Note: Descriptions are shown in the official language in which they were submitted.
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A BLADDER SYSTEM FOR A SUBMERSIBLE
Field of the Invention
[001]The present invention relates to a bladder system for a submersible and
to a
particular submersible having a bladder system. It is particularly directed to
small
submersibles which are remotely controlled or are autonomous.
[002]The invention has been developed primarily for use in submersible used in
data
gathering for underwater topological review and mapping of natural growths and
formations and particularly Underwater Autonomous Mapping (UAM) and will be
described hereinafter with reference to this application. However, it will be
appreciated
that the invention is not limited to this particular field of use.
Background of the Invention
[003] Submersibles need to be able to rise and lower in the water. This is
made possible
is by ballast and bladder systems that control ballast. Larger structures
such as submarines
can devote various cavities in different locations of the submarine as ballast
chambers
and elaborate control systems together with large pumps are required.
[004] However large submersibles are not able to undertake close proximity
underwater
topological review as they are unable to be close to the surface being
reviewed. This
closeness is needed for more accuracy and since the water in which the mapping
is being
undertaken could be low visibility due to the sediments, salts or other
particulates in the
water that causes light dispersion.
[005] Large submersibles also by their size are likely to stir up and create
greater
particulates in the water or turbulent water which each provides further
restrictions in
visibility.
[006] Overall the major problem with large submersibles is their lack of
manoueverability
in tight areas.
[007] There is also a need in the field of Underwater Autonomous Mapping as
well as in
many other uses for the submersible to take a slow methodical approach and
defined
pathway so as to fulfil accurate travel. To do this accurate control is
needed.
[008] It is therefore beneficial to have small, versatile and readily
maneuverable
submersibles. To achieve this a different system of ballast and bladders is
required.
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[009] It can be seen that known prior art submersible have the problems of:
a) Causes turbulence and therefore reduces optical effects
b) Not usable in shallow water
c) Requires large areas for manouevrability
d) Not versatile or adaptable.
e) No known ability with speed and accuracy
[0010] The present invention seeks to provide submersible with a
ballast and bladder
system, which will overcome or substantially ameliorate at least one or more
of the
deficiencies of the prior art, or to at least provide an alternative.
[0011] It is to be understood that, if any prior art information is
referred to herein, such
reference does not constitute an admission that the information forms part of
the common
general knowledge in the art, in Australia or any other country.
Summary of the Invention
[0012] According to the present invention, there is provided a submersible
and a
bladder system for providing ballast for the submersible comprising: a
submersible
elongated body; a bladder mountable in the submersible body; venting pathway
connecting between the bladder and external of the submersible body; a ballast
control
for controlling the venting in the venting pathway between the bladder and
external of the
submersible body; a power system for powering the ballast control; wherein the
ballast
control uses a one-way pump for high pressure use.
[0013] Preferably the submersible elongated body is
substantially 1 to 1.5 metres
long.
[0014] The ballast control can include at least one switching
valve fluidly connected
to the one-way pump for switching flow direction in the venting pathway. The
ballast
control can include a set of a plurality of switching valves wherein the set
of switching
valves work together to resist pressure equally on either side.
[0015] Preferably the ballast control includes a set of four
switching valves fluidly
connected to the one-way pump. The set of four of the at least one switching
valves can
be arranged to form two input switching valves on an input side of the one way
pump and
two output switching valves on an output side of the one way pump; wherein a
first of the
input switching valves fluidly connects to the venting pathway leading to
external of the
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submersible body and a second of the input switching valves fluidly connects
to the
venting pathway leading to the bladder; and wherein a first of the output
switching valves
fluidly connects to the venting pathway leading to external of the submersible
body and a
second of the output switching valves fluidly connects to the venting pathway
leading to
the bladder; and whereby the control of input switching valves to have either
the first or
second input switching valve open and the other closed and thereby feed from
either the
bladder or external to the input of the one-way pump; to simultaneously
control of input
switching valves to have either the first or second output switching valve
open and the
other closed and thereby feed from the output of the one-way pump to the other
of the
bladder or external.
[0016] Preferably the pump is a diaphragm pump.
[0017] Preferably the switching valve is a ball valve.
[0018] The control of ballast uses a pressure sensing of the
water in the bladder,
whereby the actual flow of water in the venting between the bladder and
external of the
submersible body is precisely determined.
[0019] The ballast tank includes an inner expandable bladder.
[0020] The bladder operates in the range greater than 36 psi.
but preferably the
bladder operates substantially in the range from 36 psi. to 100 psi.
[0021] Preferably the ballast system is used in a submersible
having an elongated
body with the hydrodynamic effective shape is symmetrical for travel in at
least two
opposing longitudinal directions. It can include a hydrodynamic effective
shape including
a first and a second opposing substantially conical heads and a main
cylindrical central
part therebetween with each aligned along a common elongated axis to allow the
hydrodynamic effective shape for travel in at least two opposing directions.
That direction
is along the longitudinal axis.
[0022] The submersible preferably has the main cylindrical
central part or the differing
length main cylindrical central part can include one or more of:
Batteries; Ballast; Motors; Electronics; Data and power connections; Other
Payloads.
[0023] Preferably the main cylindrical central part and the
first and the second
opposing substantially conical heads are detachable and replaceable. The main
cylindrical part can be replaced by a differing length of the main cylindrical
part and with
the first and the second opposing substantially conical heads attached to each
end.
[0024] The elongated body of the submersible is substantially in
the range of 1 to 5
metres long but preferably is substantially 1 to 1.5 metres long. The
elongated body can
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be substantially elliptical with a 1 to 1.5 metre major axis and a 0.3 to 0.5
metre minor
axis.
[0025]
The power system allows for the controllable driving of the submersible
body
is a 3 degree of freedom maneuvering system, where it can move in the at least
two
opposing directions along the axis of the elongated shape, up and down, left
and right.
Preferably the power system includes two side thrusters on either side of the
elongated
body and a top thruster on a top surface wherein the top thrusters of the
power system
on the top side of the elongated body include 2 motors spinning in opposite
directions to
counter the angular momentum of each single motor. The two side thrusters of
the power
system on either side of the elongated body are under the centre of gravity
plane, wherein
the probe is maintained stable during maneuvering.
[0026] Other aspects of the invention are also disclosed.
Brief Description of the Drawings
[0027]
Notwithstanding any other forms which may fall within the scope of the present
invention, preferred embodiments of the invention will now be described, by
way of
example only, with reference to the accompanying drawings in which:
Fig. 1 is a diagrammatic view of a submersible in accordance with a preferred
embodiment of the present invention showing a submersible body, a power system
for allowing the controllable driving of the submersible body in the at least
one
longitudinal direction and a visual image capture system including a plurality
of
optical cameras locatable on or at the surface of the elongated body;
Fig. 2 is a diagrammatic view of a submersible of Fig. 1 showing the centre of
gravity
plane and the thruster force plane of the main motor of the power system;
Fig. 3 is a diagrammatic view of a submersible of Fig. 1 showing the plane of
submersion when surfacing;
Fig. 4 is a diagrammatic view of a submersible of Fig. 1 showing the parts or
sections
of the submersible;
Figs. 5 is a diagrammatic view of a submersible of Fig. 1 showing the
detachability
of the parts or sections of the submersible and possible differing central
part with
two nose parts at either end;
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Figs. 6 is a diagrammatic view of a submersible of Fig. 1 showing the payload
use
of the central part with two nose parts at either end;
Figs. 7 is a diagrammatic view of the ballast system of a submersible of Fig.
1 in
accordance with an embodiment of the invention showing the valve and pump
5
system and interconnecting venting system between ballast tank and external
outlet;
Fig. 8 is a diagrammatic view of a one-way pump for use in the valve and pump
system of an embodiment of the invention;
Figs. 9 and 10 are exploded diagrammatic views of a ballast tank and inner
bladder
for use in the valve and pump system and interconnecting venting system
between
ballast tank and external outlet of an embodiment of the invention;
Figs 11 and 12 are diagrammatic views of an external outlet for use in the
valve and
pump system and interconnecting venting system between ballast tank and
external
outlet of an embodiment of the invention;
Figs 13 and 14 are two operational modes of the valve and pump system and
interconnecting venting system between ballast tank and external outlet of an
embodiment of the invention;
Fig 15 is a valve and pump system and interconnecting venting system between
two
ballast tanks and external outlet of an embodiment of the invention;
Fig. 16 is a diagrammatic example of the resulting operational control of
submerging
and surfacing with use of the valve and pump system and interconnecting
venting
system between ballast tank and external outlet of an embodiment of the
invention.
Description of Preferred Embodiments
[0028]
It should be noted in the following description that like or the same
reference
numerals in different embodiments denote the same or similar features.
[0029]
Referring to the drawings and particularly Figs. 1 to 5, there is shown a
submersible 11 which comprises a submersible body having an elongated body
with a
hydrodynamic effective shape for travel in at least one longitudinal
direction. There is a
power system including two longitudinal side thrusters 21 for allowing the
controllable
driving of the submersible body in the at least one longitudinal direction and
atop thruster
22 for allowing manoeuvering in a lateral plane to the longitudinal axis E-E.
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[0030] The body structure is a combination of body size, body
shape and body
sections and body material. It is also relevant for motor location and ballast
location.
Although this body structure is a preferred embodiment of the submersible it
is not the
only form of submersible that can use the ballast system of the invention.
[0031] It is important to keep the body size of the submersible 11 with the
submersible
being substantially in the range of 1 to 5 metres long and more preferably
substantially 1
to 1.5 metres long. In this way the buoyancy is readily maintained and can be
powered
with a battery power source 61 and allowing remote control or self-driving
especially with
the use of artificial intelligence of the visual capture system.
[0032] It is important to keep the body sections with the submersible being
symmetrical so that there is clear bidirectional operation. This allows ready
scanning of
a section by forward and reverse motion, without any optical detriment. It
also allows for
ready reversing when encountering a solid material or an underwater hazard
such as
trees, plant growth, coral and other natural hazards. There can be a need for
an
emergency evacuation manoeuvring due to fish or other aquatic animal dangers.
Still
further other waterway vehicle hazards might require detours or sudden
stabilising action.
Stabilisation generally occurs while in motion rather than while stationary.
[0033] As shown in Figs. 4 and 5 the elongated body of the
submersible 11 includes
a first and a second opposing substantially conical head 12 with a main
cylindrical part
13 therebetween and aligned along a common elongated axis to allow the
hydrodynamic
effective shape for travel in at least two opposing directions.
[0034] A submersible can have the main cylindrical central part
13 and the first and
the second opposing substantially conical nose heads 12 being detachable and
replaceable. Therefore, any nose head 12 that has faulty camera or connections
can be
readily replaced and repaired while the submersible is able to continue
operation with a
new nose part 12.
[0035] Also as shown in Fig. 5 the main cylindrical part 13 can
be replaced by a
differing length main cylindrical part and attached to the first and the
second opposing
substantially conical heads. A submersible with the main cylindrical part
having a differing
length main cylindrical part can include the payload.
[0036] Ballast Structure
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[0037] Referring to Fig. 6 the payload is generally locatable in
the central part 13 of
the body of the submersible and can be categorised into batteries 61, ballast
65,
electronics 69 and other payload. The size of the central part can be varied
to allow
different payloads and to allow replaceability.
[0038] Referring to Figs. 6 and 9, the ballast 65 is a ballast tank with a
one-way pump
with two-way switching valve for allowing water in and water out of the
central payload
part 13. Ballast is required as the submersible floats due to the weight of
water that it
displaces being equal to the weight of the submersible. This displacement of
water
creates an upward force or buoyant force. The submersible, with ballast, can
control its
to buoyancy, thus allowing control of the sinking and surfacing of the
submersible.
[0039] Generally, the submersible has ballast tanks, that can be
alternately filled with
water or air. When the submersible is on the surface, the ballast tanks are
filled with air
and the submersible's submerged density is less than that of the surrounding
water. To
submerge, the ballast tanks are flooded with water and the air in the ballast
tanks is
vented or pressurised to alter density until its overall density is greater
than the
surrounding water and the submersible begins to sink due to negative buoyancy.
[0040] A supply of compressed air can be maintained aboard the
submersible in air
tanks for use with the ballast tanks. However, there can merely be a pumping
out of water
and decrease in pressure and density. To keep the submersible level at any set
depth,
the submersible maintains a balance of air and water and pressure and thereby
density
in the ballast tanks so that its overall density is equal to the surrounding
water which is its
neutral buoyancy. When wishing to bring the submersible to the surface,
compressed air
flows from the air tanks into the ballast tanks and/or the water is forced out
of the
submersible until its overall density is less than the surrounding water and
forms positive
buoyancy and thereby the submersible surfaces,
[0041] The level of surfacing affects the requirements of the
ballast, the compressed
air and the balancing effect. However, the submersible of the invention is
only required
to surface sufficiently for access to the power and data access ports 41.
These are
located on a top surface of the submersible and above a surfacing line S-S of
Fig. 2 that
is above the centre of gravity of the submersible. In this way the submersible
stays in a
settled balanced upright orientation and avoids tendency to roll. Preferably
the surfacing
line S-S is in the top quartile of the submersible body.
[0042] The ballast structure comprises five main parts:
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a) Ballast tank - 65
b) Venting pathway ¨ 66, 67, 68, 70
c) One-way pump 71
d) Switching valves - A, B, C, D of 66
e) Control system
[0043] a) ballast tank
[0044] Referring to Figs 6 and 9 the ballast tank 65 is a
cylindrical pressure chamber
86 with an end cap 81 that has a central opening for receiving and connecting
to the
venting input 67 from the pump system 66 and the venting path 68 to the outlet
70 that
vents with the outside environment to the submersible.
[0045] The ballast tank includes a rubber bladder 85 within the
solid pressure
chamber 86 that is fed by a manifold 83 leading from the end cap 81 opening
and feeds
through spaced holes into the bladder at spaced distances. This ensures a
constant
pressure buildup or release of the whole bladder rather than distorted
expansion or
reduction.
[0046] In order to control the ballast tank pressure, it is a
more accurate approach to
include a relief valve that engages with a compressed gas source. In this way
the exact
pressure can be determined rather than relying on flow meters that are less
accurate.
[0047] b) Venting pathway
[0048] Referring to Figs 6, and 7 the venting pathway leads directly from
external
opening 70 to the ballast tank 65 through the directional pumping system 66.
As shown
in Figs 11 and 12 the external opening 70 includes piping 91 that feeds to
piping 68
leading to the directional pumping system 66. However, the external opening 70
does
not include a pressure control system but leaves that to be taken care of
downstream at
the directional pumping system 66. Instead the opening includes a porous body
92 with
porous holes 93 for controlling sedimentary intake but not preventing water
intake or
outtake.
[0049] c) One-way pump
[0050] Referring to Figs 6, 7 and 8 the pressure must be
maintained on one side from
the direct venting from the external opening 70 to the external pressure and
also the
pressure must be maintained ion the other side from the pressure in the
ballast tank.
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[0051] A submersible must change its pressure to submerge as
against reversing
pressure to surface the pumping system must be operative in two directions.
The ballast
pump must operate to take in water and pressure into the ballast as well as
releasing
water and pressure from the ballast pump while countering the effects of the
external
pressure.
[0052] Generally, pumps are notorious for being strong in one
direction but not in the
other. Further there is substantial weight and size limitation in submersibles
of the size
of less than 3 metres and preferably about 1 metre.
[0053] A novel solution to this problem is to use a one-way pump
with a switching
valve system. More particularly it is to use a diaphragm pump 71 in a one-way
operation
with a switching flow operation system. In this way the pump 71 provides
pressure control
on both sides of the pump and valve system 66 and operates as strongly with
flow in one
direction as with flow in the opposite direction.
[0054] The diaphragm pump can be a 12-volt system so easily
charged from the
batteries 61 of the submersible. The weight to power ratio provided can be 1.8
kilograms
providing greater that 100 psi. The rate of flow can be about 3 to 6 litres
per minute. This
allows the system to operate as a self-priming pump and to be corrosion
resistant and
have smooth operation over long continuous operation. the pump can include a
rubber
bracket to absorb the vibration from the working pump under pressure of
greater than
100psi.
[0055] d) Switching valve
[0056] For the switching valves to be able to take the pressure
on both sides of the
valve but to still allow switching and flow in opposite directions the valves
of the system
are ball valves. These type of valves do not have a weakness of operation from
one way
to the other.
[0057] Referring to Figures 13 and 14 the switching valves 79
and identified as A, B,
C, D. The four valves operate together with the one-way pump 71 with the
connected
piping to form the pump and valve system 66. This has two primary modes of
Mode A of
figure 13 where water and pressure are being vented out the outlet 70 and Mode
B of
figure 14 where water and pressure are being vented inwardly from the outlet
70.
[0058] In mode A and mode B the one-way pump 71 always forces
the flow from left
to right.
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[0059] The four valves operate as a unified set of four of the
switching valves 79
arranged to form two input switching valves A and C on an input side of the
one way
pump 71 and two output switching valves B and D on an output side of the one
way pump
71. A first of the input switching valves C fluidly connects to the venting
pathway 68
5 leading to external outlet 70 of the submersible body and a second of the
input switching
valves A fluidly connects to the venting pathway 67 leading to the bladder 65.
A first of
the output switching valves D fluidly connects to the venting pathway 68
leading to
external outlet 70 of the submersible body and a second of the output
switching valves B
fluidly connects to the venting pathway 67 leading to the bladder 65.
10 [0060] The control of input switching valves A, B, C, D is to have
either the first or
second input A or C switching valve open and the other closed and thereby feed
from
either the bladder or external to the input of the one-way pump and to
simultaneously
control of output switching valves to have either the first or second output
switching valves
B or D open and the other closed and thereby feed from the output of the one-
way pump
to the other of the bladder or external.
[0061] In mode A of Fig. 13 it can be seen that valve C is
closed and thereby not
providing a source of water or pressure. However, because of the strength of
the valve
it prevents leakage of pressure form valve D or from the external pressure
from outlet 70.
Instead in this mode valve A is open and allows input of water and pressure
from the
bladder into the input pathway of one-way pump 71. To ensure this operation of
input
flow the valve B is closed and thereby provides a strong barrier to the water
and pressure
from the bladder. The outlet bladder D is open and thereby the pump 71 is able
to ensure
pumping of water and pressure from the bladder 65 to the outlet 70.
[0062] In mode B of Fig 14 it can be seen that valve D is closed
and thereby not
providing a source of water or pressure. However, because of the strength of
the valve
it prevents leakage of pressure form valve C or from the external pressure
from outlet 70.
Instead in this mode valve C is open and allows input of water and pressure
from the
external outlet 70 into the input pathway of one-way pump 71. To ensure this
operation
of input flow the valve A is closed and thereby provides a strong barrier to
the water and
pressure from the bladder. The outlet bladder B is open and thereby the pump
71 is able
to ensure pumping of water and pressure from the outlet 70 to the bladder 65.
[0063] Referring to Fig 15 there is the ability to use the valve
array and pump to
distribute water across multiple bladders and not be restricted to just one
bladder. I.e. if
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we use two bladders, one at head and one at tail, control is achieved of the
attitude (pitch),
as well as our overall buoyancy. This operation method gives us another degree
of
freedom for control of submersible pitch and overall weight that is generally
not possible
with small submersibles.
[0064] This could be extended to any number of valves, and any number of
bladders.
[0065] The combination of diaphragm (or high pressure) pump and
valve array allows
for a compact solution that allows the dynamic movement of water through the
sub body,
to adjust for buoyancy and pitch offset. The compactness and extensibility of
the system
is what makes it ideal for the small form submersibles. In larger vessels,
where you have
space and greater weight freedoms, you could also use this system - however
you may
be better suited to using more common forms of ballast system, such as
gas/water ballast
systems, or piston pumps (with large motors to drive the units. Hence, it is
more a case
that this system has been developed for the small form factor, for
submersibles less than
5m.
[0066] e) Control system
[0067] The control system needs to undertake a number of
controls including control
of location, control of depth, control of system allowing position and/or
depth. Further the
control system must control the electronics, motors, and batteries.
[0068] In operation of the depth system it is necessary to control the flow
and pressure
through control of the valves 79 and pump 71 of the pump and valve system 66
and with
feedback of the pressure sensor on the ballast take interconnected to a
pressure source
for calibration and accurate volume and density calculation of water in the
ballast tank
and ready calculation of required pressure for required alteration of density
and thereby
alteration of buoyancy between the surface pressure and the neutral buoyancy
pressure.
[0069] The electronics includes electronics to run the motors
21, 22 as well as to
provide guidance through use of the stereoscopic cameras 35 as well as
controlling the
operation of the monoscopic wide angled cameras 31 for performing visual
capture. The
electronics collects the data from the visual image capture and is connectable
by
connector 41 when the submersible surfaces so as to transfer the data and
obtain
controlling instructions from a mother ship or other central bank.
[0070] Motor location
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[0071] As shown in Figs land 2, the power system for allowing
the controllable driving
of the submersible body is a 3 degree of freedom manoeuvering system, where it
can
move in the at least two opposing directions along the axis of the elongated
shape, up
and down, left and right. This is provided by two side thrusters 21 on either
side of the
elongated body and a top thruster 22 on a top surface.
[0072] The top thrusters 22 of the power system on the top side
of the elongated body
include 2 motors spinning in opposite directions to counter the angular
momentum of
each single motor. The top thruster is placed in the middle of the AUV
therefore the force
generated from the thruster is very close to the centre of mass point, this
helps with the
control system and reduce complication in the maneuvering control.
[0073] The side thruster 21 has a tube-like configuration to
decrease the amount of
turbulent generate from the thruster. This helps with the ability to take high
quality
pictures from the camera that are behind the thruster stream.
[0074] The two side thrusters of the power system on either side
of the elongated
body are under the centre of gravity plane, wherein the submersible is
maintained stable
during maneuvering. More preferably it is in the lower 25 percentile. The
thruster force
plane is parallel to the centre of gravity plane which extends longitudinally
down the
submersible. With the thruster force being operative longitudinally it
provides the primary
main bidirectional movement in opposing directions along the elongated axis.
[0075] A beneficial element is that the power system can be totally on the
central part
12 with the payload of the batteries 61 and controlling electronics 69 also in
the central
part. In this way the motor is spaced from the primary ring 411 of cameras 31
on the axis
A-A or B-B on the nose parts 12 of the submersible.
[0076] Apart from normal movement of the submersible an
important element is that
there are top thrusters 22 that allow movement of the submersible around a 3
to 5 metre
range around the neutral buoyancy. In this way there is ready fine tuning of
operation
without use of the ballast system. This is a substantial advantage over
submersibles that
only include ballast systems.
[0077] The combination of bladder system and top mounted
thrusters are important.
The bladder system can be used for neutral buoyancy trim, with the top
thrusters used
for ascent and descent (precise depth control). The combination of top
thrusters and
ballast system is also important for the purposes of energy efficiency, and
optimisation of
motion. E.g. If we intend to descend the submersible to a greater depth, then
we can
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adjust to be heavier than water so that we descend - without any further
actuation from
the top thrusters, thus saving energy. We can then re-trim to neutral once we
achieve our
desired depth. In this case, top thrusters could act as trimming tools, whilst
the bladder
system could be the primary driver of vertical motion.
[0078] Conversely, if we want to resurface, the submersible could simply
evacuate
the bladder completely, and rise to the surface in a highly efficient manner
(without any
further control input from thrusters), except if one wanted to control the
rate of
ascent/descent.
[0079] Our mode of operation - using bladder as primary driver
of motion, with
thrusters as trim; or thrusters as primary driver, with bladder as trim (to
trim to neutral) -
could be switched depending on the types of applications that the submersible
is
undertaking.
[0080] By tying in the use of the horizontal thrusters, we are
able to control our surge
and yaw as we descend under the effort of the bladder system. If desired, we
can adjust
is our attitude using the bladder system to point the nose of the
submersible in a specific
direction, and use the horizontal thrusters to thrust in that direction
[0081] I.e. We use the bladder system to point the submersible
and its actuators in a
desired direction, and run horizontal thrusters to actuate in that direction.
This, again,
would give us a more efficient form of motion in some situations. The bladder
system acts
as an attitude actuation method, whilst the thrusters act as a linear
actuation method.
[0082] This mode of operation could also be extended to be used
to align cameras in
a particular direction (e.g. dimming the nose to get a better view of a
particular underwater
object).
[0083] Our system (bladder + thrusters) is designed for both
trimming to neutral, as
well being the primary driver of vertical actuation. The total volume of the
bladder used
should be calculated as a percentage of the weight and total density (weight
and volume
factors) of the submersible, so that it can be used to trim in all kinds of
water conditions.
As an example, if the submersible has a density of 990kg/m^3 and weight of
100kg, and
we aim to have a bladder volume of 5% (of total weight), this will allow us to
adjust our
total weight (and hence density) from 100-105kg. This would allow us to adjust
our density
to be from 990-1039kg/m^3. Hence, we could aim for neutral buoyancy in both
fresh water
(1000kg/m^3) and salt water (1035kg/m^3).
[0084] Overall, the combination of thrusters and bladder system
is essential for
generating the types of actuation (mode of operation)
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14
[0085] Example
[0086]
With a submersible designed to operate at maximum depth the current
bladder
system is 88 metres which is roughly 142.991 psi (pounds per square inch).
Referring to Fig 16 an example of pressure characteristic of the submersible
as we are
sinking:
a) Submersible is on top of the surface. Internal pressure 14.69 psi and
External
pressure 14.69 psi. The submersible current density is less than the sea water
density
b) As we want to sink, the bladder will then take in the water. The water that
we take
in replace the available air space inside the submersible, in other words it
is
compressing the internal air space. The internal pressure now increased to
15.69
psi. We then lock our valve and stop the pump (the internal pressure has
increase
by 1 psi due to the positive displacement of the water that we take in). This
process
takes around 6 seconds. We are pumping at the rate of 8L/Min which result in a
total take in of 0.78L of sea water (0.7995kg)
c) At this point our density is higher than the water density so the
submersible start
to sink. As soon as we reach the depth that is desire (overshoot). We start to
open
the valve and pumping out the water. At this point out internal pressure is
15.69p5i
and External pressure (depends on depth ideal situation is 88meter (142.991
psi))
d) The pressure different from internal vs external is: 142.991 ¨ 15.69 =
127.301 psi.
This pressure different is what the pump needs to be working against to pump
the
water from inside the submersible to outside environment. Because the pump is
working against it ideal situation which is on the surface the pump rate is
dropped
from 8L/min down to 1L/min due to strong pressure is pushing back in the
system
from outside environment when we open the valve.
e) In order to achieve neutral buoyancy, we have to pump out the amount of
water
until the internal pressure is down to 14.909 psi (currently 15.69 psi). At
this point
it would take us roughly 36.7 seconds.
f) After this the submersible is running on engines
g) To pump out the 0.78L at this point it would take the sub around 10.2
seconds to
be positive in buoyance force. This will bring us up to surface. And the
process
repeats
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Interpretation
Embodiments:
[0087] Reference throughout this specification to "one
embodiment" or "an
embodiment" means that a particular feature, structure or characteristic
described in
5 connection with the embodiment is included in at least one embodiment of
the present
invention. Thus, appearances of the phrases "in one embodiment" or "in an
embodiment"
in various places throughout this specification are not necessarily all
referring to the same
embodiment, but may. Furthermore, the particular features, structures or
characteristics
may be combined in any suitable manner, as would be apparent to one of
ordinary skill
10 in the art from this disclosure, in one or more embodiments.
[0088] Similarly it should be appreciated that in the above
description of example
embodiments of the invention, various features of the invention are sometimes
grouped
together in a single embodiment, figure, or description thereof for the
purpose of
streamlining the disclosure and aiding in the understanding of one or more of
the various
15 inventive aspects. This method of disclosure, however, is not to be
interpreted as
reflecting an intention that the claimed invention requires more features than
are
expressly recited in each claim. Rather, as the following claims reflect,
inventive aspects
lie in less than all features of a single foregoing disclosed embodiment.
Thus, the claims
following the Detailed Description of Specific Embodiments are hereby
expressly
incorporated into this Detailed Description of Specific Embodiments, with each
claim
standing on its own as a separate embodiment of this invention.
[0089] Furthermore, while some embodiments described herein
include some but not
other features included in other embodiments, combinations of features of
different
embodiments are meant to be within the scope of the invention, and form
different
embodiments, as would be understood by those in the art. For example, in the
following
claims, any of the claimed embodiments can be used in any combination.
Different Instances of Objects
[0090] As used herein, unless otherwise specified the use of the
ordinal adjectives
"first", "second", "third", etc., to describe a common object, merely indicate
that different
instances of like objects are being referred to, and are not intended to imply
that the
objects so described must be in a given sequence, either temporally,
spatially, in ranking,
or in any other manner.
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Specific Details
[0091] In the description provided herein, numerous specific
details are set forth.
However, it is understood that embodiments of the invention may be practiced
without
these specific details. In other instances, well-known methods, structures and
techniques
have not been shown in detail in order not to obscure an understanding of this
description.
Terminology
[0092] In describing the preferred embodiment of the invention
illustrated in the
drawings, specific terminology will be resorted to for the sake of clarity.
However, the
invention is not intended to be limited to the specific terms so selected, and
it is to be
understood that each specific term includes all technical equivalents which
operate in a
similar manner to accomplish a similar technical purpose. Terms such as
"forward",
"rearward'', "radially", "peripherally", "upwardly", "downwardly", and the
like are used as
words of convenience to provide reference points and are not to be construed
as limiting
terms.
Comprising and Including
[0093] In the claims which follow and in the preceding
description of the invention,
except where the context requires otherwise due to express language or
necessary
implication, the word "comprise" or variations such as "comprises" or
"comprising" are
used in an inclusive sense, i.e. to specify the presence of the stated
features but not to
preclude the presence or addition of further features in various embodiments
of the
invention.
[0094] Any one of the terms: including or which includes or that
includes as used
herein is also an open term that also means including at least the
elements/features that
follow the term, but not excluding others. Thus, including is synonymous with
and means
comprising.
Scope of Invention
[0095] Thus, while there has been described what are believed to
be the preferred
embodiments of the invention, those skilled in the art will recognize that
other and further
modifications may be made thereto without departing from the spirit of the
invention, and
it is intended to claim all such changes and modifications as fall within the
scope of the
invention. For example, any formulas given above are merely representative of
procedures that may be used. Functionality may be added or deleted from the
block
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17
diagrams and operations may be interchanged among functional blocks. Steps may
be
added or deleted to methods described within the scope of the present
invention.
[0096] Although the invention has been described with reference
to specific
examples, it will be appreciated by those skilled in the art that the
invention may be
embodied in many other forms.
Industrial Applicability
[0097] It is apparent from the above, that the arrangements
described are applicable
to the submersible industries.
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