Waterproof Connector

This invention relates to a waterproof connector in which a sealing member is interposed between a connector housing and an electric wire.

In a connector for interconnecting the electric wires, a crimp-style terminal is engaged therein to fix both ends of the wires to be interconnected. In order to prevent entrance of the water into the space or clearance within the connector where the crimp-style terminal is located, some connectors have a sealing member fitted into the connector housing.

FIG. 1 is a sectional view of a female connector having the sealing member therein. The electric wire 3 is inserted into a connector housing 1. The end of the electric wire 3 is connected to a crimp-style terminal 5 which is engaged with the connector housing 1. A rubber plug 7 is interposed between an insulation portion 3a of the electric wire 3 and the connector housing 1.

The rubber plug 7 comprises an electric wire insertion hole 7a passing therethrough. The diameter of the electric wire insertion hole 7a is slightly smaller than that of the insulation portion 3a. By means of forcing the electric wire 3 into the electric wire insertion hole 7a, sealing performance therebetween can be secured. Subsequently, the electric wire 3 are inserted into the connector housing 1 in this condition. Further, the rubber plug 7 is crushed in the connector housing 1, thereby the sealing performance can be exhibited to prevent entrance of the water into the inside of the connector housing where the crimp-style terminal 5 is disposed.

However, in case where a thin electric wire 3 having relatively small diameter is applied, as shown in FIG. 1, may result in a clearance t between the thin electric wire 3 and the rubber plug 7. This results in poor sealing performance.

Such rubber plug is made by using a mold 11 as illustrated in FIG. 2. The mold 11 comprises a piece 11a to form the electric wire insertion hole 7a. In order to overcome the above mentioned problem of the clearance and secure sufficient crushing of the rubber plug 7, a diameter of the piece should be further reduced. However, the piece 11a of excessively small diameter tends to be broken on making the rubber plug 7, causing inadequate productivity for the rubber plug 7. Thus, there is the limitation to an internal dimension u of the insertion hole 7a of the rubber plug 7.

It is an object of the present invention to provide a waterproof connector having sufficient sealing performance.

It is another object of the present invention to provide a waterproof connector where the thin electric wire can be applied without affecting the productivity of the sealing member. In order to achieve the above mentioned objects, the present invention provides a waterproof connector receiving a terminal connected to an electric wire, comprising:

a housing for receiving the terminal, the housing having an opening portion into which the terminal and the electric wire are inserted; and

a sealing member made of an elastic material to be inserted into the opening portion, the sealing member having an insertion hole for inserting the electric wire thereinto and a circular projected portion expanded from an external periphery thereof, an inner diameter of the insertion bole being equal to or larger than an outer diameter of the electric wire, and the extreme outer diameter of the projected portion being larger than the inner diameter of the opening portion.

According to the waterproof connector having the above mentioned structure, the outer diameter of the peripheral projection of the sealing member is larger than the inner diameter of the opening portion of the connector housing. The projection is forced to an internal surface of the opening when the sealing member is inserted into the connector housing. In addition, the internal surface of the insertion hole for the sealing member is protruded toward the electric wire and adhered thereto. Thus, the sealing performance can be secured. Therefore, it is possible to determine the relatively larger diameter of the insertion hole to that of the electric wire. As a result, the piece of the mold for use in producing the sealing member can be relatively large in diameter for forming the electric wire insertion hole. Thus, it is possible to prevent breakdown of the piece on molding. In addition, the larger diameter of the insertion hole than that of the electric wire contributes to facilitating inserting operation of the electric wire to the hole.

FIG. 1 is a sectional view of a main portion of the conventional waterproof connector where a rubber plug is applied and a thin electric wire is inserted thereinto;

FIG. 2 is a schematic view illustrating the rubber plug shown in FIG. 1 and a mold for molding the rubber plug;

FIG. 3 shows a waterproof connector according to a first embodiment of the present invention, in which the rubber plug and a connector housing are illustrated for use in describing the relation between the dimensions thereof;

FIG. 4 is a perspective view of the rubber plug illustrated in FIG. 3;

FIG. 5 shows an assembly of the rubber plug and the electric wire inserted thereinto;

FIG. 6 is a sectional view of the connector housing with the assembly illustrated in FIG. 5 attached therein;

FIG. 7 is a sectional view of the connector housing only with the single rubber plug illustrated in FIG. 6 inserted thereinto; and

FIG. 8 is a sectional view showing a rubber plug according to another embodiment of the present invention.

A waterproof connector of the present invention will be described below with reference to the drawing.

FIG. 3 is a view for use in describing the dimensional relation between a thin electric wire 13, a rubber plug 15 which is shown in FIG. 4 as the perspective view and a connector housing 17. The rubber plug 15 serves as a searing member and has an insertion hole 15a where the thin electric wire 13 is inserted. The connector housing 17 comprises an opening portion 17a where the thin electric wire 13 inserted with the rubber plug 15. In the figure, the inner diameter B of the insertion hole 15a of the rubber plug 15 is equal to or larger than the diameter A of the covered portion of the electric wire 13. In addition, the outer diameter C of the circular external projection 15b formed on the periphery of the rubber plug 15 is larger than the inner diameter D of the opening portion 17a of the connector housing 17, in other words, the dimensional relation of each diameter is A.ltoreq.B<D<C. The rubber plug 15 comprises, as illustrated in FIG. 5, the insertion hole 15a, the external projection 15b and a small-diameter portion 15c. The insertion hole 15a penetrates through the rubber plug 15 in the longitudinal direction. The external projection 15b is protruded on the peripheral surface of the plug 15. The small-diameter portion 15c has the relatively small diameter as compared with the remaining portion of the plug 15.

FIG. 5 shows the assembly in which the covered portion of the thin electric wire 13 is inserted into the insertion hole 15a of the rubber plug 15 and a crimp-style terminal 19 is connected to the end of the thin electric wire 13. The crimp-style terminal 19 forces the small-diameter portion 15c of the rubber plug 15 from the periphery thereof to fix the rubber plug 15. In this state, a space s=(B-A)/2 exists between the internal surface of the insertion hole 15a of the rubber plug 15 and the thin electric wire 13 (provided when A=B, S is equal to zero). The assembly consists of the thin electric wire 13, the rubber plug 15 and the crimp-style terminal 19. This assembly is inserted into the opening portion 17a of the connector housing 17 as illustrated in FIG. 6 to fit the rubber plug 15 to the opening portion 17a. As a result, the external projection 15b is forced to the internal surface of the opening portion 17a. The outer dimension of the external projection 15b is reduced to deform the rubber plug 15. Accompanying with this, the internal surface of the insertion hole 15a corresponding to the external projection 15b of the rubber plug 15 is expanded towards the thin electric wire 13 to form a circular internal projection 15d.

FIG. 7 shows the connector housing 17 only with the single rubber plug 15 is fitted to the opening portion 17a. In this event, the internal projection 15d is formed on the internal surface of the insertion hole 15a. The inner diameter E of the internal projection 15d is determined such that it becomes smaller than the diameter A (namely, E<A) of the covered portion of the thin electric wire 13.

Thus, the circular internal projection 15d formed on the rubber plug 15 contributes to securing the sealing performance to the thin electric wire 13 by means of adhering thereto as illustrated in FIG. 6. In addition, the circular external projection 15b formed on the periphery of the rubber plug 15 contributes to securing the sealing performance to the thin electric wire 13 by means of adhering thereto.

As mentioned above, it is possible to produce the relatively large rubber plug 15 with which complete sealing performance can be exhibited. Such rubber plug 15 can be achieved by means of forming the insertion hole 15a of the inner diameter B which is larger than the diameter A of the covered portion of the thin electric wire 13. As a result, the piece of the mold for use in producing the sealing member can be relatively large in diameter for forming the electric wire insertion hole. Thus, it is possible to prevent broken down of the piece on molding. In addition, the thin electric wire 13 can be readily inserted into the insertion hole 15a, resulting in improvement of the operational efficiency.

FIG. 8 shows another embodiment of the rubber plug which serves as the sealing member. In an internal surface of an insertion hole 21a of a rubber plug 21, circular slots 21d and 21e are formed at a position close to both ends of an internal projection 21c in the longitudinal direction. Such internal projection 21 is formed due to crush of an external projection 21b. By means of forming the slots 21d and 21e, the external projection 21b is more readily deformed when the rubber plug 21 is forced into the connector housing 17. As a result, less power is required to insert the rubber plug 21 into the connector housing 17, resulting in improvement of the efficiency of the assembling process.

While the preferred embodiment of the present invention has thus been described in conjunction with the rubber plug is used as the sealing member, other elastic material may be equally used as the sealing member such as a silicone resin.