PRESSURE COMPENSATED COMPOSITE POLYMER OUTBOARD SENSOR ASSEMBLY
The use of a pressure compensation system and composite polymer materials results in a new type of outboard sensor assembly, of the type used to monitor the status and location of towed array systems from boats. The inventive system is lower in cost, easier to manufacture in quantity, lighter weight, less likely to leak, and with a lower failure rate than conventional systems.
This invention relates to the general field of towed array systems on submarines and more specifically to outboard sensor assemblies that monitor the status and location of such towed array systems.
BACKGROUNDSubmarine sonar systems include a towed sonar array that is deployed behind a moving submarine. The sonar sensor part of the towed array may be more than 1000 yards behind the submarine. This enables the total sonar system to detect other vessels and through triangulation establish an accurate distance to the detected vessel.
When the towed array is retrieved into the submarine it passes through an outboard sensor assembly (OSA), usually in the vertical stabilizer of the submarine. The outboard sensor assembly contains electronic instrumentation necessary to monitor the passage of the towed array during deployment, towing, and retrieval and to relay that information to submarine personnel.
Due to the corrosive environment of the ocean the housing of outboard sensor assemblies have been machined from Monel, an alloy containing nickel, copper, iron and other alloys, with nickel being the primary component, followed by copper and then iron. The resulting outboard sensor assembly is relatively difficult to machine, expensive, and heavy. The weight is important because divers often do repair of an outboard sensor assembly underwater while the submarine is in port. The Monel housing surrounds an interior tube composed of either Monel or polymer through which the towed array passes. A common failure mode of this design is electrical shorting caused by seawater leaking into the interior of the Monel housing where electronic components are contained. These failures and the combination of the weight and costs of the system results in high operation and support costs of replacing failed units during submarine maintenance periods.
There is an unmet need then for a new outboard sensor assembly, one that is lower cost, easier to manufacture in quantity, lighter weight, less likely to leak, and with a lower failure rate. The instant invention to be described meets those needs.
SUMMARYThe needs discussed are addressed by the instant invention.
One aspect of the instant invention is an apparatus for monitoring deployment of a towed array from a boat including at least a housing of a composite polymer; an interior passageway for movement of the towed array; and a pressure compensation bladder having an exterior surface and an interior surface wherein the pressure compensation bladder is positioned between the housing and the interior passageway.
Another aspect of the instant invention also includes the use of a fluid medium filling the housing and the interior passageway and surrounding the exterior surface of the pressure compensation bladder.
Another aspect of the instant invention also includes at least one acoustic sensor mounted within the apparatus to detect the passage of the towed array.
Another aspect of the instant invention also includes at least one electromagnetic sensor mounted within the apparatus to detect the passage of the towed array.
To insure that a clear and complete explanation is given to enable a person of ordinary skill in the art to practice the invention a specific example will be given involving applying the invention to an outboard sensor assembly for a towed array system on a military submarine. It should be understood though that the inventive concept could apply to other pressure compensation systems and the specific example is not intended to limit the inventive concept to the example application.
BRIEF DESCRIPTION OF THE DRAWINGS
An improved OSA design that is the heart of the instant invention includes the embodiments of replacing the expensive Monel with a lower cost and easier to manufacture composite polymer housing, replacing high cost acoustic transmitters and receivers with lower cost piezoelectric ceramic acoustic sensors and using a passive pressure compensation system consisting of an oil-filled housing and a bladder whose interior is vented to seawater pressure. By maintaining equal pressure at all seawater depths the driving force of seawater on seals is maintained at zero, thus eliminating the seawater leakage failure mechanism.
The interior passageway of the electromagnetic sensor module must be a polymer to allow EM sensors to detect the passage of the towed array body through the interior passageway. The interior passageways of the forward and aft sensor modules could technically be metal but for the reasons discussed earlier regarding the need for lighter weight, are polymer in the instant invention. A common failure mode of the prior art designs of outboard sensor assemblies is a failure of the seals between the Monel housing and the interior polymer passageway tube. These failures occur as large differentials develop between pressures inherent from the pressure of deep ocean water and the lower pressure of the interior volume between the interior tube and the housing. This interior volume contains the sensor elements of the system. To address this issue a bladder and oil pressure compensation system is part of the instant invention.
Acoustic sensors such as the one numbered 633 are used to detect the passage of the various parts of the towed array through the central passageway. A number of different types of acoustic sensors have been used for this type of application and the use of any of them is anticipated for this invention. Shown is a preferred embodiment of piezoelectric ceramic acoustic sensors 632,633,634 positioned around interior tube 620. A fourth sensor (not shown) would be located behind sensor 634 on the opposite side of the central passageway 620. Piezoelectric ceramic acoustic sensors are low cost and reliable and can perform the dual function of sending or receiving acoustic signals. Thus one of the two sensors 632 can send an acoustic signal that passes across central passageway 620 and sensor 633 on the opposite side can act as the actual sensor to measure the strength of the signal. The signal varies significantly as various parts of the towed array pass through the passageway.
The electromagnetic (EM) sensor module, which has a somewhat different design, also has an oil and bladder system shown generally by the numeral 650 in cutaway schematic
The bladder of the bladder and oil pressure systems of
The instant invention described herein results in a significantly improved outboard sensor assembly for towed array systems that is lower cost, easier to manufacture in quantity, lighter weight, and with a lower failure rate due to the pressure compensation system. Although the examples have focused on a submarine application the invention could be employed in any boat that deploys a towed array behind it at ocean depths.
Claims
1. An apparatus for monitoring deployment of a towed array from a boat comprising:
- a. a housing of a composite polymer;
- b. an interior passageway for movement of said towed array; and
- c. a pressure compensation bladder having an exterior surface and an interior surface wherein said pressure compensation bladder is positioned between said housing and said interior passageway.
2. The apparatus of claim 1 further comprising a fluid medium filling the space between said housing and said interior passageway and surrounding exterior surface of said pressure compensation bladder.
3. The apparatus of claim 1 wherein said pressure compensation bladder is mounted so that said interior surface is in communication with the environment exterior to said apparatus.
4. The apparatus of claim 2 wherein said fluid medium is an oil.
5. The apparatus of claim 4 wherein said oil is a castor oil.
6. The apparatus of claim 1 wherein said interior passageway is prepared from a polymer.
7. The apparatus of claim 6 wherein said polymer is a polycarbonate.
8. The apparatus of claim 1 further comprising an acoustic sensor mounted within apparatus to detect the passage of the towed array.
9. The apparatus of claim 8 wherein said acoustic sensor is a piezoelectric ceramic acoustic sensor.
10. The apparatus of claim 1 further comprising an electromagnetic sensor mounted within apparatus to detect the passage of the towed array.
11. The apparatus of claim 1 further comprising a proximity sensor mounted within apparatus to detect the passage of the towed array.
12. The apparatus of claim 1 wherein the apparatus is divided into multiple segments.
13. The apparatus of claim 12 wherein the apparatus is divided into three sub-segments.
14. The apparatus of claim 13 wherein said sub-segments comprise a forward acoustic sensor module assembly, an aft acoustic sensor module assembly, and an electromagnetic sensor module assembly.
15. The apparatus of claim 1 wherein said housing of a composite polymer is made of a reinforced polymer.
16. The apparatus of claim 15 wherein said reinforced polymer is reinforced by the addition of glass.
17. The apparatus of claim 15 wherein reinforced polymer is reinforced by the addition of long glass fibers.
18. The apparatus of claim 15 wherein the polymer of said reinforced polymer is selected from the group consisting of polyphenylene sulfide, polypropylene, polybutylene terephthalate, nylon 6/6, nylon 11, nylon 12, and polyphenylene oxide.
Type: Application
Filed: Feb 16, 2005
Publication Date: Apr 19, 2007
Inventors: Joseph Thornton (Austin, TX), Christopher Thornton (Austin, TX), Shawn Arnett (Austin, TX)
Application Number: 11/058,895
International Classification: G01V 1/38 (20060101);