electronic devices

Abstract

To improve waterproof performance such that an adhesive 19 is made to protrude from a bonding surface 28 to form a convex portion 19a.SOLUTION: A base member 4 constituting a housing 2 includes a seal groove 11 filled with an adhesive 19, and a cover 5 includes a protrusion 18 disposed within the seal groove 11. The seal groove 11 has substantially parallel first groove side surface 21 on the inside of the housing and second groove side surface 22 on the outside of the housing, and the protrusion 18 has a first protrusion side surface 25 facing the first groove side surface 21 and a second protrusion side surface 25 facing the second groove side surface 22. The second protrusion side surface 25 has a tapered surface having a larger angle than the first protrusion side surface 25, and as a result, a relatively large amount of uncured adhesive 19 is guided to the outside of the housing.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to an electronic device in which a circuit board is housed in a housing, and more particularly to an electronic device in which the housing is sealed to provide waterproofing. [Background technology]

[0002] For example, electronic devices used as various controllers in automobiles may require high waterproof performance when exposed to rainwater, etc. As shown in Patent Document 1 and other documents, a commonly used housing seal structure is one in which a seal groove is formed in one component and a protrusion that fits into the seal groove is formed in the other component, and the seal groove is filled with adhesive before the protrusions are mated to form a seal between the two components. The dimensions of each component are set so that when the protrusion is mated with the seal groove, a roughly U-shaped space is formed between the two components, and this roughly U-shaped space is filled with adhesive. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2009-70855 Summary of the Invention [Problem to be solved by the invention]

[0004] To achieve high waterproof performance, it is desirable that the adhesive slightly overflow from the above-mentioned approximately U-shaped space and spill out in a convex shape from the joining surfaces of the two components located outside the sealing groove to the outside (i.e., toward the outer surface of the housing).

[0005] However, in conventional sealing structures, the protrusions have symmetrical shapes on the inside and outside of the housing, so when the protrusions enter the adhesive filled in the seal groove during assembly, the liquid level changes in the same way on both the outside and inside of the housing.

[0006] Therefore, in order to make the adhesive protrude in a convex shape on the outer surface of the housing, an excessive amount of adhesive is required. In other words, the adhesive protrudes unnecessarily inside the housing. On the other hand, if the amount of adhesive filled into the seal groove is reduced, for example, if the positional relationship between the protrusion and the seal groove varies due to deformation of the resin member, the convex part of the adhesive will not be formed on the outside of the joining surface, resulting in a decrease in sealing or waterproof performance. [Means for solving the problem]

[0007] One aspect of the present invention is a device comprising: a circuit board on which electronic components are mounted; and a housing that houses the circuit board in an internal space; the housing includes a first member to which the circuit board is attached and which has a seal groove around its periphery, and a second member which has a wall-like continuous protrusion portion disposed in the seal groove; In an electronic device in which the first member and the second member are joined by an adhesive filled in the seal groove, In a cross section of the seal groove, the adhesive is present in a substantially U-shaped space formed by the inner surface of the seal groove and the outer surface of the protrusion, the adhesive fills the space between the outer peripheral edge of the seal groove of the first member and the opposing outer peripheral edge of the second member, and the adhesive protrudes from the joining surfaces of both members so as to be convex outward, The protrusion has an asymmetrical shape so that when the protrusion enters the seal groove, it guides a relatively large amount of uncured adhesive to the outside of the housing. And, The tip of the protrusion forms a tapered surface inclined toward the outside of the housing, The first member and the second member are provided with protruding portions adjacent to each other via a small gap so that a labyrinth structure is formed between the outer circumferential edge of the first member and the outer circumferential edge of the second member. . [Effects of the Invention]

[0008] According to the configuration of the present invention, the adhesive filled in the seal groove is guided to the outside of the housing in large amounts, and a state in which the adhesive protrudes outward from the joining surface between the first and second members in a convex shape is reliably formed, thereby improving waterproof performance without requiring an excessive amount of adhesive. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a perspective view of an electronic device according to an embodiment of the present invention; [Figure 2] Cross-sectional view taken along line AA in Figure 1. [Figure 3] Enlarged view of part B in Figure 2. [Figure 4] FIG. 4 is an enlarged view of a main part similar to FIG. 3, showing a second embodiment. [Figure 5] FIG. 10 is an explanatory diagram for explaining the operation of the second embodiment. [Figure 6] FIG. 10 is an enlarged view of a main part showing a third embodiment. [Figure 7] FIG. 10 is an enlarged view of a main part showing a fourth embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0010] An embodiment in which the present invention is applied to an electronic device for an automobile will be described in detail below with reference to the drawings.

[0011] FIG. 1 is a perspective view of an electronic device 1 according to an embodiment of the present invention, and FIG. 2 is a cross-sectional view taken along line AA. The electronic device 1 is mounted at an appropriate position on a vehicle, for example, as a controller for an automatic transmission. As shown in FIG. 2, the electronic device 1 includes a housing 2 and a circuit board 3 housed within the interior space of the housing 2. The housing 2 is comprised of a metal base member 4 having a substantially rectangular plate shape and a synthetic resin cover 5 that bulges to cover one surface of the base member 4 (the upper surface in FIG. 2). A connector 6 attached to one end of the circuit board 3 is sandwiched between the base member 4 and the cover 5, as shown in FIG. 1. The circuit board 3 is attached to the base member 4 via a plurality of screws (not shown). The base member 4 is formed, for example, by die-casting an aluminum alloy. The cover 5 is formed, for example, by injection molding a hard synthetic resin.

[0012] A continuous seal groove 11 is formed around the entire outer periphery of the base member 4 except for the connector 6. More specifically, the outer periphery of the base member 4 is formed as a flange portion 13 that is thicker than the bottom wall 12 and has a frame-like shape, and this flange portion 13 has a recessed seal groove 11 that opens toward the cover 5.

[0013] 1 and 2 correspond to the position when the base member 4 and the cover 5 are assembled, and in the following description, the terms "upper" and "lower" will be used based on this position. The actual mounting position of the electronic device 1 in the car may be different from this.

[0014] The cover 5 has a ceiling wall 15 that is substantially flat except for the connector 6 portion, and a diagonally inclined side wall 16 that surrounds the periphery, and a flange portion 17 that also forms the outer periphery of the cover 5 is formed at the lower end of the side wall 16. A wall-like continuous protrusion 18 is formed on the underside of this flange portion 17 in correspondence with the seal groove 11.

[0015] 2, the seal groove 11 is filled with adhesive 19 (e.g., FIPG), and the protrusion 18 is disposed in this adhesive 19 to form a seal therebetween. That is, a substantially U-shaped space is formed between the inner surface of the seal groove 11 and the outer surface of the protrusion 18, and this space is filled with adhesive 19.

[0016] FIG. 3 shows an enlarged view of portion B in FIG. 2. The seal structure between the base member 4 and the cover 5 in the first embodiment will be described in more detail with reference to FIG. 3. In the following description, unless otherwise specified, the term "inside the housing" refers to the direction toward the inside of the housing 2 (leftward in FIG. 3), and the term "outside the housing" refers to the direction toward the outside of the housing 2 (rightward in FIG. 3). The seal groove 11 on the base member 4 side is composed of a linear first groove side surface 21 on the inside of the housing, a linear second groove side surface 22 on the outside of the housing, and a bottom surface 23 that forms a substantially semicircular curve. The first groove side surface 21 and the second groove side surface 22 are substantially parallel to each other, although they have a draft angle necessary for die-casting. They are aligned perpendicular to the bottom surface 12 of the base member 4, i.e., along the vertical direction. Therefore, the seal groove 11 is a recessed groove with a substantially U-shaped cross section that opens upward. The upper end of the second groove side surface 22 is located slightly below the upper end of the first groove side surface 21. That is, the upper surface of flange portion 13 on the outer periphery of base member 4 has different heights between the portion outside the housing and the portion inside the housing relative to seal groove 11, with the portion outside the housing being relatively lower.

[0017] The protrusion 18 of the cover 5 is formed on the flange 17 toward the inside of the housing so as to be continuous with the inner circumferential surface of the flange 17. As shown in FIG. 3, when the base member 4 and the cover 5 are assembled, the protrusion 18 is positioned essentially at the center of the seal groove 11 in the width direction. The protrusion 18 has a first protrusion side surface 25 facing the first groove side surface 21 and a second protrusion side surface 26 facing the second groove side surface 22, and its lower end is rounded. The first and second protrusion side surfaces 25, 26 are flat surfaces extending in the vertical direction. The first protrusion side surface 25, located on the inside of the housing, is substantially vertical, although it has a slight draft angle necessary for molding. In contrast, the second protrusion side surface 26, located on the outside of the housing, is a tapered surface with a larger angle than the first protrusion side surface 25. In other words, the second protrusion side surface 26 is inclined so that the protrusion 18 has a tapered shape.

[0018] Flange portion 17 of cover 5 protrudes further outward from the housing than protrusion 18, and a small gap exists between the underside of flange portion 17 and the upper surface of flange portion 13 of base member 4 (particularly the portion outside the housing beyond seal groove 11) to allow adhesive 19 to be present. The underside of flange portion 17 and the upper surface of flange portion 13 correspond to joining surfaces 28 that are joined together via a layer of adhesive 19.

[0019] In the configuration of the embodiment described above, when the cover 5 is assembled with a predetermined amount of adhesive 19 filled in the seal groove 11, the protrusion 18 enters the adhesive 19 in the seal groove 11. At this time, the inclination of the second protrusion side surface 26 of the protrusion 18 guides a relatively large amount of the uncured adhesive 19 in the seal groove 11 toward the outside of the housing. As a result, the uncured adhesive 19 is forced out of the seal groove 11 toward the outside of the housing through the joining surface 28, and a convex portion 19a is formed on the outer surface of the housing 2, where the adhesive 19 protrudes outward from the joining surface 28. This convex portion 19a is cured together with the adhesive 19 in the seal groove 11.

[0020] By forming the convex portion 19a in this manner, the creeping distance of contact with the adhesive 19 is increased, and the joining surface 28 is not exposed, improving waterproof performance. In addition, corrosion of the metal base member 4 at the joining surface 28 is suppressed.

[0021] If the convex portions 19a are not sufficiently formed, the joining surface 28 is likely to become microscopic pockets where water accumulates, resulting in poor waterproofing performance.

[0022] Furthermore, on the inside of the housing of the seal groove 11, the uncured adhesive 19 is less likely to overflow into the internal space of the housing 2 because the inclination of the second protrusion side surface 26 as described above guides a large amount of the uncured adhesive 19 to the outside of the housing, and because the upper end position of the first groove side surface 21 is relatively higher than the upper end position of the second groove side surface 22. Therefore, the amount of adhesive 19 required to secure the convex portion 19a is minimized.

[0023] Next, a second embodiment will be described with reference to Figures 4 and 5. Like Figure 3, Figure 4 shows a cross section of the main part that will become the sealing portion. In this second embodiment, the protrusion 18 has a first protrusion side surface 25 and a second protrusion side surface 26 that are substantially parallel. Instead of the inclination of the second protrusion side surface 26 in the first embodiment, the tip of the protrusion 18 forms a tapered surface 31 that is inclined toward the outside of the housing. This tapered surface 31 guides a relatively large amount of uncured adhesive 19 toward the outside of the housing.

[0024] Furthermore, a labyrinth structure 32 is provided on the joining surface 28 to reliably form the convex portion 19a on the joining surface 28. That is, a first protrusion 33 and a second protrusion 34 are provided adjacent to each other with a small gap between them on the underside 17a of the flange portion 17 of the cover 5 and the upper surface 13a of the flange portion 13 of the base member 4, which constitute the joining surface 28, and these two protrusions form a serpentine passage, i.e., the labyrinth structure 32. In a preferred embodiment, the first and second protrusions 33, 34 each protrude from the underside 17a and upper surface 13a, which form the flange surfaces, to form a substantially semicircular cross section, with the first protrusion 33 on the cover 5 side positioned inside the housing, and the second protrusion 34 on the base member 4 side positioned inside the housing.

[0025] FIG. 5 is an explanatory diagram illustrating the effect of this labyrinth structure 32, showing three stages of the protrusion 18 entering the seal groove 11 filled with adhesive 19 during assembly. In the first stage shown in FIG. 5(a), only the tip of the protrusion 18 is inserted into the uncured adhesive 19. As the protrusion 18 moves downward from this state, the tapered surface 31 at the tip of the protrusion 18 guides the uncured adhesive 19 toward the outside of the housing. As shown in FIG. 5(b), the uncured adhesive 19 splits into two parts forming a roughly U-shape and rises so that the liquid level is higher on the outside of the housing than on the protrusion 18. Eventually, the uncured adhesive 19 overflows over the upper end of the second groove side surface 22 of the seal groove 11 and onto the joining surface 28 (on the upper surface 13a of the flange 13). Then, almost simultaneously, as shown in FIG. 5(c), the first protrusion 33 on the cover 5 presses downward the uncured adhesive 19 on the upper surface 13a of the flange 13. As a result, the uncured adhesive 19 that was present outside the housing beyond the first protrusion 33 is pushed outward to form a convex portion 19a. This convex portion 19a hardens directly on the outer surface of the housing 2, and covers the side of the joining surface 28.

[0026] Next, a third embodiment will be described with reference to FIG. 6. FIG. 6 is a cross-sectional view of a main portion similar to FIG. 4. This third embodiment differs from the second embodiment in that the bottom of seal groove 11 has a modified configuration. Seal groove 11 is composed of a linear first groove side surface 21 on the inside of the housing, a linear second groove side surface 22 on the outside of the housing, and a bottom surface 23 that forms a substantially semicircular curve. In particular, a flat surface 41 that slopes toward the outside of the housing is formed on bottom surface 23, which faces the tip of protrusion 18 having tapered surface 31, near the inside of the housing. The tip of protrusion 18, which is sharpened by tapered surface 31, is located above flat surface 41. In a preferred embodiment, flat surface 41 is inclined at an angle of approximately 40 to 50 degrees with respect to the direction of travel of protrusion 18 (i.e., the vertical direction).

[0027] In the third embodiment, as the protrusion 18 descends, the uncured adhesive 19 is pushed downward and guided to the outside of the housing along the slope of the flat surface 41. Therefore, in combination with the action of the tapered surface 31 and the action of the labyrinth structure 32, the convex portion 19a can be reliably formed.

[0028] Next, a fourth embodiment will be described with reference to FIG. 7. FIG. 7 is a cross-sectional view of a main portion similar to FIG. 4. In addition to the configuration of the second embodiment, this fourth embodiment changes the position of the protrusion 18 relative to the seal groove 11. The protrusion 18 is positioned offset from the center of the seal groove 11 toward the outside of the housing. Therefore, the width of the space 51 outside the housing (the dimension along the width of the seal groove 11) is narrower than the width of the space 52 inside the housing, forming a substantially U-shaped space (a space filled with adhesive 19) formed by the inner surface of the seal groove 11 and the outer surface of the protrusion 18. Therefore, when the protrusion 18 enters downward in the figure, the pressure of the uncured adhesive 19 in the space 51 outside the housing increases, making it easier for the adhesive 19 to be pushed outward through the joining surface 28. This ensures the formation of the convex portion 19a.

[0029] Although one embodiment of the present invention has been described above, the present invention is not limited to the above embodiment and various modifications are possible. For example, in the above embodiment, the first and second members are a combination of the plate-shaped base member 4 and the bulging cover 5, but the present invention is not limited to such first and second members and can be applied to housings of various configurations. [Explanation of symbols]

[0030] 1...electronic device, 2...housing, 3...circuit board, 4...base member, 5...cover, 11...sealing groove, 18...protrusion, 19...adhesive, 19a...convex-shaped portion, 21...first groove side, 22...second groove side, 23...bottom surface, 25...first protrusion side, 26...second protrusion side, 28...joint surface, 31...tapered surface, 32...labyrinth structure, 33...first protrusion, 34...second protrusion, 41...flat portion, 51, 52...space.

Claims

1. The device comprises a circuit board on which electronic components are mounted, and a housing that houses the circuit board in an internal space, the housing includes a first member to which the circuit board is attached and which has a seal groove around its periphery, and a second member which has a wall-like continuous protrusion disposed in the seal groove, In the electronic device, the first member and the second member are joined together by an adhesive filled in the seal groove, In a cross section of the seal groove, the adhesive is present in a substantially U-shaped space formed by the inner surface of the seal groove and the outer surface of the protrusion, the adhesive fills the space between the outer peripheral edge of the seal groove of the first member and the opposing outer peripheral edge of the second member, and the adhesive protrudes from the joining surfaces of both members so as to protrude outward, the protrusion has an asymmetric shape so as to guide a relatively large amount of uncured adhesive to the outside of the housing when the protrusion enters the seal groove, The tip of the protrusion forms a tapered surface inclined toward the outside of the housing, the first member and the second member are provided with protruding portions adjacent to each other via a small gap such that a labyrinth structure is formed between the outer circumferential edge of the first member and the outer circumferential edge of the second member; electronic equipment.

2. the protrusion of the second member is located closer to the inside of the housing, and the protrusion of the first member is located closer to the outside of the housing, Each of the protrusions protrudes from the flange surface of each outer periphery so as to form a substantially semicircular cross section. The electronic device of claim 1 .

3. a flat surface inclined toward the outside of the housing is provided on a portion of the bottom surface of the seal groove, which faces the tip of the protrusion, closer to the inside of the housing; 3. The electronic device according to claim 1 or 2.

4. the protrusion is positioned offset from the center of the seal groove in the width direction toward the outer side of the housing; The electronic device according to any one of claims 1 to 3.

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