Electrical junction box and wiring harness

Abstract

Electrical junction box (1), with: a first housing element (22) having an opening portion (22a) in an upper end portion at the time of assembly; and a second housing element (23) arranged on an upper side with respect to the first housing element (22) and blocking the opening area (22a) at the time of assembly, wherein the first housing element (22) has an insertion wall portion (22b) formed continuously along an outer periphery of the first housing element (22) in the upper end portion on the outer periphery of the first housing element (22), the second housing element (23) has a groove portion (23c) formed continuously along an outer periphery of the second housing element (23) in a lower end portion on the outer periphery of the second housing element (23), the insertion wall portion (22b) is inserted into the groove portion (23c) from a lower side when the opening portion (22a) of the first housing element (22) is blocked, and at least one rib (23g) projecting downward from a bottom portion (23f) of the groove portion (23c) is formed in the groove portion (23c), both end portions of the rib (23g) are connected to the second housing member (23) in a direction perpendicular to an up / down direction and a direction in which the groove portion (23c) extends, and a space is formed between the rib (23g) and the insertion wall portion (22b) in a state in which the second housing member (23) closes the opening portion (22a).

Description

CROSS-REFERENCE TO RELATED APPLICATION(S)

[0001] This application claims priority to Japanese Patent Application No. 2015-173550 filed in Japan on September 3, 2015, the entire contents of which are hereby incorporated by reference. BACKGROUND OF THE INVENTION 1. Field of the Invention

[0002] The present invention relates to an electrical junction box and a wiring harness. 2. Description of the state of the art

[0003] In some cases, a conventional electrical junction box, intended for a wiring harness installed in a vehicle, such as an automobile, is mounted in a location exposed to the outside environment, unlike a vehicle interior, such as an engine compartment. Typically, the electrical junction box has a split structure in which a housing comprises multiple housing elements, and a waterproof structure is used to prevent external liquid from penetrating the interior between adjacent housing elements.Normally, in this protected structure, an insertion wall portion formed along an outer periphery of a second housing member located on a lower side and projecting upward is inserted into a groove portion formed along an outer periphery of a first housing member located on an upper side and open downward (see Japanese Patent Application Laid-Open Nos. 2002-369335, 2003-252356, and 2010-130705).

[0004] At this time, a gap is formed between a bottom portion corresponding to an upper end portion of the groove portion and a distal portion of the insertion wall portion. The gap is continuously formed along the outer periphery of the first housing. Even if a liquid is splashed onto the housing from the outside, the probability of the liquid entering the gap is normally low. However, when, for example, the engine compartment is cleaned by high-pressure washing, the liquid intensively impacts the housing, and there is a probability that a large amount of liquid enters the gap. When a large amount of liquid enters the gap, liquid may flow along an extending direction of the groove portion and may remain in a corner portion on the outer periphery of the first housing member.In this way, there is a probability that liquid entering the gap will spill into the housing. OVERVIEW OF THE INVENTION

[0005] It is an object of the present invention to provide an electrical junction box and a wire harness capable of preventing liquid entering between the first housing member and the second housing member from outside the housing from entering the housing.

[0006] To achieve the above-mentioned object, an electrical connection box according to one aspect of the present invention comprises a first housing member having an opening portion in an upper end portion at the time of assembly; and a second housing member disposed on an upper side relative to the first housing member and blocking or closing the opening portion at the time of assembly, wherein the first housing member has an insertion wall portion formed continuously along an outer periphery of the first housing member in the upper end portion on the outer periphery of the first housing member, wherein the second housing member has a groove portion formed continuously along an outer periphery of the second housing member in a lower end portion on the outer periphery of the second housing member, wherein the insertion wall portion is inserted into the groove portion from a lower side,when the opening portion of the first housing member is blocked, and wherein at least one rib protruding downward from a bottom portion of the groove portion is formed in the groove portion, both end portions of the rib (23g) are connected to the second housing member (23) in a direction perpendicular to an up / down direction and a direction in which the groove portion (23c) extends, and a space is formed between the rib (23g) and the insertion wall portion (22b) in a state in which the second housing member (23) closes the opening portion (22a).

[0007] According to another aspect of the present invention, in the electrical connection box, it is preferable that the groove portion has a plurality of sides and corner portions connected to adjacent sides, and that at least one rib is formed on each of the sides.

[0008] According to still another aspect of the present invention, it is preferable that in the electrical connection box, ribs are formed so that corner portions are disposed therebetween on the respective sides.

[0009] To achieve the above-mentioned object, a wire harness according to yet another aspect of the present invention comprises an electric cable; and an electrical connection box having a first housing member having an opening portion in an upper end portion at the time of assembly; and a second housing member disposed on an upper side with respect to the first housing member and blocking the opening portion at the time of assembly, wherein the first housing member has an insertion wall portion formed continuously along an outer periphery of the first housing member in the upper end portion on the outer periphery of the first housing member, wherein the second housing member has a groove portion formed continuously along an outer periphery of the second housing member in a lower end portion on the outer periphery of the second housing member,wherein the insertion wall portion is inserted into the groove portion from a lower side when the opening portion of the first housing member is blocked, and wherein at least one rib projecting downward from a bottom portion of the groove portion is formed in the groove portion, both end portions of the rib (23g) are connected to the second housing member (23) in a direction perpendicular to an up / down direction and a direction in which the groove portion (23c) extends, and a space is formed between the rib (23g) and the insertion wall portion (22b) in a state in which the second housing member (23) closes the opening portion (22a).

[0010] The foregoing objects and other objects, features, advantages and technical and industrial significance of this invention will become more apparent from a study of the following detailed description of presently preferred embodiments of the invention when considered in conjunction with the accompanying drawings. SHORT DESCRIPTION OF DRAWINGS Fig. 1 is a perspective view illustrating an electrical junction box according to an embodiment; Fig. 2 is a perspective view illustrating a casing of the electrical connection box according to the embodiment, in which a top cover is removed from the casing; Fig. 3 is a rear view of the upper cover of the electrical connection box according to the embodiment; Fig. 4 is a cross-sectional view of a main portion of the casing of the electrical connection box according to the embodiment; Fig. 5 is a perspective cross-sectional view of a main portion of the upper cover of the electrical connection box according to the embodiment; and Fig. 6 is a view showing a modified example of the upper cover of the electrical connection box according to the embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] Hereinafter, a detailed description will be given of an embodiment of an electrical junction box and a wire harness according to the present invention based on the drawings. It should be noted that the present invention is not limited to the embodiment. Furthermore, a component in the following embodiment also includes a component that can be easily understood by those skilled in the art or a substantially equivalent component thereto. Furthermore, within the scope of the invention, a component in the following embodiment may be variously omitted, replaced, and modified without departing from the subject matter of the present invention. Embodiment

[0012] First, a description will be given of an electrical junction box and a wire harness according to an embodiment. Fig. 1 is a perspective view illustrating an electrical junction box according to an embodiment. Fig. 2 is a perspective view showing a casing of the electrical connection box according to the embodiment, with a top cover removed from the casing. Fig. 3 is a rear view of the upper cover of the electrical connection box according to the embodiment. Fig. 4 is a cross-sectional view of a main portion of the casing of the electrical connection box according to the embodiment. Fig. 5 is a perspective cross-sectional view of a main portion of the top cover of the electrical connection box according to the embodiment. Further, an X direction of the respective figures (including Fig. 6) A width direction of the electrical connection box according to the present embodiment. A Y direction in the present embodiment is a longitudinal direction of the electrical connection box and is a direction perpendicular to the width direction. A Z direction in the present embodiment is an up-down direction of the electrical connection box and is a direction perpendicular to the width direction and the longitudinal direction. A Z1 direction is an upward direction, and a Z2 direction is a downward direction.

[0013] An electrical junction box 1 in the present embodiment is mounted in a vehicle, such as an automobile, to distribute power supplied from a power source, such as a battery, to various electronic devices mounted in the vehicle via various electronic components or the like. Here, the electrical junction box 1 is installed in a wire harness 100 to assemble and accommodate electronic components, such as a connector, a fuse, a relay, a terminal, and an electronic control unit, which are included in a component for establishing a connection of an electric wire 101 or the like.The electrical junction box 1 in the present embodiment is mounted in a location exposed to an external environment, such as an engine compartment of the vehicle, and is connected between a power supply such as a battery and various electronic devices installed in the vehicle. The electrical junction box 1 is sometimes referred to as a junction box, a fuse box, a relay box, or the like. However, in the present embodiment, the electrical junction box is used as a general term. The electrical junction box 1 is mounted in the vehicle so that the up-down direction (Z) is identical to a vertical direction or forms an arbitrary angle with the vertical direction. As shown in FIG. Fig. 1, the electrical junction box 1 has a housing 2 which has several housing components.

[0014] The casing 2 is made using an insulating resin and houses an electronic component (not shown) in an internal space 2a formed therein. At this time, the electric wire 101, which is inserted into the internal space 2a from an insertion opening 2b formed in the casing 2, is connected to at least a part of the electronic component. The casing 2 includes a lower cover 21, a box main body 22, and an upper cover 23, and has a structure in which multiple layers (three layers) are stacked in the order of the lower cover 21, the box main body 22, and the upper cover 23 from a lower side, that is, a structure in which the casing 2 is divided into the plurality of casing components.

[0015] The lower cover 21 is a plate-shaped member (in the form of a pad) and blocks or closes an opening portion (lower-side opening portion) (not shown) formed in a lower end portion of the box main body 22. The lower cover 21 is locked at a lower side with respect to the box main body 22 by a plurality of locking mechanisms 24.

[0016] The box main body 22 is a first housing member, and an opening portion 22a is formed on an upper end portion thereof, as shown in Fig. 2 when viewed in the up-down direction at the time of assembly. A shape of the outer periphery of the box main body 22 is formed in a substantially rectangular shape identical (or substantially identical) to a shape of an outer periphery of the top cover 23 when viewed in the up-down direction at the time of assembly. The box main body 22 is formed in a tubular shape in which the opening portion 22a in the upper end portion and the opening portion in the lower end portion communicate with each other in the up-down direction. An interior space of the box main body 22 according to the present embodiment is divided into a plurality of sections, and an electronic component or a box accommodating the electronic component, such as a fuse box, is directly inserted and held in a divided space portion.In the box main body 22, an insertion wall portion 22b is formed in the upper end portion on an outer periphery when viewed in the up-down direction at the time of assembly. The insertion wall portion 22b is continuously formed along the outer periphery. As shown in FIG. Fig. 4, a stepped portion 22e is formed around a distal portion, that is, an upper end portion. The stepped portion 22e is formed parallel to a surface perpendicular to the up-down direction (a horizontal plane) on an outer side, that is, an outer side of the box main body 22. The stepped portion 22e is continuously formed along the outer circumference. In the box main body 22, a partition wall portion 22c is formed on an inner side, that is, an inner side of the insertion wall portion 22b. The partition wall portion 22c is continuously formed along the outer circumference parallel to the insertion wall portion 22b. In the box main body 22, a drain space portion 22d is formed between the insertion wall portion 22b and the partition wall portion 22c.The drainage space portion 22d is continuously formed along the outer periphery, and a connecting portion (not shown) connecting the insertion wall portion 22b and the partition wall portion 22c is formed at a plurality of locations along the outer periphery of the box main body 22. In the drainage space portion 22d, a lower end portion (not shown) is open to the outside of the electrical connection box 1.

[0017] The upper cover 23 is a second housing member arranged on an upper side with respect to the box main body 22 at the time of assembly, as shown in Fig. 1 when viewed in the up-down direction, and which blocks the opening portion 22a. The upper cover 23 is locked at the upper side relative to the box main body 22 by a plurality of locking mechanisms 25. As shown in Fig. 3, the top cover 23 is a lid-shaped member and includes a ceiling portion 23a and a frame portion 23b. The ceiling portion 23a has a flat plate shape and is included in a ceiling of the case 2. The frame portion 23b is included in the outer periphery of the top cover 23 when viewed in the up-down direction at the time of assembly, and is formed to protrude downward from the end portion of the outer periphery of the ceiling portion 23a. A shape of the outer periphery of the top cover 23 is designed in a substantially rectangular shape when viewed in the up-down direction at the time of assembly. In the top cover 23, a groove portion 23c is formed in a lower end portion on the outer periphery when viewed in the up-down direction at the time of assembly.

[0018] As in Fig. 3, the groove portion 23c is formed continuously along the outer circumference. As shown in Fig. As shown in Fig. 4, the insertion wall portion 22b is inserted into the groove portion 23c from the lower side when the upper cover 23 blocks the opening portion 22a of the box main body 22, that is, in a state where the upper cover 23 is locked at the upper side with respect to the box main body 22 by the plurality of locking mechanisms 25. An opening is formed in the groove portion 23c at a lower end portion. The groove portion 23c includes an outer wall portion 23d, an inner wall portion 23e, and a bottom portion 23f. The outer wall portion 23d is formed at a lower end portion on the outer periphery when viewed in the up-down direction at the time of assembly. The outer wall portion 23d is continuously formed along the outer periphery. In the outer wall portion 23d, a space portion 23h is formed at a distal portion, that is, a lower end portion.The spacer portion 23h is formed to protrude outward, that is, on an outer side of the box main body 22 and extend downward. The inner wall portion 23e is formed on an inner side, that is, an inner side, of the outer wall portion 23d. The inner wall portion 23e is connected to the outer wall portion 23d via the bottom portion 23f and is continuously formed along the outer circumference parallel to the outer wall portion 23d. In the groove portion 23c in the present embodiment, six sides S1, S2, S3, S4, S5, and S6 are formed as a plurality of sides. The respective sides S1, S2, S3, S4, S5, and S6 are formed rectilinearly. Adjacent sides S1 to S6 are respectively connected to each other by corner portions R1, R2, R3, R4, R5, and R6. In contrast to the sides S1 to S6, the corner areas R1 to R6 are curved areas and are formed in the form of curved lines.A length (depth) of the groove portion 23c in the up-down direction is set with respect to the insertion wall portion 22b such that a gap 23i is formed between the bottom portion 23f and the insertion wall portion 22b, wherein the insertion wall portion 22b is inserted into the groove portion 23c.

[0019] A rib 23g is formed in the groove area 23c. As shown in Fig. 5, the rib 23g is formed to protrude downward from the bottom portion 23f of the groove portion 23c. A length (depth) D2 of the rib 23g in the up-down direction is set with respect to a length (depth) D1 of the gap 23i in the up-down direction such that a gap is formed between the lower end portion and the insertion wall portion 22b while the insertion wall portion 22b is inserted into the groove portion 23c. The rib 23g in the present embodiment has a flat plate shape. Further, both end portions of the rib 23g in a direction perpendicular to the up-down direction and a direction in which the groove portion 23c extends are connected to the outer wall portion 23d and the inner wall portion 23e, respectively. Further, the rib 23g is integrally formed with the top cover 23. At least one rib 23g is formed on each side S1 to S6.Specifically, a plurality of ribs 23g are formed on the sides S1, S2, S4, S5, and S6, respectively, and a single rib 23g is formed on the side S3. The ribs 23g are formed at equal intervals on each of the sides S1, S2, S4, S5, and S6 on which the plurality of ribs 23g are formed. Further, the ribs 23g are formed on each of the sides S1 to S6 so that the corner portions R1 to R6 are interposed therebetween. In other words, the ribs 23g corresponding to the corner portions R1 to R6, respectively, are formed on two sides S1 to S6, each of which is connected to the corner portions R1 to R6.

[0020] Next, a description will be given of the flow of a liquid when liquid, for example, water, is splashed onto the electrical connection box 1 from the outside according to the present embodiment. A water-proof structure is formed to prevent the intrusion of liquid into the interior of the housing 2 from the outside between the box main body 22 and the top cover 23 when the insertion wall portion 22b is inserted into the groove portion 23c, the spacer portion 23h is positioned on the lower side of the stepped portion 22e, and the stepped portion 22e contacts the outer wall portion 23d, as shown in Fig. 4, when the opening portion 22a is blocked by the top cover 23, that is, in a blocked state of the top cover 23 with respect to the box main body 22 due to the plural locking mechanisms 25. Therefore, when liquid from the outside impacts only the casing 2, liquid does not penetrate to the gap 23i. Meanwhile, when liquid violently impacts the casing 2, there is a possibility that liquid penetrates into the gap 23i from the portion between the stepped portion 22e and the outer wall portion 23d, as indicated by an arrow A. When a small amount of liquid enters the gap 23i, a possibility that liquid flows in an extending direction of the groove portion 23c is small. In this case, liquid that penetrates into the gap 23i moves to the lower side of the groove portion 23c, as indicated by an arrow C in the same figure.Subsequently, a part of it is discharged to the outside of the casing 2 by flowing to the drain space region 22d between the insert wall region 22b and the inner wall region 23e, and another part of it is discharged to the outside of the casing 2 between the insert wall region 22b and the outer wall region 23d.

[0021] When liquid impacts more violently on the housing 2 and thus a large amount of liquid enters the gap 23i, the liquid flows in the extending direction of the groove portion 23c. Liquid entering a gap 23i of a portion corresponding to one of the sides S1 to S5 in the groove portion 23c and flowing in an extending direction of the wetted side S1 to S5 flows toward an end portion of the sides S1 to S5 in an extending direction indicated by an arrow B of the Fig. 3. One of the corner portions R1 to R6 is connected to the end portion of the sides S1 to S5 in the extending direction, and therefore, the liquid flowing in the extending direction of the wetted side S1 to S5 reaches the corner portions R1 to R6. Unlike the respective sides S1 to S5, which have a straight line shape, the respective corner portions R1 to R6 have the shape of a curved line and are bent. Therefore, the flow of liquid is small compared to the respective sides S1 to S5, and the liquid stays there. When the rib 23g is formed following a flow path of the liquid flowing in the extending direction of the groove portion 23c through the gap 23i of the wetted side S1 to S5 in the groove portion 23c, an area perpendicular to the flow path of the liquid (an opening area of ​​the gap 23i) becomes smaller corresponding to a part in which the rib 23g is formed.Therefore, the liquid impacts the rib 23g, and the flow of the liquid becomes small. Furthermore, a portion of the liquid impacting the rib 23g is discharged to the outside of the housing 2, while a portion flows to the drain space 22d between the insert wall portion 22b and the inner wall portion 23e. The outflow of liquid from a space formed between the rib 23g and the insert wall portion 22b is small, and a reduced amount of the liquid reaches the corner portions R1 to R6.

[0022] As described above, in the electrical connection box 1 according to the present embodiment, at least one rib 23g is formed to protrude downward from the bottom portion 23f of the groove portion 23c. Therefore, when liquid flowing toward the corner portions R1 and R2 through the sides S1 to S5 of the groove portion 23c collides with the rib 23g before arriving at the corner portions R1 to R6, a flow of the liquid arriving at the corner portions R1 to R6 can be small, and the amount of the liquid can be reduced. Therefore, it is possible to reduce the amount of liquid remaining in the corner portions R1 to R6 compared to the case where liquid arrives at the corner portions R1 to R6 without colliding with the rib 23g.In this way, liquid existing between the box main body 22 and the top cover 23 outside the housing 2 can be prevented from penetrating into the housing 2. .

[0023] Furthermore, the rib 23g is connected to the outer wall portion 23d and the inner wall portion 23e. Therefore, it is possible to mitigate or reduce deformation or collapse of the outer wall portion 23d and the inner wall portion 23e in a direction perpendicular to the up-down direction, and particularly in a direction perpendicular to the extending direction of the groove portion 23c, when a depth of the groove portion 23c is large, that is, when the length of the outer wall portion 23d and the inner wall portion 23e included in the groove portion 23c in the up-down direction from the bottom portion 23f is large. In this way, a gap between the outer wall portion 23d and the inner wall portion 23e can be prevented from becoming narrow.Thus, it can be avoided that the insertion of the insertion wall portion 22b into the groove portion 23c becomes difficult, and it can be avoided that the joining of the top cover 23 and the box main body 22 is impaired.

[0024] Further, in the electrical connection box 1 according to the present embodiment, at least one rib 23g is formed on each of the sides S1 to S5. Therefore, even if liquid enters the gap 23i from any one of the sides S1 to S5 of the respective sides S1 to S5, the amount of liquid remaining in the corner portions R1 to R6 can be reduced compared to liquid entering the corner portions R1 to R6. In this way, liquid entering between the box main body 22 and the top cover 23 from outside the housing 2 can be prevented from spilling into the housing 2 regardless of a position where the liquid enters the gap 23i.

[0025] Further, in the electrical connection box 1 according to the present embodiment, the rib 23g is formed on each of the sides S1 to S5 with the corner portions R1 to R6 interposed therebetween. Therefore, even if liquid enters the gap 23i from any one of the sides S1 to S5 of the respective sides S1 to S5 and the liquid flows toward one of the corner portions R1 to R6 connected to the wetted sides S1 to S5, the amount of liquid remaining in the corner portions R1 to R6 can be reliably reduced compared to the liquid arriving at the corner portions R1 to R6. In this way, liquid entering between the box main body 22 and the top cover 23 from outside the housing 2 can be prevented from sloshing into the housing 2 regardless of a position where the liquid enters the gap 23i.

[0026] Since the wire harness 100 described above includes the electrical connection box 1, liquid entering between the box main body 22 and the top cover 23 from outside the case 2 can be prevented from splashing or splashing into the case 2.

[0027] Furthermore, in the electrical connection box 1 according to the present embodiment, when a plurality of ribs 23g are formed on each of the sides S1 to S5, the ribs 23g are formed with equal pitch. However, the ribs 23g may be formed with unequal pitch.

[0028] Fig. 6 is a view showing a modified example of the top cover of the electrical connection box according to the embodiment. As shown in Fig.6, only ribs 23g arranged between each of the corner portions R1 to R6 are optionally formed on the respective sides S1 to S5. Further, pitches of a plurality of ribs 23g on the sides S1 to S5 may be large or small. For example, ribs 23g may be optionally formed densely on one side of the corner portions R1 to R6 and thinned out on a middle side on the sides S1 to S5. In this case, a flow of liquid at the gap 23i becomes small, and the amount of flow becomes smaller toward the corner portions R1 to R6. Thus, liquid can be reliably prevented from splashing into the housing 2.

[0029] Furthermore, in the present embodiment, the rib 23g is formed in the shape of a flat plate. However, the present embodiment is not limited to this. For example, the rib 23g may have a shape such that one side in the longitudinal direction widens toward a rear surface, such as a triangle or a trapezoid, when viewed in a direction perpendicular to the up-down direction and the extending direction of the groove portion 23c. In this case, liquid adhering to the rib 23g easily flows to a lower end portion of the rib 23g, and liquid separated from the rib 23g flows toward a lower side of the gap 23i. Therefore, liquid can be prevented from migrating in the extending direction of the groove portion 23c.

[0030] In the electrical connection box and the wire harness according to the present embodiment, at least one rib protruding downward from the bottom portion of the groove portion 23c is formed, and therefore, there is an effect that it is possible to prevent the intrusion of liquid between the first case member and the second case member from outside the case and the splashing into the case.

[0031] Although the present invention has been described with reference to specific embodiments for the purpose of complete and clear disclosure, the appended claims are not to be limited thereto, but are to be construed to include all modifications and alternative structures that may occur to one skilled in the art and are within the scope of the technical teachings presented herein.

Claims

[1] Electrical junction box (1), with: a first housing element (22) having an opening portion (22a) in an upper end portion at the time of assembly; and a second housing element (23) arranged on an upper side with respect to the first housing element (22) and blocking the opening area (22a) at the time of assembly, wherein the first housing element (22) has an insertion wall portion (22b) formed continuously along an outer periphery of the first housing element (22) in the upper end portion on the outer periphery of the first housing element (22), the second housing element (23) has a groove portion (23c) formed continuously along an outer periphery of the second housing element (23) in a lower end portion on the outer periphery of the second housing element (23), the insertion wall portion (22b) is inserted into the groove portion (23c) from a lower side when the opening portion (22a) of the first housing element (22) is blocked, and at least one rib (23g) projecting downward from a bottom portion (23f) of the groove portion (23c) is formed in the groove portion (23c), both end portions of the rib (23g) are connected to the second housing member (23) in a direction perpendicular to an up / down direction and a direction in which the groove portion (23c) extends, and a space is formed between the rib (23g) and the insertion wall portion (22b) in a state in which the second housing member (23) closes the opening portion (22a). [2] Electrical junction box (1) according to claim 1, wherein the groove area (23c) has several sides (S1 - S6) and corner areas (R1 - R6) connecting adjacent sides, and at least one rib (23g) is formed on each of the sides (S1 - S6). [3] An electrical junction box (1) according to claim 2, wherein the ribs (23g) are formed on the respective sides (S1 - S6) with the corner portions (R1 - R6) disposed therebetween. [4] Wiring harness (100), with: an electric cable (101); and an electrical junction box (1) comprising: a first housing element (22) having an opening portion (22a) in an upper end portion at the time of assembly, and a second housing element (23) arranged on an upper side with respect to the first housing element (22) and blocking the opening area (22a) at the time of assembly, wherein the first housing element (22) has an insertion wall portion (22b) formed continuously along an outer periphery of the first housing element (22) in the upper end portion on the outer periphery of the first housing element (22), the second housing element (23) has a groove portion (23c) formed along an outer periphery of the second housing element (23) in a lower end portion on the outer periphery of the second housing element (23), the insertion wall portion (22b) is inserted into the groove portion (23c) from a lower side when the opening portion (22a) of the first housing element (22) is blocked, and at least one rib (23g) projecting downward from a bottom portion (23f) of the groove portion (23c) is formed in the groove portion (23c), both end portions of the rib (23g) are connected to the second housing member (23) in a direction perpendicular to an up / down direction and a direction in which the groove portion (23c) extends, and a space is formed between the rib (23g) and the insertion wall portion (22b) in a state in which the second housing member (23) closes the opening portion (22a).

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