Abstract:
A portable, diver-operated device provides an improved method of cleaning surfaces underwater. The device includes a source of ultrasonic energy in a housing that has a compliant portion around an opening to engage and fit around a contaminated surface and clean it with the ultrasonic energy. The housing is made from material that diminishes transmission of the ultrasonic energy to ambient water. The compliant portion seals the source, the contaminated surface and some water from ambient water to concentrate the cleaning power of the source on the surface and to prevent transmission of harmful levels of energy outside of the device and through ambient water.

Description:
STATEMENT OF GOVERNMENT INTEREST 
     The invention described herein may be manufactured and used by or for the Government of the United States of America for governmental purposes without the payment of any royalties thereon or therefor. 
    
    
     BACKGROUND OF THE INVENTION 
     This invention relates to cleaning devices for underwater surfaces. More particularly, the cleaning device of this invention is portable by a diver and uses ultrasonic energy to clean contamination from surfaces underwater. 
     Underwater surfaces are cleaned, or otherwise prepared by a number of methods. Many of these methods use brushes, scrapers and/or water-jets for abrasive cleaning and surface preparation that include rust and scale removal, paint and coating removal, and marine growth removal. The support systems for these methods are too large and heavy to be carried by a single diver, and they usually require operational support from equipment located on the surface. Consequently, they are not truly portable and their use may attract unwanted attention. In addition, the systems consume large quantities of power and are expensive. 
     Ultrasonic energy has been widely used commercially in baths in open sinks at surface installations for measurement, protection, and cleaning operations. Ultrasonic energy is transmitted through the unsealed open baths that may include cleaning, or abrasive solutions to effectively clean parts; however, the sinks are inefficient and relatively bulky fixed structures and by their very nature cannot be used to clean surfaces underwater. 
     A commercially available tool marketed under the trademark SONICATOR by MISONIX Incorporated of 1938 New Highway, Farmingdale, N.Y., 11735 has shown promise for underwater cleaning of some contaminants (grease, dirt, grime, hardened thread locking compound, etc.) from parts. It has a one-half inch diameter probe-like tip that is brought about one-half inches from or in contact with contaminated surfaces on the parts. Compared to topside standard sinks that use ultrasonic energy, the power (550 watts at 20 kHz) of the probe-like tool was found to clean the parts about ten times faster, but it did not remove marine barnacle and mollusk shell growth except to clean the surfaces of the growth. In addition, the mid-frequency noise levels that were generated by cavitation bubble formation on the tip of the probe were appreciable and are likely to be unacceptable when used near some sensors and ordnance. 
     Thus, in accordance with this inventive concept, a need has been recognized in the state of the art for an ultrasonic cleaner portable by a diver-operator that seals a surface to be cleaned from ambient water and retains ultrasonic energy to clean the surface underwater. 
     SUMMARY OF THE INVENTION 
     The present invention provides an underwater tool that includes a source of ultrasonic energy in a shell-shaped housing having an opening to engage and fit around a surface to clean the surface with the ultrasonic energy. The shell retains the ultrasonic energy inside of it and a compliant portion around the opening seals the source of ultrasonic energy, the surface, and some water from the ambient water. The invention also includes a method of cleaning a surface underwater using the underwater tool. 
     An object of the invention is to provide a method of and device for using ultrasonic energy to clean a surface underwater. 
     Another object is to provide a method of and portable device for cleaning an underwater surface that seals the surface and an ultrasonic energy source from ambient, or surrounding water. 
     Another object is to provide a method of and portable device for cleaning an underwater surface that seals the surface, an ultrasonic energy source and some liquid from ambient water. 
     Another object is to provide a method of and device for cleaning an underwater surface that diminishes transmission of energy to ambient water. 
     Another object is to provide a method of and portable device for cleaning an underwater surface having a housing made from material absorptive of ultrasonic energy to reduce the level of energy transmitted to ambient seawater. 
     Another object is to provide a method of and portable device for cleaning an underwater surface having a housing with an internal coating to reduce the level of energy transmitted to ambient seawater. 
     Another object is to provide a method of and portable device for cleaning an underwater surface having a housing with an internal reflective coating to reflect energy in a chamber to enhance cleaning. 
     Another object of the invention is to provide a method of and device for cleaning a surface underwater using a dish-shaped shell having at least a compliant portion around an opening to retain ultrasonic energy and seal a source of ultrasonic energy, the surface and some water in a chamber from ambient water. 
     These and other objects of the invention will become more readily apparent from the ensuing specification when taken in conjunction with the appended claims. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The FIGURE is a schematic representation of the device of the invention shown partially in cross section for cleaning contaminants from a surface underwater. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring to the FIGURE, cleaning device  10  is portable by a diver-operator and can be deployed at various depths in water  20  to clean a surface  30  of contaminants  31 . Surface  30  can be metal (or other materials) of undersea structural components, instrumentation packages, sensors, ordnance, etc. Contaminants  31  can include fouling caused by marine growth including barnacle shells, mollusk shells, plus a host of other marine growth and organisms, and/or a number of chemical compounds such as rust, scale, sand, grease, dirt, grime, etc. 
     Cleaning device  10  has a waterproof container  40  and is sized to be portable by a diver, although larger versions of cleaning device  10  may need more than one diver to transport it. Container  40  can have a handle  40   a  at one end for carrying and positioning it, and an essentially dish-shaped shell, or housing  11  functioning as a conformal enclosure is mounted on the other end of container  40 . 
     One configuration of shell-shaped housing  11  has an annular lip-shaped portion  12  around opening  13 . Annular portion  12  is made from a material that is compliant enough to pliably conform to surface  30  and contaminants  31  as it engages them to seal a chamber  14  inside housing  11  and adjacent to surface  30  and contaminants  31 . 
     A source of ultrasonic energy  15  is disposed in chamber  14  to project, or transmit ultrasonic energy  16 . The projected energy usually passes through some water  21  that has been part of ambient water  20  before cleaning device  10  was placed on surface  30  and contaminants  31 . 
     Housing  11  and annular portion  12  can be integral with each other and can be formed as a molded elastomeric unit. A preferred choice is polyurethane as an elastomeric material that assures sealing, and another good choice is compliant natural rubber. Other natural and manmade materials can be used as long as they are compliant enough to conform to surface  30  and its contaminants  31  to seal chamber  14  from surrounding, or ambient water  20 . The compliant seal created by annular portion  12  seals source  15 , surface  30  and contaminants  31  and some water  21  from ambient water  20  to concentrate the cleaning power of ultrasonic energy  16  from source  15  on contaminants  31  on surface  30  in chamber  14 . The compliant seal created by annular portion  12  also prevents transmission of harmful levels of ultrasonic energy  16  and mid-frequency energies outside of housing  11  of cleaning device  10 . 
     In addition, the chosen material for housing  11  and portion  12  has suitable properties of absorption of ultrasonic energy  16  in the range of about 20 to 35 kHz. and mid-frequency noise in the range of about 10 to 1500 Hz. A material of such absorptional properties will serve to isolate, or at least diminish the transmission of portions of ultrasonic energy  16  and mid-frequency noise from chamber  14  to ambient water  20 . The undesirable mid-frequency noise is generated largely due to the formation and/or collapse of cavitation bubbles during projection of ultrasonic energy  16  from source  15  within chamber  14 . The compliant material, natural rubber, has such properties of absorption. The lead-impregnated vinyl material designated DSB-1 marketed under the trademark QUIET MAT by Noise Reduction Enterprises, Marine Products Division, Essex, Mass. 01929-0907 is another satisfactory sound absorbing material Other natural and manmade materials can be used as well. 
     A septum or suitable coating  17  can be provided on the inside of housing  11  and annular portion  12  in chamber  14  to reflect portions of ultrasonic energy  16  (and possibly mid-frequency energy) back onto surface  30  and contaminants  31  in chamber  14  in addition to reflections of other portions of ultrasonic energy (and possibly mid-frequency energy) caused by housing  11 . The shape of housing  11  reflects energy onto surface  30  and contaminants  31 . However, housing  11  can have different shapes, such as curved, or cone-shaped to improve reflection of ultrasonic energy from coating  17  onto surface  30  and can help focus ultrasonic energy onto surface  30 . These features help reduce transmission of possibly harmful levels of energy to the operator of cleaning device  10  and other unwanted listeners. The energy reflected can add to the process of cleaning contaminants  31  from surface  30 . 
     Housing  11  may be made from different materials than portion  12  when enhancement of different properties may be called for, for example, when a larger cleaning unit for larger surfaces needs a material that has additional structural strength. However, these different materials enhance the isolation, or at least diminishment of the transmission of ultrasonic energy  16  from chamber  14  to ambient water  20 , as compared to the material used in annular portion  12  that is likely to be primarily selected for its compliant properties to seal chamber  14  from ambient water  20 . In this configuration, material of housing  11  could be the material DSB-1 marketed under the trademark QUIET MAT by Noise Reduction Enterprises, and annular portion  12  could be compliant polyurethane, although other suitable materials might be selected as well 
     Source  15  of ultrasonic energy can be a piezoelectric transducer appropriately driven to provide suitable levels of projected, or transmitted ultrasonic energy  16 . Many different piezoelectric transducers available in the art are acceptable. The frequency and ranges of frequency of the projected signals of ultrasonic energy  16  and the power of the signals of the projected energy from the selected transducers can be selected and tuned by modular components to be identified below. Thus, cleaning of different contaminations  31  on surface  30  can be optimized, and cleaning times can be reduced. 
     Optionally, source  15  can include a plurality, or an array of piezoelectric transducers in chamber  14 . The signals projected from the transducers can be phased in accordance with known phasing techniques to focus a composite form of ultrasonic energy  16  onto surface  30  and contaminants  31 . This capability assures thoroughness and rapid completion of the cleaning process. Individual ones of the selected transducers or arrays of from one to five transducers typically project levels of ultrasonic energy, or power from source  15  that range from 500 to 2500 watts. This creates typical, or exemplary levels of power concentration of about 31 to 156 watts per cubic inch in a four-inch diameter, or sixteen cubic inch volume chamber  14 . 
     Housing  11  has a shank portion  11   a  coupling it to sealed container  40  and transmitting electrical power to drive each transducer of source  15  via leads  11   a ′. Shank portion  11   a  may also have hydraulic and/or mechanical links and couplings (not shown) between container  40  and source  15 . Container  40  is sealed and waterproof and encapsulates battery module  41 , signal generator module  42 , power amplifier module  43  and impedance matching module  44  that may also be individually sealed units and are operatively connected together via connections (not shown) to deliver suitable power to drive source  15 . 
     Battery module  41  delivers sufficient, selectable levels of power to the other modules when a waterproof dial-type switch  41   a , for example, is actuated by a diver-operator. Signal generator module  42  produces ultrasonic signals in preselected frequencies and ranges when appropriately tuned by an operator via waterproof dial-type tuning switch  42   a , for example. The selected ultrasonic signals are amplified in power amplifier stage  43 , and fed to impedance matching module  44  where maximum power transfer to transducer  15  is provided for. These modules and their tuning features are known in the art, and one of ordinary skill in the art to which this invention pertains will readily fabricate or select suitable modules and their tunable features from commercial sources. 
     As a further option, source  15  could be only a radiating, or projection structure in chamber  14 . The rest of the transducer could be contained inside container  40  with mechanical or hydraulic couplings through shank  11 a that link the transducer to projection structure of source  15 . This option may allow more powerful transducers to create higher levels of cleaning power. 
     In operation, cleaning device  10  is so compact and portable that it can be carried by a diver-operator to a remote, underwater work site where surface  30  is to be cleaned of contaminants  31 . Grasping handle  40   a  and a portion of container  40 , the diver places annular portion  12  against and around surface  30  and contaminants  31  and exerts a slight pushing, or pressing force. This pressing force holds cleaning device  10  against surface  30  and contaminants  31  and slightly deforms the compliant material of annular portion  12 . Annular portion  12  pliably accommodates, or engages surface  30  and contaminants  31  to seal source  15 , surface  30  and contaminants  31 , and some water  21  in chamber  14  from ambient water  20 . The diver may add some abrasive, or other cleaning additive  22  to water  21  in chamber  14  from a syringe-like applicator or packet to assist the cleaning process, if desired. 
     Source  15  of ultrasonic energy is activated by the diver&#39;s actuation of switch  41   a . Ultrasonic energy  16  from source  15  is projected from source  15  into water  21  in chamber  14  and onto contaminants  31 . The relatively small size of chamber  14  serves to concentrate projected ultrasonic energy  16  from source  15  onto surface  30  and contaminants  31 . Typically, concentrated levels of ultrasonic energy in the range of 31 to 156 watts per cubic inch are suitable to remove most contaminants  31 , and these levels can be transmitted by suitable control of switch  41   a.    
     Another factor to consider in the removal of contaminants is selection of frequencies of ultrasonic energy  16 . Different frequencies of projected ultrasonic energy  16  can affect the efficiency of removal of contaminants  31  and may be generated in signal generator module  42 . They are selected or tuned by the diver&#39;s control of tuning switch  42   a . The selected composition and power of ultrasonic energy  16  are projected from source  15  into chamber  14  and onto surface  30  and contamination  31 . Ultrasonic energy  16 , as well as mid-frequency noise generated by cavitation bubbles are retained or isolated, or at least diminished from transmission to ambient water  20  by the material of housing  11 . The shape of housing  11  and coating  17  reflect portions of projected ultrasonic energy  16  toward surface  30  and contaminants  31  to assist, or enhance the cleaning process and reduce the problems associated with unwanted transmissions of such energy through ambient water  20 . 
     Having the teachings of this invention in mind, modifications and alternate embodiments of this invention may be adapted. Cleaning device  10  can be made in larger or smaller sizes, and housing  11  could be made from many other elastomeric materials. Housing  11  could be block-shaped and define a chamber  14  having an annular portion  12 , or other configurations instead of shell-shaped. Levels of power projected by source  15  may be increased or decreased to clean contaminants  31  from differently sized surfaces  30 , or different contaminants  31  from different surfaces  30  at different depths as well. Generation of different power levels and spectral compositions thereof, and the components necessary to produce them will be apparent to one skilled in the art to which this invention pertains. 
     The disclosed components and their arrangements as disclosed herein all contribute to the novel features of this invention. Cleaning device  10  of this invention is a portable, cost-effective tool to reliably clean contaminants  31  from surfaces  30  underwater without transmitting levels of energy that could be harmful to operators or reveal the nature of the undersea activity. Therefore, cleaning device  10 , as disclosed herein is not to be construed as limiting, but rather, is intended to be demonstrative of this inventive concept. 
     It should be readily understood that many modifications and variations of the present invention are possible within the purview of the claimed invention. It is to be understood that within the scope of the appended claims the invention may be practiced otherwise than as specifically described.