Abstract:
A packing plug assembly to be used in a connector housing to provide a seal therewithin. The assembly is composed of a resilient plug body and one or more rigid members. The resilient plug body is formed with a through hole therein to receive an insulated wire therein whereas the remaining portion of the resilient plug body is penetrated by the reinforcing members. The leading end of the wire is attached with a terminal which is securely pressed into the connector by means of rigid reinforcing member penetrating the resilient plug body to assure latching engagement therein when the plug assembly is press fitted into the connector. Such press fitting may be done by use of a rear holder adapted to be pushed into the connector after the resilient plug body.

Description:
BACKGROUND OF THE INVENTION 
     The present invention relates to a packing plug assembly used in a waterproof connector, especially a packing plug assembly having a structure for preventing insufficient retention of a terminal therein, as well as an electrical connector made employable in an environment exposed to water by using said packing plug assembly. 
     As the prior art there is known, for example, such a waterproof connector as shown in FIG. 7, in which terminals B and B&#39; inserted in connector housings A and A&#39; are retained by flexible latch arms A and A 1  &#39;, and rubber packing plugs C and C&#39; are fitted in rear portions of the connector housings A and A&#39;; further, the packing plugs are retained by rear holders D and D&#39; and stabilizers B 1  and B 1  &#39; at the rear ends of the electrical terminals B and B 1  &#39; are brought into engagement with the packing plugs C and C&#39; to doubly retain the electrical terminals B and B&#39;. 
     In such structure, however, even when the electrical terminals B and B&#39; are inserted to an incomplete extent, the packing plugs C and C&#39; can be fitted in the connector housings incompletely due to the elasticity of the packing plugs C and C&#39;, resulting in that the packing plugs are not retained by the flexible latch arms A 1  and A 1  &#39; serving as main retainers, not to mention double retention. 
     In order to overcome the above drawback, the applicant in the present case has proposed a rubber packing plug in a connection (Japanese Laid Open No. 133587/85) in which with respect to a retaining frame comprising a pressing portion and a base portion interconnected through a connecting rod there is integrally formed a rubber plug so as to have an outer peripheral portion larger in diameter than the pressing portion and the base portion while leaving a pressing surface of the pressing portion, and in the pressing portion and the base portion there is formed an electric wire insertion hole for the rubber plug. 
     In this case, however, there have been the following problems. Since the rubber plug is molded integrally with the retaining frame, the manufacturing cost is apt to become high. Besides, since the connecting rod is not always mounted in parallel with the outer peripheral portion of the rubber plug, elastic deformations of the outer peripheral portion do not become constant and there arises a scatter of sealability. 
     In order to obtain an electric connector of a high waterseal it is necessary to use a housing of a watertight structure and it is also necessary that the gap between the housing and an electric wire with a terminal inserted and fixed in the housing be of a watertight structure. To this end, usually a packing plug which permits an electric wire to pass therethrough is fitted in a rear opening portion of the housing. 
     The packing plug is formed of a soft and elastic material, e.g. rubber, to enhance the watertightness. But, because of recovery from the deformation produced when pushing the plug into the rear opening portion of the housing and the resulting return, there easily occur troubles such as incomplete insertion and dislocation of the terminal. According to one method for preventing the occurrence of such troubles, a rear holder serving as means for preventing dislocation of the waterproof plug is provided at a rear end portion of the housing. Even by this method, however, the difficulty of insertion of the waterproof plug is still not improved. 
     SUMMARY OF THE INVENTION 
     It is an object of the present invention to provide a packing plug assembly in a connector capable of solving the above-mentioned problems and being produced inexpensively while obtaining uniform seal. 
     It is another object of the present invention to realize more economically a waterproof connector which permits easy insertion and assures retention of a terminal within the connector. 
     In order to achieve the above-mentioned objects of the present invention there is provided a packing plug assembly for use in a connector housing to provide a seal therewithin comprising a resilient plug body having first and second ends, said resilient plug body having main hole means formed therein to open at said first and second ends to accept an insulated electric wire therethrough and auxiliary hole means formed therein to open at said first end; and rigid reinforcing means inserted into said auxiliary hole means from the first end to provide a rigidity at said first and second ends of said resilient plug. 
     Further, there is also provided in another aspect of the present invention, a waterproof connector comprising a connector housing adapted to receive mating terminals therein for connection with each other and having latch means for retaining said terminals therein; a resilient plug body having first and second ends, said resilient plug body having main hole means formed therein to open at said first and second ends to accept an insulated wire therethrough and auxiliary hole means formed therein to open at said first end, said electric wire being crimped by said terminals at a leading end of said electric wire; rigid reinforcing means inserted into said auxiliary hole means from the first end to provide a rigidity at said first and second ends of said resilient plug; and means for rigid enforcing means to press in turn said terminal into engagement with said latch means. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a sectional view showing a structure of a waterproof connector in the present invention; 
     FIGS. 2a to 2c are a front view, a side view and a longitudinal sectional view, respectively, of a packing plug assembly according to an embodiment of the present invention; 
     FIGS. 3a to 3c are a sectional view of a rubber plug as a packing plug assembly according to another embodiment of the present invention, a sectional view of a reinforcing sleeve and a side view of a combined state, respectively; 
     FIG. 4 is a sectional view showing another structure of a waterproof connector; 
     FIGS. 5a to 5c are a front view, a longitudinal sectional view and a rear view of a packing plug assembly used therein according to a further embodiment of the invention; 
     FIG. 6 is a sectional view showing still another structure of a packing plug assembly; and 
     FIG. 7 is a longitudinal sectional view of a conventional connector. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Embodiments of the present invention will be described in detail hereinunder with reference to the drawings. 
     In FIGS. 1 and 2, the reference numeral 1 denotes a connector housing; numeral 2 denotes a terminal member; and numeral 3 denotes an insulated electric wire, to which is attached an electric wire connecting portion 2a of the terminal member 2 at a rear thereof by crimping. An electric contact portion 2b of the electric connector member 2 is retained primarily by means of a lance 4, whereas packing plug assembly 5 attached to a rear end of the electric wire connecting portion 2a is prevented the terminal from coming off backward by means of a rear holder 6. Thus, the terminal member 2 is doubly retained in the connector. 
     The packing plug assembly 5 is constituted by two components--a rubber plug body 7 which is a resilient member and a reinforcing sleeve 8 which is a rigid synthetic resin insulator--. The rubber plug body 7 is of a double structure comprising an inner cylindrical portion 7b which is formed with an electric wire insertion through hole extending longitudinally therewithin, said inner cylindrical portion 7b having a crimping portion 7b for the electric connector member 2, the crimping 7c portion extending at its forward side of the cylindrical portion 7b; and an outer cylindrical portion 7d formed over the outer periphery of the cylindrical portion 7b at the rearward side of the latter. Said outer cylindrical portion 7d is formed with an annular corrugated uneven surface 7e for enhancing the sealing effect, and an approximately semicircular opening 7g is formed in a fore end portion of the outer cylindrical portion 7d while leaving a connection 7f with the cylindrical portion 7b. The reinforcing sleeve 8 comprises a body 8a, a flange-like pressing portion 8b formed circumferentially at a base end portion of the body 8a, and a notched portion 8c corresponding to the connection 7f, the notched portion 8c being provided at a fore end portion of the body 8a. 
     For putting the packing plug assembly 5 and the terminal 2 together, the electric wire 3 is first inserted into the electric wire insertion hole 7a in the rubber plug body 7 and then the body 8a of the reinforcing sleeve 8 is press-fitted between the cylindrical portion 7b and the outer cylindrical portion 7d of the rubber plug, allowing the fore end of the body 8a to project from the opening 7g (the reinforcing sleeve may be fitted in the rubber plug in advance). Therafter, while a forward end face of the body 8a of the reinforcing sleeve 8 is in contact with a stabilizer 2c of the electric connector member 2, the electric wire connecting portion 2a and the stabilizer 2c are crimped whereby the crimping portion 7c of the rubber plug body 7 and the electric wire 3 are pressure-fixed together. 
     In this state, by inserting the terminal 2 into the housing 1 and fitting the rear holder 6 into the housing from behind the holder 6 is brought into engagement with the pressing portion 8b of the reinforcing sleeve 8 in the packing plug assembly 5, thereby pushing the pressing portion forward, so that the terminal 2 is sure to advance whereby the foregoing double retaining is attained. 
     In this double retention, the cylindrical portion 7b and the outer cylindrical portion 7d of the rubber plug body 7 are supported by the reinforcing sleeve 8 inserted therebetween and are given a sufficient reaction force, whereby the seal between the rubber plug 7 and the housing and that between the rubber plug 7 and the electric wire 3 are enhanced, affording a uniformly sealed condition. 
     FIGS. 3a to 3c illustrate another embodiment of a packing plug assembly accoridng to the present invention, in which a fore end part of an outer cylindrical portion 7d&#39; in a rubber plug 7&#39; is provided in the form of a thin blind wall 7f&#39; not having the foregoing opening 7g, and an annular projection 7c&#39; is formed inside the outer cylindrical portion 7d&#39;, while an annular recess 8d is formed in the outer periphery of a body 8a&#39; of a reinforcing sleeve 8&#39;. 
     In this case, the reinforcing sleeve 8&#39; is press-fitted between the cylindrical portion 7c&#39; and the outer cylindrical portion 7d&#39; of the rubber plug 7&#39; and this is the same as in the previous embodiment, but both portions are fitted and fixed together by means of the annular projection 7f and the annular recess 8d. Further, the thin blind wall 7f&#39; is provided with rigidity by means of the fore end of the rigid body 8a&#39; to firmly push the foregoing stablizer 2c of the terminal 2 through the blind wall 7f&#39;. 
     Although in the above embodiments the reinforcing sleeve is fitted between the inner cylindrical portion and the outer cylindrical portion of the rubber plug body, the rubber plug portion may be molded integrally with the reinforcing sleeve. 
     In each of the above embodiments the packing plug assembly is constituted by the two components of a rubber plug body and a reinforcing sleeve, and these components may be formed separately and combined together before use, thus resulting in that the manufacturing cost is reduced. Moreover, the reinforcing sleeve serves as a supporting wall for the inner cylindrical portion and the outer cylindrical portion of the rubber plug, thus ensuring a uniform seal. 
     FIG. 4 is a sectional view showing another example of a waterproof connector and parts connected thereby, in which the reference numerals 101, 102 and 103 denote a connector housing, a terminal and an insulated electric wire 103, respectively, the electric wire 103 being crimped and fixed by means of an electric wire crimping portion 102a provided at a rear part of the terminal 102. In the portion adjacent to the terminal 102 of the electric wire 103 there is provided a packing plug assembly 105 with the electric wire 103 extending therethrough, the packing plug assembly 105 being fitted in a rear end opening of the housing 101. Further, behind the packing plug assembly 105 is disposed a rear holder 104 having a through hole 104a which permits the electric wire 103 to pass therethrough. The rear holder 104 is held in place by engagement of an engaging pawl 104b thereof with an engaging hole 101b formed near a rear end of the housing 101. 
     As shown in FIGS. 5a to 5c, the packing plug assembly 105, which is formed from a soft elastic material such as rubber, is constituted by the comination of a plug portion 105a formed from a rigid synthetic resin and a reinforcing member 105d extending through the plug portion 105a from the rear to the fore end of the plug portion, the plug portion 105a having a through hole 105c formed centrally therein for passing therethrough of the electric wire 103, with a cylindrical portion 105b projecting from a fore end part of the plug portion 105a, the cylindrical portion 105b being capable of coming into close contact with an outer surface of the insulation covering of the electric wire 103. The reinforcing member 105d comprises a rod-like portion 105e, a pressing portion 105f forming a rear end of the rod-like portion, and a projection 105g which further projects rearward to effect positioning relative to the through hole 104a of the rear holder 104. 
     In assembling the waterproof connector using the packing plug assembly 105, first the eletric wire 103 is inserted through the packing plug assembly 105, allowing the cylindrical portion 105b to come into close contact with an outer surface of the insulation covering of the electric wire 103, then the electric wire 103 and the cylindrical portion 105b are fixed together from the outside by the crimping portion 102a of the terminal 102. Further, a core 103a is fixed by means of a conductor crimping portion 102b. The terminal 102 after assembly is inserted from the rear end opening of the housing 101, then the waterproof plug 105 is fitted and pushed in by the rear holder 104. The positioning projection 105g at the rear end of the plug body is fitted in the through hole 104a of the rear holder 104, such that the reinforcing member 105d is pushed in the forward direction through the pressing portion 105f. This pressing force is immeidately transmitted to the electric wire crimping portion 102a which constitutes a stabilizer for the terminal 102. Consequently, the engaging pawl 104b of the rear holder 104 comes into engagement with the engaging hole 101b of the housing 101 and at the same time the terminal 102 is retained by a latch arm or a lance 101a, whereby a double retention is attained. Moreover, in the waterproof connector thus assembled, the packing plug assembly 105 is sure to be fitted tightly in the housing 101 and a close contact is also attained between the electric wire 103 and the packing plug assembly 105, thus performing a perfect sealing function. 
     FIG. 6 shows an example of a waterproof connector using another shape of a packing plug assembly. A terminal 112 with an electric wire 113 fixed thereto by crimping is inserted into a housing 111 and retained by a latch arm or a lance 111a, and a rear holder 114 is provided at a rear end part of the housing 111 through a hinge 111e. An engaging portion 114b, formed at the other end of the rear holder 114 is capable of engaging an engaging pawl 111b formed at the rear end of the housing 111. 
     A packing plug assembly 115 is composed of a plug body 115a having a through hole with the electric wire 113 passing therethrough, and a reinforcing member 115d having a pressing portion 115f formed at the rear end of the plug portion and a rod-like portion 115e adjacent to the pressing portion 115f and extending through the plug portion up to the fore end of the plug portion. More specifically, the fore end of the rod-like portion 115e is slightly projecting from the fore end of the plug portion 115a. Like the preceding embodiments, the plug portion 115a is formed of a soft elastic material such as rubber whereas the reinforcing member 115d is formed of a rigid synthetic resin. Also in assembling the connector using the waterproof plug 115 there is attained the same function as in the preceding embodiments. 
     Since the packing plug assembly is of such a special structure as set forth above, the terminal can be inserted and retained in the housing positively even when the connector is assembled without considering a backward motion caused by the elasticity of the waterproof plug. Consequently, the connector assembling work efficiency is improved and it is possible to realize a highly reliable connector which scarcely breaks down.