Sealing device and method for producing a waterproof connector

Abstract: Disclosed is a sealing device for a cavity into which a wire is inserted, the sealing device including a seal member made of elastic material and sealingly engaging an inner surface of the cavity and an outer surface of the wire so as to prevent entrance of water into the cavity, and a rigid member associated with the seal member and engaging the cavity so that, when the wire is bent with respect to the cavity, a deformation of the seal member is substantially prevented. This sealing device securely prevents entrance of water even if a force acts on a wire in a transverse direction and/or if high pressure water is sprayed thereon.

Description: DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a sealing device, particularly for a connector which prevents entrance of water into a cavity for accommodating a terminal fitting. A sealing device for a connector as shown in FIG. 10 is known which prevents entrance of water into a cavity for accommodating a terminal fitting. This structure employs a cylindrical waterproof plug 90 of rubber. A wire 95 is inserted into a center hole 91 of the waterproof plug 90 in advance. After the wire 95 is cramped with the rear end of a terminal fitting 96, the waterproof plug 90 is moved to a position adjacent the terminal fitting 96. The waterproof plug 90 is pressed into a cavity 97 at the same time when the terminal fitting 96 is inserted thereinto. When fitted in the cavity 97, the waterproof plug 90 is radially compressed, resulting in deformation of projections 92 which are formed on the outer surface of the waterproof plug 90 and extend in a circumferential direction thereof. The deformed projections 92 come into sealable contact with the inner surface of the cavity 97. A projection 93 which is formed on the surface of the center hole 91 and extends in a circumferential direction of the center hole 91 is also deformed, with the result that it comes into sealable contact with the outer surface of the wire 95. In this way, water is prevented from entering from outside into a space in the cavity 97 where the terminal fitting 96 is mounted, through clearances defined between the outer surface of the waterproof plug 90 and the inner surface of the cavity 97 and between the inner surface of the waterproof plug 90 and the outer surface of the wire 95. The prior art sealing device has the following problem. When a force acts on the wire 95 extending out of the cavity 97 through the center hole 91, transversely with respect to the longitudinal direction of the waterproof plug 90, the waterproof plug 90 undergoes elastically deformation in its radial directions as shown in FIG. 11 As a result, a clearance is made between the inner surface of the cavity 97 and the projections 92 on the outer surface of the waterproof plug 90 at the side opposite from the one where the force is acting. In such a state, water is enabled to enter the cavity 97 through this clearance. Another known sealing device mountable in a connector is shown in FIG. 12. In FIG. 12, a connector 101 is formed with a cylindrical terminal fitting cavity 103 for accommodating a terminal fitting 102. The terminal fitting 102 is formed with an insulation barrel 102a for cramping an insulated part of an insulated wire 104 and a wire barrel 102b for cramping a core of the wire 104 exposed by peeling off its insulation. A rubber plug 105 as a seal member is, as a whole, formed substantially into a cylindrical body, and a plurality of flange-like ribs 105a having a diameter larger than an inside diameter of the cavity 103 are formed on the outer surface thereof. At one end of the rubber plug 105, there is formed a tube portion 105b having a smaller diameter which can be cramped with the insulation barrel 102a. This rubber plug 105 is used as follows. First, the wire 104 is inserted into the rubber plug 105 in such a manner that the tube portion 105b faces the leading end of the wire 104. The insulation of the leading end of the wire 104 is peeled off to expose the core, which is then cramped with the terminal fitting 102. At this stage, the core is cramped with the wire barrel 102b and the insulated part of the wire 104 and the tube portion 105b of the rubber plug 105 are cramped with the insulation barrel 102a. The thus mounted members are inserted into the cavity 103 of the connector 101 with the terminal fitting 102 entering first. When the rubber plug 105 is inserted, the ribs 105a are pressed by the inner wall of the cavity 103 to be deformed toward the radial center of the cavity 103 since the diameter of the ribs 105a is larger than the inside diameter of the cavity 103. As a result, the rubber plug 105 comes into sealable contact with the inner wall of the cavity 103. Thus, waterdrops generally do not enter the cavity 103. In recent years, there have widely been used high pressure car washing machines which spray water upon an automotive vehicle with high pressure. Water is sprayed not only upon a vehicle body, but also upon, for example, an engine compartment. The above-mentioned connector is often used in the engine compartment, and thus water may also be sprayed upon this connector. In such a case, with prior art seal member such as the above-mentioned rubber plug 105, when the connector 101 is positioned with respect to the sprayed water as shown in FIG. 16, water is sprayed directly upon a portion where the ribs 105a are in sealable contact with the inner wall of the cavity 103. Thus, high pressure water may deform the ribs 105a axially, and thus radially, inward of the cavity 103 and make a clearance between the ribs 105a and the inner wall of the cavity 103. Such a clearance allows entrance of water into the cavity 103. US 5,201,667 discloses a branch circuit structure with an housing into which wires are inserted wherein the wires are surrounded by an elastic sealing member which can comprise a resin-made pressure receiving body assembled therein to by integral forming. GB 2 207 817 A discloses a waterproof connector into which wires are inserted wherein an elastic sealing member surrounds each wire. A rear holder is further provided wherein the wires pass through openings in the rear holder and wherein the rear holder is inserted into the connector housing. However, the sealing member and the rear holder are two different parts so that the rear holder does not stabilize the sealing member. The present invention is developed in view of the above problems, and an object thereof is to provide a sealing device with improved sealing performance, particularly if high pressure water is sprayed thereon and/or when a force acts on the wire in a transverse direction. According to the invention there is provided a sealing device with facilitated assembling. The above object is accomplished a sealing device as defined in claim 1. Preferred embodiment are defined in the dependent subdaims. According to the invention , a sealing device comprises an elastic member in combination with a rigid member, achieving an excellent sealing performance even if external forces (e.g., high pressure water and/or transverse forces acting on the wire) are applied, wherein the rigid member is a retainer which is formed with a through hole into which the wire is inserted, and is engaged with the cavity, whereby said seal member and said rigid member are coupled by engaging projections on said seal member, and engaging holes through said rigid member complementary to said engaging projections. Furthermore the retainer is unitarily coupled with the waterproof plug. Since the retainer is coupled with the waterproof plug in advance during assembling, the retainer and the waterproof plug can be mounted in the cavity at the same time. Thus, this sealing device has better operability during the assembling than those which are assembled by mounting the retainer and the waterproof plug in the cavity at separate stages. In a preferred embodiment said engaging projections extend outwardly of said cavity and have an enlarged portion at their ends remote from said seal member, and said engaging holes have a cross-section smaller than said enlarged portion, whereby said rigid member can be pressed thereover and retained on said engaging projections. Preferably said engaging projections are formed on the outer circumferential surface of the sealing member, and said engaging holes are formed in engaging portions which are formed on the outer circumferential surface of said rigid member and which project toward the sealing member. Particularly, when a force acts on the wire in the transverse direction, the wire comes into contact with the inner surface of the through hole, thereby radially pressing the retainer. However, the retainer makes no movement because it is engaged with the cavity. Accordingly, the position of the wire at the through hole is securely held without being radially displaced. Thus, the wire inward of the retainer 20 exerts no pressing force against the waterproof plug in the transverse direction, with the result that the waterproof plug does not undergo elastic deformation in its radial directions. Thus, the waterproof plug is held in sealable contact with the outer surface of the wire and with the inner surface of the cavity, thereby securely preventing entrance of water from outside into the cavity. Preferably, an outer surface of the retainer facing outside the cavity is formed into an umbrella-like tapered surface. When the outer surface of the retainer is formed into the umbrella-like tapered surface, water on this surface runs toward the outer periphery along inclination of the tapered surface, thereby preventing water from staying on the outer surface of the retainer. Thus, the sealing device has an improved waterproof function since it is provided with a water discharging function of preventing water from staying on the outer surface of the retainer. These and other objects, features and advantages of the present invention will become more apparent upon a reading of the following detailed description and accompanying drawings in which: FIG. 1 is a perspective view of a waterproof plug and a retainer of the first embodiment in their separated state, FIG. 2 is a perspective view of the waterproof plug and the retainer of the first embodiment in their assembled state, FIG. 3 is a section of the waterproof plug and the retainer of the first embodiment in their assembled state, FIG. 4 is a section of the first embodiment in its assembled state where the waterproof plug and the retainer mounted on a wire are mounted in a cavity, FIG. 5 is a section of the first embodiment when a tensile force is acting on the wire in a transverse direction, FIG. 6 is a perspective view of a waterproof plug and a retainer of the second embodiment in their separated state, FIG. 7 is a perspective view of the waterproof plug and the retainer of the second embodiment in their assembled state, FIG. 8 is a section of the third embodiment in its assembled state where a waterproof plug and a retainer mounted on a wire are mounted in a cavity, FIG. 9 is a section of the fourth embodiment in its assembled state where a waterproof plug and a retainer mounted on a wire are mounted in a cavity, FIG. 10 is a section of a prior art seal member in its assembled state where a waterproof plug and a retainer mounted on a wire are mounted in a cavity, FIG. 11 is a section of a prior art seal member when a tensile force is acting on the wire in a transverse direction, and FIG. 12 is a section of a prior art seal member in its mounted position. Hereafter, embodiments of the invention are described with reference to FIGS. 1 to 9. A first embodiment of the invention is described with reference to FIGS. 1 to 5. A connector housing 1 is formed with a cavity 2 having a circular cross-section which extends from a rear end of the housing 1 shown in FIGS. 4 and 5 to an unillustrated front end thereof. A terminal fitting 3 is inserted from its rear end into the cavity 2 and locked in a specified position by an unillustrated locking means. A core 4b exposed by peeling off an insulation 4a of a connection end of an insulated wire 4 is cramped with a wire barrel 3a formed at the rear end of the terminal fitting 3. The connection end of the wire 4 is inserted into the cavity 2 by a specified length. A substantially cylindrical waterproof plug 10 of elastically deformable material such as rubber is mounted on the connection end of the wire 4 by inserting the wire 4 into a center hole 11 formed in the waterproof plug 10. The waterproof plug 10 is mounted in a rear end position of the cavity 2 together with the terminal fitting 3 and the wire 4. When the waterproof plug 10 is mounted in the cavity 2, projections 12 formed on the outer surface of the plug 10 and extending in the circumferential direction thereof undergo elastic deformation and come into sealable contact with the inner surface of the cavity 2 due to their elastic restoring force. At the same time, projections 13 formed on the surface of the center hole 11 and extending in the circumferential direction thereof also undergo elastic deformation and come into sealable contact with the outer surface of the insulation 4a of the wire 4 due to their elastic restoring force. The waterproof plug 10 is unitarily formed with two engaging projections 14, 14 on its rear end face, i.e., a face facing outward from the cavity 2. The engaging projections 14, 14 are opposed with the center hole 11 therebetween. At a projecting end portion of each engaging projection 14, there is formed a locking portion 15 which projects radially outward at the engaging projection 14, thereby forming a stepped portion, and whose diameter tapers toward a projecting end, forming a tapered surface 15a. A retainer 20 is also mounted in the cavity 2. The retainer 20 is of synthetic resin or other material which is unlikely to be deformed and is in the form of a circular plate. A thickness of the retainer 20 corresponds to a distance between the rear end face of the waterproof plug 10 and the locking portions 15 of the engaging projections 14, and an outside diameter thereof is equal to an inside diameter of the rear end of the cavity 2. The retainer 20 is formed with a through hole 21 in conformity with the center hole 11 of the waterproof plug 10. At an outer opening edge of the through hole 21, there is formed a tapered surface 21a whose diameter tapers toward the inner surface of the retainer 20. Further, at the opposite sides of the through hole 21, there are formed engaging holes 22 in conformity with the engaging projections 14 of the waterproof plug 10. A diameter of the engaging holes 22 corresponds to that of the engaging projections 14. At an inner opening edge (facing the waterproof plug 10) of each engaging hole 22, there is formed a tapered surface 22a whose diameter tapers toward the outer surface of the retainer 20. Next, the action of this embodiment is described. The respective members are mounted into the cavity 2 as follows. First, the locking portions 15 of the engaging projections 14 of the waterproof plug 10 are placed in position with respect to the engaging holes 22 of the retainer 20 and then pressed into the engaging holes 22 so as to couple the waterproof plug 10 and the retainer 20. The locking portions 15 are inserted through the engaging holes 22 while undergoing elastic deformation such that the diameters thereof decrease. Due to the corresponding tapered surfaces 15a and 22a, insertion is easy. When coming out of the engaging holes 22, the locking portions 15 regain their original shape and are locked at the rear edges of the engaging holes 22. thereby engaging the engaging projections 14 with the engaging holes 22. In this way, the retainer 20 is unitarily coupled with the waterproof plug 10 while being locked by the locking portions 15. The connection end of the wire 4 is inserted through the center hole 11 and the through hole 21 of the waterproof plug 10 and the retainer 20 which are unitarily coupled. At this stage, the core 4b of the wire 4 is cramped with the wire barrel 3a of the terminal fitting 3. Thereafter, the waterproof plug 10 and the retainer 20 are moved toward the terminal fitting 3 to a predetermined position. In this way, the waterproof plug 10, the retainer 20, the terminal fitting 3 and the connection end of the wire 4 are made integral with one another. These integrated members, the terminal fitting 3 heading, are moved into the cavity 2 against friction acting between the outer surface of the waterproof plug 10 and the inner surface of the cavity 2, until the retainer 20 is fittingly mounted at the rear end of the cavity 2. At this stage, the assembling is completed. In an assembled state, the projections 12 on the outer surface of the waterproof plug 10 are elastically deformed and are in sealable contact with the inner surface of the cavity 2, whereas the projections 13 on the surface of the center hole 11 are elastically deformed and are in sealable contact with the outer surface of the insulation 4a of the wire 4. This prevents water from entering from outside into the cavity 2 through clearances between the outer surface of the waterproof plug 10 and the inner surface of the cavity 2 and between the surface of the center hole 11 and the outer surface of the wire 4, respectively. If a tensile force acts transversely (e.g., toward above in FIG. 5) on the wire 4 extending out of the cavity 2 with respect to the longitudinal direction of the waterproof plug 10, the wire 4 comes into contact with the inner surface of the through hole 21, thereby pressing the retainer 20 upward. However, the retainer 20 does not move upward since it is mounted in contact with the inner surface of the cavity 2. Accordingly, the part of the wire 4 located within and inwardly of the retainer 20 is held in the same state as when the tensile force is not acting, and thus the waterproof plug 10 located inwardly of the retainer 20 does not undergo elastic deformation. Thus, the outer surface of the waterproof plug 10 and the inner surface of the cavity 2 and the surface of the center hole 11 and the outer surface of the wire 4, respectively, are kept in sealable contact with each other over their entire circumferences, thereby preventing entrance of water into the cavity 2 from outside. Since the waterproof plug 10 and the retainer 20 are first unitarily coupled in assembling the sealing device in this embodiment, operability thereafter is improved. It should be noted that an operation of unitarily coupling the waterproof plug 10 and the retainer 20 can be performed at any stage of the assembling. Formation of the tapered surfaces 22a in the engaging holes 22 of the retainer 20 as in this embodiment facilitates insertion of the locking portions 15 (having also tapered surfaces 15a) of the engaging projections 14 into the engaging holes 22. Similarly, the tapered surface 21a is formed in the through hole 21 of the retainer 20 in this embodiment. This prevents the insulation 4a of the wire 4 from being ripped when the wire 4 is bent with respect to the cavity 2, i.e., is bent about an angular corner of the through hole 21, e.g., when a force acts on the wire 4 in a transverse direction. Next, a second embodiment of the invention is described with reference to FIGS. 6 and 7. This embodiment differs from the first embodiment in the means for unitarily coupling the waterproof plug and the retainer. Since the other construction and action of this embodiment are identical to those of the first embodiment, no description will be given therefor. At the outer circumferential surface of an attachment portion (jaw portion) 31 formed at the rear end of a waterproof plug 30, four pairs of notches 32, 32 spaced apart by a small distance are formed in positions circumferentially spaced apart by 90 degrees. An engaging projection 33 is defined between each pair of notches 32 and 32. On the outer circumferential surface of a retainer 40, there are formed four engaging portions 44 which include engaging holes 45 engageable with the corresponding engaging projections 33 and project toward the waterproof plug 30. When the retainer 40 is placed in position with respect to the rear end face of the waterproof plug 30 and pressed so that these two members are closely coupled with each other, opposed side parts of the engaging portions 44 are fitted into the corresponding notches 32, 32 and the engaging projections 33 are engaged with the engaging holes 45. During this operation, the engaging projections 33 are deformed and the engaging portions 44 are outwardly deformed. In this way, the waterproof plug 30 and the retainer 40 are unitarily coupled with each other. Next, a third embodiment of the invention according to the invention is described with reference to FIG. 8. This embodiment differs from the first embodiment in the shape of the retainer and that of engaging projections of the waterproof plug. Since the other construction and action of this embodiment are identical to those of the first embodiment, no description will be given therefor. A retainer 60 is such that its side opposite from the one facing a waterproof plug 50 is substantially in the form of an umbrella-like projection. The outer surface thereof forms a tapered surface 62 slanting toward the outer periphery from a through hole 61 in the center. Engaging projections 51 of the waterproof plug 50 are longer than the engaging projections 14 of the first embodiment so as to conform to the thickness of the retainer 60. Further, a stepped portion of each locking portion 52 is slanted so as to conform to the inclination of the tapered surface 62. When the retainer 60 is placed in position with respect to the rear end face of the waterproof plug 50 and pressed so that these two members are sealably coupled with each other, the locking portions 52 are inserted through engaging holes 63 of the retainer 60 while undergoing elastic deformation such that the diameters thereof decrease. When coming out of the engaging holes 63, the locking portions 52 regain their original shapes and are locked at the edges of the engaging holes 63, thereby engaging the engaging projections 51 with the engaging holes 63. In this way, the retainer 60 and the waterproof plug 60 are unitarily coupled. Since the outer surface of the retainer 60 is formed into the tapered surface 62 in this embodiment, even if the connector is so held that the rear end of the cavity 2 faces upward, water runs toward the outer periphery along the tapered surface 62 without staying on the tapered surface 62, thereby being discharged outside the opening edge of the cavity 2. This prevents water staying on the outer surface of the retainer 60 from entering the cavity 2 through a clearance between the outer surface of the retainer 60 and the inner surface of the cavity 2, realizing an improved waterproof function. Next, a fourth embodiment of the invention is described with reference to FIG. 9. This embodiment differs from the third embodiment in the shape of the retainer and that of the engaging projections of the waterproof plug. A retainer 80 has, in its entirety, a larger thickness than the retainer 50 of the third embodiment such that it overlaps the cavity 2. Preferably, its diameter corresponds to the outer diameter of the connector housing. The outer surface of the retainer 80 is formed into a tapered surface 82. The outer periphery thereof projects outward from the opening edge of the cavity 2 to thereby define an engaging jaw portion 83. Further, engaging projections 71 of a waterproof plug 70 are longer than the engaging projections 51 of the third embodiment so as to conform to the thickness of the retainer 80. When the retainer 80 is placed in position with respect to the rear end face of the waterproof plug 70 and pressed so that these two members are closely coupled with each other, the locking portions 72 are inserted through engaging holes 84 while undergoing elastic deformation such that the diameters thereof decrease and consequently the engaging projections 71 are engaged with the engaging holes 84. In this way, the waterproof plug 70 and the retainer 80 are unitarily coupled with each other. Since the engaging jaw portion 83 is formed at the outer periphery of the retainer 80 to completely cover the opening of the cavity 2 in this embodiment, water running toward the outer periphery of the retainer 80 along the tapered surface 82 is discharged outside beyond the opening edge of the cavity 2. This prevents entrance of water into a clearance between the outer surface of the retainer 80 and the inner surface of the cavity 2, thereby realizing a more secure waterproof function. Particularly in recent years, high pressure water is often sprayed on a car in a car washing machine. In such cases, the sprayed water is discharged along the tapered surface outside the opening edge of the cavity, thereby preventing entrance of water into the cavity. The invention is not limited to the foregoing illustrated and described embodiments, but may be embodied as follows. (1) A movement or play of the retainer relative to the cavity 2 is prevented by unitarily coupling the retainer with the waterproof plug in the foregoing embodiment and adapting its diameter to that of the cavity. However, according to the invention, a play of the retainer may be prevented by engaging the retainer with an engaging member formed on the inner surface or at the opening edge of the cavity, even without being coupled with the waterproof plug.

Claims: A sealing device for a cavity (2) into which a wire (4) is inserted, the sealing device comprising: a seal member (10; 30; 50; 70) made of elastic material and sealingly engaging an inner surface of the cavity (2) and an outer surface of the wire (4) so as to prevent entrance of water into the cavity (2), and a rigid member (20; 40; 60; 80) associated with the seal member (10; 30; 50; 70) and engaging the inner surface of the cavity (2) so that, when the wire (4) is bent with respect to the cavity (2), a deformation of the seal member (10; 30; 50; 70) is substantially prevented, wherein the rigid member is a retainer (20; 40; 60; 80) which is formed with a through hole (21; 61) into which the wire (4) is inserted, whereby said seal member (10; 30; 50; 70) and said rigid member are coupled by engaging projections (14; 33; 51; 71) on said seal member (10; 30; 50; 70), and engaging holes (22; 45; 63; 84) through said rigid member (20; 40; 60; 80) complementary to said engaging projections (14; 33; 51; 71). A sealing device according to claim 1, wherein said engaging projections (14; 51; 71) extend outwardly of said cavity (2) and have an enlarged portion (15; 52; 72) at their ends remote from said seal member (10; 50; 70), and said engaging holes (22; 63; 84) have a cross-section smaller than said enlarged portion (15; 52; 72) whereby said rigid member (20; 60; 80) can be pressed thereover and retained on said engaging projections (14; 51; 71). A sealing device according to claim 1, wherein said engaging projections (33) are formed on the outer circumferential surface of the sealing member (30), and said engaging holes (45) are formed in engaging portions (44) which are formed on the outer circumferential surface of said rigid member (40) and which project toward the sealing member (30). A sealing device according to one of the preceeding claims, wherein the through hole (21;61) of the retainer (20;40;60;80) has a tapered surface (21a) facing outside the cavity (2) and preventing the wire (4) from being ripped when it is bent with respect to the cavity (2). A sealing device according to one of the preceeding claims, wherein an outer surface of the retainer (60;80) facing outside the cavity (2) is formed into an umbrella-like tapered surface (62;82). A sealing device according to one of the preceeding claims wherein the retainer (80) is lapping over the cavity (2).

Inventors: TABATA MASAAKI, WAKATA SHIGEKAZU, TABATA, MASAAKI, WAKATA, SHIGEKAZU, TABATA, MASAAKI, C/O SUMITOMO WIRING SYSTEMS, LTD., WAKATA, SHIGEKAZU, C/O SUMITOMO WIRING SYST., LTD.
Applicants: SUMITOMO WIRING SYSTEMS, SUMITOMO WIRING SYSTEMS, LTD.
Application year: 1995
Main classification: H01R13
IPC codes: H01R13