Wire seal arrangement for waterproof electrical connectors

Abstract: A wire seal formed of an elastic material is fitted with an electrical wire (12) to be inserted into a housing (7) of a waterproof electrical connector. The wire seal is then inserted into a cylindrical portion (11) of the connector housing (7) to provide seal. The wire seal includes a seal body (16) having a through aperture (17) through which the electrical wire (12) is inserted, the seal body (16) being inserted into the cylindrical portion (11) of the connector housing (7) and a cover piece (22) integrally formed on the seal body (16) to project peripherally of the seal body (16). The cover piece (22) is in contact with the whole peripheral edge of an opening of the housing cylindrical portion (11) through which the electrical wire (12) is inserted.

Description: This invention relates to a wire seal for sealing a gap between an electrical wire and a cavity of a waterproof electrical connector. In an electrical connector, a terminal secured to one end of an electrical wire is inserted in a cavity of a connector housing. A wire seal formed of an elastic material has conventionally been employed for sealing a gap between the cavity of the connector housing and the wire. The prior art has provided the following arrangement for this purpose. A cylindrical wire seal is previously fitted with the end of the wire and crimped thereto. The terminal is then inserted into the cavity of the connector housing through its one open end and the wire seal is press fitted into the open end of the cavity to close a gap between the wire and the inner peripheral face of the cavity, thereby providing the waterproof. In the above-described arrangement, the wire seal is formed into a cylindrical shape so that the wire is inserted therethrough, and the wire seal has a lip portion formed on its outer peripheral face. The wire seal provides an elasticity due to the fitting thereof with the wire between the wire and the wire seal. The elasticity acts toward the inner periphery of the wire seal. The wire seal further provides another elasticity due to the press fitting thereof into the open end of the cavity. The elasticity acts toward the outer periphery of the wire seal. The wire seal is subjected to a hydraulic Pressure higher than a normal pressure when a high-pressurized water or liquid is applied to the connector for the cleaning thereof or when an automotive vehicle in which the connector is employed runs in muddy water at a high speed. In such a case, the water sometimes invades the connector housing. The water enters through the gap between the inner peripheral face of the housing cavity and the wire seal rather than between the wire and the wire seal. The reason for this is that the wire seal is fitted with the wire end before the wire seal is press fitted into the housing cavity, as described above, and the wire seal is allowed to deform to expand outwardly when it is fitted with the wire end. Accordingly, the inner diameter of the cylindrical wire seal can be set at a value sufficiently smaller than that of the wire without lowering an efficiency of the work for fitting the wire seal with the wire, so that a relatively large sealing force can be achieved between the wire and the wire seal. On the other hand, the outer diameter of the wire seal needs to be reduced to its minimum in view of an efficiency of the work for press fitting it into the housing cavity so that a force required for the press fitting is rendered as small as possible. Consequently, a sufficient sealing force cannot be obtained between the inner peripheral face of the housing cavity and the wire seal. Document FR-A-2 415 375, which is considered as the next-coming prior art, relates to an electrical connector comprising a cylindrical portion and a seal body into which the electrical contacts are incorporated. The seal body has the form of a cylinder the end portion of which has a larger diameter. This large diameter portion comprises a locking means which engages a rib portion formed on the outer face of the cylindrical portion for providing sealing. When assembling the electrical connector a large force has to be applied to the seal body in order to engage the rib portion. Therefore, an object of the present invention is to provide a connector including a wire seal which can provide for a sufficient sealing performance for its contact face with the connector housing, in which contact face the sealing performance has conventionally insufficient. Another object of the invention is to provide a connector including a wire seal which can provide for a sufficient sealing performance both for its contact face with the connector housing and its contact face with the electrical wire. Furthermore a force required for the press fitting of the wire seal into the housing cavity has to be rendered as small as possible. The invention provides a connector comprising a wire seal which is fitted with an electrical wire to be inserted into a connector housing, the wire seal being then inserted into a cylindrical portion of the connector housing to thereby provide seal, the wire seal being formed of an elastic material and having a seal body with a through aperture through which the electrical wire is inserted, the seal body being inserted into the cylindrical portion of the connector housing; and a cover piece integrally formed on the seal body to project peripherally thereof, the cover piece being in contact with the whole peripheral edge of an opening of the housing cylindrical portion through which the electrical wire is inserted, wherein said cover piece includes a cylindrical portion rising from the end face of the seal body and having a diameter slightly smaller than the inner diameter of the cylindrical portion of the housing; and said seal body being crimped to a metal terminal, which is provided at the free end of said electrical wire, said metal terminal being held inside said connector housing. The potential water invasion path between the wire seal and the cylindrical portion of the connector housing is covered by the cover piece projecting peripherally of the wire seal. Consequently, a liquid invasion path, which is sometimes formed on the contact face between the wire seal and the housing, can be closed by the cover piece. In a preferable form, the wire seal is characterized by one or a plurality of lip portions formed on an outer peripheral face of the seal body into an annular shape to be in contact with the inner peripheral face of the housing cylindrical portion. In another preferable form, the wire seal is characterized in that one or a plurality of lip portions are defined by a plurality of annular grooves formed in the inner peripheral face of a through aperture of the seal body, each lip portion having a distal end in contact with the outer peripheral face of the wire inserted through the through aperture. The invention will be described, merely by way of example, with reference to the accompanying drawings, in which: FIG. 1 is an enlarged sectional view of the wire seal of one embodiment in accordance with the present invention, the wire seal being applied to an electrical wire connected to the waterproof electrical connector; FIG. 2 is a sectional view of male and female connectors; FIG. 3 is a front view of the wire seal; and FIG. 4 is an enlarged sectional view of the wire seal of another embodiment; An embodiment of the invention will now be described with reference to the accompanying drawings. Referring to FIG. 2, there is shown a part of a male connector 1 and a female connector 2 both composing a waterproof electrical connector as well known in the art. The male connector 1 includes a cylindrical connection portion 4 opposite the female connector 2. A lock claw 3 is integrally formed on the outer peripheral face of the connection portion 4 near its distal end for the purpose of locking the female connector 2 when the male connector is mated with it. A male terminal 5 projects in the cavity of the connection portion 4 so that the male terminal 5 is inserted into a female terminal 6 when the male connector 1 is mated with the female connector 2. A housing 7 of the female connector 2 includes a fitting cavity 8 into which the male connector 1 is fitted. The female connector 2 has a claw 9 is engaged with and disengaged from the lock claw 3 of the female connector 2. The claw 9 faces the fitting cavity 8 for elastic deformation upwardly as viewed in FIG. 2. The housing 7 also has a partition wall 10 formed therein. A cylindrical portion 11 of the housing 7 extends from the partition wall 11 axially both forward and rearward. The female terminal and a wire seal 13, which will be described later, are attached to an end of a wire 12. In this state, the wire 12 is inserted into the female connector 2 through the right- hand open end thereof as viewed in FIG. 2 until the distal end of the female terminal 6 reaches the distal end of the side of the cylindrical portion 11 opposite the male connector 1. A claw 14 projects from the partition wall 10 to the interior at this side of the cylindrical portion 11 of the housing 7. The claw 14 is engaged with the female terminal 6 to prevent fallout of the the terminal. A connector seal 15 formed of rubber is fitted with the outer periphery of the cylindrical portion 11 for sealing a gap between the female and male connectors. The wire seal 13 comprises a seal body 16 formed of rubber into a generally cylindrical shape. The seal body 16 has a central wire insertion aperture 17 through which the wire 12 is inserted. The diameter of the aperture 17 is so set as to be sufficiently smaller than the outer diameter of the wire 12 such that a suitable clamping force is applied to the wire 12. Two annular grooves 18 each preventing water invasion are formed in the inner periphery of the wire seal 13 at the side of its open end through which the wire 12 is inserted, whereby two inner peripheral lip portions 19 are provided. Two annular outer peripheral lip portions 20 are integrally formed to extend around the whole outer periphery of the seal body 16 such that a suitable pressing force is applied to the inner peripheral wall of the cylindrical portion 11. A groove 21 is provided between the outer peripheral lip portions 20 for the purpose of preventing water invasion. The contact pressure of the each outer peripheral lip portion 20 is limited to its required minimum in consideration of the work for inserting the terminal 6 and the wire 12 into the cylindrical portion 11. Accordingly, an amount of detormation of each inner peripheral lip portion 19 is larger than that of each outer peripheral lip portion 20, so that a large sealing force can be achieved between the wire 12 and the seal body 16 as compared with the outer peripheral lip portion 20 and the inner peripheral wall of the cylindrical portion 11, as described in the description of the prior art. The seal body 16 has a cover piece 22 integrally formed on one end face thereof (the right-hand end face in FIG. 1). The cover piece 22 covers portions of the seal body 16 and the cylindrical portion 11 in contact with each other. The cover piece 22 includes a cylindrical portion 23 rising from the end face of the seal body 16 and having a diameter slightly smaller than the inner diameter of the cylindrical portion 11 of the housing 7. The cover piece 22 further includes a generally U-shaped folded portion 24 continuous to the cylindrical portion 23. The U-shaped folded portion 24 is folded to be engaged with an opening edge of the cylindrical portion 11 of the connector housing 7 and is in close contact with an outer peripheral face of the cylindrical portion 11. The cover piece 22 covers the water entry path via the contact faces of the wire seal 13 and the housing cylindrical portion 11, which path has been a drawback in the prior art. High-pressurized water from the end side of the cylindrical portion 11 collides with the connector when a high-Pressurized water or liquid is applied to the connector for the cleaning thereof or when an automotive vehicle in which the connector is employed runs in muddy water at a high speed. However, the water can be prevented by the cover piece 22 from, entering the interior of the con nector housing 11 through the contact face of the wire seal 13 and the inner peripheral face of the housing cylindrical portion 11. Furthermore, if the water from the opposite direction collides with the connector, the water would be considered to enter the connector housing 7 through the contact faces of the folded portion 24 of the cover piece 22 and the outer peripheral face of the cylindrical portion 11. However, since the distance between the end of the folded portion 24 and the outer peripheral lip portion 20 is sufficiently long, the contact faces of the lip portion 20 and the inner peripheral face of the housing cylindrical portion 11 are not subjected to the high hydraulic pressure, which prevents invasion of water through the contact faces. In the embodiment, particularly, the U- shaped folded portion 24 of the cover piece 22 is closely adhered to an outer peripheral face of the cylindrical portion 11. The folded portion 24 itself provides a sealing function when that part of the cylindrical portion 11 is subjected to the hydraulic pressure, thereby improving sealing performance. The folded portion 24 of the cover piece 22 need not be formed by folding the end of the cover piece 22 into the U-shape. For example, FIG. 4 illustrates a modified form in which the distal end of the cylindrical rising portion 23 of the cover piece 22 is in contact with the opening edge 25 of the housing cylindrical portion 11 of the housing 7. The present invention is applicable to various types of waterproof electrical connectors and should not be limited to the connector of the type described above. Although the folded portion 24 is merely in contact with the housing cylindrical portion 11 in the foregoing embodiment, it may be formed to have such a diameter that it is press fitted with the cylindrical portion 11 so that it achieves the sealing performance. The foregoing disclosure and drawings are merely illustrative of the principles of the present invention and are not to be interpreted in a limiting sense. The only limitation is to be determined from the scope of the appended claims.

Claims: A connector comprising a wire seal which is fitted with an electrical wire (12) to be inserted into a connector housing (7), the wire seal being then inserted into a cylindrical portion (11) of the connector housing (7) to thereby provide seal, the wire seal being formed of an elastic material and having a seal body (16) with a through aperture (17) through which the electrical wire (12) is inserted, the seal body (16) being inserted into the cylindrical portion (11) of the connector housing (7); and a cover piece (22) integrally formed on the seal body (16) to project peripherally thereof, the cover piece (22) being in contact with the whole peripheral edge of an opening of the housing cylindrical portion (11) through which the electrical wire (12) is inserted, characterized in that said cover piece (22) includes a cylindrical portion (23) rising from the end face of the seal body (16) and having a diameter slightly smaller than the inner diameter of the cylindrical portion (11) of the housing (7); and said seal body being crimped to a metal terminal, which is provided at the free end of said electrical wire (12), said metal terminal being held inside said connector housing (7). A connector comprising a wire seal according to claim 1, characterized by one or a plurality of lip portions (20) formed on an outer peripheral face of the seal body (16) into an annular shape to be in contact with the inner peripheral face of the cylindrical portion (11). A connector comprising a wire seal according to claim 1 or 2, characterized in that one or a plurality of lip portions (19) are defined by a plurality of annular grooves (18) formed in the inner peripheral face of a through aperture (17) of the seal body (16), each lip portion (19) having a distal end in contact with the outer peripheral face of the wire (12) inserted through the through aperture (17). A connector comprising a wire seal according to claim 1, 2 or 3, characterized in that the cover piece (22) has an end folded so as to extend from the inner peripheral side to the outer peripheral side of the cylindrical portion (11) of the connector housing (7) such that the cover piece (22) covers the outer peripheral face of the cylindrical portion (11) of the connector housing (7) in contact with the same.

Inventors: ITOU HIKARU, ITOU, HIKARU, ITOU, HIKARU, C/O SUMITOMO WIRING SYSTEMS, LTD.
Applicants: SUMITOMO WIRING SYSTEMS, SUMITOMO WIRING SYSTEMS, LTD.
Application year: 1993
Main classification: H01R13
IPC codes: H01R13