As cables laying around the world are seeking to be situated underground as much as possible, and this chiefly relies on the network of pipelines. The cable splice boxes that connect cables underground are situated in the manholes and hand-holes of underground cable pipelines, and many manholes and hand-holes accumulate huge amounts of water yearly, thus the cable splice boxes situated within these holes are immersed in water yearlong. Please refer to FIG. 1, as a cross-section of the underground network of cable splice boxes. In FIG. 1, man hole covers 11, 12 have man holes 111, 121 installed beneath them, man holes 111, 121 have cable splice boxes 13, 14 disposed in them, cable splice boxes 13 and 14 are connected by cable 14, cable splice boxes 13, 14 are further connected with other cable splice boxes with cables 15, 17 (not shown). In practice, cables 15, 16, 17 are curled up in man holes 111, 121. Regardless of whether a cable splice box is made with an electric cable or a optical fiber cable, if there is insufficient waterproofing, water leaking into cable splice boxes due to water built up from manholes or hand-holes will affect the transmission quality of the cable in addition to accelerating the deterioration of the cable, resulting in transmission malfunctions and reducing the lifespan of cables.
Existing technology of optical fiber cable networking and splicing techniques, in telecommunications, cable television, monitoring systems and other types of cable transmission industries, has long relied on heat shrink cable splice boxes. Although the manufacturing cost for a heat shrink cable splice box is comparatively lower, the cable has a longer applicable outer diameter, along with faster and simpler construction, thus being widely used in the industry, the heat shrink cable splice box is heavily criticized for its common water leakage problems. During the torching of the heat shrink tube of the first cable entry opening to waterproof the opening in a heat shrink cable splice box, and when torching heat shrink tubes of other cable entry openings on the optical fiber cable entry place, neighboring heat shrink pipes that are already torched are subjected to further heating, therefore they soften, loosen and causes water leakage in cable splice box. Please refer to FIG. 2(A), for a vertical view of the practical technology of a heat shrink cable box. In FIG. 2(A), heat shrink cable splice box 20 (abbreviated as splice box) has cables entering and exiting entry opening 21, there are hollow cylindrical columns 22, 23A, 23B, 23C, 23D, 23E, the hollow cylindrical columns 22, 23A-23E are sealed before cables are introduced, when cables are ready to penetrate, they can be opened through sawing or hammering, etc. Main cables 24A, 24B go through hollow cylindrical column 22 into splice box 20, the main cables 24A, 24B are separated by branch clip 29 using heat shrink pipes. Branch cables 25A, 25B, 25C, 25D, 25E, respectively, go through hollow cylindrical columns 23A˜23E to enter splice box 20. Please refer to FIGS. 2(B) and (C) which are schematic diagrams illustrating the technology of the structure of waterproofing heat shrink cable splice boxes. In FIGS. 2(B) and (C), heat shrink cable splice box 30 (abbreviated as splice box) is constructed with at least protective cover 22, cable entering and exiting entry opening 31 and hollow cylindrical columns 32, 33A, 33B. The user first takes main cables 24A and 24B to penetrate hollow cylindrical column 32 that is wrapped by heat shrink tube 36, through opening 38A into the splice box; main cables 24A and 24B are divided by a manifold clip used by heat shrink pipes, then heat shrink tube 36 and manifold clip are torched with fire, finishing the waterproofing of the cable entry opening whereby main cables 24A and 24B goes through. The branch cable 35B penetrates hollow cylindrical column 33B that is wrapped by heat shrink tube 37, through opening 38B into the splice box, then heat shrink pipe 33B is torched, in order to complete the waterproofing of the entry opening where the branch cable 35B enters and exits. The main cables 24A, 24B and branch cable 35B have their spliced point stored in the cable splicing distribution plate 39. However, when torching the heat shrink pipe 37, the already torched heat shrink pipe 36 being nearby heat shrink tube 37 is subjected to further heating, thus softens, loosens and causes water leakage in splice box 30. Similarly, during the torching of other heat shrink tubes of cable entry opening 33A, neighboring heat shrink pipes that are already torched are subjected to further heating, therefore they soften, loosen and cause water leakage in splice box 30.
Using optical fiber splice box as example, the cable entry place of a telecommunication optical fiber splice box has a diameter usually 15 cm to 20 cm or even smaller, while the cable entry place usually is required to a provide access for 2 main optical fiber cables and 4 branch optical fiber cables or more, so every optical fiber opening is very close to the other, on the cable entry place. Therefore, in the current technology that uses heat shrink tubes to waterproof optical fiber cable entry openings of the heat shrink cable splice box, one has to complete torching the heat shrink tube of the first optical fiber cable entry opening, and then torch heat shrink tubes of other optical fiber cable entry openings, on top of the optical fiber entry place. This often results in heat shrink tubes that are already completed to be subjected to further torching, causing them to soften, loosen and resulting in water leakage problems in splice boxes. This shortcoming and vital flaw has always been the most pressing and difficult problem that needs to be solved, in the technological field.
Taiwan's telecommunications industry, for example, due to the popularity and trend of fiber-optic broadband service, Chunghwa Telecom in recent years laid out fiber-optic cables on a massive scale and heavily utilizes fiber-optic cable splice boxes, and also announced that beginning in 2009, for five consecutive years, will invest 30 billion a year, a total of NT $150 billion of funds for fiber-optic network infrastructure. In recent years, the company placed heat shrink optical fiber cable splice boxes in manholes and hand-holes, with far more than half of them suffering from serious leakage. As the water leakage problem in heat shrink optical fiber cable splice box is not resolved, the company has had to purchase mechanical optical fiber cable splice boxes that are 3 times more expensive than heat shrink optical fiber cable splice boxes, and a variety of mechanical means of sealing to establish a waterproof structure for optical fiber cable entry openings. The suitable optical fiber cable outer diameters for these waterproof optical fiber cable entry openings is restrictively small, accessories needed are diverse and complicated, with cumbersome construction procedures, needing a variety of tools, resulting in inconvenience and higher costs of construction, among other issues. Mechanical optical fiber cable splice boxes, in addition to being less straightforward and efficient than heat shrink optical fiber cable splice boxes, the procurement costs have increased threefold. Thus, by eliminating the shortcomings and improving the waterproofing capacity of heat shrink optical fiber cable splice devices, not only can communication quality issues due to water leakage in heat shrink optical fiber splice boxes be avoided, it also can significantly reduce the cost of investing enterprises.
Although the applicant can use elastic rubber shrinkable pipe to replace heat shrink tube, in order to solve the problems caused by torching to waterproof the optical fiber cable entry opening in heat shrink optical fiber cable splice boxes. When torching other optical fiber cable openings of heat shrink tubes, it often results in heat shrink tubes that are already completed to be subjected to further torching, causing them to soften, loosen and resulting in water leakage problems in splice boxes. However, the elastic rubber shrinkable pipe is suitable for only one optical fiber cable penetrating one entry opening, to waterproof main optical fiber cables and branch optical fiber cables which are cut and introduced into the optical fiber splice box during straight splicing or branch splicing where. It is unable, in the situation of mid-span splicing there are two optical fiber cables entering and exiting a optical fiber cable entry opening, to simultaneously and effectively waterproof the depression between two main optical fiber cables. Please refer to FIG. 3(A), because the elastic rubber tube system is a highly elastic and ductile hollow synthetic rubber tube 41, and the rubber tube's hollow walls are first installed with flexible and hard rubber strip 42, with hollow screw-like tube configuration coiled in the rubber tube and stretches the rubber tube 41's hollow diameter. When rubber strip 42 situated in rubber tube 41 is extracted, the rubber tube 41, which is stretched by rubber strip 42, results in elastic contraction of its hollow diameter, almost returning the smaller diameter before being stretched by rubber strip 42. Please refer to FIG. 3(B), wherein the cables 54, 55 in the cable entry opening's hollow cylindrical columns 52, 53 of the cable entry place 51, using elastic rubber shrinkable pipe 56 which shrinks and tight contracts, enveloping the exteriors of the hollow cylindrical columns 52, 53 and a portion of cables 54, 55 that have not penetrated the hollow cylindrical tube, forming a waterproof structure.
The majority of early optical fiber cables only carry out straight splicing and branch splicing, the main optical fiber cables are cut first before introduced into the optical fiber cable splice box to carry out splicing. Every main optical fiber cable entry opening, in the optical fiber cable entry place of the optical fiber splice box, only encompasses a main optical fiber cable. There are no problems in using elastic rubber shrinkable pipe instead of heat shrink tube to carry out waterproofing of main optical fiber cables and branch optical fiber cables that are introduced into the optical fiber cable splice box after being cut; due to the advent of FTTH (fiber to the home), many main optical fiber cables presently used in telecommunication must be introduced into optical fiber cable splice boxes under the condition that they are not cut. Whereas the unused optical fiber cables are branch spliced for the usage of other customers, this mode of operation is called mid-span connecting branch splicing. In using elastic rubber shrinkable pipe to waterproof the optical fiber cable splice box, due to the inability to effectively carry out waterproofing of the main optical fiber cables which go through mid-span connecting branch splicing, when encountering mid-span connecting splicing, there is only the choice of mechanical cable optical fiber splice box or heat shrink optical fiber cable splice box, whereby the disadvantages of using mechanical cable optical fiber splice box have already been mentioned before. Therefore the other choice, please refer to FIG. 2(B), is to switch to using the heat shrink optical fiber cable splice box 30, which allows the penetration of main cables 24A, 24B into main optical fiber cable opening 32 and is waterproofed by heat shrink tube 36.
In the realm of practical technology, the installation of the main optical fiber cable entry opening of a optical fiber cable splice box, can only provide only either heat shrink tube mechanism or elastic rubber shrinkable tube mechanism as a way of waterproofing the main cable. In the process of establishing the cable network of FFTH, because of the innumerable variables encountered in whether to execute mid-span connecting branch splicing operations. This difficulty in estimation results in persisting problems among telecommunication enterprises; there's question in how much to purchase and how many in the inventory can proceed with mid-span connecting branch splice box, and how much to purchase and how many in the inventory to not proceed with mid-span connecting branch splice box. In the event if only heat shrink optical fiber cable splice boxes were chosen, it solves the problems of purchasing, rise in cost due to diversified inventory, work distribution and complexities regarding the utilization of materials by workers. However in regards to the problem of waterproofing the main optical fiber cable, it exponentially raises safety issues that can be prevented by not using a fire source, and it defeats the safety goal of telecommunication enterprises to minimize and lower the frequency of fire usage during construction.
Therefore, the applicant in view of the shortcomings and defects arising from the lack of technology, after detailed research and careful deliberation, along with a spirit of perseverance, finally arrived at the present invention “A cable splice box that utilizes different ways to carry out waterproofing of the main cable”, the following is a brief explanation of the case.
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