The application is directed towards a spool that can be used for storing a fiber in underwater applications.
Fibers such as optical fibers have been used in underwater applications to transmit and receive information. For example, an underwater device can have a propulsion system and a direction control mechanism. The underwater device can be deployed by a support ship and an optical fiber can be coupled between the underwater device and the support ship. The support ship can transmit control information to the underwater device that is used to operate the direction control mechanism.
An optical fiber is stored on a spool having a cylindrical portion and a compressible member over the cylindrical portion. The compressible member is not affected by ambient water pressure. Thus, when the spool is submerged, the water will saturate the compressible member and the water pressure will not cause the compressible member to collapse. When the optical fiber is wound on the spool, the tension will cause the compressible member to be slightly compressed. This cushioning prevents excess tension from being applied to the optical fiber. In an embodiment, the compressible member is an open cell foam. When the spool is submerged the water fills the cells and the open cell foam will not collapse under pressure. In other embodiments, the compressible member can include a mechanical spring. When submerged, the water will fill the spaces between the spring and the spool. The springs will not be compressed by the water pressure. In order to improve the movement of water into the compressible member, the spool may have holes or openings.
If the compressible member of the spool was made of a closed cell foam, the pressure would eventually cause the compressible member to collapse. This would cause the optical fiber to become loose on the spool and potentially tangled. In order to properly utilize the optical fiber, it must not be tangled as it is removed from the spool.
The spool of optical fiber may be placed on a remotely operated vehicle (ROV). As the ROV moves through the water, a feed system will pull the optical fiber from the spool at a rate that is approximately equal to or faster than the movement of the ROV. By emitting the optical fiber from the ROV, the optical fiber is essentially stationary in the water and there is no tension applied to the fiber. If the optical fiber becomes tangled, it will not go through the feed system and the movement of the ROV can create tension and possibly breakage of the optical fiber. In another embodiment, a second spool of optical fiber can be mounted in a surface structure on or adjacent to a surface support ship. A second feed system can be coupled to the second optical fiber spool. If the ship moves, the optical fiber can be released from the second spool to prevent tension in the fiber.
The present invention is directed towards a spool for storing a fiber for underwater applications. With reference to
The spool 107 of the optical fiber 109 is stored on the ROV 101. As the ROV 101 travels, the spool 107 can rotate which causes the optical fiber 109 to stream out of the ROV 101. The end of the optical fiber 109 can be coupled to a rotating coupling 111 so the spool 107 can rotate freely. In an embodiment, a sensor can detect the relative velocity of the ROV 101 through the water and then control the rotational rate of the spool 107 to emit the optical fiber 109 at a rate that is substantially equal to or greater than the relative velocity of the ROV 101 through the water.
In an embodiment, a feeder mechanism 301 is used to remove the optical fiber 109 from the spool 107. The spool 107 can be mounted on an axle which allows the spool 107 to rotate. The feed mechanism 301 can be coupled to a velocity sensor 303 that detects the speed of the ROV 101 through the water. The feed mechanism 301 can remove the optical fiber 109 from the spool 107 at a rate that is equal to or greater than the velocity of the ROV 101. In order for the optical fiber 109 to be removed smoothly, the compressible cylindrical structure must maintain a constant tension on the optical fiber 109 regardless of the ambient pressure.
In order for the optical fiber 109 to be properly drawn from the spool 107, the optical fiber 109 must be wrapped around the spool 107 with a small amount of tension, for example, less than 1 pound of tension. If the optical fiber 109 is loose on the spool 107, it may become tangled as it is removed from the spool 107. This can result in damage or breakage of the optical fiber 109. The optical fiber 109 can have a tensile strength of about 10 pounds, however, it is very brittle and can be easily broken if bent. Thus, if the tangles to the optical fiber results in excessive tension or bending, the optical fiber 109 can very easily break resulting in a complete loss of control and communication between the ROV 101 and the support ship 103.
In order to maintain a proper tension of the optical fiber 109 on the spool 107, the optical fiber 109 can be wrapped around a compressible cylindrical structure 121. In an embodiment,
With reference to
The optical fiber 501 can have one or more coatings. An inner primary coating 505 can act as a shock absorber to minimize attenuation caused by microbending. Fiber optic coatings can be applied in various different methods. In a “wet-on-dry” process, the optical fiber passes through a primary coating application, which is then UV cured. The fiber optic coating is applied in a concentric manner to prevent damage to the fiber during the drawing application and to maximize fiber strength and microbend resistance.
Because the spool is being used in a pressurized underwater environment, the compressible cylindrical structure cannot be deformed by increased water pressure. The ambient pressure is directly proportional to the depth of the ROV in the water. For example, in fresh water the pressure increase is about 0.43 pounds per square inch gage (PSIG) per foot of depth and in salt water, the pressure increase is about 0.44 PSI per foot of depth. Thus, a 100 foot dive will result in an ambient pressure of 43-44 PSIG and a 5,000 foot dive will result in an ambient pressure of 2,150-2,200 PSIG. The compressible cylindrical structure 121 must be able to retain its shape and remain compressible in very high ambient pressures. With reference to
With reference to
With reference to
In other embodiments, other materials or structures can be used that do not compress with ambient pressure. With reference to
Because the optical fiber can be very closely spaced when wound on the spool, water may not flow through the optical fiber to compressible cylindrical structure of the spool easily. Similarly, if the spool is not made of a water permeable material, the water may not be able to easily reach the cylindrical structure when the spool is submerged. The water can be blocked from the inner diameter by the inner surface of the spool and the flanges can block water from the sides.
With reference to
With reference to
It will be understood that the inventive system has been described with reference to particular embodiments, however additions, deletions and changes could be made to these embodiments without departing from the scope of the inventive system. Although the systems that have been described include various components, it is well understood that these components and the described configuration can be modified and rearranged in various other configurations.