Grommet and wire harness wiring structure

Abstract

To provide a grommet and a wire harness wiring structure using the same in which stress concentration on a wire harness in a grommet when bent is suppressed, whereby the durability of the grommet and the wire harness can be improved.SOLUTION: A bellows portion 3 is disposed in at least a portion of a grommet 1. In the bellows portion 3, crest sections 11 and trough sections 13 are repeatedly formed on an outer surface with respect to a tube axis direction. In a section with respect to the tube axis direction, a wire harness support 15 protruding to a tube center direction is formed on an inner surface side of each of the trough sections 13. For example, in a bent portion, a wire harness comes into contact with the wire harness supports 15 of the bellows portion 3. Therefore, the contact area between the wire harness and the grommet 1 can be prevented from increasing, thereby a friction force can be suppressed from increasing.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present invention mainly relates to grommets through which wire harnesses are inserted in automobiles and a wire harness routing structure using the same.

Background Art

[0002] In automobiles, many electrical components are used. To connect these electrical components to power sources, other devices, etc., many wire harnesses are used. Such wire harnesses are routed to various parts of the automobile, and may be routed in a bent manner at movable parts, for example, between the body and the door of the automobile.

[0003] Normally, wire harnesses routed at such bent parts are inserted into grommets for purposes such as protection, dust prevention, and waterproofing. For example, the grommet is disposed at a movable part such as between the door (including the rear and trunk) and the vehicle body. Since the grommet is made of, for example, rubber and has flexibility, it bends in response to the opening and closing of the door or the like.

[0004] Here, the grommet is composed of a relatively flexible member such as rubber, and the friction between the wire harness and the inner surface of the grommet is large. Therefore, when inserting the wire harness into the grommet, the free deformation of the wire harness within the grommet is inhibited, which becomes a factor in local bending of the wire harness.

[0005] In addition, since the grommet is bendable as described above, when the grommet and the wire harness bend, for example, when the door or the like is opened and closed, the wire harness is pressed against the inner wall of the grommet, and the outer surface of the wire harness and the inner surface of the grommet are deformed, increasing the contact area. The friction at this time becomes a factor in the bending of the wire harness and the grommet.

[0006] Fig. 7(a) is a conceptual cross-sectional view of a state where a part of the wire harness 100 is in contact with the bent portion of the grommet 101 having a bellows shape. In Fig. 7(a), the left-right direction is the tube axis direction, and the figure is a cross-sectional view of the inside of the bend. When the inner surface shape of the bellows portion is formed as a curved surface in the cross-section in the tube axis direction, in an ideal state, the wire harness 100 and the grommet 101 come into point contact in the cross-section for each valley pitch of the bellows.

[0007] However, as described above, since the grommet 101 is made of a relatively flexible material, as shown in Fig. 7(b), the wire harness 100 is pressed against the inner peripheral surface of the grommet 101 and they are deformed together, increasing the contact area, and thus a large frictional force is generated. When, for example, a compressive force is applied in the axial direction of the wire harness 100 in this state, there is a risk that the wire harness 100 may be locally bent without the wire harness 100 and the grommet 101 sliding.

[0008] Such local deformation particularly generates unintended stress concentration on the wire harness, leading to a reduction in the life of the wire harness, and also generates unintended friction between the wire harness and the grommet, which is also a factor in the damage of the grommet.

[0009] On the other hand, a method has been proposed to suppress unintended deformation of the wire harness due to friction and relieve stress concentration by reducing the friction between the grommet and the wire harness during bending. For example, in order to suppress the contact between the wire harness and the inner peripheral surface of the grommet body having a bendable bellows portion, a method has been proposed in which a harness restricting portion that protrudes inward from the inner peripheral surface by more than the minimum inner diameter of the bellows portion is provided on the inner peripheral surface of the grommet body (Patent Document 1).

Prior Art Documents

Patent Documents

[0010]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0011] According to Patent Document 1, since the wire harness and the grommet only come into contact with each other in the harness regulating portion, it is possible to suppress the wire harness from coming into contact with the grommet on the inner surface of the bellows portion that becomes a bent portion.

[0012] However, when bending the grommet, it is difficult to prevent the wire harness and the bellows portion from coming into complete contact. In addition, with respect to the diameter of the wire harness, it is necessary to increase the diameter of the bellows portion so that the wire harness does not come into contact with the grommet even when the grommet is bent, and the grommet becomes larger than necessary.

[0013] The present invention has been made in view of such problems, and an object thereof is to provide a grommet capable of improving the durability of the grommet and the wire harness by suppressing stress concentration on the wire harness during bending within the grommet, and a wiring structure of a wire harness using the same.

Means for Solving the Problems

[0014] In order to achieve the above-described object, a first invention is a substantially tubular grommet into which a wire harness is inserted, and at least a part thereof has a bellows portion in which ridges and valleys are repeatedly formed on the outer surface with respect to the tube axis direction. In a cross section with respect to the tube axis direction, a wire harness support portion protruding in the tube center direction is formed on the inner surface side of at least a part of the valleys.

[0015] In a cross section with respect to the tube axis direction, it is desirable that the width of the tip side of the wire harness support portion is narrower than that of the base side.

[0016] It is desirable that a plurality of the wire harness support portions are formed on the inner surface side of one of the valleys.

[0017] At least a part of the grommet is formed with a diameter-expanded portion, and on the inner surface side near the diameter-expanded portion, a groove continuous in the circumferential direction is formed, and an annular sliding member is provided in the groove. The sliding member may be made of a material having a small coefficient of friction with respect to the material constituting the grommet.

[0018] At least a part of the grommet is formed with a diameter-expanded portion, and at least a part of the inner surface side near the diameter-expanded portion is formed with a surface treatment portion. The surface treatment portion may have a small coefficient of friction with respect to other portions.

[0019] According to the first invention, in a grommet having a bellows, by forming a wire harness support portion protruding in the tube center direction on the inner surface side of the valley portion of the bellows, the contact area between the wire harness and the bellows can be reduced. Therefore, the friction with the wire harness during bending can be reduced, and stress concentration due to friction can be suppressed.

[0020] Also, in a cross-section with respect to the tube axis direction, by making the width of the tip side narrower than the base side of the wire harness support portion, the contact area with the wire harness can be reduced more efficiently.

[0021] Also, by forming a plurality of wire harness support portions on the inner surface side of one valley portion, local bending of the wire harness support portion can be suppressed, and the wire harness can be reliably supported.

[0022] Also, by forming a groove continuous in the circumferential direction on the inner surface side near the diameter-expanded portion formed in at least a part of the grommet, and providing an annular sliding member in the groove, the friction with the wire harness near the diameter-expanded portion can be reduced and stress concentration can be suppressed.

[0023] Also, by forming a surface treatment portion having a small coefficient of friction on at least a part of the inner surface side near the diameter-expanded portion, the friction with the wire harness near the diameter-expanded portion can be reduced and stress concentration can be suppressed.

[0024] The second invention is a wiring structure of a wire harness using the grommet according to the first invention, wherein the wire harness is inserted through the grommet, at least a part of the bellows is bent, and at least in the vicinity of the bent part, a wire harness support part is formed on the inner surface of the trough part, and the wire harness is in contact with the wire harness support part. A wiring structure of a wire harness characterized by this.

[0025] According to the second invention, at the bent portion of the grommet, even if the wire harness is strongly pressed against the inner surface of the bellows, it is supported by the wire harness support portion, so that an increase in the contact area can be suppressed, and stress concentration on the wire harness due to friction can be suppressed.

Effect of the Invention

[0026] According to the present invention, it is possible to provide a grommet capable of improving the durability of the grommet and the wire harness by suppressing stress concentration on the wire harness during bending within the grommet, and a wiring structure of a wire harness using the same.

Brief Description of the Drawings

[0027]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Best Mode for Carrying Out the Invention

[0028] Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a perspective view of grommet 1, and FIG. 2(a) is a side view of grommet 1. Grommet 1 is a substantially tubular member through which a wire harness is inserted inside. Grommet 1 has flexibility and is made of, for example, rubber.

[0029] Grommet 1 has bellows 3 and enlarged diameter portions 5a, 5b. The enlarged diameter portions 5a, 5b are, for example, portions to be fixed to a vehicle body, a door, etc. For example, one of the enlarged diameter portions 5a, 5b is fixed to the vehicle body, and the other enlarged diameter portion 5a, 5b is fixed to a door or the like. By doing so, a bendable bellows 3 is arranged between the vehicle body and the door. Details of the bellows 3 will be described later.

[0030] FIG. 2(b) is a cross-sectional view taken along line A-A of FIG. 2(a) (a cross-sectional view in the tube axis direction of grommet 1), and FIG. 3(a) is an enlarged view of portion B of FIG. 2(b). In the vicinity of one end of bellows 3, enlarged diameter portions 5a, 5b are formed so as to separate bellows 3. Enlarged diameter portion 5a has a tapered shape that gradually expands in diameter from the center side to the end side in the tube axis direction (left-right direction in the figure) of grommet 1, and enlarged diameter portion 5b has a flange shape that is arranged at a predetermined interval from the maximum diameter portion of enlarged diameter portion 5a.

[0031] Note that the arrangement and form of enlarged diameter portions 5a, 5b are not limited to the illustrated example. For example, enlarged diameter portions 5a, 5b may be arranged in at least a part of grommet 1. Also, it is not necessary to have enlarged diameter portions 5a, 5b. Thus, as long as it has at least bellows 3, the shape of the grommet of the present invention is not particularly limited.

[0032] As shown in Fig. 3(a), grooves 7 that are continuous in the circumferential direction are formed on the inner surface side near the minimum diameter portion of the diameter-expanded portion 5a provided near the end of the bellows 3 and on the inner surface side of the diameter-expanded portion 5b. Also, annular sliding members 9a are fitted and arranged in the respective grooves 7. Further, in this embodiment, an annular sliding member 9b is arranged at the outermost end of the grommet 1. The sliding members 9a and 9b are made of a material having a small coefficient of friction with respect to the material constituting the grommet 1. For example, the material of the sliding members 9a and 9b is a hard resin.

[0033] Details will be described later, but the grommet 1 is bendable at the bellows 3, and for example, the grommet 1 and the wire harness inserted therein come into contact at the bent portion. When the wire harness contacts strongly, the outer surface of the wire harness is pressed against the grommet surface and a large frictional force is generated. As a result, there is a possibility that a large stress concentration is applied to the corresponding portion of the wire harness.

[0034] Also, since the vicinity of the diameter-expanded portions 5a and 5b serves as a fixing portion to the vehicle body or the like, the grommet 1 often bends at the bellows 3 on both sides of the diameter-expanded portions 5a and 5b. In this way, by arranging the sliding members 9a and 9b at portions such as the vicinity of the diameter-expanded portions 5a and 5b and the tip of the grommet 1 where the wire harness may come into strong contact during bending, even if the wire harness contacts the sliding members 9a and 9b on the inner surface of the grommet 1, the generation of a large frictional force is suppressed, and the wire harness slides appropriately on the inner surface of the grommet 1, thereby suppressing the occurrence of stress concentration.

[0035] Note that, as shown in Fig. 2(b), in this embodiment, an example is shown in which the sliding members 9a and 9b are arranged near the diameter-expanded portions 5a and 5b on one side (the left side in the figure) arranged between the bellows 3 and at the tip of the grommet 1, but the sliding members 9a and 9b may also be arranged for the diameter-expanded portions 5a and 5b and the tip on the other side (the right side in the figure).

[0036] Next, the details of the bellows 3 will be described. FIG. 3(b) is an enlarged view of part C in FIG. 2(b). As described above, the bellows 3 is provided on at least a part of the grommet 1. In the bellows 3, ridges 11 and valleys 13 are repeatedly formed on the outer surface in the tube axis direction.

[0037] In the cross-section in the tube axis direction, the ridge 11 is a part (large outer diameter part) that protrudes outward on the outer surface side of the grommet 1, and the valley 13 is a recess (small outer diameter part) formed between the ridges 11 on the outer surface side of the grommet 1. That is, the valley 13 is a part (small inner diameter part) that protrudes in the central direction on the inner surface side of the grommet 1.

[0038] In the cross-section with respect to the tube axis direction, wire harness support portions 15 that protrude in the tube center direction are formed on the inner surface side of each valley 13. The wire harness support portions 15 are formed so as to be continuous in the inner circumferential direction and are sufficiently narrower than the width of the valley 13. For example, in the illustrated example, the width of the wire harness support portion 15 in the tube axis direction is smaller than the protruding height of the wire harness support portion 15 from the inner surface of the valley 13 in the tube center direction.

[0039] In the cross-section with respect to the tube axis direction, it is desirable that the wire harness support portion 15 has a narrower width on the tip side (tube center side) than on the base side (inner surface side of the valley 13). For example, the cross-sectional shape of the tip portion of the wire harness support portion 15 can be a tapered shape with a curved surface shape or a tapered shape.

[0040] Also, it is desirable that a plurality of wire harness support portions 15 are formed on the inner surface side of one valley 13. In the illustrated example, on the inner surface of one valley 13, three wire harness support portions 15 are arranged in a brush shape at a predetermined interval with respect to the tube axis direction. Note that the heights (tip positions) of all the wire harness support portions 15 are substantially the same.

[0041] Next, the effects of the wire harness support portion 15 will be described. FIG. 4(a) is a diagram showing a wire harness routing structure 20 in which a wire harness 21 is inserted into a grommet 1, and FIG. 4(b) is a diagram showing a state in which the grommet 1 and the wire harness 21 are bent.

[0042] As shown in the figure, with the wire harness 21 inserted into the grommet 1, at least a part of the bellows portion 3 is bent, so that the wire harness 21 may be strongly pressed against the inner surface of the grommet 1 inside the grommet 1.

[0043] FIG. 5(a) is an enlarged view of part D in FIG. 4(b). As described above, at least a wire harness support portion 15 is formed on the inner surface of the trough portion 13 in the vicinity of the bent portion. For example, at the bent portion, the wire harness 21 contacts the wire harness support portion 15 of the bellows portion 3. Therefore, it is possible to prevent an increase in the contact area between the wire harness 21 and the grommet 1 and suppress an increase in the frictional force.

[0044] Note that, as described above, for example, the grommet 1 may be deformed. FIG. 5(b) is a conceptual diagram showing a state in which the wire harness support portion 15 is deformed. Even if the wire harness 21 is strongly pressed against the wire harness support portion 15 (on the inner surface side of the grommet 1) and the wire harness support portion 15 is deformed, the contact area between the wire harness 21 and the grommet 1 can be reduced.

[0045] In this way, the wire harness support portion 15 can suppress an increase in the contact area between the wire harness 21 and the grommet 1, and thereby suppress an increase in the frictional force. Therefore, sliding (movement) between the wire harness 21 and the grommet 1 is allowed, and local deformation can be suppressed. Further, even if a force is applied in the axial direction of the wire harness 21 from this state, since the deformation of the wire harness support portion 15 allows some movement of the wire harness 21, local deformation of the wire harness 21 can be suppressed without sliding between the two.

[0046] As described above, according to grommet 1 of the present embodiment, for example, an increase in the contact area between wire harness 21 and grommet 1 during bending can be suppressed, and the occurrence of unintended stress concentration on wire harness 21 or grommet 1 due to local deformation can be suppressed. Therefore, a decrease in the life of wire harness 21 and the occurrence of damage to grommet 1 can be suppressed.

[0047] In addition, since the frictional force between grommet 1 and wire harness 21 can be reduced, when threading wire harness 21 through grommet 1, the snagging of wire harness 21 is suppressed, and the threading operation becomes easier.

[0048] In particular, by narrowing the width of the tip of wire harness support portion 15, the contact area with wire harness 21 can be reduced more efficiently. At this time, if the width of the base side of wire harness support portion 15 is also narrow, the bending of wire harness support portion 15 will be large, but since it has a sufficient width on the base side, excessive tilting of wire harness support portion 15 can be suppressed to support wire harness 21.

[0049] Also, by forming a plurality of wire harness support portions 15 on the inner surface side of one valley portion 13, a sufficient support force for wire harness 21 can be ensured. Therefore, local bending of wire harness support portion 15 can be suppressed, and wire harness 21 can be reliably supported. For example, even if wire harness support portion 15 is dragged by the movement of wire harness 21 inside grommet 1 during bending, a change in the shape of wire harness support portion 15 can be suppressed, and the function of reducing friction can be maintained.

[0050] In the above-described embodiment, wire harness support portions 15 are provided on the inner surfaces of all valley portions 13, but wire harness support portions 15 may be formed only on the inner surface sides of some valley portions 13. For example, wire harness support portions 15 may be formed only at sites where there is a high possibility of contact with wire harness 21, or wire harness support portions 15 may be formed at valley portions 13 at predetermined intervals.

[0051] Further, by providing the sliding members 9a and 9b at at least a part inside the grommet 1, it is possible to suppress stress concentration due to friction between the wire harness 21 and the grommet 1 in the vicinity of the diameter-expanded portions 5a and 5b.

[0052] In the above-described embodiment, the sliding members 9a and 9b are provided in the vicinity and at the tip of the diameter-expanded portions 5a and 5b, but the present invention is not limited to this. If the wire harness support portion 15 alone is sufficiently effective, the sliding members 9a and 9b are not necessarily required.

[0053] Also, as shown in FIG. 6, a surface treatment portion 23 may be formed in place of the sliding member on at least a part of the inner surface in the vicinity of the diameter-expanded portions 5a and 5b of the grommet 1 and at the tip of the grommet 1. In this case, the surface treatment portion 23 is a portion having a small friction coefficient with respect to other portions, and for example, silicon baking, embossing, fluororesin processing, etc. can be applied.

[0054] As described above, the embodiments of the present invention have been described with reference to the accompanying drawings. However, the technical scope of the present invention is not limited by the above-described embodiments. It is obvious that those skilled in the art can conceive of various modification examples or correction examples within the scope of the technical idea described in the claims, and it is naturally understood that those also belong to the technical scope of the present invention.

Explanation of Reference Numerals

[0055] 1......... Grommet 3......... Bellows 5a, 5b...... Diameter-expanded portions 7......... Groove 9a, 9b...... Sliding members 11......... Ridge portion 13......... Valley portion 15......... Wire harness support portion 20......... Wire harness routing structure 21......... Wire harness 23......... Surface treatment portion 100........ Wire harness 101……… grommet

Claims

1. A substantially tubular grommet through which a wire harness is inserted, having a bellows portion in at least a part thereof, in which ridges and valleys are repeatedly formed on the outer surface in the tube axis direction, characterized in that in a cross section with respect to the tube axis direction, a wire harness support portion protruding in the tube center direction is formed on the inner surface side of at least a part of the valleys.

2. The grommet according to claim 1, characterized in that in a cross section with respect to the tube axis direction, the wire harness support portion has a narrower width on the tip side than on the base side.

3. The grommet according to claim 1, characterized in that a plurality of the wire harness support portions are formed on the inner surface side of one of the valleys.

4. At least a part of the grommet has an enlarged diameter portion, and a groove continuous in the circumferential direction is formed on the inner surface side in the vicinity of the enlarged diameter portion, and an annular sliding member is provided in the groove, the grommet according to claim 1, characterized in that the sliding member is made of a material having a small coefficient of friction with respect to the material constituting the grommet.

5. At least a part of the grommet has an enlarged diameter portion, and a surface treatment portion is formed on at least a part of the inner surface side in the vicinity of the enlarged diameter portion, the grommet according to claim 1, characterized in that the surface treatment portion has a small coefficient of friction with respect to other portions.

6. A wire harness routing structure using the grommet according to any one of claims 1 to 5, wherein a wire harness is inserted through the grommet, and at least a part of the bellows portion is bent, characterized in that the wire harness support portion is formed on the inner surface of the valley in the vicinity of at least the bent portion, and the wire harness is in contact with the wire harness support portion.

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