JP4805074B2 - Manufacturing method of automobile harness with terminal - Google Patents

Description

The present invention relates to a method of manufacturing a terminal-equipped automobile harness.

The temperature in the engine room of an automobile rises while the engine is running due to traveling or the like, and falls when the engine is stopped. For this reason, in an automobile harness, for example, an automobile harness wired through a bulkhead that partitions between an engine room and a vehicle compartment, it has entered the engine room from the outside due to a pressure difference caused by a temperature difference in the engine room. In some cases, moisture penetrated into the terminal portion of the automobile harness.

Therefore, in an automobile harness, a cap is provided at a concentrated joint portion where a terminal portion and a plurality of conductors are bundled and welded, and liquid silicone rubber is poured into the cap, and a sealing material is provided at the concentrated joint portion, such as The intrusion of moisture was prevented.

By the way, there is one using silver paste or the like as a sealing material, but it is very expensive. On the other hand, the liquid silicone rubber is a low price and has no influence on the manufacturing process of the automobile harness, so it is an extremely simple waterproof measure. However, since the conventional liquid silicone has a relatively high viscosity, the gap between the welds of the concentrated joint portion may not be sufficiently filled, and it may be severely affected by temperature cycles, humidity, mechanical vibration, etc. like an automobile harness. In such a use environment, there was a problem in terms of reliability because the adhesiveness with the terminal portion or the like was lowered and the waterproofness was insufficient.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a method of manufacturing a terminal-equipped automobile harness capable of exhibiting sufficient waterproofness even in a severe use environment.

In order to achieve the above-mentioned object, the present inventors diligently studied the above-mentioned problems related to the liquid silicone rubber. As a result, if the liquid silicone rubber used as the sealing material penetrates into the conductor of the automobile harness without any gaps, it can prevent a decrease in adhesiveness, prevent water from entering, and have a lower viscosity and more easily penetrate. Further, the present inventors have found the fact that the lower the viscosity, the lower the hardness at the time of curing, and the better the adhesion and the better the adhesion can be achieved.

That is, in order to achieve the above object in the present invention, there is provided a method of manufacturing an automobile harness with a terminal, wherein the automobile harness with a terminal includes an automobile harness made of a conductor and an insulation coating, and the insulation coating is removed from the automobile harness. The terminal with the wire barrel and the insulation barrel attached integrally with the conductor portion and the insulation coating portion by gripping the exposed conductor portion and the insulation coating portion with the wire barrel and the insulation barrel, respectively. And a liquid silicone rubber is applied and cured only at a portion between the wire barrel and the insulation barrel so that the exposed conductor and the insulating coating are continuously covered. A sealing material having an elastic modulus in the range of 0.55 to 0.72 MPa is formed. It proposes a manufacturing method comprising and. Further, it is desirable that the automobile harness is a ground wiring and a ground terminal is attached to the exposed conductor.

Preferably, the automobile harness ground is formed by concentrating conductors of a plurality of ground wirings to form a concentrated joint portion. More preferably, the liquid silicone rubber is a solventless type one-component curable type.

At the time of curing, liquid silicone rubber with an elastic modulus of less than or equal to 0.8 MPa at 25 ° C. is applied to the exposed joint where the harness conductor of the grounding terminal is exposed and the concentrated joint part where a plurality of conductors of the ground wiring are bundled. When the material is provided, the adhesion is improved and unlike conventional silicone rubber, even if a temperature cycle or humidity cycle test is performed, the adhesion to the terminal part etc. does not decrease and the water tightness for a long time is maintained. Is done.

This is because the liquid silicone rubber used as the sealing material of the present invention has a relatively low viscosity and is easy to penetrate, and the exposed portion where the conductor of the automobile harness is exposed, the concentrated joint portion, and the gap between the core wires constituting the conductor are ensured. It has sufficient flexibility against strain caused by curing shrinkage and distortion caused by expansion and shrinkage caused by temperature change in the insulation coating of the conductor due to improved adhesion and easy to follow these strains It depends.

That is, the conventional sealing material may not be able to sufficiently fill the gaps between the conductors, and is not necessarily used for synthetic resins such as polyvinyl chloride (PVC) and polyolefin used for insulation coating of automobile harnesses. Does not have good adhesion. In addition, in the case of an automobile harness using PVC insulation coating, conventional silicone rubber is affected by adhesiveness, and thus water tightness, even if a slight distortion occurs because the plasticizer of PVC lowers the adhesive strength. easy.

On the other hand, the sealing material of the present invention can reliably fill the gap between the conductors, has sufficient flexibility against distortion, and exposes the exposed portion of the automobile harness even in a severe environment where the temperature changes rapidly. Since the adhesive strength between the concentrated joint portion and the insulating coating is maintained over a long period of time, it is extremely suitable as a material for maintaining watertightness.

Liquid silicone rubber is a liquid polyorganosiloxane compound having a functional group capable of condensation reaction or addition reaction (reacting a silane compound having a functional group with a polyorganosiloxane compound having a hydroxy group such as dihydroxypolydimethylsilicone oil). Is used as a raw material. For this reason, the liquid silicone rubber is in a liquid state before being cured, but becomes a rubbery polymer or silicone rubber by being polymerized and cured at a functional group portion by moisture in the atmosphere or heating. Therefore, a type that undergoes a condensation reaction with moisture in the atmosphere in the curing reaction is classified as a condensation type, and a type that performs an addition reaction of an Si—H group to an unsaturated group in the presence of a platinum catalyst or the like is classified as an addition type. Also, depending on the packaging form, it is classified into a one-pack type that uses what is in the package as it is, and a multi-pack type that uses two or more components mixed immediately before use. Moreover, it is classified into room temperature curing type and heat curing type according to the curing temperature. Further, the condensed type is further subdivided by a gas generated during condensation due to a difference in functional group. For example, there are dealcoholization type, deketone type, and deacetic acid type.

The liquid silicone rubber used as the sealing material of the present invention may be a condensation type or an addition type as long as the elastic modulus at 25 ° C. is 0.8 MPa or less at the time of curing. Are preferred. Condensation type liquid silicone rubber is a type that cures by hydrolysis condensation reaction with moisture in the air in the presence of a catalyst, etc., so it is a dehydrogenation type, dealcohol type, deacetic acid type among the compounds generated during the condensation reaction. , Deoxime type, deketone type, deamine type, deamid type, dehydroxyamine type, etc., but can be used as the sealing material of the present invention, except for deacetic acid type with metal corrosiveness . Furthermore, the liquid silicone rubber used as the sealing material of the present invention is not a two-component or more multi-component curable type having a pot life problem that must be prepared each time it is used, but a one-component curable type, particularly a one-component curable type. The condensed type is convenient and preferable.

Here, as means for reducing the elastic modulus of the liquid silicone rubber at the time of curing, it is possible to roughen the crosslink density of the cured product or to add liquid silicone oil having no reactive functional group to the raw material. . However, in any case, when the crosslink density of the cured product becomes too coarse, or when the amount of liquid silicone oil added is large, the liquid silicone rubber becomes a so-called gel, and the surface adhesiveness is maintained even after curing. This is not preferable because it has a drawback that it easily adheres to other parts.

Hereinafter, an embodiment of the present invention will be described in detail with reference to FIGS.

First, as a first embodiment of the present invention, a waterproofing method for the automobile harness 1 shown in FIG. 1 will be described. As shown in FIGS. 1A and 1B, the automobile harness 1 has a ground terminal 3 attached to the end of the ground wiring 2, and liquid silicone rubber is applied and cured to provide a seal material 4. Yes. At this time, the automobile harness 1 before applying the liquid silicone rubber is shown in FIGS. 2 (a) and 2 (b).

In the ground wiring 2, a conductor 2 a made of a stranded wire is covered with an insulating coating 2 b such as PVC or polyolefin. As shown in FIG. 3, the ground terminal 3 includes a fixed plate 3a at one end, a wire barrel 3b that grips the conductor 2a at the other end, and an insulation barrel 3c that grips the ground wiring 2 at a portion of the insulating coating 2b. Is a round plate terminal for automobile (JIS D 5403) in which a mounting plate is provided with a mounting hole 3d.

The sealing material 4 is a one-part curable liquid silicone rubber having an elastic modulus at 25 ° C. of 0.8 MPa or less at the time of curing, and the conductor 2a and the insulating coating 2b are provided between the wire barrel 3b and the insulation barrel 3c. It is applied and cured so as to cover continuously. At this time, the sealing material 4 penetrates into the conductor 2a and reaches the ground terminal 3 side, and is bonded not only to the conductor 2a but also to the insulating coating 2b and the ground terminal 3.

Here, applying the liquid silicone rubber over a wide range of the ground wiring 2 and the ground terminal 3 does not hinder the effect of watertight sealing, and is good in terms of sealing properties. However, for the purpose of the present invention, as described above, the sealing material 4 is applied between the wire barrel 3b and the insulation barrel 3c so as to continuously cover at least the conductor 2a and the insulating coating 2b. If it is provided, sufficient effect will be demonstrated.

In addition, it is preferable to use a dispenser (an apparatus that controls the discharge amount by air pressure and time) because the discharge amount of the liquid silicone rubber can be given quantitativeness. Since the automobile harness 1 has a waterproof structure as described above, the space between the exposed conductor 2a and the insulating coating 2b is sealed in a watertight manner by a sealing material 4 formed by curing, and water is discharged from the end of the ground wiring 2. Will not invade.
[Reference example]

Next, an embodiment according to a reference example will be described with reference to FIGS. The automobile harness 10 having the waterproof structure shown in FIG. 4 has a concentrated joint portion 10a formed by bundling the conductors 11a at the end portions of the three ground wires 11. The concentrated joint portion 10a is a portion for connecting the three ground wirings 11 to other electrical connection bodies in a lump. The conductor 11a exposed by removing the insulating coating 11b from the ground wiring 11 is, for example, ultrasonic welded. As shown in FIG. 5, a plurality of parts are integrated by electrical welding or the like. As shown in FIG. 4, the concentrated joint portion 10a is covered with a sealing material 12 provided by applying and curing liquid silicone rubber so as to continuously cover the entire conductor 11a from the insulating coating 11b of the ground wiring 11. Has been.

As the sealing material 12, a one-part curable liquid silicone rubber having an elastic modulus at 25 ° C. of 0.8 MPa or less at the time of curing is used. This liquid silicone rubber can be applied, for example, by immersing the concentrated joint portion 10a in the liquid silicone rubber, or can be applied by a normal application means. To penetrate.

Since the waterproofing method for the automobile harness 10 according to the reference example is performed as described above, the space between the exposed conductor 11a and the insulating coating 11b is made watertight by the sealing material 12 provided by curing the liquid silicone rubber. It is sealed and water does not enter from the end of the ground wiring 11. Here, after applying the liquid silicone rubber, the automobile harness 10 is covered with a cap 13 as shown in FIG. 6, or a plurality of conductors 11a are integrated in a cap previously filled with the liquid silicone rubber, as shown in FIG. The concentrated joint portion 10a shown may be dipped and cured. If it does in this way, dirt of concentration joint part 10a can be prevented until liquid silicone rubber hardens.

Table 1 shows the evaluation results of Examples 1 and 2 and Comparative Example 1.
Twenty automobile harnesses 1 each employing the waterproofing method shown in FIG. 1 were prepared for each example and comparative example, and the waterproofness based on a temperature cycle test was evaluated. Here, Example 1 is a type in which methanol is generated during the condensation curing reaction as a liquid silicone rubber forming the sealing material, and a one-part curable liquid silicone rubber having an elastic modulus at 25 ° C. of 0.68 MPa at the time of curing. Similarly, Example 2 is a type in which methanol is generated during the condensation curing reaction, and a one-part curable liquid silicone rubber having an elastic modulus at 25 ° C. of 0.55 MPa was used at the time of curing.

On the other hand, Comparative Example 1 is a type that generates methanol during the condensation curing reaction, and a one-component curable liquid silicone rubber having an elastic modulus of 0.93 MPa at 25 ° C. was used during curing. In the temperature cycle test, the automobile harness 1 was raised from room temperature to 120 ° C., left at this temperature for 1 hour, cooled to −40 ° C., left for 1 hour, and then raised to 120 ° C. again. With this as one cycle, the temperature of 1000 cycles was changed.

Before and after the temperature cycle test, nitrogen gas whose pressure was adjusted to 0.098 MPa was sent from one end of the automotive harness 1 to be inspected for 5 minutes, and the seal material 4 side at the other end was immersed in water to be waterproofed by the presence or absence of leakage. Sex was evaluated. The results are shown in Table 1. As is apparent from Table 1, the automotive harness of Comparative Example 1 in which the sealing material was formed of a liquid silicone rubber having an elastic modulus exceeding 0.8 MPa specified in the present invention was airtight after the temperature cycle test, and thus waterproof. I lost my sex. On the other hand, the automotive harnesses of Examples 1 and 2 in which the sealing material is formed of the liquid silicone rubber having the elastic modulus defined in the present invention have good adhesion of the sealing material, and the air-tightness before and after the temperature cycle test. It has been found that it has excellent water tightness while maintaining its properties and thus waterproof.

Table 2 shows the evaluation results of Reference Examples 1 and 2 and Comparative Example 2.
Comparative Example 2 is an automobile harness 10 having the structure shown in FIG. 4 that is a type that generates methanol at the time of condensation curing reaction and is coated with a one-part curable liquid silicone rubber having an elastic modulus of 0.93 MPa at 25 ° C. as a waterproof before and after a temperature cycle test, a type which generates acetone during condensation curing reaction, curing time, reference example 1 that the elastic modulus at 25 ° C. was applied one-part curable liquid silicone rubber 0.72MPa Further, a type in which methanol is generated during the condensation curing reaction and a one-part curable liquid silicone rubber having an elastic modulus at 25 ° C. of 0.55 MPa applied at the time of curing is referred to as Reference Example 2, and Examples 1, 2 and Evaluation was performed in the same manner as in Comparative Example 1.

The results are shown in Table 2. As is apparent from Table 2, the waterproof structure of the automobile harness in which the sealing material is formed of the liquid silicone rubber satisfying the elastic modulus defined in the present invention has good adhesion of the sealing material and is excellent before and after the temperature cycle test. It was found to have water tightness.

According to the first aspect of the present invention, the terminal- carrying automobile harness capable of reliably filling the gap between the conductors with the sealing material and exhibiting sufficient waterproofness even in a severe use environment by improving the adhesion of the sealing material. The manufacturing method of can be provided.

According to invention of Claim 2 , it is excellent in the usability of a sealing material and can be handled easily.

It is the front view (a) and side view (b) which show 1st Embodiment which concerns on the motor vehicle harness waterproofed by the waterproofing method of this invention. It is the front view (a) and the side view (b) before forming a sealing material in the motor vehicle harness of FIG. It is a perspective view which shows the state which attaches a terminal to earth wiring in the motor vehicle harness of FIG. It is a front view which shows 2nd Embodiment which concerns on the motor vehicle harness waterproofed with the waterproofing method of this invention. It is a front view before forming a sealing material in the automobile harness of FIG. It is the front view which showed the modification of the motor vehicle harness which has the waterproof structure of FIG. 4 partially in cross section.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Automotive harness 2 Ground wiring 2a Conductor 2b Insulation coating 3 Ground terminal 3a Fixing plate 3b Wire barrel 3c Insulation barrel 3d Mounting hole 4 Sealing material (silicone rubber)
DESCRIPTION OF SYMBOLS 10 Automobile harness 10a Concentration joint part 11 Ground wiring 11a Conductor 11b Insulation coating 12 Seal material (silicone rubber)
13 cap

Claims (2)

A method for manufacturing an automobile harness with terminals,
By gripping the automobile harness with a terminal, an automobile harness composed of a conductor and an insulation coating, and a conductor portion and an insulation coating portion exposed by removing the insulation coating from the automobile harness, respectively, with a wire barrel and an insulation barrel, A terminal with the wire barrel and the insulation barrel attached integrally with the conductor portion and the insulating covering portion;
A liquid silicone rubber is applied and cured only in a portion between the wire barrel and the insulation barrel so that the exposed conductor and the insulating coating are continuously covered. The manufacturing method characterized by forming the sealing material which is the range of 55-0.72 MPa. The manufacturing method according to claim 1, wherein the liquid silicone rubber is a solvent-free one-component curing type.