the coil portion 10 is disposed within the envelope volume of the case 40. In this embodiment, the coil portion 10, including the winding portion 30, the core 20, and a bobbin (described later), is inserted into the housing recess 42 of the case 40 and housed in the case 40. At this time, the coil wire including the winding portion 30, the core 20, and a portion of the bobbin 70 are housed in the housing recess 42. In this embodiment, a portion of the bobbin 70 (the connector portion 79) is disposed outside the case 40. The case 40 in this embodiment is made of resin and is a member with higher insulating properties than the coil portion 10. Preferably, the case 40 is a member with a lower thermal expansion coefficient than the first resin 50 or the second resin 60 (described later). The case 40 may be integrally formed from a single resin material, as in this embodiment. Alternatively, the case 40 may be formed by combining multiple components by fitting, bonding, or the like. As shown in FIG. 3 , the case 40 has an accommodating recess 42 that opens forward. That is, in this embodiment, the opening direction of the accommodating recess 42 faces forward. The accommodating recess 42 is defined by a bottom 48 and a peripheral wall 49. The depth direction of the accommodating recess 42 is the front-to-rear direction, and the bottom 48 of the accommodating recess 42 is part of the rear side of the case 40. The peripheral wall 49 is part of the upper, lower, left, and right sides of the case 40. That is, the peripheral wall 49 is the part of the case 40 that surrounds the core 20 around the longitudinal direction (front-to-rear direction) of the core 20. The accommodating recess 42 opening in a predetermined direction means that the case 40 opens in the predetermined direction when viewed alone. For example, in this embodiment, as will be described later, the opening of the case 40 is sealed with the first resin 50, and part of the accommodating recess 42 is a closed space. In addition, as will be described later, part of the accommodating recess 42 is also a closed space due to the fitting portion 78 of the bobbin 70.Even in these cases, regardless of whether the first resin 50 or the fitting portion 78 is present or not, when focusing on the case 40 alone, the accommodating recess 42 opens forward, so it can be said that the accommodating recess 42 opens in a predetermined direction.

[0018] 3, the case 40 in this embodiment has legs 47 formed to extend downward from a peripheral wall 49 that defines the accommodating recess 42. The case 40 (coil device 1) is placed on another member so that the lower surfaces of the legs 47 (the lowermost parts of the case 40) come into contact with the surface of the other member.

[0019] As shown in FIG. 2 , the coil device 1 of this embodiment includes a bobbin 70. The bobbin 70 is disposed between the core 20 and the winding portion 30 and extends in the direction of extension of the core 20. More specifically, the bobbin 70 is a hollow cylindrical body into which the core 20 is inserted. In other words, the core 20 is disposed inside the cylindrical body. The winding portion 30 is disposed outside the bobbin 70. The bobbin 70 has a rod-like shape that is elongated in the front-rear direction, similar to the shape of the core 20. The bobbin 70 of this embodiment includes four plate-like wall portions 72 (two short wall portions 72 a and two long wall portions 72 b, described below) that are arranged to have a rectangular cross section and cover the outer periphery of the core 20. In this embodiment, the cross section of the core 20 as viewed from the front-rear direction is rectangular. In other words, the surfaces of the core 20 include an upper surface, a lower surface, a left surface, and a right surface that extend in the front-rear direction. Each wall portion 72 covers the top, bottom, left, and right surfaces of the core 20. The bobbin 70 is provided with a flange 71 (a distal flange 71a and a proximal flange 71b) for preventing the winding portion 30 from loosening. In this embodiment, the flange 71 is a protrusion that protrudes radially from the distal or proximal end of the bobbin 70 beyond some of the bobbins 70 arranged inside the winding portion 30. Specifically, as shown in FIG. 4 , the distal flange 71a is a protrusion that protrudes on both the left and right sides of the distal end (bobbin distal end 74) of the bobbin 70 beyond some of the bobbins 70 arranged inside the winding portion 30. Also, as shown in FIGS. 3 and 4 , the proximal flange 71b is a protrusion that protrudes leftward and downward from some of the bobbins 70 arranged inside the winding portion 30 at the proximal end of the bobbin 70. Here, the radial direction refers to a direction perpendicular to the helical axis direction (front-rear direction), and is a radial direction from the helical axis toward the circumferential surface of the winding section 30. Furthermore, the base end of the bobbin 70, the winding section 30, the core 20, or the coil device 1 refers to one end in the opening direction. The tip end of the bobbin 70, the winding section 30, the core 20, or the coil device 1 refers to one end facing opposite the opening direction. Furthermore, as shown in FIG. 3 , the tip end (core tip end 22) and base end (core base end 24) of the core 20 are exposed from the bobbin 70.More specifically, the tip of the bobbin 70 opens rearward, and the core tip portion 22 protrudes rearward from the bobbin 70. As shown in FIGS. 3 and 4 , the bobbin 70 opens upward and leftward midway along its length, and the surfaces of the core base end portion 24 (part of the upper surface and left surface, in particular) are exposed from the openings of the bobbin 70. Alternatively, the coil device 1 may not have a bobbin 70. That is, no other member may be disposed between the core 20 and the winding portion 30. For example, the coil wire may be wound directly around the core 20.

[0020] The bobbin 70 has a fitting portion 78 at its base end that fits into the opening of the accommodating recess 42 of the case 40. It is preferable that the fitting portion 78 be press-fitted into the case 40. That is, the fitting portion 78 forms a closed space in part of the accommodating recess 42. Alternatively to this embodiment, the bobbin 70 may not have the fitting portion 78. That is, the accommodating recess 42 may not be closed in part by the fitting portion 78. More specifically, the accommodating recess 42 may be closed in part by only the first resin 50. The bobbin 70 also has a connector portion 79. A connector of another device or the like is inserted into the connector portion 79. The connector portion 79 is electrically connected to the winding portion 30, and the coil device 1 is connected to the other device via the connector portion 79. In this embodiment, the connector portion 79 is disposed on an extension of the helical axis. Alternatively, the connector portion 79 may be disposed at a position offset from the helical axis in the left-right or up-down direction. For example, the connector portion 79 may be disposed on either the left or right side of the core base end portion 24 .

[0021] As shown in FIG. 3 , the coil portion 10 is fixed to the case 40 by a first resin 50 and a second resin 60. Fixing the coil portion 10 to the case 40 by the first resin 50 or the second resin 60 means that the first resin 50 or the second resin 60 suppresses the oscillation of the coil portion 10 inside the case 40. In this embodiment, the first resin 50 or the second resin 60 is in close contact with the coil portion 10 and the case 40, respectively, thereby suppressing the oscillation of the coil portion 10. Alternatively, the first resin 50 or the second resin 60 may not be in close contact with the coil portion 10 or the case 40. For example, the first resin 50 or the second resin 60 may have a predetermined shape and be in contact with the coil portion 10 and the case 40, thereby suppressing the oscillation of the coil portion 10 inside the case 40. The first resin 50 or the second resin 60 having a predetermined shape means, for example, that the shape of the first resin 50 or the second resin 60 is approximately the same as the shape of the space between the coil portion 10 and the inner wall (case inner wall 46) of the case 40. Filling the space between the coil portion 10 and the case inner wall 46 with the first resin 50 or the second resin 60 can suppress oscillation of the coil portion 10 relative to the case 40. The coil portion 10 being fixed to the case 40 by the first resin 50 or the second resin 60 means that the winding portion 30, the core 20, or the bobbin 70, or a combination of these, is fixed to the case 40 by the first resin 50 or the second resin 60. In this embodiment, the base end of the bobbin 70 and the core base end 24 exposed from the bobbin 70 are fixed to the case 40 by the first resin 50. Furthermore, the core tip end 22 protruding from the bobbin 70, the bobbin 70, and the winding portion 30 are fixed to the case 40 by the second resin 60. In this embodiment, the first resin 50 and the second resin 60 are arranged side by side in the front-rear direction. Specifically, the first resin 50 is arranged closer to the opening of the accommodation space 44 than the second resin 60, and the second resin 60 is arranged closer to the bottom 48 of the accommodation space 44 than the first resin 50.More specifically, at least a portion of the first resin 50 is disposed closer to the opening than the entire second resin 60, and at least a portion of the second resin 60 is disposed closer to the bottom 48 than the entire first resin 50. A portion of the first resin 50 may be disposed so as to overlap a portion of the second resin 60 in the left-right direction or the up-down direction. For example, a portion of the first resin 50 may be disposed radially outward of a portion of the second resin 60.

[0022] The second resin 60 being softer than the first resin 50 means that the elastic modulus of the second resin 60 is greater than that of the first resin 50. More specifically, the Young's modulus of the second resin 60 is greater than that of the first resin 50. The second resin 60 being softer than the first resin 50 may be achieved by the second resin 60 containing more bubbles than the first resin 50. That is, the second resin 60 may be a foamable resin, so that the Young's modulus of the second resin 60 is greater than that of the first resin 50. In this case, the materials of the first resin 50 and the second resin 60 may be different types of resin or the same type of resin. Alternatively, the first resin 50 and the second resin 60 may be formed of a resin that is substantially free of bubbles. In this embodiment, the second resin 60 is formed of a resin that contains more bubbles than the first resin 50. More specifically, the first resin 50 is a resin that is substantially free of bubbles, and the second resin 60 is a foamable resin. The ratio of the volume of bubbles to the total volume of the second resin 60 (bubble content) is preferably 1% or more and 30% or less. More preferably, the bubble content is 5% or more and 10% or less. By having the bubble content in this range, the second resin 60 can adequately support the coil portion 10, and at the same time, even if the second resin 60 thermally expands, the external force on the coil portion 10 can be sufficiently reduced.

[0023] 3 , the first resin 50 seals the opening of the accommodating recess 42. The first resin 50 sealing the opening of the accommodating recess 42 means that the first resin 50 is disposed inside the case 40, forming a closed space in part of the accommodating recess 42. Preferably, the accommodating recess 42 is liquid-tightly sealed by the first resin 50.

[0024] As shown in FIG. 3 , the second covering portion 12, which is at least a part of the coil portion 10, is exposed from the first resin 50 and covered with the second resin 60. The second covering portion 12 is a part of the surface of the coil portion 10 (particularly, the outer peripheral surface centered on the helical axis). In this embodiment, the second covering portion 12 mainly includes the outer peripheral surface of the winding portion 30, the outer peripheral surface of the bobbin tip portion 74, and the surface of the core tip portion 22. Here, the outer peripheral surface of the winding portion 30 or the bobbin tip portion 74 refers to the surface of the winding portion 30 or the bobbin tip portion 74 facing radially outward. In this embodiment, the entire surface of the coil portion 10 is covered with either the first resin 50 or the second resin 60. Alternatively, if the accommodation space 44 has a bottom hollow portion 44 a or a central hollow portion 44 c, as described below, a part of the surface of the coil portion 10 may be exposed from both the first resin 50 and the second resin 60.

[0025] As shown in FIG. 4 , in this embodiment, the first resin 50 and the second resin 60 extend in the extension direction of the core 20. Also, as shown in FIG. 5A , the second resin 60 is arranged around the coil portion 10 in contact with the coil portion 10 and the inner wall of the case 40 (the case inner wall 46). Similarly, as shown in FIG. 5B , the second resin 60 is arranged around the coil portion 10 in contact with the coil portion 10 and the case inner wall 46. Here, the periphery of the coil portion 10 refers to the periphery of the coil portion 10 when viewed in the extension direction (front-rear direction) of the coil portion 10. In other words, the periphery of the coil portion 10 refers to a portion of the outer diameter side of the coil portion 10. That is, the first resin 50 or the second resin 60 is arranged on a portion of the outer diameter side of the coil portion 10. 5( a) and 5(b), the first resin 50 and the second resin 60 are arranged so as to surround the periphery of the coil portion 10 when viewed in the extension direction of the core 20. Here, "arranging the first resin 50 and the second resin 60 so as to surround the periphery of the coil portion 10" means that the first resin 50 and the second resin 60 surround substantially the entire circumference of the coil portion 10 in a continuous manner on the outer diameter side of the coil portion 10. In other words, the first resin 50 and the second resin 60 may surround the entire circumference of the coil portion 10, or the first resin 50 and the second resin 60 may surround approximately the entire circumference of the coil portion 10, but a portion of the coil portion 10 in the radial direction may be exposed from the first resin 50 or the second resin 60. Furthermore, the phrase "the first resin 50 or the second resin 60 surrounds the periphery of the coil portion 10 (surrounds the outer diameter side of the coil portion 10)" includes both the first resin 50 or the second resin 60 directly covering the coil portion 10 and the first resin 50 or the second resin 60 indirectly covering the coil portion 10. "The first resin 50 or the second resin 60 directly covering the coil portion 10" means that no other member is disposed between the first resin 50 or the second resin 60 and the coil portion 10. For example, this may be the case where the first resin 50 or the second resin 60 is disposed on the outer diameter side of the coil portion 10 in direct contact with the coil portion 10.Another example of the first resin 50 or the second resin 60 directly covering the coil portion 10 is when the first resin 50 or the second resin 60 is disposed on the outer diameter side of the coil portion 10 at a distance from the coil portion 10. Furthermore, when the first resin 50 or the second resin 60 indirectly covers the coil portion 10, for example, the first resin 50 or the second resin 60 is disposed on the outer diameter side of another member that covers the outer diameter side of the coil portion 10. In this embodiment, the first resin 50 or the second resin 60 indirectly covers the coil portion 10. That is, the first resin 50 or the second resin 60 is disposed on the outer diameter side of the bobbin 70 that covers the first resin 50 or the second resin 60, and further surrounds the bobbin 70 that surrounds the periphery of the coil portion 10. However, in this embodiment, another portion of the first resin 50 or another portion of the second resin 60 is in contact with the coil portion 10.

[0026] As shown in FIG. 3 , in this embodiment, the second resin 60 contacts the first resin 50 at a contact region 62 facing the opening direction. The contact region 62 is a partial or entire region of an opening-side end surface 64 of the second resin 60. The opening-side end surface 64 of the second resin 60 is an end surface of the surface of the second resin 60 facing the opening side (front side). In this embodiment, the contact region 62 is arranged to intersect with the extension direction (front-rear direction) of the bobbin 70. The contact region 62 is arranged to pass through a portion of the coil portion 10 that is closer to the base end than the winding portion 30. Specifically, the contact region 62 in this embodiment is arranged to pass through the base end flange portion 71b of the bobbin 70. More specifically, the contact region 62 is arranged to pass through the middle of the base end flange portion 71b in the front-rear direction. In other words, a portion of the tip side of the base end flange 71b is covered with the second resin 60, and a portion of the base end side of the base end flange 71b is covered with the first resin 50. When the first resin 50 or the second resin 60 expands due to heat or when an external force is applied to the coil device 1, the first resin 50 or the second resin 60 may shift up and down or left and right at the boundary between the first resin 50 and the second resin 60. Because the contact region 62 (the boundary between the first resin 50 and the second resin 60) passes through the base end flange 71b, which is thicker than the winding portion 30 in the bobbin 70, even if the first resin 50 or the second resin 60 shifts up and down or left and right, the external force caused by the shift is less likely to be transmitted to the core 20. As a result, deformation or damage to the core 20 is suppressed.

[0027] 3 (a part of the coil wire) is disposed from the first resin 50 to the second resin 60. More specifically, the binding terminal 77 (see FIG. 2) is embedded in the first resin 50, and the winding portion 30 is embedded in the second resin 60. Because the draw-out portion 34 is drawn out from the winding portion 30 to the opening side, a part of the draw-out portion 34 on the winding portion 30 side (tip side) is embedded in the second resin 60, and a part of the draw-out portion 34 on the opening side (base end side) is embedded in the first resin 50.

[0028] As shown in FIG. 3 , the dimension of the second resin 60 in the extension direction (front-rear direction) of the core 20 may be larger than the dimension of the first resin 50 in the extension direction of the core 20. This makes the portion of the surface of the core 20 covered by the second resin 60 larger than the portion covered by the first resin 50. As a result, deformation or damage to the core 20 due to thermal expansion of the first resin 50 is more effectively suppressed. In this embodiment, the first resin 50 covers a portion of the base end side of the core 20 (core base end 24) and a portion of the base end side of the bobbin 70. Meanwhile, the entire winding portion 30 is not covered by the first resin 50 and is exposed from the first resin 50. In other words, the first resin 50 is not provided on the radially outer side of a portion of the core 20 arranged inside the winding portion 30, but the second resin 60 is provided. This makes the portion of the core 20 inside the winding portion 30 particularly less susceptible to external forces due to thermal expansion of the first resin 50. Therefore, deformation or breakage of the part of the core 20 inside the winding portion 30 is suitably suppressed.

[0029] In this embodiment, as shown in FIG. 3 , the second resin 60 covers the core tip portion 22. More specifically, the second resin 60 is disposed from the base end of the winding portion 30 to the tip of the core 20. As such, in this embodiment, the second resin 60 suppresses deformation or damage to substantially the entire core 20. Also, in this embodiment, the second resin 60 contacts the bottom portion 48 of the accommodating recess 42. More specifically, the second resin 60 contacts the entire surface of the bottom portion 48. The second resin 60 abuts or adheres to the bottom portion 48. As a result, even when an external force is applied to the coil device 1 (particularly when an external force is applied to the coil device 1 in the front-rear direction), the second resin 60 reduces the front-rear oscillation of the coil portion 10. This can suppress deformation or damage to the core 20.

[0030] As shown in FIG. 8 , instead of this embodiment, the second resin 60 may be spaced apart from the bottom 48 of the accommodating recess 42. Specifically, the accommodating space 44 may have a bottom hollow portion 44a, which is a hollow portion disposed between the bottom 48 and the second resin 60. This allows the second resin 60 to expand toward the bottom hollow portion 44a (rearward) even if the second resin 60 expands slightly due to heat, thereby reducing the external force applied by the second resin 60 to the core 20 and the bobbin 70. As a result, deformation or damage to the core 20 is more effectively suppressed. In FIG. 8 , the end face (base end face 65) of the second resin 60 facing the bottom 48 (base end side) is positioned so as to pass through the bobbin tip portion 74. More specifically, the base end face 65 is positioned distal to the winding portion 30 and proximal to the tip of the bobbin 70. In other words, the entire winding portion 30 and a portion of the bobbin 70 are covered with the second resin 60, but the bobbin tip portion 74 and the core tip portion 22 are exposed from the second resin 60. Since the core tip portion 22 is exposed from the second resin 60 and is not fixed by either the first resin 50 or the second resin 60, deformation or cracking of the core 20 is more effectively suppressed. Specifically, in the present embodiment, when a connector portion 79 is provided at one end (front end) and other components are fixed thereto, unexpected external forces may be applied to the front end of the coil device 1 if the other components (particularly the connector connected to the connector portion 79) unexpectedly move. In particular, external forces may be applied to the front end in the vertical or horizontal direction. At this time, similar external forces may also be applied to the front end (base end) of the core 20. In this embodiment, the base end of the core 20 is fixed to the case 40 by the hard first resin 50, the middle portion of the core 20 in the front-rear direction is fixed by the soft second resin 60, and the tip end of the core 20 is not fixed by resin or the like, so that the core 20 gradually bends from the base end to the tip end. Therefore, compared to when the entire length of the core 20 is fixed to the first resin 50 or the second resin 60, the core 20 bends appropriately even when an external force is applied to the base end of the coil device 1, so stress is less likely to concentrate on a portion of the core 20. As an alternative to the embodiment shown in FIG. 8 , the base-side end face 65 may be arranged to pass through a portion of the core 20 protruding rearward from the bobbin 70.That is, the second resin 60 may cover the bobbin tip portion 74 including the tip of the bobbin 70 , and the core tip portion 22 may be exposed from the second resin 60 .

[0031] As shown in FIG. 3 , in this embodiment, the end face (opening-side end face 64) of the second resin 60 facing the opening direction extends along a direction perpendicular to the extension direction of the core 20. Furthermore, the case 40 has a through-hole 49a penetrating the peripheral wall 49 in the thickness direction in a portion of the peripheral wall 49 that defines the accommodation space 44 and that contacts the first resin 50. That is, the through-hole 49a opens to the accommodation space 44 and the outside of the case 40. The through-hole 49a may be a hole for injecting a resin such as the first resin 50. With the above configuration, the direction of the normal to the opening-side end face 64 (front-rear direction) and the penetration direction of the through-hole 49a (up-down direction) are approximately perpendicular. As a result, even if a force is applied to the first resin 50 at the interface between the first resin 50 and the second resin 60 (near the opening-side end face 64) due to thermal expansion of the first resin 50 or the second resin 60, the direction of the force applied to the first resin 50 is the front-rear direction. Furthermore, even when a force is applied to the second resin 60 at the boundary surface, the direction of the force applied to the second resin 60 is the front-rear direction. That is, because the thermal stress of the first resin 50 or the second resin 60 acts in the front-rear direction, damage or deformation of the core 20 due to the thermal stress is suppressed. Furthermore, because the direction in which the thermal stress acts is the front-rear direction and the penetration direction of the through hole 49a is perpendicular to the front-rear direction, the first resin 50 is suppressed from being pushed out of the through hole 49a due to the thermal stress. Alternatively, because the penetration direction of the through hole 49a is perpendicular to the front-rear direction, the first resin 50 is less likely to be pressed against a portion of the case 40 near the through hole 49a. Therefore, deformation of the first resin 50 due to the shape of the portion near the through hole 49a is suppressed, or deformation of the portion is suppressed due to the reduced stress from the first resin 50. As in the second embodiment shown in Figure 10 and described later, when the opening side end face 64 of the second resin 60 and the rearward-facing end face (base side end face 52) of the first resin 50 are spaced apart, it is preferable that the base side end face 52 also extends along a direction perpendicular to the extension direction of the core 20.As shown in FIG. 3 , the opening-side end face 64 extending in a direction (vertical and horizontal directions) perpendicular to the extension direction of the core 20 means that the opening-side end face 64 is generally parallel to the vertical and horizontal directions. More specifically, the extension direction of the opening-side end face 64 has a vertical component greater than a front-rear component, and a horizontal component greater than a front-rear component. Note that the opening-side end face 64 extending in a predetermined direction refers to the direction in which the entire opening-side end face 64 extends. That is, even if the opening-side end face 64 has an irregularity formed by a first contact portion 66 a, a second contact portion 66 b, and a non-contact portion 66 c, as described below, the extension direction of the opening-side end face 64 may be defined as the approximate extension direction of the opening-side end face 64. In this embodiment, the case 40 is provided with two through holes 49 a 1 and 49 a 2. The two through holes 49 a 1 and 49 a 2 are arranged side by side in the front-rear direction.

[0032] As shown in FIG. 7( a), the end portion (opening-side end portion 66) of the second resin 60, including the end face (opening-side end face 64) facing the opening direction, includes a first contact portion 66a, a second contact portion 66b, and a non-contact portion 66c. The first contact portion 66a contacts the coil portion 10 (particularly the bobbin 70, the core 20, or the winding portion 30). The second contact portion 66b contacts the case inner wall 46. The non-contact portion 66c is disposed between the first contact portion 66a and the second contact portion 66b. The non-contact portion 66c is not in contact with either the coil portion 10 or the case inner wall 46. The first contact portion 66a and the second contact portion 66b are located on or near the outer surface of the second resin 60 that contacts the coil portion 10 or the case inner wall 46. The first contact portion 66a, the second contact portion 66b, and the non-contact portion 66c are part of the second resin 60, and are parts that have a thickness in the radial direction. The first contact portion 66a, the second contact portion 66b, and the non-contact portion 66c are each arranged to surround the outer periphery of the coil portion 10. That is, the first contact portion 66a is located on the outer diameter side of the coil portion 10, the non-contact portion 66c is located further outer diameter than the first contact portion 66a, and the second contact portion 66b is located further outer diameter than the non-contact portion 66c. In this embodiment, the first contact portion 66a and the second contact portion 66b protrude (forward) toward the opening of the case 40 beyond the non-contact portion 66c. That is, a portion of the opening-side end surface 64 is a concave surface with a center recessed rearward between the case inner wall 46 and the coil portion 10. The unevenness of the opening-side end surface 64 makes the change in rigidity between the second resin 60 and the first resin 50 more gradual than if the opening-side end surface 64 were flat. As a result, cracks and the like are suppressed from occurring between the first resin 50 and the second resin 60. Furthermore, because the protruding first contact portion 66a is in contact with the coil portion 10, when the coil portion 10 swings inside the case 40, the first contact portion 66a can deform to follow the orientation of the coil portion 10. As a result, the second resin 60 and the coil portion 10 are well adhered to each other, so that the coil portion 10 is suitably held in the case 40. Similarly, when the case 40 is moved relative to the coil portion 10, the second contact portion 66b can deform to follow the case 40, and the coil portion 10 is suitably held in the case 40. Alternatively to this embodiment, the opening side end surface 64 may be a generally flat surface without any irregularities.Alternatively, the non-contact portion 66 c may protrude further in the opening direction (forward) than the first contact portion 66 a and the second contact portion 66 b. That is, the opening-side end face 64 may be a convex surface whose radially central portion protrudes forward.

[0033] The first contact portion 66a or the second contact portion 66b protruding further forward than the non-contact portion 66c means that at least a portion of the first contact portion 66a or the second contact portion 66b protrudes further forward than the non-contact portion 66c. The first contact portion 66a and the second contact portion 66b are portions having thickness, and are surfaces (the radially outward surface or the radially inward surface of the second resin 60) that contact the coil portion 10 or the case inner wall 46, and portions in the vicinity thereof. Therefore, the first contact portion 66a may protrude most forward at the contact surface between the first contact portion 66a and the coil portion 10, as illustrated in FIG. 7(a). Alternatively, the first contact portion 66a may protrude most forward near the center of the first contact portion 66a in the radial direction (the up-down direction in the drawing), as illustrated in FIG. 7(b). Similarly, the second contact portion 66b may protrude most forward at the contact surface between the second contact portion 66b and the case inner wall 46, as shown in FIG. 7( a), or may protrude most forward near the center of the second contact portion 66b in the radial direction (the up-down direction in the figure), as shown in FIG. 7( b). In this embodiment, the first resin 50 and the second resin 60 are in contact with each other at the contact region 62, as described above. A portion of the base end of the first resin 50 has a shape corresponding to the opening-side end 66. Specifically, a central portion 51 of the base end of the first resin 50, sandwiched between the coil portion 10 and the case inner wall 46, protrudes rearward, and the central portion 51 is in contact with the non-contact portion 66c.

[0034] In this embodiment, as shown in FIG. 7A , the position in the front-rear direction of the opening-side end 66e arranged on the upper side of the coil portion 10 (position indicated by dashed dotted line A) is substantially the same as the position in the front-rear direction of the opening-side end 66d arranged on the lower side of the coil portion 10 (position indicated by dashed dotted line B). The positions of the opening-side end portions 66d, 66e in the front-rear direction refer to, for example, the positions of the non-contact portions 66c of the opening-side end portions 66d, 66e in the front-rear direction. Alternatively, the position of the opening-side end 66e arranged on the upper side of the coil portion 10 in the front-rear direction may be shifted relative to the position of the opening-side end 66d arranged on the lower side of the coil portion 10 in the front-rear direction. For example, as shown in FIG. 7C , the position of the opening-side end 66e arranged on the upper side of the coil portion 10 in the front-rear direction (position indicated by dashed dotted line A) may be closer to the opening side (forward) than the position of the opening-side end 66d arranged on the lower side of the coil portion 10 in the front-rear direction (position indicated by dashed dotted line B). By extending the opening-side end 66e further forward, the core 20 exposed from the bobbin 70 can be more suitably protected by the second resin 60. Alternatively, the opening-side end 66d arranged below the coil portion 10 may be arranged closer to the opening (more forward) than the opening-side end 66e arranged above the coil portion 10.

[0035] As shown in FIG. 6( a), the bobbin 70 includes four walls 72. Specifically, the four walls 72 are rectangular when viewed in the front-to-rear direction. Here, the walls 72 forming the shorter sides of the rectangle are referred to as short walls 72a, and the walls 72 forming the longer sides of the rectangle are referred to as long walls 72b. As shown in FIG. 6( a), in this embodiment, a pair of opposing walls has a protrusion 72c that protrudes outward in the radial direction. More specifically, the tip of each of the pair of short walls 72a, 72a has a protrusion 72c that protrudes outward in the left-right direction. As shown in FIG. 6( b), the protrusion 72c contacts the case inner wall 46. The protrusion 72c may be in pressure contact with the case inner wall 46 or may simply abut against the case inner wall 46. At one end (bobbin tip 74) of the bobbin 70 opposite the opening direction, slits 76 extending in the front-rear direction are provided between each of the four wall portions 72. That is, the tip of the bobbin 70 is branched into four. Each of the pair of short wall portions 72a curves toward the opposite side of the opening direction (toward the tip of the bobbin 70) so as to approach the core 20 and contacts the core 20 at its tip. Because the slits 76 separate the walls 72, the short wall portions 72a can be deformed to curve. Therefore, when the protruding portion 72c is pressed toward the core by the case inner wall 46, the short wall portion 72a curves and contacts the core 20. With the protruding portion 72c of the bobbin 70 in contact with the case inner wall 46 and the bobbin tip 74a in contact with the core 20, the core 20 can be securely held in the case 40. In this embodiment, the protrusion 72c is not formed on the longitudinal wall portion 72b. Alternatively, the protrusion 72c may be formed on both the short wall portion 72a and the longitudinal wall portion 72b. Alternatively, the protrusion 72c may be formed only on the longitudinal wall portion 72b, and not on the short wall portion 72a. As shown in FIG. 3 , in this embodiment, the tip portion of the longitudinal wall portion 72b becomes thinner toward the tip. More specifically, the inner wall of the longitudinal wall portion 72b (the surface facing the core 20; tapered surface 72b1) has a tapered shape, and the vertical dimension in the hollow inside the bobbin 70 increases toward the tip.Therefore, the tip of the longitudinal wall portion 72b is separated from the core 20. In this embodiment, the second resin 60 is arranged to fill the space between the tapered surface 72b1 and the core 20. Alternatively, the second resin 60 may not be arranged between the tapered surface 72b1 and the core 20, and the space between the tapered surface 72b1 and the core 20 may be part of the bobbin hollow portion 44b.

[0036] The bobbin 70 according to this embodiment may be provided alone, without the core 20, the winding portion 30, or the case 40. Specifically, as described above, the bobbin 70 houses the core 20 therein. The bobbin 70 has a hollow space extending in a predetermined direction (the front-rear direction) and is housed in a housing recess 42 provided in the case 40. The hollow space inside the bobbin 70 is defined by four wall portions 72 arranged in a rectangular shape when viewed in the front-rear direction. At one end of the bobbin 70 in the front-rear direction (the bobbin tip portion 74), a slit portion 76 extending in the front-rear direction is provided between each of the four wall portions 72. A pair of opposing wall portions 72 has protruding portions 72c that protrude outward. As described above, when the bobbin 70 is housed in the case 40, the protruding portions 72c can be pressed against or abut against the inner wall 46 of the case. Furthermore, when the bobbin 70 is housed in the case 40, each of the pair of short wall portions 72a curves toward the tip of the bobbin 70 so as to approach the core 20, and can come into contact with the core 20 at the tip.

[0037] As shown in FIG. 3 or 4 , in this embodiment, a hollow portion, i.e., a bobbin hollow portion 44b, is provided between the core 20 and the bobbin 70. The first resin 50 and the second resin 60 are not disposed in the bobbin hollow portion 44b. The presence of a hollow portion between the core 20 and the bobbin 70 makes it difficult for the external force to be transmitted to the core 20, even if the first resin 50 or the second resin 60 expands due to heat and applies the external force to the bobbin 70. More specifically, as shown in FIG. 3 , the upper surface of the core 20 is separated from the inner wall of the bobbin 70, and the space between the upper surface of the core 20 and the inner wall of the bobbin 70 is the bobbin hollow portion 44b. Furthermore, the lower surface of the core 20 is in contact with the inner wall of the bobbin 70, except for the tapered surface 72b1. In other words, the bobbin hollow portion 44b is not disposed between the lower surface of the core 20 and the inner wall of the bobbin 70. As shown in FIG. 4 , the left and right surfaces of the core 20 are spaced apart from the inner wall of the bobbin 70, and the spaces between the left surface of the core 20 and the inner wall of the bobbin 70 and between the right surface of the core 20 and the inner wall of the bobbin 70 are bobbin hollow portions 44b. As shown in FIG. 5B , at the core base end 24, the bobbin 70 covers the left, right, and lower sides of the core base end 24 but does not cover the upper side. In this case, the first resin 50 is in contact with the upper surface of the core base end 24, and the inner wall of the bobbin 70 is in contact with the lower surface of the core base end 24. The left and right surfaces of the core base end 24 are each spaced apart from the inner wall of the bobbin 70, and the spaces between the left surface of the core base end 24 and the inner wall of the bobbin 70 and the space between the right surface of the core base end 24 and the inner wall of the bobbin 70 are part of the bobbin hollow portion 44b. 5A, the second resin 60 may be disposed in the slit portion 76 (the space between adjacent wall portions 72). That is, the second resin 60 may penetrate between the short wall portion 72a and the long wall portion 72b. This makes it difficult for the second resin 60 to displace the positions of the wall portions 72. As a result, even if the second resin 60 expands slightly due to heat and applies an external force to the wall portions 72, the external force is not easily transmitted to the core 20, making it difficult for damage or deformation of the core 20 to occur.In this embodiment, the second resin 60 is disposed in the entire slit portion 76 (the space between adjacent wall portions 72). However, the second resin 60 may be disposed only in a portion of the slit portion 76. Alternatively, the second resin 60 may not be disposed in the slit portion 76. That is, the slit portion 76 (the space between adjacent wall portions 72) may be a portion of the bobbin hollow portion 44b. In this case, even if the second resin 60 expands slightly due to heat, the hollow slit portion 76 allows the wall portion 72 to deform in response to the expansion of the second resin 60. As a result, external forces due to the expansion of the second resin 60 are less likely to be transmitted to the core 20. In this embodiment, the thickness (radial dimension) of the bobbin hollow portion 44b is smaller than the thickness (radial dimension) of the bobbin 70. The small thickness of the bobbin hollow portion 44b reduces the amount of gas in the bobbin hollow portion 44b. This reduces the impact of gas expansion due to heat generated during use of the coil device 1.

[0038] As shown in FIG. 3 , the coil portion 10 is arranged parallel to the opening direction (front-rear direction) of the accommodating recess 42. Alternatively, the coil portion 10 may be inclined obliquely with respect to the opening direction of the accommodating recess 42. Specifically, as shown in FIG. 9 , the coil portion 10 may be arranged obliquely downward toward the bottom. That is, the tip end of the coil portion 10 may be arranged lower than the base end of the coil portion 10. By arranging the coil portion 10 obliquely with respect to the opening direction in this manner, the thickness (vertical dimension) of the second resin 60 arranged above the coil portion 10 on the bottom side can be increased. The coil portion 10 is supported by the case 40 at a fitting portion 78 that fits into the case 40. However, the tip end of the coil portion 10 is spaced apart from the fitting portion 78 and is therefore more likely to swing relative to the case 40 than the fitting portion 78. When an external force is applied to the coil device 1 (particularly when an external force is applied to the coil device 1 from above), the thick second resin 60 is disposed above the tip of the coil portion 10, thereby suppressing the external force from being transmitted to the tip. As a result, deformation or breakage of the coil portion 10 due to swinging or the like is suppressed.

[0039] Second Embodiment Fig. 10 is a longitudinal sectional view of a coil device 1 according to this embodiment. First, an overview of the coil device 1 of this embodiment will be described.

[0040] The coil device 1 of this embodiment is characterized in that at least a portion of the coil portion 10 is exposed from the first resin 50 and covered with the second resin 60, similar to the first embodiment.

[0041] Next, the coil device 1 of this embodiment will be described in detail. The coil device 1 of this embodiment differs from the first embodiment in that the second resin 60 is spaced apart from the first resin 50. Specifically, as described above, the first resin 50 and the second resin 60 are arranged to surround the periphery of the coil portion 10 when viewed in the extension direction of the core 20. Furthermore, as shown in FIG. 10 , the first resin 50 and the second resin 60 are arranged spaced apart from each other in the extension direction of the core 20. The accommodation space 44 includes a central hollow portion 44c, which is a hollow portion arranged between the first resin 50 and the second resin 60. By arranging the central hollow portion 44c adjacent to the second resin 60 and the first resin 50, the first resin 50 and the second resin 60 can thermally expand toward the central hollow portion 44c. This reduces the stress applied to the coil portion 10 by the first resin 50 or the second resin 60. Furthermore, when the pair of legs 47 of the case 40 are in contact with the mounting surface as in this embodiment, if an external force in the up-down or left-right direction is applied to a portion of the core 20 extending in the length region sandwiched between the two legs 47 (in other words, the middle portion of the core 20 in the front-to-back direction), the middle portion may deform or crack. The provision of the central hollow portion 44c and the middle portion not being fixed to either the first resin 50 or the second resin 60 allows the middle portion to flex flexibly, thereby suppressing deformation or cracking in the middle portion.

[0042] In this embodiment, both front-rear end portions of the coil portion 10 are supported by the first resin 50 and the second resin 60. This allows the coil portion 10 to be suitably held in the case 40. In this embodiment, as shown in FIG. 10 , the opening end 66 of the second resin 60 and the base end face 52 of the first resin 50 are spaced apart in the front-rear direction. In this embodiment, the opening end 66 and the base end face 52 are arranged to intersect (substantially perpendicular to) the front-rear direction. The space defined by the base end face 52, the opening end 66, the outer peripheral surface of the coil portion 10, and the case inner wall 46 is the central hollow portion 44c. The second resin 60 and the first resin 50 are not disposed in the central hollow portion 44c. In this embodiment, as in the first embodiment, the base end face 52 of the first resin 50 passes through the base flange portion 71b. That is, a portion of the base end side of the base end flange 71b is covered with the first resin 50, and a portion of the tip end side of the base end flange 71b is exposed from the first resin 50 and the second resin 60. Furthermore, in this embodiment, the lead-out portion 34 extends from the central hollow portion 44c to the first resin 50. That is, a portion of the lead-out portion 34 on the winding portion 30 side (base end side) is exposed from the first resin 50 and the second resin 60, and a portion of the tip end side of the lead-out portion 34 is covered by the first resin 50. Furthermore, the dimension of the central hollow portion 44c in the front-rear direction is preferably larger than the dimension of the first resin 50 in the front-rear direction and larger than the dimension of the second resin 60 in the front-rear direction. That is, a sufficient length region (length region in the front-rear direction) of the coil portion 10 is an exposed region that is exposed from the first resin 50 and the second resin 60. Even when an external force is applied to the coil device 1, the exposed area can bend appropriately, thereby preventing damage such as cracks from occurring in the coil portion 10 (particularly the core 20).

[0043] In this embodiment, the second resin 60 is disposed in contact with the bottom 48 of the accommodating recess 42. One end of the core 20 opposite the opening direction (core tip end 22) is covered with the second resin 60. One end of the winding portion 30 opposite the opening direction (winding tip end 32) is exposed from the second resin 60. This makes it difficult for a portion of the core 20 disposed inside the winding portion 30 to be subjected to thermal stress from the second resin 60. It is sufficient that the winding tip end 32, which is a portion of the winding portion 30, is exposed from the second resin 60. Preferably, the entire winding portion 30 (the length region from the tip to the base end of the winding portion 30) is exposed from the second resin 60. In this embodiment, the opening side end surface 64 of the second resin 60 passes through a portion of the bobbin 70 on the tip side of the winding portion 30. In other words, the entire winding portion 30 is exposed from the first resin 50 and the second resin 60, the bobbin tip portion 74 is covered with the second resin 60, and a portion of the bobbin 70 further forward than the base-end flange portion 71b is covered with the first resin 50. Note that a portion of the bobbin 70 and a portion of the core 20 arranged inside the winding portion 30 are exposed from the first resin 50 and the second resin 60. Alternatively, the opening-side end surface 64 of the second resin 60 may pass through a portion of the coil portion 10 further forward than the tip of the bobbin 70. For example, the opening-side end surface 64 may pass through a portion of the core 20 protruding rearward from the bobbin 70.

[0044] The coil device 1 of this embodiment differs from the first embodiment in that it has a central hollow portion 44c as described above, but has other features similar to those of the first embodiment. For example, in this embodiment, as in the first embodiment, the opening-side end surface 64 of the second resin 60 extends along a direction perpendicular to the extension direction of the core 20. Furthermore, the case 40 has a through-hole 49a penetrating the peripheral wall 49 in the thickness direction in a portion of the peripheral wall 49 that defines the housing space 44 and that contacts the first resin 50. Also in this embodiment, the first contact portion 66a and the second contact portion 66b protrude further toward the opening of the case 40 than the non-contact portion 66c (see FIGS. 7(a) to 7(c) in the first embodiment). Furthermore, the bobbin tip portion 74 may have a slit portion 76, and each of the wall portions 72 at the bobbin tip portion 74 may be curved and contact the core 20 (see FIGS. 6(a) and 6(b) in the first embodiment). Furthermore, a bobbin hollow portion 44 b may be provided between the core 20 and the bobbin 70 .

[0045] The present invention is not limited to the above-described embodiment, but includes various modifications and improvements as long as the object of the present invention is achieved.

[0046] The above embodiments encompass the following technical concepts: (1) A coil device comprising: a core; a coil portion including a winding portion formed in a spiral shape with the extension direction of the core as a helical axis and arranged around the core, the winding portion being a conductive material; and a case that houses the coil portion, wherein the case has a housing space that houses the core and the winding portion and a bottomed recess that opens in an opening direction that is one of the extension directions, the coil portion being fixed to the case by a first resin and a second resin that is softer than the first resin that are respectively arranged in the housing space, the first resin sealing the opening of the recess, the second resin being arranged closer to the bottom of the recess than the first resin in the housing space, and at least a portion of the coil portion being exposed from the first resin and covered by the second resin. (2) The coil device described in (1), wherein the first resin and the second resin are arranged to surround the periphery of the coil portion when viewed in the extension direction of the core, and the second resin is in contact with the first resin at a contact region that faces the opening direction. (2-1) The coil device according to (2), wherein the contact region is arranged to pass through a flange portion formed on the bobbin and arranged closer to the opening than the winding portion. (3) The coil device according to (2), wherein a dimension of the second resin in the extension direction of the core is larger than a dimension of the first resin in the extension direction of the core. (3-1) The coil device according to (3), wherein the first resin is not arranged, but the second resin is arranged, radially outward of a portion of the core arranged inside the winding portion. (4) The coil device according to (2) or (3), wherein the second resin is spaced from a bottom of the recess, and the accommodating space has a bottom-side hollow portion that is a hollow portion arranged between the bottom and the second resin. (4-1) The coil device according to (4), wherein a base-side end face, which is an end face of the second resin facing the bottom, is arranged to pass through a tip portion of the bobbin, and the base-side end face is arranged closer to the tip than the winding portion and closer to the base than the tip of the bobbin.(5) The coil device according to (1), wherein the first resin and the second resin are arranged to surround the periphery of the coil portion as seen in the extension direction of the core, the first resin and the second resin are spaced apart from each other in the extension direction of the core, and the accommodating space includes a central hollow portion that is a hollow portion arranged between the first resin and the second resin. (5-1) The coil device according to (5), wherein a dimension of the central hollow portion in the extension direction of the core is larger than a dimension of the first resin in the extension direction and larger than a dimension of the second resin in the extension direction. (6) The coil device according to (5), wherein the second resin is arranged in contact with a bottom portion of the recess, one end of the core opposite to the opening direction is covered with the second resin, and one end of the winding portion opposite to the opening direction is exposed from the second resin. (6-1) The coil device according to (6), wherein an opening-side end face of the second resin that faces the opening direction extends along a direction perpendicular to the extension direction of the core, and the opening-side end face passes through a part of the bobbin that is further forward than the winding portion. (7) The coil device according to any one of (2) to (6), wherein an end face of the second resin that faces the opening direction extends along a direction perpendicular to the extension direction of the core, and the case has a through-hole that penetrates in a thickness direction of the peripheral wall in a part that contacts the first resin in a peripheral wall that defines the accommodation space. (8) A coil device described in any one of (2) to (7), wherein the second resin extends in the extension direction of the core, and is arranged around the coil portion in contact with the coil portion and the inner wall of the case, and an end of the second resin including an end face facing the opening direction includes a first contact portion in contact with the coil portion, a second contact portion in contact with the inner wall, and a non-contact portion arranged between the first contact portion and the second contact portion, and the first contact portion and the second contact portion protrude further than the non-contact portion toward the opening.(9) A coil device according to any one of (2) to (8), further comprising a bobbin disposed between the core and the winding portion and extending in the extension direction of the core, wherein the cross section of the core viewed from the extension direction is rectangular, and the bobbin includes four plate-shaped wall portions arranged to have a rectangular cross section so as to cover the outer periphery of the core, and two of the pair of opposing walls are provided with protrusions that protrude outward and contact the inner wall of the case, and at one end of the bobbin opposite the opening direction, a slit portion extending in the extension direction is provided between each of the four walls, and each of the wall portions having the protrusions is curved so as to approach the core in the direction opposite the opening direction and is in contact with the core at the opposite end. (9-1) The coil device according to (9), wherein two of the four wall portions that are a pair of opposing wall portions do not have protrusions formed thereon, wherein the inner walls of the bottom-side ends of the other wall portions have a tapered shape, wherein the other wall portions become thinner toward the bottom, and wherein the hollow dimension of the interior of the bobbin increases toward the bottom in the direction in which the other wall portions face each other. (10) The coil device according to (9), wherein a bobbin inner hollow portion that is a hollow portion is provided between the core and the bobbin, and wherein the first resin and the second resin are not disposed in the bobbin inner hollow portion. (10-1) The coil device according to (10), wherein the space between adjacent wall portions is part of the bobbin inner hollow portion. (10-2) The coil device according to (10), wherein a second resin is disposed in the space between adjacent wall portions. (10-3) The coil device according to (10), wherein the thickness (diameter dimension) of the hollow portion in the bobbin is smaller than the thickness (diameter dimension) of the bobbin. (11) The coil device, wherein the position of the opening-side end portion arranged on the upper side of the coil portion in the extension direction of the core is closer to the opening side than the position of the opening-side end portion arranged on the lower side of the coil portion in the extension direction of the core.(12) A bobbin having a hollow interior that accommodates a core and extends in a predetermined direction, and that is accommodated in a recess provided in a case, wherein the hollow interior is defined by four wall portions arranged in a rectangle when viewed in the predetermined direction, and at one end of the bobbin in the predetermined direction, a slit portion extending in the predetermined direction is provided between each of the four wall portions, and a pair of opposing wall portions are provided with protrusions that protrude outward.

[0047] REFERENCE SIGNS LIST 1 coil device 10 coil portion 12 second covering portion 20 core 22 core tip portion 24 core base portion 30 winding portion 32 winding tip portion 34 lead-out portion 40 case 42 accommodation recess 44 accommodation space 44a bottom side hollow portion 44b bobbin inner hollow portion 44c central hollow portion 46 case inner wall 47 leg portion 48 bottom portion 49 peripheral wall 49a, 49a1, 49a2 through hole 50 first resin 51 central portion 52 base end side end face 60 second resin 62 contact region 64 opening side end face 65 base end side end face 66 opening side end portion 66a first contact portion 66b second contact portion 66c non-contact portion 66d opening side end portion 66e opening side end portion 70 Bobbin 71 Flange portion 71a Tip flange portion 71b Base flange portion 72 Wall portion 72a Short wall portion 72b Long wall portion 72b1 Tapered surface 72c Protrusion portion 74 Bobbin tip portion 76 Slit portion 77 Bound terminal 78 Fitting portion 79 Connector portion

Claims

1. A coil device comprising: a core; a coil section including a winding section which is a conductive member formed in a spiral shape with the extension direction of the core as the helical axis and arranged around the core; and a case in which the coil section is housed; wherein the case has a storage space which houses the core and the winding section and a bottomed recess which opens in an opening direction which is one of the extension directions, the coil section being fixed to the case by a first resin and a second resin which is softer than the first resin which are respectively arranged in the storage space; the first resin sealing the opening of the recess; and the second resin being arranged in the storage space closer to the bottom of the recess than the first resin; and at least a portion of the coil section being exposed from the first resin and covered by the second resin.

2. A coil device as described in claim 1, wherein the first resin and the second resin are arranged to surround the coil portion when viewed in the extension direction of the core, and the second resin is in contact with the first resin in a contact area facing the opening direction.

3. The coil device according to claim 2, wherein the dimension of the second resin in the extension direction of the core is larger than the dimension of the first resin in the extension direction of the core.

4. A coil device as described in claim 2 or 3, wherein the second resin is spaced apart from the bottom of the recess, and the accommodating space has a bottom hollow portion that is a hollow portion disposed between the bottom and the second resin.

5. A coil device as described in claim 1, wherein the first resin and the second resin are arranged to surround the coil portion when viewed in the extension direction of the core, the first resin and the second resin are spaced apart from each other in the extension direction of the core, and the accommodating space includes a central hollow portion that is a hollow portion arranged between the first resin and the second resin.

6. A coil device as described in claim 5, wherein the second resin is arranged in contact with the bottom of the recess, one end of the core opposite to the opening direction is covered with the second resin, and one end of the winding portion opposite to the opening direction is exposed from the second resin.

7. A coil device as described in any one of claims 2 to 6, wherein an end face of the second resin facing the opening direction extends along a direction perpendicular to the extension direction of the core, and the case has a through hole that penetrates in the thickness direction of the peripheral wall in a part of the peripheral wall that defines the storage space and that comes into contact with the first resin.

8. A coil device as described in any one of claims 2 to 7, wherein the second resin extends in the extension direction of the core, and is arranged around the coil portion in contact with the coil portion and the inner wall of the case, and an end of the second resin including an end face facing the opening direction includes a first contact portion in contact with the coil portion, a second contact portion in contact with the inner wall, and a non-contact portion arranged between the first contact portion and the second contact portion, and the first contact portion and the second contact portion protrude further than the non-contact portion toward the opening.

9. A coil device according to any one of claims 2 to 8, further comprising a bobbin arranged between the core and the winding portion and extending in the extension direction of the core, wherein the cross section of the core viewed from the extension direction is rectangular, and the bobbin includes four plate-like wall portions arranged to have a rectangular cross section so as to cover the outer periphery of the core, and each pair of two opposing walls is provided with a protrusion that protrudes outward and contacts the inner wall of the case, and at one end of the bobbin opposite the opening direction, a slit portion extending in the extension direction is provided between each of the four walls, and each of the wall portions having the protrusion is curved so as to approach the core in the direction opposite the opening direction and is in contact with the core at the opposite end.

10. A coil device as described in claim 9, wherein a hollow portion is provided between the core and the bobbin, and the first resin and the second resin are not disposed in the hollow portion within the bobbin.

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