Lift bag with automatic gas volume regulation

A lift bag for moving an object underwater includes a lift bag body and a buoyancy regulator device within an internal cavity of the lift bag body. The buoyancy regulator device includes concentric regulator tubes. Each regulator tube includes a regulator tube opening and the regulator tube openings may be aligned to define a regulator tube aperture. The regulator tube aperture is in fluid communication with a lift bag slot formed in the lift bag body. A constant buoyancy for the lift bag is determined by adjusting the position of the regulator tube aperture by moving the inner and outer regulator tubes with respect to each other.

BACKGROUND

Lifting or moving heavy objects underwater can be accomplished using lift bags. The buoyancy of the lift bag is used to move the object vertically underwater or to assist with using the object horizontally underwater. One common danger with the use of a lift bag is the risk of runaway if the buoyancy force of the lift bag is too great in comparison to the weight of the object to be moved. Runaway creates an uncontrolled descent or ascent that could cause injury to divers or could cause damages to the object to be moved or to support structures on the surface of the water. The expansion of air within the lift bag during ascent due to decreasing water pressure causes an increase in the buoyancy force provided by the lift bag. The increasing buoyancy force creates a substantial risk of runaway if not properly controlled.

Many commercially available lift bags include a valve that may be manually operated by a diver to control buoyancy during ascent. However, this can be a dangerous operation, as there is a risk of entanglement with the diver's breathing equipment if the lift bag starts to uncontrollably rise or sink if the valve is operated incorrectly. Additionally, the diver has to continuously monitor the valve as the water pressure surrounding the lift bag changes as the water depth of the lift bag changes.

Thus, there is a need for improvement in this field.

SUMMARY

Certain embodiments include a lift bag for moving or lifting an object while that object is underwater. In one form, the lift bag includes a lift bag body defining an internal cavity. A lift bag slot is defined through a portion of the lift bag body. The lift bag slot allows fluid communication between the internal cavity of the lift bag body and the external environment.

A buoyancy regulator device is positioned within the internal cavity of the lift bag body. The buoyancy regulator device includes an outer regulator tube that has a hollow outer regulator tube body that defines an outer regulator interior. An outer regulator tube opening is defined through the outer regulator tube body. The outer regulator tube opening is in fluid communication with the outer regulator interior.

The buoyancy regulator device also includes an inner regulator tube that has a hollow inner regulator tube body that defines an inner regulator interior. An inner regulator tube opening is defined through the inner regulator tube body and the inner regulator tube opening is in fluid communication with the inner regulator interior. The inner regulator tube fits concentrically within the outer regulator tube.

When the inner regulator tube is fit concentrically within the outer regulator tube, the outer regulator tube opening is configured to align with the inner regulator tube opening to create a regulator tube aperture. The position of the regulator tube aperture is adjustable by moving the inner regulator tube with respect to the outer regulator tube.

The buoyancy regulator device is positioned within the internal cavity of the lift bag body so that the outer regulator tube opening is aligned with the lift bag slot so that the lift bag slot is in fluid communication with the regulator tube aperture. This alignment allows excess air within the internal cavity of the lift bag body to be expelled through the regulator tube aperture and the lift bag slot. The buoyancy force of the lift bag can be changed by adjusting the position of the regulator tube aperture.

In another form, a buoyancy regulator device for a lift bag comprises an outer regulator tube including an outer regulator tube body that defines an outer regulator tube interior. A plurality of outer regulator tube holes is defined through the outer regulator tube body. An outer regulator tube hole axis is defined through the outer regulator tube holes.

An inner regulator tube includes an inner regulator tube body that defines an inner regulator tube interior. The inner regulator tube is configured to fit concentrically within the outer regulator tube interior. A plurality of inner regulator tube holes are defined through the inner regulator tube body. The inner regulator tube holes are aligned along an inner regulator tube hole axis that is oblique to the outer regulator tube hole axis when the inner regulator tube is concentric with the outer regulator tube. One of the inner regulator tube or the outer regulator tube may be rotated with respect to the other regulator tube when the inner regulator tube is fit concentrically within the outer regulator tube interior. This rotation aligns one of the inner regulator tube holes with a corresponding outer regulator tube holes to determine a buoyancy force provided by the lift bag.

In some embodiments, the inner regulator tube is rotatable with respect to the outer regulator tube. Typically, in these embodiments, the outer regulator tube hole axis is substantially parallel to a sidewall of outer regulator tube body. In other embodiments, the outer regulator tube is rotatable with respect to the inner regulator tube. Typically, in these embodiments the inner regulator tube hole axis is substantially parallel to a sidewall of inner regulator tube body.

In other aspect, a buoyancy regulator device for a lift bag comprises an outer regulator tube including an outer regulator tube body that defines an outer regulator tube interior. An inner regulator tube including an inner regulator tube body is configured to fit concentrically within the outer regulator tube interior. The outer regulator tube and the inner regulator tube are mechanically coupled by a stud fit into a tube slot. The tube slot includes a length and a plurality of tube slot arms extending from the tube slot each at a different position along the length of the tube slot.

When the stud is aligned with one of the tube slot arms along the length of the tube slot, the outer regulator tube and the inner regulator tube may be rotated with respect to each other so that the stud enters the tube slot arm. A buoyancy force of the lift bag is adjusted by positioning the stud within a different tube slot arm. In some embodiments, the tube slot is defined through the outer regulator tube and the stud extends from the inner regulator tube. In other embodiments, the tube slot is defined through the inner regulator tube and the stud extends from the outer regulator tube.

DESCRIPTION OF THE SELECTED EMBODIMENTS

FIG.1illustrates an embodiment of a lift bag20that is used to help control the movement of objects underwater. Lift bag20may be used to assist with lifting objects that are underwater to the surface of the water or may be used to control the descent of an object from the surface to a desired position underwater. Lift bag20may also be used to assist with moving objects laterally underwater.

The lift bag20includes a lift bag body24that has a top portion26and a bottom portion27. The lift bag body24is preferably made from a durable fabric that is impervious to both air and water. An upper strap29is attached at the top portion26of lift bag body24and a lower strap31is attached at the bottom portion27of lift bag body24. An eyelet32is positioned on lower strap31and provides a connection point for connecting lower strap31to an object to be lifted by lift bag20.

An opening38is defined in the bottom portion27of the lift bag body24to allow access to and from an internal cavity34that is defined by the lift bag body24of lift bag20. When the lift bag20is submerged underwater, the internal cavity34may be partially filled with water and partially filled with air that provides the buoyancy force that allows the lift bag20to lift an object that is underwater.

A lift bag slot42is defined through a portion of lift bag body24and extending from the top portion26of lift bag body24toward the bottom portion27of lift bag body24. The lift bag slot42allows the internal cavity34of lift bag20to be in fluid communication with the outside environment. The lift bag slot42is aligned with a buoyancy regulator device50(shown in phantom lines inFIG.1) that is positioned within the internal cavity34of lift bag20. Buoyancy regulator device50may be connected to lift bag body24by sewing a connection between buoyancy regulator device50and lift bag body24, by the use of adhesive, using a flange type connection, or any other suitable attachment method.

When lift bag20is submerged underwater, internal cavity34is initially filled with water. The object to be lifted is attached to the lift bag20, for example at the eyelet32on lower strap31. Then, an air source, such as the air supply of the diver, is used to introduce air into internal cavity34through the opening38at the bottom portion27of lift bag body24. In other embodiments, any other suitable alternative source of air may be used, such as a portable air source like a separate compressed air cylinder. In other examples, a hose may be extended from an air source on a boat or platform at the surface of the water and the hose may be used to supply air to the internal cavity34of lift bag20. The air introduced into internal cavity34displaces at least a portion of the water filling the internal cavity34and provides a buoyancy force that is capable of lifting the object that is attached to lift bag20.

The amount of buoyancy force that is created is directly proportional to the volume of air within internal cavity34. According to Boyle's Law, during ascent, as the lift bag20rises and the depth of the water decreases, the water pressure on the lift bag20also decreases. The decrease in water pressure allows the air within the internal cavity34to expand. This expansion of air within the internal cavity34increases the volume of the air and therefore the buoyancy force. Too much buoyancy can create runaway ascent, where the lift bag20and the object lifted by the lift bag20rises too quickly.

The buoyancy regulator device50is used to control the amount of air that is within internal cavity34to control the lift force that is generated by lift bag20. The buoyancy regulator device50is positioned within internal cavity34so that it may communicate with lift bag slot42that is defined through lift bag body24. The buoyancy regulator device50provides an opening that opens the internal cavity34of lift bag body24to a determined water level. This allows excess air volume within internal cavity34that is created during ascent of the lift bag20to be released into the outside environment through lift bag slot42. The release of the excess air prevents an increase of buoyancy and in lift force to help prevent runaway during ascent of the lift bag20. In some embodiments, as described further below, the position of the opening provided by buoyancy regulator device along lift bag slot42may be adjusted to allow a diver to regulate the amount of lift force provided by lift bag20.

An exploded view of an embodiment of a buoyancy regulator device50is shown inFIG.2. Buoyancy regulator device50includes an outer regulator tube55. Outer regulator tube55has a hollow outer regulator tube body56that surrounds and defines an outer regulator tube interior57. An outer regulator tube opening is defined through a portion of outer regulator tube body56and allows fluid communication between the outer regulator tube interior57and the environment outside the outer regulator tube body56. In the embodiment shown inFIG.2, the outer regulator tube opening is an outer regulator tube slot58. However, in other embodiments the outer regulator tube opening may be any shape that allows for fluid communication between the outer regulator tube interior57and the outer regulator tube body56.

The outer regulator tube slot58is oriented vertically along outer regulator tube body56, generally perpendicular to the top and bottom edges of outer regulator tube body56. In some embodiments, the outer regulator tube slot58may be shaped and sized to correspond with the lift bag slot42defined through lift bag body24. The outer regulator tube slot58may be milled through outer regulator tube body56or may be formed by any other suitable process.

Buoyancy regulator device50also includes an inner regulator tube65that fits concentrically within outer regulator tube55. Inner regulator tube65has a hollow inner regulator tube body66that surrounds and defines an inner regulator tube interior67. An inner regulator tube slot68is defined through inner regulator tube body66and is in fluid communication with the inner regulator tube interior67. Inner regulator tube slot68is positioned on inner regulator tube body66so that inner regulator tube slot68is oriented at an oblique angle with respect to outer regulator tube slot58when inner regulator tube65is concentric with outer regulator tube55. Although the outer regulator tube slot58and inner regulator tube slot68are shown extending through the bottom edge of the outer regulator tube55and the inner regulator tube65, respectively, in other embodiments, the outer regulator tube slot58and the inner regulator tube slot68may stop short of the bottom edge of the outer regulator tube55and the inner regulator tube65.

As shown inFIG.3A, when the inner regulator tube65is inserted within the outer regulator tube interior57, the inner regulator tube slot68and the outer regulator tube slot58align to create a regulator tube aperture70. The size of regulator tube aperture70is limited by the intersection of inner regulator tube slot68and outer regulator tube slot58so that the portions of the regulator tube slots58,68that are not aligned are blocked by the regulator tube bodies56,66and do not allow fluid communication between the regulator tube interiors57,67and the outside environment. Inner regulator tube65may be retained within outer regulator tube55by a retainer ring or any other suitable method of retention to keep the regulator tubes55,65vertically aligned and to prevent any movement between the regulator tubes55,65other than rotation.

Because inner regulator tube slot68is arranged at an oblique angle with respect to outer regulator tube slot58, the position of regulator tube aperture70can be changed by rotating inner regulator tube65within outer regulator tube55. In the embodiment shown inFIG.3B, rotating inner regulator tube65clockwise within outer regulator tube55moves the regulator tube aperture70vertically upward along outer regulator tube55. However, in other embodiments, the position of regulator tube aperture70can be changed by rotating outer regulator tube55with respect to inner regulator tube65.

Rotation of the regulator tubes55,65may be accomplished in any suitable fashion. In one embodiment, the top of the inner regulator tube65and/or the outer regulator tube55may be accessible on the exterior of lift bag body24to allow rotation of one of or either of the regulator tubes55,65by hand. In another embodiment, a small handle accessible by a diver may be operationally connected to either of the regulator tubes55,65to allow a user to rotate one of the regulator tubes55,65to adjust the position of regulator tube aperture70. In other embodiments, the regulator tubes55,65may be accessible by a diver reaching within internal cavity34of lift bag body24through opening38in the bottom portion27of lift bag20.

The position of regulator tube aperture70may be used to regulate the volume of air that is contained within the lift bag20shown inFIG.1, and therefore regulates the amount of lift force that is provided by the lift bag20. Air that is introduced into lift bag20is able to remain within lift bag body24above the position of regulator tube aperture70. However, when the volume of the air exceeds the volume of the interior of lift bag body24above the regulator tube aperture70, the excess air exits lift bag20through regulator tube aperture70and the corresponding lift bag slot42. Therefore, adjusting the position of regulator tube aperture70to be closer to the top portion26of lift bag20decreases the volume of air within lift bag body24and decreasing the buoyancy force. Similarly, adjusting the position of regulator tube aperture70to be closer to the bottom portion27of lift bag20increases the volume of air that can be held within lift bag body24and increases the buoyancy force.

The buoyancy regulator device50automatically regulates the buoyancy force provided by the lift bag20even as the lift bag20is ascending and the volume of air within the lift bag body24increases due to decreased water depth and water pressure. The excess volume of air that is created during ascent is released from lift bag body24through regulator tube aperture70so that the volume of air within lift bag body24, and therefore the buoyancy, remains constant. The constant volume of air prevents the risk of runaway as the lift bag20ascends. The vertical position of regulator tube aperture70can be preset by a diver to create a specific volume of air within lift bag body24that provides a desired lift force for the object that is to be lifted underwater. This desired lift force remains unchanged as the lift bag20ascends because the excess air created within lift bag body24due to decreased water pressure is expelled through regulator tube aperture70.

FIG.4illustrates an alternative embodiment of a buoyancy regulator device150. Buoyancy regulator device150includes an outer regulator tube155and an inner regulator tube165that is capable of fitting concentrically within outer regulator tube155. Instead of including a slot for the regulator tube opening as shown inFIGS.2-3, the outer regulator tube opening for the outer regulator tube155is represented as a series of outer regulator tube holes158that extend through an outer regulator tube body156and that are in fluid communication with an outer regulator tube interior157. The inner regulator tube opening for the inner regulator tube165is represented by a series of inner regulator tube holes168that extend through an inner regulator tube body166and that are in fluid communication with an inner regulator tube interior167.

Outer regulator tube holes158are aligned vertically on outer regulator tube body156. As shown inFIGS.5A and5B, the inner regulator tube holes168are aligned on inner regulator tube body166along an axis163that is oblique to an axis153aligned through the centers of the outer regulator tube holes158, when the inner regulator tube165is concentric with the outer regulator tube155. Therefore, when the inner regulator tube165is concentric with outer regulator tube155, a single inner regulator tube hole168is aligned with a single outer regulator tube hole158to create a regulator tube aperture170. In this embodiment, the axis153extending through the centers of the outer regulator tube holes158is substantially parallel to a sidewall154of the outer regulator tube155.

As shown inFIG.5B, the position of the regulator tube aperture170may be changed by rotating the regulator tubes155,165with respect to each other so that different corresponding regulator tube holes158,168are aligned. InFIG.5B, the inner regulator tube165is rotated clockwise so that the position of the regulator tube aperture170moves vertically upward to decrease the volume of air that can be held within lift bag20. Likewise, rotating the inner regulator tube165counterclockwise would move the position of the regulator tube opening vertically downward to increase the volume of air that can be held within lift bag20.

In some embodiments, as shown inFIG.6, seals169may surround the inner regulator tube holes168to provide an additional seal between the inner regulator tube165and the outer regulator tube155when the inner regulator tube165is concentrically located within the outer regulator tube interior157. In some embodiments, these seals169are O-rings that surround the inner regulator tube holes168. In other embodiments, the seals169may be positioned on the inner surface of the outer regulator tube body156and surround the outer regulator tube holes158.

Although the embodiment shown inFIGS.4-5, both the inner regulator tube165and the outer regulator tube155include circular regulator tube holes158,168, as shown inFIG.7, inner regulator tube65may be combined with outer regulator tube155to combine the angled inner regulator tube slot68from inner regulator tube65with the circular regulator tube holes158from outer regulator tube155. The angled inner regulator tube slot68may align with one of the circular regulator tube holes158to determine the position of the regulator tube aperture170and corresponding lift force for the lift bag20.

Another embodiment of a buoyancy regulator device250is shown inFIGS.8-9. Buoyancy regulator device250includes an outer regulator tube255and an inner regulator tube265. The outer regulator tube opening takes the form of an outer regulator tube slot258that includes a series of tube slot arms259is defined through outer regulator tube255. Outer regulator tube slot258is configured to correspond with lift bag slot42on lift bag20. Inner regulator tube265includes a stud268protruding from inner regulator tube265that is able to fit into and slide within outer regulator tube slot258.

As shown inFIG.9, inner regulator tube265may be inserted within outer regulator tube255so that inner regulator tube265is concentric with outer regulator tube255, when stud268is aligned with outer regulator tube slot258. When stud268is aligned with a tube slot arm259, inner regulator tube265may be rotated with respect to outer regulator tube255so that stud268enters tube slot arm259. The stud268can rest within tube slot arm259and prevent further rotation of the inner regulator tube265with respect to outer regulator tube255. In some embodiments, the tube slot arms259may be positioned at pre-specified increments of air displacement to correspond to certain amounts of lift force. For example, each tube slot arm259may correspond to either an increase or a decrease of 1 pound of lift force or, in some embodiments, each tube slot arm259may correspond to an increase or a decrease of 10 pounds of lift force.

The stud268can be moved to align with different tube slot arms259along outer regulator tube slot258by sliding inner regulator tube265through outer regulator tube255. The height of the regulator tube aperture270formed beneath the inner regulator tube265is adjusted by inserting stud268into different tube slot arms259along outer regulator tube slot258. Adjusting the height of regulator tube aperture270modifies the volume of air that is held within lift bag body24and therefore controls the lift force applied by lift bag20. As excess air volume is created upon ascent of the lift bag20, the extra air is discharged from lift bag body24through the regulator tube aperture270.

Other embodiments may include different adjustment methods for positioning the regulator tube aperture70created by the buoyancy regulator device50. As an example, in one embodiment, the buoyancy regulator device50may include a rack and pinion system. A handle on the rack and pinion system is rotated to disengage the teeth and the handle may then be moved vertically to determine a desired height for the regulator tube opening. Once the desired height is reached, the handle is rotated in the opposite direction to reengage the teeth and hold the system in place.

It should be recognized by a person of ordinary skill in the art that the arrangement of the regulator tube openings on the inner regulator tube and outer regulator tubes may be switched in alternative embodiments. As an example, for buoyancy regulator device50, the inner regulator tube slot68may be a vertical slot that is substantially parallel to a sidewall of the inner regulator tube body66and the outer regulator tube slot58may be angled with respect to a sidewall of the outer regulator tube body56. In this embodiment, the outer regulator tube55is rotated with respect to the inner regulator tube65to adjust the position of the regulator tube aperture170.

As another example, for buoyancy regulator device150, the inner regulator tube holes168may be aligned along an axis that is substantially parallel to a sidewall of the inner regulator tube body166, and the outer regulator tube holes158may be aligned along an axis that is angled with respect to a sidewall of the outer regulator tube body156. In this embodiment, the outer regulator tube155is rotated with respect to the inner regulator tube165to adjust the position of the regulator tube aperture170.

Similarly, for buoyancy regulator device250, the stud268may be located on an inner surface of the outer regulator tube255and the regulator tube slot258and tube slot arms259may be defined through the inner regulator tube265. In this embodiment, the outer regulator tube255is translated and rotated with the respect to the inner regulator tube265to adjust the height of the regulator tube aperture270.

FIG.10illustrates an embodiment of the buoyancy regulator device50and an example of a method of attaching the buoyancy regulator device50to a lift bag20. An outer regulator tube355is positioned on the interior of lift bag body24and an inner regulator tube365is positioned concentrically within outer regulator tube355. O-ring grooves358are defined in outer regulator tube355and O-rings359are seated within O-ring grooves358to provide a seal between outer regulator tube355and the concentric inner regulator tube365.

A top flange315is positioned on the exterior of lift bag body24and surrounds the inner regulator tube365and aligns with a top surface357of the outer regulator tube355. A flange bolt318extends through the top flange315, the lift bag body24, and the outer regulator tube355to attach the buoyancy regulator device50to the lift bag20. In some embodiments, a top retainer ring372is positioned between the top flange315and the inner regulator tube365to prevent inner regulator tube365from sliding vertically within outer regulator tube355. An additional bottom retainer ring374may be positioned around the bottom of inner regulator tube365.

Inner regulator tube includes an inner tube cover367. A vent hole368or multiple vent holes368may be defined through inner tube cover367cover for allowing excess air to escape. A handle376is attached to inner tube cover367and positioned so that the handle is on the exterior of lift bag body24. Rotation of handle376causes rotation of inner regulator tube365with respect to outer regulator tube355, changing the orientation of an inner regulator tube slot on inner regulator tube365with respect to an outer regulator tube slot on outer regulator tube355to adjust the desired lift force provided by the lift bag20. In some embodiments, markings may be made on the handle or on the top flange315to give a visual indication to the diver as to the position of inner regulator tube365with respect to the outer regulator tube355so that the diver can easily discern the buoyancy force provided by the lift bag20. The markings could directly indicate the position of the regulator tubes355,365, or may be translated to show the effective buoyancy force provided by the lift bag based on the position of the regulator tubes355,365.

Alternative embodiments of the buoyancy regulator device50are shown inFIGS.11-12. InFIG.11, the handle376is attached to the bottom edge of inner regulator tube365. Rotation of handle376rotates inner regulator tube365with respect to outer regulator tube355. InFIG.12, handle376is attached to outer regulator tube355so that rotation of handle376causes rotation of the outer regulator tube355with respect to the inner regulator tube365. In some embodiments, the handle376may be positioned within the internal cavity34of the lift bag20so that a diver reaches into internal cavity34to rotate handle376. In other embodiments, the handle376extends through internal cavity34so that it extends below opening38of the lift bag20and can be rotated without needing to reach within internal cavity34. Some embodiments include multiple handles376. As an example, one handle376is on the exterior of the lift bag20and a second handle376extends into the internal cavity34of the lift bag20(for example, seeFIG.15).

Alternative embodiments of the buoyancy regulator device250having the stud and slot arrangement are shown inFIGS.13-14. InFIG.13, the handle376is attached to the inner tube cover367. The top retainer ring372and bottom retainer ring374shown inFIG.10have been removed to allow inner regulator tube365to translate within outer regulator tube355when handle376is pushed and/or pulled. Handle376may also be rotated to allow inner regulator tube365to rotate with respect to outer regulator tube355.FIG.14is similar toFIG.13, but the handle376is instead connected to the bottom edge of inner regulator tube365. Pushing or pulling handle376allows translation of inner regulator tube365within outer regulator tube355, while rotating handle376causes inner regulator tube365to rotate with respect to outer regulator tube355.

In other embodiments, handle376may be included on any of the embodiments of buoyancy regulator device50,150,250as desired. Handle376may be attached to the buoyancy regulator device50,150, or250on the portion of the buoyancy regulator device50,150, or250that is exterior of the lift bag20or on the interior of the lift bag20. Some embodiments may include a handle376that is exterior to the lift bag20and another handle376that extends within the interior of the lift bag20.

FIG.15illustrates a cross-sectional view of an alternative embodiment of a buoyancy regulator device450. Buoyancy regulator device450includes a conically shaped outer regulator tube455and a conically shaped inner regulator tube465that fits concentrically within outer regulator tube455. The inner regulator tube465includes inner regulator tube holes468that may be aligned with an outer regulator tube slot as described in the embodiments discussed above.

A top flange415is positioned on the exterior of lift bag body24and aligns with a top surface457of the outer regulator tube455. A flange bolt418extends through the top flange415, the lift bag body24, and the outer regulator tube455to attach the buoyancy regulator device450to the lift bag20. A top retainer ring472is positioned adjacent the top surface457of the outer regulator tube455to prevent inner regulator tube465from moving vertically within outer regulator tube455. O-rings459may also be positioned between inner regulator tube465and outer regulator tube455to provide a seal and further assist in preventing vertical movement of inner regulator tube465with respect to outer regulator tube455. The O-rings459also provide a lubricated contact point between the outer regulator tube455and the inner regulator tube465to improve the ability of the regulator tubes455,465to rotate with respect to each other or to translate with respect to each other smoothly.

A top handle476is attached to a top surface of the inner regulator tube465so that the top handle476extends to the exterior of the lift bag body24and lift bag20. A bottom handle486is attached to a bottom surface of the inner regulator tube465so that the bottom handle486extends within the internal cavity34of lift bag20. A diver may rotate inner regulator tube465with respect to outer regulator tube455by rotating either the top handle476or the bottom handle486. This provides the diver with an option in instances where it may be easier for the diver to access either the top handle476or access the bottom handle486to adjust the desired buoyancy force provided by buoyancy regulator device450.

FIG.15shows that the inner regulator tube465and the outer regulator tube455are conically shaped so that surfaces of the regulator tubes455,465are wider near the surface of the lift bag body24and become narrower extending into the internal cavity34of the lift bag20. However, in other embodiments, the regulator tubes455,465may be narrower near the surface of the lift bag body and become wider extending into the internal cavity34of the lift bag20.

Although lift bag20and buoyancy regulator device50have thus far been described generally in terms of controlling the ascent of an object underwater, buoyancy regulator device50may also be used to control the descent of an object to an underwater location using a lift bag20. For descent, lift bag20is filled with a volume of air that is small enough to create neutral buoyancy where there is some buoyancy force, but not enough buoyancy force to cause the object to ascend. As the object descends, the volume of air in the lift bag decreases, so that the buoyancy force provided by the air trapped within lift bag20also decreases. Without the addition of extra air, this causes the object to sink faster. However, a diver may provide additional air to lift bag20to increase the air volume. By setting the buoyancy regulator device50to a desired air volume, any air added to the lift bag20that is in excess of the desired air volume is released from the internal cavity34of lift bag body24, and a constant lift force is maintained to maintain a steady speed for descent.

The application of lift bag20for a controlled descent greatly improves safety when compared to a typical descent that involves the use of weight anchors. Anchors may sink quickly and dangerously with little ability to regulate the speed of descent. The lift bag20allows divers to use tag lines to maintain a safe distance from the descending object and allows the desired object to descent in a controlled manner.

The concentric tube design for the buoyancy regulator device50provides several advantages for the regulation of air volume and lift force created by a lift bag. Because the buoyancy regulator device50is found within the interior of lift bag body24, there are no exterior entanglement hazards that could be caught or snagged on objects found underwater such as algae, jellyfish, or other obstacles such as fishing or anchor lines. Additionally, the relatively few moving parts and connection points provide for only a few possible points of failure, even in situations under increased water pressure.

Dump valves that are commonly used for manually releasing excess air in a lift bag will sometimes stick or not seat correctly. This could cause more air to escape than is intended by the diver, creating negative buoyancy and causing the lift bag to sink rather than rise. In response, the diver may need to use air from their own breathing apparatus to add additional air to offset the loss caused by the stuck dump valve. The buoyancy regulator device50eliminates the need for a manual dump valve and reduces the risk of excess air escaping form lift bag20.

The buoyancy regulator device50is compact and only causes a small air volume displacement within the internal cavity34of lift bag20, so that there is a minimal impact on the lift capacity of lift bag20. The compactness also makes buoyancy regulator device50easy to attach to diver gear.

Buoyancy regulator device50may be included as a component of a new lift bag or may be sold as a standalone unit that is capable of being retrofitted into an existing, standard lift bag that does not have buoyancy control. Buoyancy regulator device50can be modified to accommodate many different types of lift bags from small lift bags to industrial lift bags.

The mechanical nature of the buoyancy regulator device50means that no batteries, chemical agents, or electricity is needed to operate the buoyancy regulator device50. This increases safety for a diver operating the lift bag20and reduces the risk of environmental damage caused by any of these types of hazards. This also minimizes the cost of upkeep and continued use, as the buoyancy regulator device50is easy to clean and does not require replacement of components such as chemicals, batteries, valves, solenoids, or sensors.

Additionally, multiple lift bags20may be used to lift a large, unbalanced load without requiring multiple divers to be present to monitor each individual lift bag20. Typically, a diver needs to be stationed near each lift bag to manually regulate the lift capacity of the lift bag during ascent or descent. However, since the lift bags20are capable of automatically regulating the lift force without intervention by a diver, multiple divers are not necessary to monitor each of the lift bags20used.