JPH07107807B2 - Automotive wire harness sealing insulation structure - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a sealing and insulating structure for a wire harness wired in, for example, an engine room or a vehicle compartment of an automobile.

[Prior Art] Generally, in a portion where a wire harness in which various kinds of wiring of an automobile are bundled is branched, the branch portions are crimped with crimp sleeves in a bare wiring state, and the crimp sleeves are wound with an insulating tape. In addition to being electrically insulated, it has a structure that seals against ingress of water and the like by cutting off the outside air.

However, in the conventional sealing structure using the crimp sleeve and the insulating tape, it is impossible to prevent the infiltration of water from the gap between the wirings and the gap between the wiring and the insulating tape due to the capillary phenomenon, and the cause of failure of the instruments in the vehicle interior. It was.

In order to solve such a problem, conventionally, a means has been adopted in which a bare crimping sleeve at a branch portion of a wire harness is covered and an epoxy resin, a silicone resin, or a rubber sealant is injected from the outside and sealed. .

[Problems to be Solved by the Invention] However, in the case of a sealing structure formed by injecting an epoxy resin, since the epoxy resin is in a solid state having extremely high hardness, the degree of freedom between harness wirings is reduced, and wiring is difficult. There is a problem that it may bend and cause a disconnection. Further, in the case of the silicone resin, the sealing force against water infiltration is weak in terms of material, as in the case of the above insulating tape.
Further, as a common point between these two resins, there is a problem in that workability is deteriorated due to sagging before curing.

Therefore, the present invention has been made to solve the above-mentioned conventional problems, and seals insulation that cuts off water in the bare crimping sleeve portion where the wire harness wiring is branched and at the same time imparts electrical insulating characteristics to the bare crimping sleeve portion. It is intended to provide structure.

[Means for Solving the Problems] In order to solve the above problems, a sealing insulation structure for an automobile wire harness according to the present invention has a bare crimping sleeve portion of a branch portion of a wire harness that bundles a plurality of bare wires. In the above method, polyurethane is filled in the gap between the bare wirings of the bare crimping sleeve portion by a molding die and foamed to fix and seal the wirings.

Incidentally, in the insertion portion into the wall portion of the wire harness in which a plurality of wires are bundled, the gap between the wires is filled with polyurethane so that the wires are foamed to fix and seal the wires to each other. The sealing structure of the above has been previously proposed by the present inventor (JP-A-63-1).
98210).

Here, as the polyurethane, for example, those having the following formulation are used. It is desirable to impart flame retardancy to this polyurethane.

(Formulation Example 1) Polyoxypropylene glycol 100 parts by weight (MW = 2000) Water 1.8 Diethanolamine 0.08 Triethylenediamine glycol solution (Dabco 33LV)
18 Triethylamine 0.10 Isocyanate TDI-80 (2,4-TDI / 2,6-TDI = 80/20) 11
0 Silicon type foam stabilizer (Toray Silicone product SH193) 1.5 Flame retardant (Michigan Chemical product LV-T23P) 2.0 (Formulation example 2) Polytetramethylene glycol (MW = 2000) 100 parts by weight Water 2.5 Diethanolamine 0.8 Triethylamine 0.3 Silicon type conditioner Foaming agent (UCC product L-5309) 1.75 Flame retardant (Staffa Chemical product Fyrol SF58) 1.5
TDI-80 105 In addition, silicone oil,
The addition of several parts by weight of fluorine-based oil, mineral oil, etc. further improves the sealing effect such as waterproofness.

Such formulations obtained from the formulation polyurethane foam is about 0.1 g / cm ³ or less as a value in free foaming, to preferably be high foaming such that densities of about 0.05~0.08g / cm ^3. As a result, the high foaming pressure completely fills the gap,
Moreover, since the closed cell ratio is high, the hermeticity is also high, and the polyurethane formed has good adhesiveness to firmly adhere to the wiring and a sealing structure without peeling is formed there.

Next, an embodiment of the sealed insulating structure according to the present invention will be described with reference to the drawings.

1 to 4, a wire harness H composed of a bundle of a plurality of bare wirings 1 is further branched into a plurality of harnesses H ₁ and H _2, and a bare wiring portion 1 ′ of this branch portion is made of a copper crimp sleeve. Two
A cylindrical body 5 in which polyurethane 3 is foamed as shown in FIG. 4 is formed at the portion crimped and crimped. That is, the split mold 4 as shown in FIG. 2 is applied to the bare wiring portion S of FIG. 1, and the polyurethane foaming liquid 3 is injected therein to foam, thereby filling the gap and fixing the wirings 1 to each other. This forms a sealing structure that acts such as preventing water from leaking through the gap.

Specifically, a split mold 4 is prepared, and a mold release agent is applied to the inner surface of the mold 4. Next, the bare wirings 1 ′ at the branching points are unraveled to each other, and the unraveled portions are formed by the molding die 4
Then, the urethane foaming liquid 3'is injected into the gap between the bare wirings 1'covered and loosened [Fig. 3]. After the urethane foaming liquid 3'is foamed and hardened in the molding die 4 and a predetermined time has elapsed, when the molding die 4 is released from the foaming part, the foamed polyurethane 3 is formed.
As a result, a cylindrical foam 5 fixed by filling the gap between the bare wirings 1'is obtained as shown in FIG. At this time,
Since the curing time of the polyurethane 3 is short, there is no sagging during construction, and workability at the site is also good.

[Water Leakage Test] The water leak degree of the sample of the wire harness formed with the cylindrical foam was measured by the water leak test apparatus shown in FIG.

That is, the cylindrical foam part 5 of the harness sample is fixed by silicone RTV6, and this fixed part is liquid-tightly mounted inside a transparent polyurethane tube 7 having a diameter of 75 mm, and the polyurethane tube 7 which is vertically stood up The colored water 8 with the dye is poured from the opening to a depth of about 60 cm. At this time, the water pressure due to the colored water acting on the surface of the cylindrical foam part is about 0.54 Kg / cm ^{2 according} to a usual calculation formula. As a result of such a test,
After standing for 8 hours, no leakage of colored water was observed in the vicinity of the cylindrical foam portion and in each wire harness H site behind this.

[Comparative Example] A bare wire 1'was crimped and crimped with a crimping sleeve 2 was wound on the outside with an insulating tape, and the current wire harness was used as a sample under the same conditions by the water leakage tester shown in FIG. When the degree of water leakage was measured, it was found that water was leaked in about 1 to 2 minutes after pouring the colored water, and most of the colored water flowed out in about 20 minutes.

[Short-circuit test by energization] When each wiring in the harness sample after the above-mentioned water leakage test was energized and a short-circuit test was attempted between these wirings, an electrical short-circuit phenomenon was not found in each wiring.

The water leakage test was continued for 10 days, then heated at 100 ° C. with a heater and allowed to stand for one day and night, and then the cylindrical foam part was cut, and the pressure-bonded part at this cutting point was observed. As a result, no rust was found on each wiring and the copper pressure-bonding sleeve, and rust was found on the conventional sealing structure having an insulating tape wrapped around it.

[Effects of the Invention] As described above, the sealing insulation structure for a wire harness for an automobile according to the present invention is provided at a branch portion of various wire harnesses wired in an engine room or a vehicle compartment. The gap between a large number of bare wires is filled by foaming and curing the polyurethane with a molding die to fix the wires to each other, so that water from the outside that penetrates the wires and enters the room etc. is blocked by the polyurethane foam layer. Therefore, by preventing the water from entering the room, it is possible to obtain practical effects such as being able to protect the instruments from failure due to the water. Further, as compared with the conventional one in which the insulating tape is wound, no electrical short-circuit phenomenon is observed in the portion crimped by the crimping sleeve inside the polyurethane foam layer, which is also effective in preventing electric contact. .

Further, the surface of the formed polyurethane foam also has good adhesiveness and adhesion to a usual vinyl chloride covering tape which is usually wound around and used as a covering outer cover of a wire harness.
Furthermore, after the polyurethane is cured, it is chemically stable, and there is almost no influence of volatile substances on peripheral devices.

[Brief description of drawings]

1 to 4 show an embodiment of a sealing and insulating structure for a wire harness for an automobile according to the present invention, FIG. 1 is a side view of a sealing structure construction portion, and FIGS. 2 to 4 are polyurethane foams. A procedure for forming a body is shown. Moreover, FIG. 5 shows a cross-sectional view of the water leakage test apparatus. [Explanation of symbols] 1 ... Wiring of wiring harness 2 ... Crimping sleeve 3 ... Polyurethane 4 ... Mold 5 ... Cylindrical polyurethane foam

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Claims (1)

[Claims] 1. In a bare crimping sleeve portion of a branch portion of a wire harness in which a plurality of bare wirings are bundled, polyurethane is filled in a gap between the bare wirings of the bare crimping sleeve portion with a molding die to foam the wiring. A sealing and insulating structure for an automobile wire harness, which is fixed and sealed to each other.