JP2017208982A - Tube for electric wire protection and wiring harness - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a tube for electric wire protection in which inexpensive polyolefin resin having heat shrinkability is used as a base material, strength of the tube is equal to multiple of that of the polyolefin resin itself, and the tube can be used instead of the conventional hard tube so as to be capable of reducing work man-hour of a wire harness assembly, and number of components.SOLUTION: A wire harness 1 is formed to be cylindrical by using polyolefin resin having heat shrinkability in which cellulose nanofiber is added at a prescribed ratio and scattered. A required dimension of inner diameter d thereof before heat shrinkage is larger than a diameter D of a wire bundle W, and the inner diameter is shrunk to be a dimension d' closely adhered to the wire bundle W at the heat shrinkage.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a wire protection tube and a wire harness using a material containing cellulose nanofibers.

  2. Description of the Related Art Conventionally, in an automobile, a wire harness is routed for supplying power to an electrical component along an interior of an engine room and an instrument panel on the vehicle compartment side, a floor, a door, and a roof. An electric wire protection tube is widely used to protect a wire harness that bundles electric wires in contact with the vehicle side.

  In particular, a hard tube made of hardened PVC or the like is used instead of a normal corrugated tube to protect the wire bundle in a portion where vibration is required and the wiring is large, such as inside the instrument panel. It has been. When the wire harness is fixed to the vehicle side, the hard tube is half-wrapped with a fixing tape as shown in FIG. 3 in order to ensure the fixing.

  Similarly, in Patent Document 1, the wire group 11 a is covered with the hard tube 14, and the outer peripheral surface of the hard tube 14 is covered with the heat resistant sheet 16, and both ends of the heat resistant sheet 16 are wound so as to be tightened with the tape 17. Is disclosed.

JP 2002-305824 A

  However, the hard tube described in Patent Document 1 needs to be wound with a tape in order to fix it to the electric wire bundle, generating extra work steps and increasing the number of parts.

  The present invention has been made in order to solve the above-described problems. The base material is an inexpensive polyolefin resin having heat shrinkability, and has a strength several times that of the polyolefin resin itself. An object of the present invention is to provide a wire protection tube and a wire harness that can be used in place of the above, reduce the man-hours for assembling the wire harness, and reduce the number of parts.

  In order to achieve the above object, the wire protection tube according to the present invention is formed into a cylindrical shape with a polyolefin resin having heat shrinkability, to which cellulose nanofibers are added and dispersed in a predetermined ratio, and the inner diameter before heat shrinkage. The size is larger than the diameter of the wire bundle to be inserted through, and shrinks to a size that closely contacts the wire bundle when heat shrinks.

  With this configuration, the wire protection tube according to the present invention is formed into a cylindrical shape from a polyolefin resin having heat shrinkability, so that the material cost can be reduced compared to a conventional hard tube, and further, cellulose Since it is molded into a cylindrical shape by a polyolefin resin having heat shrinkability to which nanofibers are added in a predetermined ratio, the material strength of the polyolefin resin can be increased several times and can be used in place of a conventional hard tube.

  Furthermore, since the electric wire protection tube according to the present invention has a cylindrical shape having an inner diameter that is in close contact with the electric wire bundle at the time of heat shrinkage, it can be fixed to the electric wire bundle without using a component such as a tape. For this reason, the wire protection tube according to the present invention does not require a tape winding operation, reduces the work man-hours for assembling the wire harness, and reduces the number of parts.

  Moreover, the tube for electric wire protection of the said structure is good also as a structure which has a shrinkage rate of 60 to 75%.

  With this configuration, the wire protection tube according to the present invention can be applied to wire bundles having a wide range of outer diameters because the inner diameter shrinks to 60 to 75% of the size before heat shrinkage when heat shrinks. It is.

  The wire harness according to the present invention includes the wire bundle composed of a plurality of electric wires and the wire protection tube, and the wire harness is inserted into the wire protection tube and the wire protection wire is protected by heat shrinkage. The tube is in close contact with the wire bundle.

  With this configuration, the wire harness according to the present invention is formed of a heat-shrinkable polyolefin resin, and has a cylindrical shape with an inner diameter that is in close contact with the wire bundle during heat shrinkage. Without being fixed to the wire bundle.

  Therefore, the work man-hours for assembling the wire harness can be reduced, and the number of parts can be reduced. Further, since cellulose nanofibers are added to the polyolefin resin, the material strength can be increased.

  According to the present invention, an inexpensive heat-shrinkable polyolefin resin is used as a base material, which is several times stronger than the polyolefin resin itself, and can be used in place of a conventional hard tube. It is possible to provide an electric wire protection tube that can reduce the number of parts.

Fig.1 (a) is a perspective view which shows the state before heat shrink of the wire harness which concerns on embodiment of this invention, and FIG.1 (b) shows the state after heat shrink. Fig.2 (a) is sectional drawing which shows the state before heat shrink of the wire harness which concerns on embodiment of this invention, and FIG.2 (b) is the state after heat shrink. It is a top view which shows the state which fixed with tape the hard tube which coat | covered the conventional wire bundle.

  Embodiments of the present invention will be described below with reference to the drawings.

  FIG. 1 is a perspective view showing a wire harness 1 according to the present embodiment. FIG. 1 (a) shows a state before heat-shrinking a wire protection tube 10, and FIG. 1 (b) shows a state after heat-shrinking. Show. 2 (a) and 2 (b) are cross-sectional views as viewed from the axial direction of the wire harness 1 in the states of FIGS. 1 (a) and 1 (b), respectively.

  The wire harness 1 includes an electric wire bundle W composed of a plurality of electric wires Wa and an electric wire protection tube 10. In the state where the wire bundle W shown in FIG. 1A is inserted through the wire protection tube 10, the wire harness 1 is closely attached to the wire bundle W as shown in FIG. Has been.

  The wire protection tube 10 is formed into a cylindrical shape from a polyolefin resin having heat shrinkability. As shown in FIG. 2A, the wire protection tube 10 is configured such that the inner diameter d formed by the inner surface portion 10 b before heat shrinkage is larger than the outer diameter D of the wire bundle W and the wire bundle W can be inserted. ing. The length in the axial direction of the wire protection tube 10 can be determined by appropriately cutting according to the region where the wire bundle W is desired to be protected.

  The wire protection tube 10 is in the state shown in FIG. 1B when the wire protection tube 10 is thermally contracted from the state where the wire bundle W shown in FIG. The inner diameter is d ′. At this time, as shown in FIG. 2 (b), the wire protecting tube 10 has an inner diameter d ′ substantially equal to the outer diameter D of the wire bundle W. That is, the electric wire protection tube 10 is formed in a cylindrical shape having an inner diameter d ′ that is in close contact with the electric wire bundle W during thermal contraction.

  The contraction rate from the inner diameter d to the inner diameter d ′ when the electric wire protection tube 10 is thermally contracted is about 60 to 75%. Therefore, the inner diameter d of the wire protection tube 10 is larger than the outer diameter D of the wire bundle W and is in a range of about 2.5 to 4 times the outer diameter D. Therefore, the electric wire protection tube 10 can be applied to the electric wire bundle W having the outer diameter D in a wide range.

  In addition, a margin can be given to the difference between the inner diameter of the wire protection tube 10 and the outer diameter of the wire bundle W when the wire bundle W is inserted through the wire protection tube 10 before heat shrinkage, and workability is improved. . When the outer diameter D of the wire bundle W is larger than the size of 60 to 75% of the inner diameter d of the electric wire protection tube 10 before heat shrinkage, the electric wire protection tube 10 is heated according to the size of the outer diameter D. Shrink.

  Further, the thickness of the wire protecting tube 10, that is, the distance from the outer surface portion 10a to the inner surface portion 10b, is about 0.3 to 0.4 mm before heat shrinkage and expands to about 0.6 to 0.7 mm after heat shrinkage. To do.

  The electric wire protection tube 10 is applied to a portion where vibration is large and needs to be arranged linearly, mainly inside the instrument panel, but may be applied to other portions in the vehicle. Since the electric wire protection tube 10 is applied to such a portion and needs a predetermined strength, a polyolefin resin to which cellulose nanofiber described later is added as a material is used.

  Since the heat-shrinkable electric wire protection tube 10 tightens the electric wire bundle W, the electric wire protection tube 10 can be fixed to the electric wire bundle W without using a tape like a conventional hard tube. Therefore, a fixing tape is not required, and the number of parts can be reduced, and the tape winding work can be eliminated, and the number of work steps can be reduced.

  As the polyolefin resin in the present embodiment, a cellulose nanofiber added in a predetermined ratio and dispersed is used. The predetermined ratio here is about 10 to 15% with respect to the polyolefin resin, but it may be more or less.

  As the polyolefin resin, for example, any one of polypropylene, polyethylene, polyamide and the like having heat shrinkability is selected. As the cellulose nanofiber in the present embodiment, any of lignocellulose nanofiber, cellulose nanofibril, and cellulose nanocrystal is selected.

  Cellulose nanofibers used in the present embodiment are obtained by an electrospinning method in which a raw material solution is subdivided by electric force to obtain nanosized fibers.

  When cellulose nanofibers are added to a polyolefin resin, the surface of the cellulose nanofibers is subjected to a hydrophobic treatment so that it is uniformly dispersed in the polyolefin resin. Specifically, the hydroxyl group on the surface of the cellulose nanofiber is substituted with a hydrophobic functional group, the polarity is lowered, and it is easy to become familiar with the polyolefin resin.

  The cellulose nanofibers used in the present embodiment include those having a diameter of 1 to 1000 nm and a light wavelength of 400 to 700 nm. When the diameter of the cellulose nanofiber is smaller than the wavelength of light, irregular reflection of light hardly occurs and transparency becomes high. The transparency of the polyolefin resin can be enhanced by adding cellulose nanofibers having a diameter smaller than the wavelength of light to the highly transparent polyolefin resin.

  By applying the polyolefin resin with improved transparency to the wire protection tube 10, the wire bundle W can be visually recognized from the outside of the wire protection tube 10. Therefore, since the state of the wire bundle W constituting the wire harness 1 can be visually confirmed from the outside, an abnormal state such as disconnection of the wire bundle W can be discovered early.

  As described above, the wire protection tube 10 according to the present embodiment is an electric wire having a required outer diameter D made of a polyolefin resin having heat-shrinkability, to which 10 to 15% of cellulose nanofibers are added and dispersed. The bundle W has an inner diameter d through which the bundle W can be inserted, and is formed into a cylindrical shape having an inner diameter d ′ that is in close contact with the wire bundle W during thermal contraction.

  With this configuration, the wire protection tube 10 according to the present embodiment is based on an inexpensive heat-shrinkable polyolefin resin, has a strength several times that of the polyolefin resin itself, and has a heat-shrinkable polyolefin. Since it is molded with resin and has a cylindrical shape with an inner diameter d ′ that is in close contact with the wire bundle W during heat shrinkage, it can be used in place of a conventional hard tube, and without using parts such as tape, the wire bundle It can fix to W, can reduce the work man-hour of wire harness assembly, and can reduce a number of parts.

  Therefore, the work man-hours for assembling the wire harness can be reduced, and the number of parts can be reduced. Further, since cellulose nanofibers are added to the polyolefin resin, the material strength can be increased. This is because the cellulose nanofiber has a diameter of 1 to 1000 (nm) and a length of 100 times or more of the diameter, and has a high adsorption performance, strong adhesion, and high molecular recognition due to the super specific surface area effect. This is because it has the characteristics that it is light and strong with a density 1/5 that of steel and a strength 5 times or more.

  The polyolefin resin thus obtained has a strength of 3 to 4 times when polyethylene or polyamide is used alone as a polyolefin resin and 2 to 3 times when polypropylene is used. can get. By using cellulose nanofibers having these properties for the polyolefin resin, the wire protecting tube 10 can be reduced in weight.

  Moreover, the tube 10 for electric wire protection is good also as a structure which has a shrinkage rate of 60 to 75%.

  With this configuration, the wire protection tube 10 according to the present embodiment has an inner diameter d that shrinks to a size of 60 to 75% before heat shrinkage at the time of heat shrinkage. The size can be 2.5 to 4 times the size of D, and can be applied to a wire bundle W having a wide range of outer diameters.

  In addition, the wire harness 1 according to the present embodiment includes a wire bundle W composed of a plurality of wires Wa and a wire protection tube 10, and in a state where the wire bundle W is inserted into the wire protection tube 10, The electric wire protection tube 10 is in close contact with the electric wire bundle W by contraction.

  With this configuration, the wire harness 1 according to the present embodiment is formed of a heat-shrinkable polyolefin resin and has a cylindrical shape with an inner diameter d ′ that is in close contact with the wire bundle W during heat shrinkage. It can be fixed to the wire bundle W without using a component such as a tape.

  Therefore, the work man-hours for assembling the wire harness 1 can be reduced, and the number of parts can be reduced. Further, since cellulose nanofibers are added to the polyolefin resin, the material strength can be increased.

  The technical scope of the wire protection tube and the wire harness according to the present invention is not limited to the above-described embodiment, but includes various modifications of each component described in the claims.

  As described above, the wire protection tube and the wire harness according to the present invention have a strength several times higher than that of the polyolefin resin itself, using an inexpensive heat-shrinkable polyolefin resin as a base material. It can be used in place of the above, has the effect of reducing the work man-hours for assembling the wire harness and reducing the number of parts, and is useful for the wire protection tube and the wire harness in general.

1 Wire Harness 10 Wire Protection Tube W Wire Bundle Wa Wire

Claims (3)

  Cellulose nanofibers are added in a specified proportion and are formed into a cylindrical shape with a heat-shrinkable polyolefin resin, and the inner diameter before heat shrinkage is larger than the diameter of the wire bundle to be inserted. An electric wire protection tube that shrinks to a size that closely contacts the electric wire bundle.   The said wire protection tube of Claim 1 which has a shrinkage rate of 60 to 75%. The wire bundle comprising a plurality of wires;
The electric wire protection tube according to claim 1 or 2,
A wire harness, wherein the wire protection tube is brought into close contact with the wire bundle by thermal contraction in a state where the wire bundle is inserted into the wire protection tube.

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