Patent Publication Number: US-6210191-B1

Title: Waterproof electrical connector with pressure reducing structure

Description:
FIELD OF THE INVENTION 
     This invention relates to waterproof electrical connectors, especially to waterproof electrical connectors having a waterproof sealing means disposed at a mating end of a housing and waterproof sealing means providing watertight connection for a bundle of electrical wires. 
     BACKGROUND OF THE INVENTION 
     An example of a known waterproof electrical connector can be found in Japanese Patent Publication No. 95-326422. The waterproof electrical connector according to this publication has an integral rubber waterproof sealing means that is secured on a housing and is disposed at a mating side of the housing and at a side of the housing accommodating a bundle of electrical wires thereby providing a watertight seal for the bundle of wires. The rubber waterproof sealing means is applied from a back side of the housing, that is from the side accommodating the leads, and it is secured in position by a cap member. The rubber waterproof sealing means exerts a watertight connection when a mating housing of a mating connector is engaged with the connector housing, and its housing forms a waterproof coupling therebetween. 
     Connectors of this type must offer good waterproof properties in order to increase the reliability of the electrical connection. However, the measures aimed at the improvements of waterproof properties create trouble when the mating housings of the connector are coupled together. The reason for this is that in connectors with superior waterproof properties, when the mating housings of the connector are coupled together, air is locked in the space between the mating housings, and since there is no escape for the air, it remains inside the connector at a rather high pressure. 
     Therefore, the purpose of the present invention is to provide a waterproof electrical connector, the design of which makes it possible to reduce pressure of the air trapped between the mating housings of the mating connectors. 
     SUMMARY OF THE INVENTION 
     The waterproof electrical connector according to the present invention comprises a housing containing multiple electrical terminals for electrical connection to multiple electrical wires and having waterproof sealing means secured on the housing at a mating side of the housing to provide a watertight connection with a mating housing of a mating connector and at the side of the housing accommodating electrical wires that are passed through water tight openings therein wherein the waterproof sealing means has a deformable pressure-relieving structure intended to reduce pressure of the air trapped in the vicinity of the mating side inside the housing. 
     The pressure-reducing structure is made in the form of a thin wall that is molded in a cavity having a round cross section. The thin wall is best configured in the form of a dome. 
     Deformation or displacement of the pressure-reducing structure is of an elastic nature. 
     The pressure-reducing structure is made as a part of the wire waterproof-sealing member. 
     The pressure-reducing structure has a through hollow cavity facing the mating side of the housing. No electrical terminals shall be disposed inside the hollow cavity. 
     There are several hollow cavities and that at least one of them has a relatively narrow opening facing the mating side of the housing. 
     The hollow cavities are aligned with the pressure-reducing structure. 
     A waterproof electrical connector for matable connection with a mating connector comprises a housing having contact-receiving cavities in which electrical contacts are to be disposed, a waterproof-sealing member in the housing including a coupling-sealing section for sealing engagement with a mating housing of the mating connector and a wire-sealing section through which electrical wires to be electrically connected to the electrical contacts sealingly extend, wherein a pressure-reducing structure is provided by the wire-sealing section for reducing the air pressure that is trapped within the connector when it is mated with the mating connector. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     An embodiment of the present invention will now be described by way of example with reference to the accompanying drawings in which; 
     FIG. 1 is an exploded perspective view of a waterproof electrical connector according to the present invention. 
     FIG. 2 is a front view of the waterproof electrical connector of FIG.  1 . 
     FIG. 3 is a cross-sectional view taken along line  3 — 3  in FIG.  2 . 
     FIG. 4 is an enlarged cross-sectional view of detail B shown in FIG.  3 . 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     As can be seen from FIGS. 1-3, waterproof electrical connector  10  comprises an inner housing  20 , an outer housing  30 , a waterproof-sealing member  50  disposed between the housings that is fabricated from an elastic rubber material, and a retaining member  40  preventing electrical contacts or terminals (not shown) from being pulled out of the connector. At a rear end of the inner housing  20 , flexible latching arms  21 ,  22  are provided. The latching arms  21 ,  22  are provided to secure the inner housing  20  to the outer housing  30 . When the inner housing  20  is secured to the outer housing  30  by latches  21 ,  22 , the waterproof-sealing member  50  is pressed between the inner housing  20  and the outer housing  30 , thus forming a subassembly including the inner housing  20 , the outer housing  30  and the waterproof-sealing member  50 . The electrical contacts with electrical wires connected thereto are inserted in the inner housing  20 , and the retaining member  40  is placed on the subassembly from the mating side, thus securing the contacts in the connector. 
     FIGS. 2 through 4 show the waterproof electrical connector in the assembled state. As can be seen from FIGS. 2 and 3, when the waterproof-sealing member  50  is inside the assembly formed by the inner housing  20  and the outer housing  30 , coupling-sealing section  52  is positioned for engaging a surface of a mating housing of a mating connector (not shown), and wire-sealing section  53  is accommodated in a rear end at an electrical wire outlet of outer housing  30 . The coupling-sealing section  52  provides watertight sealing between the waterproof electrical connector  10  and the mating connector, and the wire-sealing section  53  provides watertight sealing for the bundled electrical wires connected to the electrical contacts (not shown )as the wires sealingly extend through sealing holes  53   a.    
     As can be seen from FIGS. 2 and 3, the inner housing  20  of the waterproof electrical connector  10  has two rows of contact-receiving cavities  23 ,  24  and hollow cavities  25 ,  26 ,  27  located near the contact-receiving cavities but having no contacts therein. Three hollow cavities  25  open only to the surface of the mating housing  15  through ports  41  of the retaining member  40 . The hollow cavities  25  can be used, for example, to accept ribs provided on the mating connector to prevent gouging during the joining of the connectors, or they may be just left as hollow cavities. The advantages of these cavities are explained below. Hollow cavities  26  are formed near the upper end of housing  20 . The hollow cavities  26  are connected to the surface of the mating connector through relatively small diameter openings  42  of the retaining member  40 . The hollow cavities  26  are connected to the wire-sealing section  53  of the waterproof-sealing member  50  through holes  26   a  of small diameter. The hollow cavity  27  is similar to the hollow cavities  25  but larger than each cavity  25 ; it is connected to the surface of the mating connector through port  43  of the retaining member  40 . 
     The wire-sealing section  53  of the waterproof-sealing member  50  has round cavities  55  aligned with the small diameter holes  26   a . Inside the cavities  55 , a thin-wall partition constituting a pressure-reducing structure  56  is provided that divides the cavity  55  in two parts. The thin-wall partition  56  maintains the water tightness even when it is moved back or forward. The thin wall partition  56  is dome shaped. 
     As was mentioned above, when conventional waterproof connectors are coupled and their waterproof sealing units join each other, the air has no openings to escape and it is compressed. Therefore, the operator joining the mating of the connectors has to overcome the air pressure resistance in addition to the normal coupling resistance, which requires extra time and can lead to reduced reliability of the connection. The cavity  55  and thin-wall partition  56  therein make it possible to solve this problem. 
     When the waterproof electrical connector  10  is coupled with a mating connector, air trapped between the coupling-sealing section  52  of the waterproof sealing member  50  and the mating housing of the mating connector, and there is no escape route for the air, the air pressure rises in the inner housing  20 . But in this case, the air pressure is reduced due to deformation of the thin-wall partition  56  (its stretch deformation). Therefore, the thin-wall partition  56  makes it possible to reduce the air pressure trapped in the vicinity of the mating housing. 
     The configuration and dimensions of the thin-wall partition  56  depends on the number of the electrical contacts and their overall dimensions. For example, the thin-wall partition  56  may be made in the form of a dome bulging forward toward a front end of the cavity  55  rather than to the back end as shown in FIGS. 3 and 4. It is also possible to make the pressure-reducing structure larger. 
     The hollow cavities  25 ,  27  that are not used also contribute to the reduction of the air pressure, due to the fact that the enclosed volume occupied by the air under pressure is larger resulting in a lower pressure. 
     Above, an explanation concerning a preferred embodiment of the waterproof electrical connector according to the present invention has been set forth. However, this embodiment is only an example and the present invention by no means is limited to the example described herein, various changes and modifications may therefore be made. 
     A specific feature of the waterproof electrical connector according to the present invention is a deformable pressure-reducing structure of a waterproof-sealing member which makes it possible to reduce inner pressure of the air trapped and compressed inside the housing when the connector is coupled with a mating connector, thus facilitating the task of joining the mating connectors and improving reliability of the electrical connections by eliminating the coupling defects.