Background Art Typical double wall drain pipes formed of synthetic resin are coupled by using a socket or flange provided at an end portion thereof.

The double wall drain pipes are connected in a welding connection method or an insertion connection method.

In the welding connection method, an additional synthetic rein sheet including heat wires is wound around a connection portion of the drain pipes to be connected and then electricity is applied to the sheet to perform welding as heat is generated by the heat wires. However, the welding connection method is disadvantageous since an electricity supplying apparatus to generate heat must be carried by car to a work place and an additional welding apparatus is needed.

Also, in the insertion connection method, a plurality of stainless bands or plastic bands is wound around a connection portion and then fastened by a bolt and nut. However, in the insertion connection method since a plurality of bands needs to be wound around the connection portion to obtain firm connection, a coupling work takes long and it is difficult to disassemble once fixed even when the pipes are incorrectly connected.

Meanwhile, drain pipes to be installed underground sometimes need to be installed in an angled direction due to a condition of a underground structure. If an angle portion is a connection portion between the drain pipes, it is very difficult to connect the conventional drain pipes and so a specially designed curved pipe must be used.

Disclosure of the Invention To solve the above problems, it is an objective of the present invention to provide a connector for connecting end portions of double wall drain pipes. A holder portion having a spherical inner space is fixed to one of drain pipes and a spherical insertion portion is fixed to the other drain pipe to be connected. The double wall drain pipes are connected with each other by inserting the insertion portion into the holder portion. Thus, one drain pipe can be installed to be angled with respect to the other drain pipe under a predetermined angle.

To achieve the above objective, there is provided a connector for connecting end portions of double wall drain pipes, which comprises a holder portion fixed to an outer circumference of an end portion of one drain pipe and having a spherical inner space connected to the outside through an entrance, and an insertion portion fixed to an outer circumference of an end portion of the other drain pipe and inserted in the inner space of the holder portion through the entrance so that the insertion portion relatively moves with respect to an inner circumferential surface of the holder portion in the state of surface-contacting the inner circumferential surface of the holder portion.

It is preferred in the present invention that the maximum diameter of the outer circumference of the insertion portion is greater than the inner diameter of the entrance, a plurality of cut portions is formed around the entrance of the holder portion to be opened wide when the insertion portion is inserted into the holder portion, and a packing for

sealing a gap between the insertion portion and the holder portion is provided around the outer circumferential surface of the insertion portion.

It is preferred in the present invention that the a fastening band for fastening the outer circumference surface of the entrance in a state in which the insertion portion is inserted in the holder portion is provided at the outer circumference of the entrance of the holder portion.

Brief Description of the Drawings FIG. 1 is a perspective view of a holder portion of a connection portion of a double wall drain pipe according to a preferred embodiment of the present invention; FIG. 2 is a perspective view of an insertion portion of a connection portion of a double wall drain pipe according to a preferred embodiment of the present invention; FIG. 3 is a sectional view showing a state in which the insertion portion is inserted into the holder portion; FIG. 4 is a longitudinal sectional view of the holder portion; FIG. 5 is a longitudinal sectional view of the insertion portion; and FIG. 6 is a sectional view taken along line VI-VI of FIG. 3.

Best mode for carrying out the Invention Basically, a connection portion of a double wall drain pipe according to the present invention can be applied to a typical pipe and is most effective when it is applied to a pipe having a diameter of 20 mm through 120 mm.

Referring to FIG. 1, in a connection portion according to the present invention, a holder portion 2 is an extension type pipe integrally formed with an end portion of a drain pipe 1. As shown in FIG. 4, the holder portion 2 has a spherical inner space and is open to the outside

through an entrance 6.

The holder portion 2 accommodates an insertion portion 7 of FIG.

2 in the spherical inner space thereof and prevents the insertion portion 7 from escaping. The diameter of the entrance 6 of FIG. 4 is less than the maximum diameter of the inner space. The maximum diameter of the insertion portion 7 is greater than the inner diameter of the entrance 6.

A plurality of cut portions 3 is formed at the identical intervals around an edge portion of the holder portion 2. The cut portions 3 are cuts in the lengthwise direction of the holder portion 2 and are opened wide in a radial direction when the insertion portion 7 is inserted into the inner space of the holder portion 2 through the entrance 6.

A band groove 4 is formed along the outer circumference of the holder portion 2 corresponding to a portion where the cut portions 3 is formed. A fastening band 11 of FIG. 3 is inserted in the band groove 4.

By fastening the fastening band 11, the entrance 6 is not radially opened wide.

FIG. 2 shows the insertion portion of a connection portion of a double wall drain pipe according to a preferred embodiment of the present invention. As shown in the drawing, the insertion portion 7 is integrally formed with an end portion of another drain pipe 1'to be connected to the drain pipe 1 of FIG. 1. The insertion portion 7 has a spherical shape so that it can surface-contact the inner circumferential surface 5 of FIG. 4 of the holder portion 2.

Also, a packing groove 8 is formed in the outer circumferential surface of the insertion portion 7 and a packing 9 is inserted into the packing groove 8. The packing 9 prevents a water leak between the inner circumferential surface 5 of the holder portion 2 and the outer circumferential surface of the insertion portion 7.

FIG. 3 shows a state in which the insertion portion 7 is inserted into the holder portion 2. Referring to the drawing, the drain pipes 1 and 1'are connected as the insertion portion 7 is inserted into the inside of the holder portion 2. Here, the packing 9 prevents a water leak between the inner circumferential surface 5 of the holder portion 2 and the outer circumferential surface of the insertion portion 7.

Also, the diameter of the drain pipe 1'corresponding to the rear portion of the insertion portion 7 is less than the inner diameter of the entrance 6. This means that, when the insertion portion 7 rotates in a direction b inside the holder portion 2, the drain pipe 1'can pivot in a direction a. Consequently, the drain pipe 1'connected to the drain pipe 1 can be angled by an angle permitted by a space between the inner circumferential surface of the entrance 6 and the outer circumferential surface of the drain pipe 1'.

The fastening band 11 is provided in the band groove 4. The fastening band 11 is fastened by a bolt 12 and a nut 13 of FIG. 6 to support the entrance 6 of the holder portion 2 so that the entrance 6 is prevented from being opened wide. Thus, as long as the fastening band 11 fastens the entrance 6, the insertion portion 7 does not escape from the holder portion 2.

FIGS. 4 and 5 are longitudinal sectional views of the holder portion 2 and the insertion portion 7, respectively. As shown in the drawings, the holder portion 2 is integrally formed at an end portion of the drain pipe 1. The inner space of the holder portion 2 into which the insertion portion 7 is inserted has the inner circumferential surface having a spherical curvature. Also, the fastening band 11 is provided in the band groove 4 formed in one end portion of the holder portion 2.

The insertion portion 7 is integrally formed with an end portion of the drain pipe 1'. The packing 9 is provided at the outer circumferential

surface of the insertion portion 7. Although the packing 9 is provided at the insertion portion 7 in the present preferred embodiment, the packing 9 may be fixed to the inner circumferential surface 5 of the holder portion 2.

FIG. 6 is a sectional view taken along line VI-VI of FIG. 3.

Referring to the drawing, the fastening band 11 wound around the outer circumference of the holder portion 2 is fastened by the bolt 12 and the nut 13. As the fastening band 11 is fastened, the cut portions 3 are not open wide so that the insertion portion 7 inserted in the holder portion 2 is prevented from escaping.

While this invention has been particularly shown and described with reference to preferred embodiments thereof, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims.

Industrial Applicability As described above, in the connector for connecting end portions of double wall drain pipes according to the present invention, the holder portion having the spherical inner space is fixed to one of drain pipes to be connected, and the spherical insertion portion is fixed to the other drain pipe to be connected corresponding to the inner surface of the holder portion. Thus, as the spherical insertion portion is inserted into the holder portion, the drain pipe is installed to be angled with respect to the other drain pipe under a predetermined angle.