Pipe joint for connecting a pipe having a small diameter
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention relates to an improved pipe joint for connecting, for example, a metal pipe and a synthetic resin tube which are used to form a pipeline having a relatively small diameter not exceeding about 15 mm for supplying oil or air to an automobile, machine or apparatus. 
     2. Description of the Prior Art 
     A known pipe joint of the type to which this invention pertains is shown by way of example in FIG. 3. It comprises a main body 21 having an axial bore 22 in which a pipe P 1  is received at one end thereof. The main body 21 is provided at one end thereof with an axially projecting connecting portion 23. The bore 22 has a diameter which increases in a plurality of steps as it becomes remoter from the connecting portion 23. The connecting portion 23 has an axial bore connected with the bore 22. The main body 21 has a wall portion 24 within which the bore 22 has its maximum diameter, and which is provided therethrough with a plurality of holes 26. Each hole 26 defines a radially outwardly projecting flange 25 at the other end of the main body 21 remote from the connecting portion 23. A pair of seal rings are provided between the pipe P 1  and the inner surface of that portion of the main body 21 in which the bore 22 has its minimum diameter. The pipe P 1  has a radially outwardly projecting wall portion P 1  &#39; which is located in the main body 21 when it is connected thereinto. The joint also includes a generally cylindrical supporting member 27 which can be resiliently fitted into the main body 21 through the opening at the other end thereof. The supporting member 27 has a plurality of elastic wall portions 28 each having a radially outwardly projecting shoulder received in one of the holes 26 and held against the flange 25. Each wall portion 28 has a radially and axially inwardly directed pawl engaging the radially outwardly projecting wall portion P 1  &#39; of the pipe P 1  to hold the pipe P 1  in position. 
     The supporting member 27, however, has an open end 29 surrounding the pipe P 1 . The open end 29 and the holes 26 of the main body 21 allow dust, water and other foreign matter to enter the joint. The dust, water, etc. are likely to disable the maintenance of a tight seal between the seal rings and the pipe P 1 . When the pipe which has been disconnected is connected again, it is often difficult to obtain a leakproof connection. 
     SUMMARY OF THE INVENTION 
     Therefore, it is an object of this invention to provide an improved pipe joint which can effectively overcome the drawbacks of the prior art as hereinabove pointed out, and which is suitable for repeated use for a long period of time without allowing any dust, water or other foreign matter to enter it. 
     This object is attained by a pipe joint comprising a generally cylindrical main body having an axial bore in which an end portion of a pipe and a plurality of seal rings surrounding the end portion of the pipe can be fitted, the main body having a tubular extension defining a connector for another tubular member to be connected to the pipe by the joint and having an axial bore which can be connected with that of the pipe, the main body also having cap engaging means projecting from its outer peripheral surface; the pipe having a radially outwardly projecting wall portion provided near its end portion; and a generally cylindrical cap having an end wall portion provided therethrough with a central opening through which the pipe can extend into the main body, and a plurality of resilient arms projecting from the end wall portion and each having a free end provided with means with which the cap engaging means of the main body is engageable, the end wall portion of the cap being engageable with the radially outwardly projecting wall portion of the pipe to hold the pipe in its properly connected position. 
     The cap engaging means may comprise a plurality of pawllike projections and each of the resilient arms may have adjacent to its free end a hole in which one of the pawllike projections can be received. Alternatively, the cap engaging means may comprise a radially extending shoulder and each of the arms may have at its free end a radially inwardly extending pawllike projection which is engageable with the shoulder. 
     When the cap is placed about the main body, they form an effectively closed joint assembly and do not permit any dust, water or other foreign matter to enter it. There is no possibility that dust, water, etc. may adversely affect a tight seal between the seal rings and the pipe. Therefore, the joint can be used repeatedly for a long period of time for connecting or disconnecting a pipeline. The cap can be easily removed from the main body whenever required. 
    
    
     BRIEF DESCRIPTION OF THE DRAWING 
     FIG. 1 is a front elevational view, partly in section, of a pipe joint embodying this invention; 
     FIG. 2 is a view similar to FIG. 1, but showing another embodiment of this invention; and 
     FIG. 3 is a front elevational view, partly in section, of a known joint. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     A pipe joint embodying this invention is shown by way of example in FIG. 1. It comprises a generally cylindrical main body 1 having an axial bore 2 in which an end portion of a pipe P is fitted. A pair of seal rings 6 are provided in the bore 2 and surround the pipe P. The seal rings 6 are axially spaced apart from each other by an annular spacer. The seal rings 6 and the spacer are held in position by a flanged bush fitted into the bore 2. The main body 1 has an axial tubular extension 3 defining a connector for, say, a synthetic resin tube or rubber hose to be connected to the pipe P by the joint. The tubular extension 3 has an axial bore which is smaller in diameter than the bore 2. The main body 1 also has a plurality of pawllike projections 11 on its outer peripheral surface adjacent to the tubular extension 3. 
     A generally cylindrical cap 7 comprises a metal or plastic tube. The cap 7 has an end wall portion 8 provided with a central opening 9 through which the pipe P extends into the main body 1. A pair of diametrically opposite resilient arms 7&#39; and 7&#34; extend from the end wall portion 8. Each arm has adjacent to its free end a hole 12 in which one of the pawllike projections 11 on the main body 1 is received, whereby the cap 7 is removably secured to the main body 1. 
     The pipe P has a radially outwardly projecting wall portion P&#39; adjacent to its end portion which is fitted in the bore 2. The end wall portion 8 of the cap 7 is engaged with the wall portion P&#39; to hold the pipe P in its properly connected position. Another seal ring 15 is provided between the end wall portion 8 of the cap 7 and the pipe P. 
     Another embodiment of this invention is shown in FIG. 2. The joint shown in FIG. 2 is substantially identical in construction to the joint shown in FIG. 1. Therefore, only the features which differentiate the joint of FIG. 2 from that of FIG. 1 will hereinafter be described. The cap engaging means 5 that is employed by the joint of FIG. 2 comprises a radially extending shoulder 13. The cap 7 has three resilient arms which are circumferentially equally spaced apart from one another, though only two arms 7&#39; and 7&#34; are shown in FIG. 2. Each arm has at its free end a radially inwardly extending pawl-like projection 14 which is engaged with the shoulder 13. The projections 14 define the means 10 with which the cap engaging means 5 is engageable, while in the joint of FIG. 1, the pawllike projections 11 on the main body 1 define the cap engaging means 5 and the holes 12 define the means 10. 
     It is, of course, possible to employ a cap having more than three resilient arms.