Pipe joint

Abstract: A pipe joint for joining two pipes (10,11) end to end comprises a hollow cylindrical spigot portion (2) having an annular projection (1) on the outer periphery of a base end thereof, a hollow cylindrical socket portion (4) having an inside diameter approximately equal to the outside diameter of the spigot portion (2) and formed with two opposed apertures (3) in its peripheral wall close to a forward end thereof and with a stepped part (4b) on the inner surface of the peripheral wall for the projection (1) to come into contact with, the stepped part (4b) being closer to a base end of the socket portion (4) than the apertures (3), and a stopper (6) having a pair of circular-arc resilient legs (5) fittable into the respective apertures (3) from outside to project inward and each having a slanting inner surface (5a), the legs (5) being opposed to each other for the inwardly curved surfaces thereof to face each other. The projection (1) is fixedly held between the stepped part (4b) and the legs (5) by inserting the stopper (6) into the apertures (3) with the slanting surfaces (5a) facing toward the insertion side of the spigot portion (2) and inserting the spigot portion (2) into the socket portion (4) until the projection (1) moves past the legs (5). The spigot (2) and socket portions (4) are provided at the joint ends of the two respective pipes (10,11) to be joined.

Description: The invention relates to a pipe joint structure according to the preamble of claims 1 and 4. With reference to FIGS. 21 to 22, a pipe 170 has at an end thereof a housing 171 which is formed with a pair of upper and lower approximately square apertures 172 in each of its opposite sides. Another pipe 173 to be joined to the housing 171 has a tapered portion 174. Provided inside the housing 171 are a bush 175 shaped in conformity with the contour of the pipe 173 and an O ring 176 positioned at the base end of the bush 175. When the pipe 173 is to be inserted into the housing 171, each of opposite legs 177a of a U-shaped stopper 177 is inserted the pair of apertures 172 of the housing. The pipe 173 is then inserted inside the housing 171 until the tapered portion 174 moves past the stopper 177. This brings a stepped part 174a of the tapered portion 174 of the pipe 173 into contact with the inner end face 177b of the stopper 177, whereby the pipe 173 is joined to the housing (see Unexamined Japanese Patent Publication No. 225290/1983). FIG. 24 shows another pipe joint which is prepared by inserting a pipe 181 into a housing 180 and inserting a U-shaped stopper 182 into the housing 180 from outside for opposite legs 183 of the stopper 182 to hold the pipe 181 therebetween (see Examined Japanese Patent Publication No. 44876/1982). With the former joint of the prior art, the legs 177a of the U-shaped stopper 177 need to be manually inserted into the respective pairs of upper and lower apertures of the the housing 171, and a similar problem is encountered in removing the pipe 173 from the housing 171. Furthermore, the bush 175 and the O ring 176 must be set in position inside the housing 171 in advance in addition to the manual insertion of the U-shaped stopper 177. Accordingly, the pipe joint has the problem of necessitating time for joining the pipes and being inefficient to fabricate, for example, when it is used for preparing piping for an air conditioner within the limited space of engine room of the motor vehicle shown in FIG. 20. The construction wherein the U-shaped stopper 177 is inserted in the housing 171 has other problems. As shown in FIG. 23, the stopper 177 is in contact with the housing 171 locally at four portions against an external force acting in a direction to slip off the pipe 173, and concentration of force occurs at these portions. The construction is therefore undesirable from the viewpoint of strength. These portions readily permit ingress of extraneous matter, which could lead to corrosion. With the latter pipe joint, the pipe 181 must be inserted into the housing 180 before the insertion of the stopper 182. Like the fomer, the pipe joint has the problem of a reduced work efficiency when used in the piping for automotive air conditioners. Heat exchangers have a header pipe for distributing the heat exchange medium to the core portion. For connecting an oulet or inlet pipe for the medium to the header pipe, a union joint is used, or a pipe flange is provided at the joint end portion of each of the header pipe and the other pipe. However, these joint means have problems. The union joint requires a length of time for tightening up the union nut, while the latter necessitates labor for fastening the pipe flanges with screws. FIG. 25 illustrates another example of joint, i.e., a joint for connecting liquid transport pipes 196 to a receiver 191. The receiver 191 has at opposite sides of its head 192 a liquid inlet poriton 193 and a liquid outlet portion 194 each formed with a tubular male screw. The transport pipe 196 has an annular projection 195 close to the outer end thereof, and a cap nut 197 fitted therearound and positioned closer to the other end thereof than the projection 195. The pipe 196 is joined to each of the inlet portion 193 and the outlet portion 194 by inserting the pipe 196 into the portion and screwing the cap nut 197 on the tubular male screw. FIG. 26 shows a receiver 201 which has a refrigerant inlet pipe 202 and a refrigerant outlet pipe 203 connected to the top of the receiver by block joints 204, 205, respectively (Unexamined Japanese Patent Publication No. 195256/1986). In this case, the block joints 204, 205 respectively have bolts 205, 207 which are screwed into holes 208 in the top portion of the receiver 201 from above with a tool, whereby the inlet and outlet pipes 202, 203 are attached to the receiver. The former of the receivers described has an increased number of components, while the pipe must be joined to each side of the head 192 by manually turning the cap nut 192 and finally tightening up the cap nut with a tool. The joint therefore has the problem that the pipe requires cumbersome work for attachment and removal. With the latter receiver, the pipe can be attached more easily than when the cap nut is used, but the tool is indispensable for screwing or removing the bolts 206, 207, hence a low work efficiency. FIGS. 27 and 28 show a pipe joint which comprises a first pipe 222 having an annular outer peripheral projection 221 close to a pipe end and an O ring 223 provided around a spigot portion 22a closer to the pipe end than the projection 221, and a second pipe 224 having an enlarged tubular portion 224a at a pipe end. The enlarged tubular portion 224a of the second pipe 224 is formed with two pairs of vertically opposed small holes 224b. When the first pipe 222 is inserted into the tubular portion 224a with a U-shaped pin 225 inserted through the small holes 224b, the annular projection 221 of the first pipe 222 forces the pin 225 open to fit into the portion 224a inwardly of the pin, with the result that the first pipe 222 is joined to the second pipe 224 inside thereof. FIGS. 29 and 30 show another pipe joint. When a first pipe 222 is inserted into an enlarged tubular portion 224a of a second pipe 224 with a ringlike stopper 227 fitted in slits 226 formed in opposite sides of the tubular portion 224a, an annular peripheral projection 221 of the first pipe 222 forces the stopper 227 open to further fit into the tubular portion inwardly of the stopper, whereby the first pipe 222 is joined to the second pipe 224. With the former of the conventional pipe joints described, the U-shaped pin 225 is merely inserted and is therefore likely to slip off due to vibration, for example, when the joint is used for the piping for an automotive air conditioner. With the latter pipe joint, a space S is formed between the ringlike stopper 227 and the annular projection 221 of the first pipe 222, so that the first pipe 222 is liable to move at its base end side relative to the second pipe 224, for example, owing to vibration. Thus, the pipe joint has the problem of being unstable. The EP-A 0 530 778 published after the priority date of the present application discloses a pipe joint comprising a first pipe having a spigot portion formed with an annular projection on the outer periphery thereof, a stopper having a pair of circular-arc resilient legs, and a pair of apertures in a socket portion of a second pipe corresponding in shape to the shape of the legs of the stopper. When the first pipe having the annular projection is inserted into the socket portion of the second pipe, the stopper is mounted on the socket portion with the legs of the stopper entering the apertures of the socket portion and holding the annular projection of the first pipe. The annular legs of the stopper have slanting inner surfaces with the slanting surface directed to the insertion side of the first pipe, so that the first pipe with the annular projection may be pushed through the circular legs from the insertion side. It is an object of the present invention to provide a structure for preventing inverted installment of a stopper within a pipe joint which allows reliable and simple assembly of the pipe joint with good stability. To comply with this object, the structure according to the invention is characterized by the features of claims 1 and 4. FIG. 1 is a perspective view of a stopper embodying the invention; FIG. 2 is a plan view of the stopper; FIG. 3 is a view in vertical section of a socket portion; FIG. 4 is a view in section taken along the line 38-38 in FIG. 3; FIG. 5 is a front view of a stopper embodying the invention; FIG. 6 is a view in section taken along the line 40-40 in FIG. 5; FIG. 7 is a bottom view of the stopper; FIG. 8 is a view in vertical section of a socket portion in which the stopper is to be installed; FIG. 9 is a view in section taken along the line 43-43 in FIG. 8; FIG. 10 is a view in horizontal section showing the stopper as installed properly in the socket portion; FIG. 11 is a view in horizontal section showing the stopper as installed in the socket portion reversely; FIG. 12 is a front view of another stopper embodying the invention; FIG. 13 is a view in section taken along the line 47-47 in FIG. 12; FIG. 14 is a rear view of the stopper; FIG. 15 is a view in vertical section of a socket portion in which the stopper is to be installed; FIG. 16 is a view in section taken along the line 50-50 in FIG. 15; FIG. 17 is a view in horizontal section showing the stopper as installed properly in the socket portion; FIG. 18 is a view in horizontal section showing the stopper as installed in the socket portion reversely; FIG. 19 is a perspective view of a modified pipe joint structure to show a socket portion, stopper and pipe as separated; FIG. 20 is a perspective view showing a piping system in the engine room of a motor vehicle; FIG. 21 is an exploded perspective view of a conventional pipe joint; FIG. 22 is a view in longitudinal section of the conventional pipe joint shown in FIG. 21; FIG. 23 is a reference view showing a stopper in contact with a housing in the joint shown in FIG. 21; FIG. 24 is a fragmentary view in section showing another conventional example; FIG. 25 is an exploded front view showing a conventional exmaple of pipe joint for a receiver; FIG. 26 is a fragmentary view in section showing another conventional example for a receiver; FIG. 27 is a view in vertical section showing a conventional example; FIG. 28 is an exploded perspective view of the conventional example shown in FIG. 27; FIG. 29 is a sectional view of another conventional example; and FIG. 30 is a perspective view of a stopper included in the example of FIG. 29. Pipe joint structures embodying the present invention will be described below. FIGS. 1 to 4 show an embodiment of the invention. The embodiment, i.e., a stopper 122, is shaped asymmetrically with respect to the direction in which circular-arc resilient legs 124 thereof are opposed to each other. At opposite sides of the center of head 126 of the stopper 122, right and left halves thereof, each including a circular-arc resilient leg 124, have different thicknesses tl, t2, respectively. In corresponding relation with this, a pair of apertures 127 formed in a socket portion 121 are so shaped that one of the apertures, 127a, has a large width in conformity with the thick leg 124a, and that the other aperture 127b has a small width in conformity with the thin leg 124b. Only when the stopper 122 is installed in the socket portion 121 with slanting surfaces 128a thereof facing toward the pipe insertion side, the thick leg 124a is fittable in the aperture 127a of large width, and the thin leg 124b in the aperture 127b of small width. Thus the combination of aperture and leg is specified. Accordingly, if the stopper 122 is to be installed as inverted into the socket portion 121, the thick leg 124a will be in combination with the aperture 127b of small width. The stopper 122 is then not fittable properly into the apertures 127. This indicates the wrong orientation of the stopper 122. FIGS. 1 to 11 show another embodiment of the invention, i.e., a stopper 122, which is asymmetric with respect to the direction of its thickness. The head 126 of the stopper 122 is formed on the inner surface thereof with right and left two engaging projections 129 over the lower half of the stopper with respect to the direction of its thickness (direction of height of the head). On the other hand, a socket portion 121 has a bridge 121a, which is formed with right and left two engaging holes 130 over the lower half thereof with respect to the direction of width (direction of the length of the socket portion, the holes 130 corresponding to the projections 129. Accordingly, when a tapered portion 128a of the stopper 122 is directed toward the pipe insertion side, the engaging projections 129 are snugly fittable into the holes 130 as shown in FIG. 18, permitting the stopper 122 to be properly installed in the socket portion 121. However, when the stopper 122 is inverted, the projections 129 strike against the wall face of the bridge 121a above the holes 130 as shown in FIG. 11. This makes it impossible to further push the stopper 122 into the socket portion 121 radially inwardly thereof and to properly fit the legs 124 into the apertures 127. This indicates the inverted or reversed position of the stopper 122. With this embodiment, the engaging holes 130 are formed in each of two bridges 121a, such that the stopper 122 is installable from the side of either one of the bridges. FIGS. 12 to 18 show another embodiment, in which an engaging projection 131 having a height equal to the thickness of the stopper is provided on the inner surface of head 126 of the stopper 122 at the right or left side, i.e., at one side with respect to the direction of opposition of the legs 124. On the other hand, the bridge 121a of the socket portion 121 is formed with an engaging hole 132 coinciding with the projection 131 in posiiton when the stopper 122 is fitted in place with the slanting surfaces 128a facing toward the pipe insertion side. Accordingly, when the stopper 122 is positioned with the slanting surfaces 128a thereof facing toward the pipe insertion side, the projection 131 is snugly fittable into the hole 132 as seen in FIG. 17, enabling the stopper 122 to be properly installed into the socket portion 121. In contrast, when the stopper 122 is positioned as inverted or reversed, the projection 131 strikes against the wall face of the bridge 121a of the socket portion 121 as shown in FIG. 18, preventing the insertion of the stopper 122. This indicates the wrong position. As in the above embodiment, the hole 132 is formed in each of the bridges 121a so as to render the stopper 122 installable from either side. With the embodiments shown in FIGS. 1 to 18, a separate aluminum pipe 125 is inserted into the socket portion 121 and diametrically enlarged in advance for an O ring 133 to be pressed into contact with the inner periphery of end portion of the pipe 125. However, as shown in FIG. 19, the O ring 133 on the pipe 123 may be pressed directly against the inner surface of end part of the socket portion 121, with an annular projection 134 of the pipe 123 held between the stopper 122 and the steppped part 121b of the socket portion 121. With some of the embodiments described, the stopper 122 is asymmetric with respect to one of the direction of thickness of the stopper 122 and the direction in which the legs 124 are opposed to each other, wheres the stopper may be made asymmetric with respect to each of these directions. The present invention can be embodied variously without departing from the spirit and basic features of the invention. Accordingly, the embodiments herein disclosed are given for illustrative purposes only and should not be construed as being limitative. The scope of the invention is defined by the appended claims rather than by the specification. All the alterations and modifications within the definition and scope of the claims are included in the scope of the invention.

Claims: Pipe joint structure comprising a first pipe (123) having a spigot portion formed with an annular projection (134) on an outer periphery thereof, a stopper (122) having a pair of circular-arc resilient legs having holding surfaces for fixedly holding the annular projection (134), a socket pipe (125) having a socket portion (121) having two opposed apertures (127,127a,127b) into which the legs fit to project inward, the legs (124,124a,124b) matching the apertures (127,127a,127b) so that the legs fit into the apertures and the installation of the stopper is performed when the stopper is to be installed in the socket portion (121), the legs (124,124a.124b) of the stopper (122) being formed with slanting surfaces (128a) for introducing the annular projection (134) of the spigot portion of the first pipe (123), the slanting surfaces (128a) of the legs (124,124a,124b) facing the pipe insertion side, characterized in that the stopper (122) is shaped asymmetrically with respect to an imaginary plane extending through the axis of the stopper and a center between the ends of the legs, the apertures (127,127a,i27b) into which the legs (124,124a,124b) fit as the stopper (122) matches the socket portion (121) being shaped asymmetrically with respect to an imaginary plane extending through the axis of the socket pipe (125) and a center between the ends of the apertures, the legs (124,124a,124b) not matching with the apertures (127,127a,127b) so that the engagement is prevented when the stopper (122) is to be installed in the socket portion (121) with the slanting surfaces (128a) of the legs facing opposite to the pipe insertion side. Structure as claimed in claim 1, characterized in that the legs (124,124a, 124b) being formed asymmetrically with respect to the imaginary plane extending through the axis of the stopper and the center between the ends of the legs have a different thickness. Structure as claimed in claim 1 or 2, characterized in that an engaging projection (131) is provided on the stopper (122) asymmetrically with respect to the imaginary plane extending through the axis of the stopper (122) and the center between the ends of the legs (124,124a,124b), an engaging hole (132) being provided on the socket portion (121) for receiving the engaging projection and corresponding to the engaging projection so as to be disposed asymmetrically with respect to an imaginary plane extending through the axis of the socket pipe (125) and the center between the ends of the apertures (127,127a,127b). Pipe joint structure comprising a first pipe (123) having a spigot portion formed with an annular projection (134) on an outer periphery thereof, a stopper (122) having a pair of circular-arc resilient legs having holding surfaces for fixedly holding the annular projection (134), a socket pipe (125) having a socket portion (121) having two opposed apertures (127,127a,127b) into which the legs fit to project inward, the legs (124,124a,124b) matching the apertures (127,127a,127b) so that the legs fit into the apertures and the installation of the stopper is performed when the stopper is to be installed in the socket portion (121), the legs (124,124a,124b) of the stopper (122) being formed with slanting surfaces (128a) for introducing the annular projection (134) of the spigot portion of the first pipe (123), the slanting surfaces (128a) of the legs (124,124a,124b) facing the pipe insertion side characterized in that an engaging projection (129,131) is provided on the stopper (122) asymmetrically with respect to the axial direction of the stopper or with respect to the direction of the thickness of the stopper, an engaging hole (130,132) being provided on the socket portion (121) for receiving the engaging projection (129,131) and corresponding to the engaging projection so as to be disposed asymmetrically with respect to the axial direction of the socket pipe (125) or with respect to the width of the apertures, an engaging projection (129,131) of the stopper (122) matching the engaging hole (130,132) on the socket portion (121) and the stopper legs (124) fitting into the apertures (127) of the socket portion so that the installment of the stopper is performed when the stopper (122) is to be installed in the socket portion (121), the engaging projection (129,131) not matching the engaging hole (130,132) so that the engagement is prevented when the stopper is to be installed in the socket portion (121) with the slanting surfaces (128a) of the leg facing opposite to the pipe insertion side.

Inventors: INOUE KOICHI, ITO SHINJI, OKUDA NOBUYUKI, TOKUTAKE TOSHINORI, INOUE, KOICHI, ITO, SHINJI, OKUDA, NOBUYUKI, TOKUTAKE, TOSHINORI
Applicants: HONDA MOTOR CO LTD, SHOWA ALUMINUM CORP, HONDA GIKEN KOGYO KABUSHIKI KAISHA, SHOWA ALUMINUM CORPORATION
Application year: 1993
Main classification: F16L37
IPC codes: F16L37