1. Field of the Invention
The invention relates to a waterproof resilient plug, and particularly a waterproof plug that can be mounted to a terminal fitting and inserted into a terminal insertion hole of a connector housing.
2. Description of the Related Art
Japanese Unexamined Patent Publication No. 7-282893 and FIGS. 4(A) and 4(B) herein disclose a terminal fitting 1 with opposite front and rear ends. Insulation barrels 1a are adjacent the rear end of the terminal fitting 1 and wire barrels 1b are forward of the insulation barrels 1a. The terminal fitting 1 is used with a wire W and a tube-shaped waterproof rubber plug 2. The plug 2 has lips 2a on the outer circumferential surface and a fixing portion 2b at the leading end of the plug 2. As shown in FIG. 4(B), the waterproof rubber plug 2 is slid over the wire W. The insulation barrels 1a then are crimped into connection with the fixing portion 2b of the plug 2 and the wire barrels 1 are crimped into connection with a core Wa exposed by stripping the insulation coating from the leading end of the wire W.
The connected fixing portion 2b is compressed in direction A, as shown in FIG. 4(B), and accordingly the leading end of the fixing portion 2b is turned up in direction B. The state of the plug 2 causes no problem if the terminal fitting is relatively large, and there is a diameter difference between the lips 2a of the waterproof rubber plug 2 and the fixing portion 2b. However, a problem may occur when there is only a small diameter difference between the lips 2a and the fixing portion 2b, such as in a miniaturized terminal fitting. Specifically, the turned-up front end of the fixing portion 2b may be caught by the inner circumferential surface of a terminal insertion hole C when the terminal fitting 1 is inserted into the terminal insertion hole C of a connector housing H. As a result, the insertion resistance increases, and in an extreme case, the fixing portion 2b may be disengaged from the insulation barrels 1a. 
The invention was developed in view of the above problem and an object thereof is to provide an improved waterproof resilient plug.
The invention is directed to a waterproof resilient plug with a trunk that can be brought into close contact with the inner circumferential surface of a terminal insertion hole of a connector housing. The plug also has a fixing portion that extends from the leading end of the trunk. The fixing portion is configured for fixed connection to a terminal fitting. A wire insertion hole is formed through both the trunk and the fixing portion and is dimensioned for close resilient contact with the outer circumferential surface of the wire. The inner diameter of the wire insertion hole is smaller through the fixing portion than through the trunk. Accordingly, the plug can solve problems of an increased insertion resistance when a small terminal fitting with a waterproof resilient plug is inserted into a terminal insertion hole of a connector housing.
According to a preferred embodiment of the invention, the trunk has at least one lip formed on the outer circumferential surface thereof.
Preferably, the wire insertion hole is formed substantially along the longitudinal axes of the trunk and the fixing portion.
The fixing portion preferably is pressed against the outer circumferential surface of a wire by crimping, folding or bending one or more insulation barrels of the terminal fitting.
Resilient contact between the fixing portion of the waterproof rubber plug and the outer surface of the wire is closer than the resilient contact between the trunk and the outer surface of the wire. Thus, the leading end of the fixing portion is prevented from being turned up in a radially outer direction even if the fixing portion is compressed by crimping, bending or folding the insulation barrels of the terminal fitting into connection with the outer circumferential surface of the fixing portion. Thus, the leading end of the fixing portion will not turn up and catch the inner circumferential surface of the terminal insertion hole, and resistance is not increased during the insertion of the terminal. Further, the area in close contact with the wire is only the thin fixing portion and has a small diameter. Accordingly, insertion resistance is not increased during the insertion of the wire into the terminal insertion hole.
The inner diameter of the wire insertion hole at the fixing portion preferably is reduced gradually toward the front end of the fixing portion. As a result, the leading end of the fixing portion, which is more likely to be turned up by the crimping of the insulation barrels, can be held strongly in contact with the wire and prevented from being turned up. Therefore, the area to be held strongly in contact can be reduced, and an increase in the insertion resistance during the insertion of the wire into the wire insertion hole will be small.
Recesses preferably are formed in the inner circumferential surface of the trunk. The recesses may be formed at longitudinal positions substantially corresponding to the lips. Accordingly, the insertion resistance of the wire into the wire insertion hole is reduced.
The outer diameter of the fixing portion is gradually reduced towards a distal end thereof.
The fixing portion may comprise a chamfer at its distal end.
The fixing portion preferably is thinner than the trunk.
These and other features of the invention will become more apparent upon reading the following description of preferred embodiments and the drawings. It should be understood that even though embodiments are described separately, single features may be combined to other embodiments.