Connection structure, and grommet

Abstract

To provide a technique that enhances insertability of a corrugated tube into a cylindrical portion of a grommet.SOLUTION: A connection structure 10 comprises a grommet 12 having a cylindrical portion 20, and a corrugated tube 14 inserted into the cylindrical portion 20. The corrugated tube 14 has ridges and valleys alternately. The cylindrical portion 20 has a plurality of protrusions formed on an inner circumferential surface so as to protrude in an annular shape, and annular recesses formed on the inner circumferential surface and arranged alternately with the protrusions. The protrusions are formed so as to have a pitch larger than the valleys.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a technique for connecting a corrugated tube to a cylindrical portion of a grommet. [Background technology]

[0002] Patent Document 1 discloses a grommet that is fitted onto a corrugated tube. This grommet includes a cylindrical corrugated end portion that can be connected to the outer periphery of the corrugated tube in a sealed state, and a plurality of sealing lips that are provided on ridges on the inner periphery of the corrugated end portion so as to fit closely to the valleys of the corrugated tube. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2017-225339 Summary of the Invention [Problem to be solved by the invention]

[0004] In the technique described in Patent Document 1, the sealing lip of the grommet enters the valleys of the corrugated tube and climbs over the peaks of the corrugated tube each time, so improvement in insertion ease is desired.

[0005] An object of the present invention is to provide a technique for improving the ease of inserting a corrugated tube into a cylindrical portion of a grommet. [Means for solving the problem]

[0006] In order to solve the above problems, a connection structure according to one aspect of the present invention includes a grommet having a cylindrical portion and a corrugated tube inserted into the cylindrical portion. The corrugated tube has alternating peaks and valleys. The cylindrical portion has a plurality of annular projections formed on an inner peripheral surface thereof and annular recesses formed on the inner peripheral surface thereof and arranged alternately with the projections. The projections are formed at a larger pitch than the valleys.

[0007] Another aspect of the present invention is a grommet to be connected to a corrugated tube. The grommet includes a cylindrical portion into which the corrugated tube is inserted. The cylindrical portion has a plurality of annular projections formed on an inner peripheral surface thereof and annular recesses formed on the inner peripheral surface thereof and arranged alternately with the projections. The projections are formed at a larger pitch than the valleys of the corrugated tube. [Effects of the Invention]

[0008] According to the present invention, a technique can be provided that improves the ease of inserting a corrugated tube into a cylindrical portion of a grommet. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 2 is a perspective view of a connecting structure according to an embodiment. [Figure 2] FIG. 2 is a cross-sectional view of the connection structure of the embodiment. [Figure 3] FIG. 4 is an enlarged cross-sectional view of a connecting portion between the grommet and the corrugated tube. [Figure 4] 10A and 10B are diagrams for explaining an operation when the grommet and the corrugated tube are connected to each other. DETAILED DESCRIPTION OF THE INVENTION

[0010] Fig. 1 is a perspective view of a connecting structure 10 according to an embodiment. Fig. 2 is a cross-sectional view of the connecting structure 10 according to an embodiment. The connecting structure 10 includes a grommet 12, a corrugated tube 14, and a band 16. The connecting structure 10 has an internal through-space and is used to surround and protect wires such as harnesses and wires. The connection between the grommet 12 and the corrugated tube 14 is sealed to prevent water from entering the inside of the connecting structure 10.

[0011] The grommet 12 is formed from a resin material and is connected to the corrugated tube 14. The grommet 12 has a tubular portion 20, a small tubular portion 22, a connecting portion 24, and a step portion 26. The tubular portion 20 is located at one end of the grommet 12 and opens, and the connecting portion 24 is located at the other end of the grommet 12 and opens.

[0012] The corrugated tube 14 is inserted into the cylindrical portion 20 through the opening 20a. The small cylindrical portion 22 is formed with a smaller diameter than the cylindrical portion 20. The step portion 26 is a portion that connects the cylindrical portion 20 and the small cylindrical portion 22. The step portion 26 is formed in an annular shape so that the diameter decreases from the cylindrical portion 20 to the small cylindrical portion 22. The step portion 26 forms a step surface that extends in a direction intersecting the axial direction.

[0013] The connecting portion 24 is formed in the shape of an elongated hole. The connecting portion 24 has an annular seal lip on its inner circumferential surface. The connecting portion 24 is connected to another member. The grommet 12 is formed by curving between the tubular portion 20 and the connecting portion 24, but is not limited to this form and may have any other shape as long as the hollow shape ensures sealing.

[0014] The corrugated tube 14 is inserted into the cylindrical portion 20. The band 16 is wound around the outer periphery of the cylindrical portion 20 and tightens the cylindrical portion 20 radially inward from the outside. By tightening the band 16, the corrugated tube 14 is fixed to the cylindrical portion 20.

[0015] 3 is an enlarged cross-sectional view of the connecting portion between the grommet 12 and the corrugated tube 14. The tubular portion 20 has a plurality of protrusions 28 and a plurality of recesses 30. The protrusions 28 are formed to protrude from the inner circumferential surface of the tubular portion 20 and are formed in an annular shape. The recesses 30 are formed to be recessed into the inner circumferential surface of the tubular portion 20 and are formed in an annular shape. The plurality of protrusions 28 and the plurality of recesses 30 are arranged alternately.

[0016] The tip of the protrusion 28 is formed flat and abuts against the mountain portion 32. The protrusion 28 is located at the position of the open end of the cylindrical portion 20, and the recess 30 is located at the innermost position adjacent to the step portion 26.

[0017] The corrugated tube 14 has a plurality of peaks 32 and a plurality of valleys 34. The peaks 32 are formed to protrude annularly, and the valleys 34 are formed to be recessed annularly. The peaks 32 and valleys 34 are arranged alternately. The tips of the peaks 32 are formed to be flat, and the side surfaces of the peaks 32 are inclined so as to taper toward the tips.

[0018] The pitch L1 of the convex portions 28 is formed to be larger than the pitch L4 of the valley portions 34. This prevents the convex portions 28 from entering the valley portions 34. Therefore, when the corrugated tube 14 is inserted into the tubular portion 20, the convex portions 28 are prevented from entering the valley portions 34 and blocking the insertion of the corrugated tube 14. Furthermore, the pitch of the convex and concave portions on the inner circumferential surface of the tubular portion 20 can be made larger than if the pitch of the concave portions 30 were smaller than the pitch of the ridge portions 32, making molding easier. The pitch L1 of the convex portions 28 is the length of the flat portion of the tip of the convex portions 28. Furthermore, the pitch L4 of the valley portions 34 is the radially outermost portion where the inclined valley portions 34 are at their widest.

[0019] The pitch L2 of the recesses 30 may be equal to or greater than the pitch L1 of the protrusions 28. By increasing the pitch L2 of the recesses 30, the cylindrical portion 20 can be configured to be easily flexible.

[0020] The height to which the convex portions 28 protrude inward in the radial direction is lower than the height to which the ridge portions 32 protrude outward in the radial direction, thereby making it possible to reduce the thickness of the cylindrical portion 20.

[0021] The pitch L3 of the recesses 30a adjacent to the step portion 26 may be greater than the pitch L5 of the peaks 32. The recesses 30a on the innermost side are formed so that the peaks 32 can fit therein.

[0022] FIG. 4 is a diagram for explaining the operation when the grommet 12 and the corrugated tube 14 are connected.

[0023] 4(a) shows a state in which one end of the corrugated tube 14 begins to be inserted through the opening 20a of the tubular portion 20 and hits the edge of the opening 20a. In the tubular portion 20 in its free state before the corrugated tube 14 is inserted, the inner diameter of the convex portion 28 is smaller than the outer diameter of the peak portion 32. Therefore, the peak portion 32 hits the convex portion 28 of the tubular portion 20 when the corrugated tube 14 is inserted.

[0024] 4(b) shows the state in which the convex portions 28 come into contact with the peak portions 32 and expand in diameter. The tubular portion 20 is formed of a material that is softer than the corrugated tube 14 and is formed to be more flexible than the corrugated tube 14, and the peak portions 32 come into contact with the convex portions 28 and are pushed apart, thereby expanding in diameter.

[0025] FIG. 4(c) shows the state in which the corrugated tube 14 is further inserted into the tubular portion 20, and the diameter of the tubular portion 20 gradually expands from the opening 20a side. As the peaks 32 enter the tubular portion 20, the diameter of the tubular portion 20 expands. Because the pitch L1 of the convex portions 28 is greater than the pitch L4 of the valley portions 34, the convex portions 28 enter the valley portions 34 and do not fit into them. Therefore, the convex portions 28 and the valley portions 34 do not fit together, and the corrugated tube 14 can be inserted while expanding the diameter of the tubular portion 20. The convex portions 28 and the valley portions 34 do not fit together during insertion, and the insertion of the corrugated tube 14 does not stop.

[0026] 4(d) shows a state in which the corrugated tube 14 is further inserted into the cylindrical portion 20 and one end of the corrugated tube 14 abuts against the step portion 26. The step portion 26 functions as a stopper for the corrugated tube 14 when the corrugated tube 14 is inserted into the cylindrical portion 20. When the corrugated tube 14 abuts against the step portion 26, the worker can recognize that the insertion of the corrugated tube 14 is complete.

[0027] The cylindrical portion 20 expands in diameter as the corrugated tube 14 is inserted. When the insertion of the corrugated tube 14 is complete, the cylindrical portion 20 expands in diameter until the inner diameter of the convex portions 28 becomes the same as the outer diameter of the ridge portions 32. The innermost concave portion 30a is curved so that its diameter decreases toward the step portion 26. The ridge portions 32 fit into the concave portion 30a. The band 16 tightens around the outer periphery of the cylindrical portion 20, fixing the corrugated tube 14 to the cylindrical portion 20. This completes the connection of the corrugated tube 14. The convex portions 28 elastically contact the ridge portions 32, ensuring a seal between the grommet 12 and the corrugated tube 14.

[0028] The present disclosure has been described above based on examples. The present disclosure is not limited to the above examples, and various modifications such as design changes may be made based on the knowledge of those skilled in the art. [Explanation of symbols]

[0029] 10 connecting structure, 12 grommet, 14 corrugated tube, 16 band, 20 tubular portion, 20a opening, 22 small tubular portion, 24 connecting portion, 26 stepped portion, 28 convex portion, 30 concave portion, 32 ridge portion, 34 valley portion.

Claims

1. a grommet having a cylindrical portion; a corrugated tube inserted into the cylindrical portion, The corrugated tube has alternating peaks and valleys, The cylindrical portion is a plurality of protrusions formed annularly on the inner circumferential surface; annular recesses formed on the inner circumferential surface and arranged alternately with the protrusions; A connecting structure, characterized in that the convex portions are formed at a larger pitch than the valley portions.

2. 2. The connecting structure according to claim 1, wherein the cylindrical portion is formed to be more flexible than the corrugated tube, and the diameter of the cylindrical portion is expanded when the peaks come into contact with the protrusions.

3. The grommet is a small cylindrical portion formed to have a smaller diameter than the cylindrical portion; 3. The connecting structure according to claim 1, further comprising an annular step portion formed from the cylindrical portion to the small cylindrical portion.

4. The connecting structure according to claim 3 , wherein the step portion functions as a stopper for the corrugated tube when the corrugated tube is inserted into the cylindrical portion.

5. A grommet connected to a corrugated tube, a cylindrical portion into which the corrugated tube is inserted, The cylindrical portion is a plurality of protrusions formed annularly on the inner circumferential surface; annular recesses formed on the inner circumferential surface and arranged alternately with the protrusions; A grommet, wherein the convex portions are formed at a pitch greater than that of the valley portions of the corrugated tube.

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