GB2249884A - Waterproof plug for electrical connector - Google Patents

Abstract

A waterproof plug (A), for an electrical connector, comprises a rubber plug (20) and a rigid stabilising member (21). The rubber plug (20) has an elliptical sealing portion (20c) for sealingly engaging the inner surface of a socket in a connector housing and is formed on the outer periphery of a tubular portion which has an electrical wire insertion bore (20b) therethrough. The rigid stabilising member (21) has supporting columns (21c) projecting in the same direction on opposite sides of a wire insertion hole (21b) in an elliptical base portion (21a). The rubber plug (20) is integrally moulded around the supporting columns (21c) of the stabilising member (21) to encase the supporting columns in the elliptical sealing portion of the rubber plug. The plug enables the size of the connector in which it is used to be minimised. <IMAGE>

Description

WATERPROOF PLUG FOR ELECTRICAL CONNECTOR The present invention relates to a waterproof plug in a connector used to connect electric wires together.

The Applicant has previously proposed a waterproof plug as shown in Figs. 1 to 3 and 10A, 10B and 10C (Japanese Utility Model Application Laid-open No.

147277/1987).

According to the aforesaid application, a waterproof plug 5 is designed in such a manner that a tubular portion 7a,whose inner portion is formed as an electric wire inserting hole 7b, is provided at one side thereof with a caulking portion 7c for suppressingly fixing the electric wire together with a caulking member 2a of a connecting terminal 2 and provided at the outer periphery of the other side with a rubber plug 7 formed with an outer tube portion 7d which is capable of fitting to the inner wall of a connector housing 1, and a stabilizing tube 8 formed of a hard rigid resin insulator is provided between the tubular portion 7a and the outer tube portion 7d. An electric wire 3 inserted into the tubular portion 7a is suppressingly fixed by means of the caulking portion 7c of the rubber plug 7 and a caulking element 2a of the connecting terminal 2.The connecting terminal 2 is doubly prevented from disengagement by a flexible stopping arm 4 and a rear holder 6 fitted facing to a flange portion 8a of the stabilizing tube 8.

Recently, with an increase of electric appliances loaded on a vehicle, smaller size of connectors and connecting terminals have been earnestly demanded. If a connector is minimized to meet such demand as described, the rubber plug 7 is also minimized. As shown in Figs. 2 and 4A, the inner diameter R of the stabilizing tube 8 is slightly larger than the external diameter D of the electric wire 3, and a tubular portion 7a' of the rubber plug 7 becomes extremely thin. The tubular portion 7a' comes into contact with the surface of the electric wire 3 when the latter is inserted, and therefore, the tubular portion 7a' is pulled and tends to be torn inwardly as shown in Fig. 7B.Therefore, this gives rise to a drawback in that the tubular portion 7a' is to generate a difference in level between the tubular portion 7a' and the pleat 7e within the electric wire inserting hole 7b so that the waterproof sealing property is lowered and the insertion of the electric wire is made difficult.

Furthermore, with a recent increase of electric appliances loaded on the vehicle, a number of electric wires are wired within a limited space and therefore1 smaller size of connectors and connecting terminals have been earnestly demanded.

In view of the above, as a means to make a waterproof connector smaller, the external diameter of the rubber plug 7 (or a waterproof plug 5) can be made small in order to reduce a lateral pitch. However, a sealing portion (a tubular portion 7a) between the electric wire 3 and the rubber plug 7 and that (an outer tube portion 7d) between the plug 7 and a housing 1 are in a concentric circular relation, and the rubber plug 7 including the stabilizing tube 8 needs to have a specified thickness in order to maintain the sealing property and the strength.

It is noted that even if the stabilizing tube 8 is omitted, the waterproof plug will still function only with the tubular portion 7a of the rubber plug but it is not possible to provide a double engagement of the connecting terminal. Accordingly, it is difficult to minimise the size of the connector having a waterproof plug of the conventional construction.

It is therefore an object of the present invention to provide a waterproof plug having no drawback as noted above and adapted for formation of a connector into a small size.

It is a further object of the present invention to provide a waterproof plug for a connector suitable for minimisation of the size of a connector without impairing the sealing property of the connector and the double engaging function of a connecting terminal.

According to the present invention, there is provided a waterproof plug, for an electrical connector, comprising a rubber plug having an elliptical sealing portion for sealingly engaging the inner surface of a socket in a connector housing and being formed on the outer periphery of a tubular portion which has an electrical wire insertion bore therethrough, and a rigid stabilising member having supporting columns projecting in the same direction on opposite sides of a wire insertion hole in an elliptical base portion, the rubber plug being integrally moulded around the supporting columns of the stabilising member to encase the supporting columns in the elliptical sealing portion of the rubber plug.

In the drawings: Fig. 1 is a perspective view showing a conventional waterproof plug; Fig. 2 is a perspective view of a stabilising tube of the conventional waterproof plug; Fig. 3 is a sectional view showing a construction of a waterproof connector using a conventional waterproof plug; Figs. 4A and 4B are sectional views respectively showing the function of the conventional waterproof plug; Fig. 5 is an exploded perspective view showing an example of a waterproof plug according to the present invention; Fig. 6 is a sectional view of the assembly taken along line II-II of Fig. 5; Fig. 7 is a sectional view taken along line III-III of Fig. 5; Figs. 8A and 8B are respectively front views of a three-way waterproof connector using a waterproof plug according to the present invention and a conventional product respectively;; Fig. 9 is a sectional view taken along line V-V of Fig. 8A; and, Figs. 10A to lOC are a front view, a side view and a sectional view, respectively, showing a waterproof plug of a conventional product.

A waterproof plug A for a connector according to the present invention comprises, as shown in Figs. 5 to 7, a rubber plug 20 formed with an elliptical seal portion 20c capable of fitting to an inner wall of a connector housing 22 (see Fig. 8A and Fig. 9) formed in the outer periphery of one side of a tubular portion 20a whose inner portion is formed as an electric wire inserting hole 20b, and a stabilising member 21 having a rigidity with supporting columns 21c projected on opposite sides of an elliptical base plate portion 21a which is provided with an electric wire inserting hole 21b in the central portion thereof, the rubber plug 20 being integrally formed with the stabilising member 21, and the support columns 21c and 21c' being encased in the elliptical seal portion 20c.

Since the connector housing 22 and the seal portion 20c of the rubber plug 20 are elliptical in shape, the shorter axis w thereof can be made substantially equal to the external diameter of the tubular portion 20a having a thickness required to seal an electric wire 25 (see Fig.

9), and the longer axis h thereof can be dimensioned to cover two supporting columns 21c of the stabilising member 21 and provides a thickness to meet the required flexibility for sealing.

The stabilising member 21 is pre-moulded from a hard rigid resin insulator, and the rubber plug 20 is integrally formed with the moulded member 21 by double moulding.

Preferably, a through-hole 21d for rubber during the moulding operation is provided between the base plate portion 21a and the support column 21c so as to form a bridge for preventing disengagement of the rubber plug 20 and the stabilising member 21.

A caulking portion 20d provided for better wire connections together with a connecting terminal 23 (see Fig. 9) is extended in the tubular portion 20a of the rubber plug 20, and a plurality of pleats 20e are peripherally provided in the inner periphery of the tubular portion 20a and in the outer periphery of the sealing portion 20c to enhance the sealing property.

Figs. 8A and 8B show a three-way waterproof connector using the waterproof plug A according to the present invention and the conventional product B, respectively. As will be apparent from the drawings, since the waterproof plug A of the above embodiment is elliptical, heights H and H' of both connectors are substantially equal to each other but the widths W and W' are in the relation W < W', so the lateral width of the connector can be made small.

Fig. 9 is a sectional view taken along line V-V of Fig. 8A, wherein reference numeral 22 designates a male connector housing encasing a male connecting terminal 23, and 22' a female connector housing encasing a female connecting terminal 23'. A lip packing 24 is mounted in a fitted portion between both housings to provide waterproof sealing therebetween. An electric wire 25 is suppressingly fixed by means of the caulking portion 20d of a rubber plug 20 and a caulking element 23a of the connecting terminals 23 (23'), and waterproof sealing between each of the connecting terminal and the housing is effected by the elliptical seal portion 20c in close contact with the inner wall of the housing. Reference numeral 26 designates a flexible stopping arm and 27 denotes a rear holder.

The present plug has a construction well suited for formation of a connector into small size. Moreover, the lateral width of the waterproof connector can be made small to provide formation thereof into a small size as a whole.

Reference is made to application no. 8902705.6, from which this application is divided, and in which there is disclosed a waterproof plug, for an electrical connector, comprising a rubber plug having a tubular portion with an outer sealing surface for sealingly engaging the inner surface of a socket in a connector housing, the tubular portion having an electrical wire insertion bore therethrough, and a rigid stabilising tube mounted in the rubber plug at one end, between the bore and the outer sealing surface, the rubber plug being integrally moulded around the stabilising tube and at least a part of one end surface of the stabilising tube being covered by a collar portion of the rubber plug formed in extension of the tubular portion.

Claims (3)

1. A waterproof plug, for an electrical connector, comprising a rubber plug having an elliptical sealing portion for sealingly engaging the inner surface of a socket in a connector housing and being formed on the outer periphery of a tubular portion which has an electrical wire insertion bore therethrough, and a rigid stabilising member having supporting columns projecting in the same direction on opposite sides of a wire insertion hole in an elliptical base portion, the rubber plug being integrally moulded around the supporting columns of the stabilising member to encase the supporting columns in the elliptical sealing portion of the rubber plug.

2. A plug according to claim 1, wherein a through hole is provided in the stabilising member between the base portion and a supporting column, through which rubber extends in order to secure the stabilising member in the plug.

3. A waterproof plug substantially as described with reference to Figure 5 to 7, 8A and 9 of the accompanying drawings.