JP5786761B2 - Cable with grommet - Google Patents

Description

  The present invention relates to a cable with a grommet in which a grommet is integrally formed on the outer peripheral surface of the cable.

  When a cable is attached to a swinging portion around a vehicle, it is common to attach a grommet to the cable and attach the grommet to the vehicle body.

  Conventionally, a cylindrical grommet made of rubber such as EPDM (ethylene propylene diene rubber) has been generally used. When using this grommet, the cable is inserted into the grommet with the grommet's inner diameter being forcibly expanded, and then the grommet's diameter is released. Form the cable.

  In the conventional cable with grommet formed in this way, the grommet and the cable are only in close contact with each other. Therefore, when the cable is bent, the cable and the grommet are separately deformed.

  The prior art document information related to the invention of this application includes the following.

JP 2005-332607 A JP-A-2005-294132

  However, in the conventional cable with grommet described above, since it is necessary to attach the grommet to the cable after the grommet is formed, there is a problem that it takes time to manufacture and the cost increases.

  The present inventor considered forming a grommet on the outer peripheral surface of the cable by injection molding in order to simplify the manufacturing process and reduce the cost.

  By the way, cables with grommets used for vehicle undercarriages, such as cables with grommets for ABS (Anti-lock Braking System) sensors, require bending durability at a low temperature of −20 ° C. or lower (for example, −40 ° C.). The

  When the above conventional cable with grommet is formed by injection molding, the resin used for the grommet is stretched at a lower temperature than the cable sheath (outer skin), can be molded at a temperature that does not melt the cable sheath, and molding shrinkage It is necessary to use a resin having a large (clamping force to the cable). However, the resin having such characteristics is expensive and eventually becomes expensive. As an example, when a prototype was made using Hytrel (registered trademark) as a resin for grommet, a cable with grommet having sufficient bending durability was realized, but there was a problem in terms of environmental resistance (hydrolysis). It was.

  In addition, the method of directly molding TPE (thermoplastic elastomer) on the cable is often carried out in parts that require flexibility, such as outlets, and it is generally practiced to make it easier to bend by making holes in the bent parts. It has been broken. However, these are premised on the use at room temperature, that is, the temperature at which the flexibility of the material is maintained (at least about 0 ° C.), and the flexibility of the material is lost. It cannot be applied as it is to a cable with a grommet for a vehicle that requires bending durability.

  For example, in an outlet or the like, the entire resin provided on the cable is usually fused and fixed to the cable and integrated with the sheath of the cable, but if the resin is fused to the cable at the bent portion, the fusion The cable has a shape in which the outer diameter of the cable is thickened at the worn portion, and stress is concentrated on the portion having a large outer diameter at the time of bending, and the cable is broken together with the molded resin.

  The present invention has been made in view of the above circumstances, and in a cable with a grommet in which a grommet is integrally formed on the outer peripheral surface of the cable, it is possible to improve the bending durability at low temperatures, and the environment around the undercarriage of the vehicle It aims at providing the cable with a grommet which can endure.

The present invention has been developed to achieve the above object, and is a cable with a grommet in which a grommet is integrally formed on the outer peripheral surface of the cable, and the grommet is fused and fixed to the sheath of the cable. A main body part, which is integrally formed with the main body part, is provided so as to cover the periphery of the cable extending from the main body part, and is provided so as to be in close contact with the cable without being fused and fixed to the sheath. And a guide part that guides the extending direction of the cable extending from the main body part, and the guide part is arranged so that the interval becomes narrower as the distance from the main body part increases in the length direction of the cable. A ring-shaped support portion, and a plurality of connecting pieces that are formed in a linear shape along the length direction of the cable and connect the main body portion, the support portion, and the support portions. The connecting portions adjacent to each other with the support portion interposed therebetween are rotated by 180 / n ° in the circumferential direction of the cable, where n is the number of the connecting pieces. A cable with grommet.

  The guide portion may be formed in a tapered shape that is reduced in diameter as the distance from the main body portion increases.

  The connecting portion includes two connecting pieces, and both connecting pieces are provided at positions facing each other with the cable interposed therebetween, and the connecting portions adjacent to each other with the support portion interposed therebetween are arranged in the circumferential direction of the cable. May be rotated 90 °.

  The grommet may be formed using a resin having lower hardness and larger elongation than the sheath.

  The grommet may be formed by injection molding.

  ADVANTAGE OF THE INVENTION According to this invention, the bending durability at low temperature can be improved and the cable with a grommet which can endure the environment around the vehicle's undercarriage can be provided.

It is a figure which shows the cable with a grommet which concerns on one embodiment of this invention, (a) is a side view, (b) is the 1B-1B sectional view taken on the line, (c) is a side view when a bracket is attached. is there. (A) is a perspective view of the cable with a grommet of FIG. 1, (b) is a perspective view of a grommet. (A), (b) is a side view which shows the modification of the cable with a grommet of FIG. In this invention, it is a figure explaining a bending test. (A) is a side view which shows the cable with a grommet of the comparative example used for the comparison with this invention, (b) is the 5B-5B sectional view taken on the line. (A) is a side view which shows the cable with a grommet of the comparative example used for the comparison with this invention, (b) is the 6B-6B sectional view taken on the line.

  Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

  1 and 2 are diagrams showing a cable with a grommet according to the present embodiment. FIG. 1A is a side view, FIG. 1B is a sectional view taken along line 1B-1B, and FIG. FIG. 2A is a perspective view when the bracket is attached, FIG. 2A is a perspective view, and FIG. 2B is a perspective view of the grommet.

  As shown in FIGS. 1 and 2, the cable 1 with grommet is one in which a grommet 3 is integrally formed on the outer peripheral surface of a cable 2. The grommet 3 is formed by injection molding TPE (thermoplastic elastomer) directly on the cable 2. The cable 1 with grommet is used as a cable with grommet for an ABS sensor of a vehicle, for example.

  The cable 2 is provided with two insulated wires 4 each having an insulator formed on the outer periphery of the central conductor, and provided with a common sheath 5 so as to cover the two insulated wires 4 together. The configuration of the cable 2 is not limited to this. In the present embodiment, the cable 2 having a diameter of 4.0 mm is used.

  The grommet 3 is formed integrally with the main body (fused portion) 6 that is fused and fixed to the sheath 5 of the cable 2, and guides the extending direction of the cable 2 that extends from the main body 6. And a guide portion (bent portion) 7. The guide portion 7 is provided so as to cover the periphery of the cable 2 extending from the main body portion 6, and is provided so as to be in close contact with the cable 5 without being fused and fixed to the sheath 5.

  Since the grommet 3 should not be displaced from the cable 2, a part of the grommet 3 needs to be fixed to the cable 2. In the present embodiment, the grommet 3 is fixed to the cable 2 by fusing and fixing the main body 6 to the sheath 5. Further, since the cable 2 is difficult to be held when the main body 6 is easily bent, the main body 6 is formed to be sufficiently thick so that the main body 6 is not bent.

  A groove 8 for attaching a bracket 9 for fixing the cable 2 to the vehicle body or the like is formed in the main body 6 along the circumferential direction of the cable 2. The main body portion 6 is attached to the bracket 9 by inserting the main body portion 6 into a hole (not shown) formed in the bracket 9 and locking the peripheral portion of the hole of the bracket 9 in the groove 8 portion. By fixing the bracket 9 to the vehicle body or the like using a bolt or the like, the cable 2 is attached to the vehicle body or the like.

  In order to facilitate the insertion of the main body 6 into the hole of the bracket 9 at the end of the main body 6 on the guide part 7 side, a tapered part 10 that is reduced in diameter toward the guide part 7 is formed. . The main body portion 6 is inserted into the hole of the bracket 9 from the guide portion 7 side. The main body 6 is formed with a larger diameter than the guide 7, and the guide 7 is formed with a diameter smaller than the diameter of the hole of the bracket 9.

  Moreover, when the cable 2 is pulled (when pulled to the right side in FIG. 1C), the end of the main body 6 opposite to the tapered portion 10 is opposite to the tapered portion 10 of the main body 6. Reinforcing ribs 11 are formed to reinforce the body portion 6 so that the body portion 6 does not come out of the hole of the bracket 9 due to deformation. In the present embodiment, the cross-shaped reinforcing rib 11 is formed in front view, but the shape of the reinforcing rib 11 is not particularly limited.

  Instead of forming the reinforcing rib 11, it is also possible to form a thick portion (a width along the length direction of the cable 2) thicker on the opposite side of the taper portion 10 of the main body portion 6. However, in this case, since the thickness of the resin becomes too thick and voids and sink marks are likely to occur during injection molding, the reinforcing rib 11 is formed as in the present embodiment to keep the thickness of the resin as thin as possible. More desirable. In addition, in FIG.1 (c), although the case where the bracket 9 is formed in L shape by side view is shown, the shape of the bracket 9 is not specifically limited.

  The guide portion 7 prevents the stress from concentrating on the connection portion of the cable 2 to the main body portion 6 when bent, and distributes the stress when bent and guides the extending direction of the cable 2 to guide the track of the cable 2. It plays a role to stabilize In particular, when the cable 1 with grommet is used for wiring around the vehicle's undercarriage, it is necessary to wire it in a limited space. In order to stabilize the track of the cable 2 and avoid interference with other members, the guide Part 7 is essential.

  The guide portion 7 includes a ring-shaped support portion 12 disposed at a predetermined interval in the length direction of the cable 2, and a main body portion 6, the support portion 12, and a connecting portion 13 that connects the support portions 12 to each other.

  The connecting portion 13 is formed in a linear shape along the length direction of the cable 2, and includes a main body portion 6, a supporting portion 12, and a plurality of connecting pieces (guides) 13 a that connect the supporting portions 12 to each other. Further, when the number of the connecting pieces 13a is n, the adjacent connecting portions 13 with the support portion 12 interposed therebetween are provided to rotate 180 / n ° in the circumferential direction of the cable 2.

  In the present embodiment, two connecting pieces 13 a are provided, and both connecting pieces 13 a are provided at positions facing each other with the cable 2 interposed therebetween. Further, the connecting portions 13 that are adjacent to each other with the support portion 12 interposed therebetween are provided to be rotated by 90 ° in the circumferential direction of the cable 2. In the present embodiment, seven pairs of the support part 12 and the connection part 13 are provided, but the number of pairs of the support part 12 and the connection part 13 is not limited to this.

  The connection piece 13a is provided at a position facing the cable 2 with the cable 2 interposed therebetween, and is bent in a direction in which the connection piece 13a is not formed (for example, when the connection piece 13a is provided above and below the cable 2). This is for facilitating and suppressing stress concentration on the connecting piece 13a during bending. By providing adjacent connecting portions 13 rotated 90 degrees in the circumferential direction of the cable 2, the connecting pieces 13 a can be bent in all directions without applying an excessive load.

  The connecting piece 13 a is formed in an arcuate cross-sectional shape along the outer periphery of the cable 2. If the width of the connecting piece 13a (the length along the circumferential direction of the cable 2) is too thick, the load at the time of bending becomes large and it is easy to break. Therefore, it is good to adjust to an appropriate thickness. In the present embodiment, the width of the connecting piece 13a and the width of the support portion 12 (the width along the length direction of the cable 2) are made equal to 1.6 mm (40% of the diameter of the cable 2).

  The guide portion 7 is bent together with the cable 2 when the cable 2 is bent. However, if the guide portion 7 is fused and integrated with the cable 2, the outer diameter of a part of the cable 2 becomes thicker. As a result, stress concentrates on a portion having a large outer diameter during low-temperature bending, and the cable 2 is broken together with the grommet 3. Therefore, it is necessary to configure the guide portion 7 so as not to be fused to the sheath 5 of the cable 2 so that the cable 2 and the guide portion 7 are separately deformed.

  As described above, the grommet 3 is formed by injection molding using a mold, but the area where the resin touches the mold at the time of molding is formed by forming the guide portion 7 in a net shape including the support portion 12 and the connecting portion 13. The (surface area) can be increased, and the resin can be quickly cooled by the mold to prevent the guide portion 7 from being fused to the sheath 5 of the cable 2. That is, in the guide portion 7 that is not desired to be fused with the sheath 5, the portion is in contact with the mold with a net-like shape with the meat removed so that the temperature of the sheath 5 is not lowered by cooling the resin. . The position of the gate for introducing the resin is the position facing the main body 6, and the high temperature resin immediately after the introduction is brought into contact with the sheath 5 to melt the sheath 5, and the main body 6 is fused and fixed to the sheath 5. Good.

  Further, in the present embodiment, the guide portion 7 is formed so that the interval between the support portions 12 becomes narrower as the distance from the main body portion 6 increases. Moreover, in this Embodiment, the guide part 7 is formed in the taper shape reduced in diameter, so that it leaves | separates from the main-body part 6 as a whole. By configuring in this way, the role of dispersing the stress at the time of bending and the role of the guide of the cable 2 are balanced, and the bending durability at a low temperature is further improved while sufficiently fulfilling the role as a guide. It becomes possible.

  In the present embodiment, the distance between the main body 6 and the support part 12 arranged closest to the main body 6 is 5 mm, and the distance between the support parts 12 is 4.5 mm, 4 mm, and 3.5 mm from the main body 6 side. ..., And 5 mm narrower. Further, the guide portion 7 was formed so that the diameter of the guide portion 7 was reduced from 10 mm to 6.4 mm as the distance from the main body portion 6 was increased (taper angle was about 2 °). The entire length of the grommet 3 including the main body portion 6 and the guide portion 7 (the length along the length direction of the cable 2) was 49.3 mm.

  As shown in FIG. 3A, the guide portion 7 may not be tapered, and only the interval between the support portions 12 may be formed so as to become narrower as the distance from the main body portion 6 increases. ), The distance between the support portions 12 may be constant, and the guide portion 7 may be formed in a tapered shape with a diameter reduced as the distance from the main body portion 6 increases. However, from the standpoint of further improving the bending durability at low temperatures, the guide portions are tapered such that the distance between the support portions 12 decreases as the distance from the main body portion 6 increases, and the diameter decreases as the distance from the main body portion 6 increases. 7 is desirable.

  As the resin used for the grommet 3, it is preferable to use a resin having a hardness lower than that of the sheath 5 and a large elongation so that the cable 2 can be flexibly followed. In the present embodiment, the resin used for the grommet 3 is the same material as the sheath 5 (for example, PE (polyethylene)), has a low hardness, has a larger elongation than the sheath 5, and has a low molding temperature. If the hardness is lowered, the solidification time becomes longer and the molding time becomes longer. Therefore, as the resin used for the grommet 3, it is desirable to select a resin having a certain degree of hardness within a range where bending is established.

  The operation of the present embodiment will be described.

  In the cable 1 with grommet according to the present embodiment, the grommet 3 is fused and fixed to the sheath 5 of the cable 2, and the cable 2 is formed integrally with the main body 6 and extends from the main body 6. A guide portion 7 that is provided so as to cover the periphery of the cable 5 and that is provided so as to be in close contact with the cable 2 without being fused and fixed to the sheath 5 and that guides the extending direction of the cable 2 extending from the main body portion 6. The guide portion 7 is formed in a ring-shaped support portion 12 arranged at a predetermined interval in the length direction of the cable 2 and a linear shape along the length direction of the cable 2, and is supported by the main body portion 6. And a connecting portion 13 provided with a plurality of connecting pieces 13a for connecting the support portions 12 to each other, and when the number of connecting pieces 13a is n, adjacent connecting portions 13 sandwiching the supporting portion 12 are provided. , Cable 2 to each other It is provided to rotate 180 / n ° in the circumferential direction.

  By providing the guide portion 7 so as to be in close contact with the cable 2 without being fused and fixed to the sheath 5, the cable 2 and the guide portion 7 can be deformed separately, and bending resistance at low temperatures is achieved. Can be improved.

  Moreover, in this Embodiment, the guide part 7 is comprised by the connection part 13 which arrange | positioned the ring-shaped support part 12 and the two connection pieces 13a facing each other, and the adjacent connection parts 13 are mutually circumferential directions of the cable 2. Therefore, the stress at the time of bending can be dispersed so that the stress is not concentrated on the specific connecting piece 13a when the cable 2 is bent. It will be possible to fulfill sufficiently.

  Furthermore, by forming the guide portion 7 in a net shape composed of the support portion 12 and the connecting portion 13, the area (surface area) where the resin touches the mold during molding is increased, and the resin is quickly cooled by the mold, It is possible to prevent the guide portion 7 from being fused to the sheath 5 of the cable 2.

  Further, the cable 1 with grommet is easy to manufacture because the grommet 3 can be formed by injection molding, and an inexpensive resin can be used. Therefore, the cost can be greatly reduced as compared with the conventional cable.

  That is, according to the present invention, it is possible to improve the bending durability at low temperatures, and it is possible to realize an inexpensive cable 1 with grommet that can withstand the environment around the undercarriage of the vehicle.

  The present invention is not limited to the above-described embodiment, and it is needless to say that various modifications can be made without departing from the spirit of the present invention.

  For example, the number of connecting pieces 13a is not limited to two and may be three or more.

Example 1
The cable 1 with grommet shown in FIG. 1 was prepared and evaluated for bending durability at low temperatures. The hardness of the sheath 5 of the cable 2 was A90 (A represents Shore A hardness), and the hardness of the grommet 3 was A80 and A70.

  In a bending test for evaluating bending durability at a low temperature, it is assumed that the cable 1 with grommet is used for wiring around the undercarriage of the vehicle, and the grommet 3 is formed at both ends of the cable 2 as shown in FIG. When the cable 2 is bent in a U-shape, one grommet 3 is fixed, and the other grommet 3 is moved downward from the position of the grommet 3 when the tire moves up. The bend test was performed by moving to the position of the grommet 3.

  In the bending test, first, the cable 2 was bent 200,000 times at −35 ° C., then bent 300,000 times at −20 ° C. and 700,000 times at room temperature using the same sample, It was confirmed whether the grommet 3 had cracks.

(Example 2)
The cable 1 with grommet of FIG. 3A in which the diameter of the guide portion 7 was constant was created, and the bending durability at a low temperature was evaluated in the same manner as in Example 1.

(Example 3)
The cable 1 with grommet of FIG. 3B in which the distance between the support portions 12 was constant was created, and the bending durability at low temperatures was evaluated in the same manner as in Example 1. In Example 3, the interval between the support parts 12 was fixed at 4 mm, and 10 pairs of the support parts 12 and the connection parts 13 were provided. The width of the support portion 12 was 3.2 mm.

(Comparative Example 1)
For comparison with Examples 1 to 3 of the present invention, a cable 51 with grommet as shown in FIGS. 5A and 5B was prepared, and the bending durability at low temperature was evaluated in the same manner as Example 1. . In the cable 51 with grommet, the entire grommet 52 including the guide portion 7 is fused to the sheath 5, the diameter of the guide portion 7 is constant, and the interval between the support portions 12 is constant at 2 mm. The connecting pieces 13 a are arranged at equal intervals in the circumferential direction of the cable 2 to form the connecting portion 13. The width of the support portion 12 was 1.5 mm, the width of the connecting piece 13a was 2 mm, and the number of pairs of the support portion 12 and the connecting portion 13 was nine. The hardness of the grommet 52 was A90.

(Comparative Example 2)
In Comparative Example 1, the grommet 52 was formed by injection molding in the same manner as in Examples 1 to 3. However, in Comparative Example 2, the grommet 52 shown in FIG. 5 was prepared as a single item, and the prepared grommet 52 was attached to the cable 2. I did it. When attaching the grommet 52, the inner diameter of the grommet 52 was forcibly expanded, and after the cable 2 was inserted, the expanded diameter was released, and the cable 2 was tightened with the tight binding force of the grommet 52. Thereafter, the bending durability at a low temperature was evaluated in the same manner as in Example 1.

(Comparative Example 3)
As shown in FIGS. 6A and 6B, a cable 61 with a grommet in which a grommet 62 of only the main body 6 is formed on the cable 2 is created, and the bending durability at a low temperature is evaluated in the same manner as in the first embodiment. did. The hardness of the grommet 62 was A90.

  Table 1 summarizes the evaluation results of bending durability at low temperatures in Examples 1 to 3 and Comparative Examples 1 to 3.

  As shown in Table 1, in the cable 51 with grommet of Comparative Example 1, when the grommet 52 was bent 100,000 times at −35 ° C., a break occurred at the portion where the grommet 52 was formed. Both were cut and all were disconnected. In Comparative Example 2, the cable 2 did not break, but a crack occurred in the grommet 52 in the -35 ° C. bending test. In the cable 61 with grommet of Comparative Example 3, when the grommet 52 was bent 10,000 times at −35 ° C., a break occurred at the portion where the grommet 52 was molded, resulting in complete disconnection.

  On the other hand, in Example 1 of the present invention, there was no problem in the −35 ° C. bending test, and the cable 2 was broken or the grommet 3 was cracked even when bent at −35 ° C. for 2 million times or more. Did not occur. In Example 2, cracks occurred in grommet 3 when bent 1.7 million times at −35 ° C., and cracks occurred in grommet 3 when bent 1.8 million times at −35 ° C. , −35 ° C. × 200,000 times flexion test passed sufficiently. As described above, the first to third embodiments of the present invention have high bending durability at low temperatures, and can be used for wiring around a vehicle's undercarriage.

DESCRIPTION OF SYMBOLS 1 Cable with grommet 2 Cable 3 Grommet 4 Insulated wire 5 Sheath 6 Main body part 7 Guide part 8 Groove 9 Bracket 10 Tapered part 11 Reinforcement rib 12 Support part 13 Connection part 13a Connection piece

Claims (5)

A cable with a grommet in which a grommet is integrally formed on the outer peripheral surface of the cable,
The grommet is provided so as to cover the periphery of the cable that is formed integrally with the main body portion and is formed integrally with the main body portion, and is fixed to the sheath of the cable. A guide portion that is provided so as to be in close contact with the cable without being fused and fixed, and that guides the extending direction of the cable extending from the main body portion,
The guide portion is formed in a linear shape along the length direction of the cable, and a ring-shaped support portion that is arranged so that an interval becomes narrower as the distance from the main body portion increases in the length direction of the cable. And a connecting portion provided with a plurality of connecting pieces for connecting the supporting portion and the supporting portions,
When the number of the connecting pieces is n, the connecting portions adjacent to each other with the support portion interposed therebetween are provided to rotate 180 / n ° in the circumferential direction of the cable. The guide portion according to claim 1, wherein the cable with the grommet being formed in a tapered shape which is reduced in diameter as the distance from the body as a whole. The connecting portion includes two connecting pieces,
The both connecting pieces are provided at positions facing each other across the cable,
The cable with a grommet according to claim 1 or 2 , wherein the connecting portions adjacent to each other with the support portion interposed therebetween are rotated by 90 ° in the circumferential direction of the cable. The cable with a grommet according to any one of claims 1 to 3 , wherein the grommet is formed using a resin having lower hardness and larger elongation than the sheath. The cable with a grommet according to any one of claims 1 to 4 , wherein the grommet is formed by injection molding.