Our Ref: 47251nno P/00/009 Regulation 3.2 AUSTRALIA Patents Act 1990 INNOVATION SPECIFICATION FOR AN INVENTION ENTITLED Invention title: Leakproof Structure for a Connection Part of an Oil Pipe Name of Applicant: Kazuyoshi Uematsu Address for Service A.P.T. Patent and Trade Mark Attorneys PO Box 222 Mitcham, S.A. 5062 The invention is described in the following statement: LEAKPROOF STRUCTURE FOR A CONNECTION PART OF AN OIL PIPE BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a leakproof structure for a connection part of an oil pipe, and more particularly, to a covering unit having a protruding rib and a notch part. The covering unit is applied to the connection part of an oil pipe for preventing the connection part from leakage or corrosion. 2. Description of the Prior Art In order to deliver electricity from a power plant to everywhere and to decrease energy loss during transportation, high tension electricity is adopted to deliver electricity for a long distance. After the electricity is delivered to the surrounding of a user's place, a transformer is used for transforming high tension electricity into lower tension electricity. The transformer has an oil pipe body therein. The oil pipe body has a cylinder therein for insulation and cooling of the transformer. An oil pipe body 1 consists of a number of oil pipes, depending on the demand. As shown Fig. 1, a conventional oil pipe body includes two oil pipes 11. The two oil pipes 11 have a first annual flange 11a and a second annual flange 11b, respectively. A gasket 12 is provided between the first annual flange 11a and the second annual flange 11b. A fastening member 13 is used to lock the annual flange 11a, the gasket 12, and the annual flange 11b together. The assembly of the annual flange 11a, the gasket 12, the annual flange 11b, and the fastening member 13 is referred to as a connection part 2. The oil pipe body 1 is adapted for delivering oil. During transportation, the oil passes through the connection part 2 from one oil pipe 11 at one end to the other oil pipe 11 at the other end. Because the transformer will generate heat, the parts of the transformer and the connection part are at a high temperature for a long period of time, which cause the gasket 12 ageing. Sometimes, the connection part 2 may be exposed outside the transformer. After a period of time to be exposed to the sun and rain, the gasket 12 will be spoiled by weathering. There may be water accumulated in each part, which causes the annular rings 11a, 11b rusty. Accordingly, the annular rings 11a, 11b, the gasket 12 or the fastening member 13 are unable to be sealed, which leads the leakage of the connection part. In order to solve the leakage of the connection part 2, a familiar technique is to use sealant 3. The sealant 3 is coated on an outside of the connection part 2 to fill in seams of the connection part 2 for preventing the oil from leakage. However, the sealant 3 may be peeling off because erosion by moisture. It is required to make up the sealant 3. Accordingly, the inventor of the present invention has devoted himself based on his many years of practical experiences to solve this problem. For the purposes of this specification the word "comprising" means "including but not limited to", and the word "comprises" has a corresponding meaning. Also a reference within this specification to a document is not to be taken as an admission that the disclosure therein constitutes common general knowledge in Australia. SUMMARY OF THE INVENTION The present invention is to provide a covering unit fitted on a connection part of an oil pipe, preventing the oil in the oil pipe from leakage. The covering unit is composed of a first covering body and a second covering body, and corresponds in size to the connection part of the oil pipe. The first covering body has a protruding rib part. The second covering body has a notch part. When the first covering body and the second covering body are assembled together, the protruding rib part engages with the notch part to form a sealed structure. In case the connection part is leaking oil, the covering unit is capable of preventing the oil from leakage and blocking water or moisture from entering the covering unit. Furthermore, the covering unit corresponds in size to the connection part, it is easy to install the covering unit without needing a large space.
BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a cross-sectional view of the prior art which is leaking oil; Fig. 2 is an exploded view of the present invention; Fig. 3 is a partially enlarged view showing engagement of a protruding rib part and a notch part of the present invention; Fig. 4 is a partially cross-sectional view of the present invention fitted on a connection part; Fig. 5 is a side cross-sectional view of the present invention fitted on the connection part; and Fig. 6 is a front cross-sectional view of the present invention fitted on the connection part. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will now be described, by way of example only, with reference to the accompanying drawings. As shown in Fig. 2, a leakproof structure for a connection part of an oil pipe comprises a covering unit 4 which is composed of a first covering body 41 and a second covering body 42. The first covering body 41 has a protruding rib part 411 and a first contact surface 412. The second covering body 42 has a notch part 421 and a second contact surface 422. When the first covering body 41 and the second covering body 42 are assembled together, the protruding rib part 411 will engage with the notch part 421 and the first contact surface 411 will attach to the second contact surface 421 tightly. Fig. 3 is a partially enlarged view showing engagement of the protruding rib part 411 and the notch part 421. Referring to Figs. 4 to 6, the covering unit 4 is fitted on an oil pipe body 1. The oil pipe body 1 consists of two oil pipes 11. The two oil pipes 11 have a first annual flange 11a and a second annual flange 11 b, respectively. A gasket 12 is provided between the first annual flange 11a and the second annual flange 11b. A fastening member 13 is used to lock the annual flange 11a, the gasket 12, and the annual flange 11b together. The assembly of the annual flange 11a, the gasket 12, the annual flange 11b, and the fastening member 13 is referred to as a connection part 2. The inside of the oil pipe 1 is circulated with oil which is adapted for insulation and cooling of a transformer. Furthermore, the covering unit 4 corresponds in size to the oil pipes 11 and the connection part 2. Before the covering unit 4 is fitted on the connection part 2, the first contact surface 412 and the second contact surface 422 are coated with adhesive 5 ahead. The connection part 2 is sandwiched in the covering unit 4 by the first covering body 41 and the second covering body 42. The protruding part 411 and the notch part 421 are bound with the adhesive 5. The covering unit 4 of the present invention can be made of synthetic resin, metal, ceramics or the like. The metal or ceramics is able to bear corrosiveness. The gasket 12 is made of cork, rubber, or the like. The primary feature of the present invention is engagement of the protruding rib part 411 and the notch part 421. In addition, the first contact surface 412 and the second contact surface 422 are adapted to increase contact area for the adhesive 5 to provide a better connecting effect, so that a gas-proof, water-proof, and oil-proof structure is formed to prevent water and moisture from entering the covering unit 4. If the connection part 2 is leaking oil, the covering unit 4 is able to restrain leakage. Furthermore, the covering unit 4 corresponds in size to the connection part 2 for fitting the covering unit 4 with ease. Although particular embodiments of the present invention have been described in detail for purposes of illustration, various modifications and enhancements may be made without departing from the spirit and scope of the present invention. Accordingly, the present invention is not to be limited except as by the appended claims.