CA2160605C

CA2160605C - Wave-powered ocean profiler

Info

Publication number: CA2160605C
Application number: CA002160605A
Authority: CA
Inventors: George A. Fowler
Original assignee: Individual
Current assignee: Individual
Priority date: 1995-10-16
Filing date: 1995-10-16
Publication date: 2001-01-30
Anticipated expiration: 2015-10-16
Also published as: CA2160605A1

Abstract

An ocean profiler that utilizes ocean wave energy to provide power for repeated ascent and descent of an oceanographic instrument. In one embodiment the instrument assembly is provided with either positive or negative buoyancy such that the instrument can traverse one half of the travel cycle rapidly utilizing the buoyancy force. Utilizing wave power for instrument traversing greatly reduces the power requirement of the apparatus allowing extended unattended operation.

Description

2l6o6os TITLE
Wave-Powered Ocean Profiler FIELD OF THE INVENTION
This invention relates to a wave-powered apparatus for collecting oceanographic profile data.
BACKGROUND OF THE INVENTION
Time series profiles of salinity and temperature of the upper layers of the ocean are useful for the study of valious ocean conditions such as the variation Or ocean currents. Various types of oceanographic profilers have been used or proposed to measure ocean parameters at diffelent depths.
A number of prior profilers involve moving the sensing instrument up and down along a moored line. Many of these prior devices operate by changing the buoyancy for each c~cle of operation. An example of such a device is disclosed iU.S. Patent 3,927,~62 which uses a plurality of gas generators wherein one gas generator is utilized to vary buoyancy for each cycle of ascent and descent.
One of the difficulties with plesent plofilers is that considerable stored energy, in the profilel is required to repeatedly change buoyancy, or otherwise raise and lower the instrument, over many cycles of operation.
For the ocean culrent variation studies refelred to above, it would be desirable to have a high resolution oceanographic profiler that can operate lln~tt~nd( d for long periods of time, such as two yeals or longer, and be capable of daily operation to a depth of 2,000 m.

21606o~
SUMMARY OF THE INVENTION
An object of the present invention is to provide an apparatus for collecting O~ profile data that requires little stored energy and can be used to operate l~n ~tten~led for relatively long periods of time.
It has been found that oceanographic plofile data can be obtained by ~
device that utilizes wave energy to convey the plofiler iu~llu~ up and down.
The present invention provides a wave-powered ocean profiler, ~ illg.
an - UIII~IIL for collecting oceanoglapllic plofile data; a buoyant member for riding the waves on a body of watel; a line suspended from a lower end of the buoyant member; a line traversing assembly operatively disposed on the line for supporting the ill~ll ull~lll and conveying the instrument along the line; said traversing assembly including a disengagable one-way clutch, operative, while engaged, to allow travel incrementally along the line in one direction as the line rises and falls under the action of waves, and to prevent travel along the line in the opposite dilection; and actuating means for tlle one-way clutch, responsive to a condition l~ se~ldlive of a desiled travel limit of the traversing assembly along the line, and operative for selectively engaging or disengaging the one way clutch.
BRIEF DESCRIPTION OF THE DRAWING~
Fig. 1 is a schematic l~ se..ldlion of the oce~r.~apl.ic plofiler of the present invention.
Fig. 2 is an enlarged view of the ill~llulll~lll assembly shown in Fig. 1.
Fig. 3 is an enlarged view of a portion of the instrument assembly illustrating details of one embodiment of the one-way clutch and clutch actuatin~
I..r. 1,~1~;'.-ll Figs. 4(a), (b), and (c) show the one-way clutch of Fig. 3 in the engaged position, disengaged position, and locked position, respectively.

216060~
DESCRIPTION OF THE PREFERRED EMBODIMENTS
With reference to Fig. 1, the present invention comprises a buoyant member 1 having suspended therefrom a line 2. Operatively associated with the line is a line traversing assembly 6 for conveying instrument components for thea~q~liciti~n and ~ ion of pl-oSle data.
With reference to Fig. 2, the profile ill~llL..~ U..I~JU.._llt~ 10 include profile data sensing and recording means 11, battery 12, and electronic . 13 for data processing and ~ ;vil and may include a computer 15 for system control.
As illustrated in Fig. 2, the traversing assembly 6 comprises a sealed enclosure 16 that encloses a numbel- of the system ~vlllpu~ . In the pleferred embodiment of the invention, the enclosure 16 is designed such that the line traversing assembly 6 has a specific g~avity diffelent from that of the water toprovide either positive or negative buoyancy. For example, positive buoyancy canbe achieved by a sealed enclosure 16 containing air or gas.
In the embodiment illustrated in ~igs. 1 to 3, the ill~ll Ulll~,l.. traversing assembly 6 has a single riic~ng~ c one-way clutch 8, operative, while engaged, to allow travel i...~ dlly along the line 2 in a direction against the buoyancy force of the assembly as the buoyant membel 1 and line 2 rises and falls under the action of waves, and prevents travel along the line in the opposite direction.
In this embodiment the buoyancy force is utili~ed to retuln the assembly 6 to the original position, by disengaging the clutch from the line 2.
~s best seen in Fig. 3 and 4, the one-way clutch 8 is selectively engaged or rlic~ng;l~ed by actuator 17 by means of alm 18. When disengaged, the assembly moves freely in the direction of the buoyancy force. Figs. 4(a), (b), and (c) show the one-way clutch of Fig. 3 in the engaged position, disengaged position, and locked position respectively.

216060~
Fig. 3 shows details of one embodiment of an actuator mechanism 17 which includes an arm 18, drive motor 19 and interrr~nr~in~ motion translating ~ 20. It will be understood that othel forms of Inr~ could be used.
Activation of the one-way clutch by actuator 17 may be made responsive to a condition ~ selll~ive of a desired travel position of the traversing assembly 6 along the line, with the use of suitable control means. The control means may, for example, include a marker, or mal*ers, on the line l~ i,.g travel limits, and a suitable marker sensor, or the contlol means may be made responsive to the position by suitable depth sensing means. The control means may include suitable computer 15. Altelnatively, activation of the one-way clutch may be activated entirely, or partly, by mechanical means, for example with the use of stoppers 4, defining upper and lower travel limits.
The c~,.,.p~ ~t referled to as a "one-way clutch" helein, may take any of various forms which allows the instrument assembly 6 to tlavel along the line il, one direction only, when engaged, and to allow fiee travel when disengaged. A
device found to be suitable is known as a "Chicago Clamp" which has been used atsea for many years. Other devices could be used, such as a collet.
The one-way clutches could be contlolled mechanically, for example, with the use of upper and lower mechanical stoppels which could provide that th~
.i assembly cycles continuously between the stoppers. For greater ~dexibility the one-way clutches are pleferably contlolled by a computer 15 which facilitates greater flexibility in cycle timing and/or for transfer of data.
Since there is the possibility of wear occurring whele the clutch locks repeatedly onto the line, it may be desirable to introduce a "dither" command intc the locking cycle.

.
~j 2l6o6o5 The assembl~ 6 is shown provided witll bumpers 14 which are adapted to contact with stoppers or bumpers 4 disposed at the upper and lower travel limitsof the line 2, as shown in Fig. 1.
Preferably the line 2 will be provided with some form of tightening means to provide that the line is taut and moves up and down with the buoyant member 1, as it rides up and down with the waves S. This can be achieved by the use of suitable ballast 3, as shown in Fig. 1, or may be achieved by the use of sufficient mass of the line 2, itself. Alternatively, an elastic member my be interconnected between the lower end of the line 2 and the ocean bottom.
The system may be anchored in the desired location with a suitablc anchor 8 shown attached to the ballast 3, or be allowed to drift freely.
The buoyant member may be made up of a group of intel-u. --trd bouys, rather than a single unit as illustrated. Such an arrangement can be advantageous for ~tt~ntl~tin~ motion of the line, and hence the travelsing assembly, in beavylS weather. Protection in heavy weather for the tlavelsing assembly and/ol illD~lU~ .~11 D can also be obtained by ill~ol~J~Jla~;ng suitable suspension and/or damping means.
In operation, the action of ocean waves moves the buoyant member 1 up and down. The line 2 which is attached to the buoyant member 1, also moves up and down, along with any attached ballast 3. The instrument assembly 6 is attached to the line 2 by means of a one-way clutch 8. With the one-way clutch engaged, by actuator 18, as shown in Fig. 4(b), the assembly is pulled along with the line as it moves in one direction, while allowing the line to slide relative to the iUD~lUlUCill~ assembly 6 in the opposite direction. With lepeated up and down motion of the line, the ;IIDLII~ Will advance incrementally in one directio determined by the selected orientation of the one-way clutch 8.
For return to the original position, the one-way clutch is disengaged fiom the line as shown in Fig. 4(b), returning fol example, by utilizing the buoyancy 216060~
force of the traversiDg assembly. When no advancing motion of the assembly is desired, such as when ll g data, the one-way clutch can be locked as shown in Fig. 4(c) Profile data can be recorded by the i~ luul during descent, ascent, or both directions. In an embodiment that utilizes buoyancy for ascent, data during the ascent may be preferably for a number of reasons. With a suitable buoyancy force, the ill~llulllelll can be made to rise rapidly so that power to the sensors and data logger need be supplied for a shorter time. Furthermore,the ascent will be smoother and more consistent. Also, ~l,u~ ;on of data to the surface buoy can be achie~ed with a less powerful transmitter.
Data recorded by the i .llulll~ can be collected and/or transmitted by kDown telemetering tl~nhniq~ For example, an acoustic ~ " system can be used to transfer data to the surface buoyant member from which it can be transmitted elsewhere via satellite.
For proper operation the instrument assembly must be provided with sufflcient inertia and/or ll~dlu(lyllalllic drag to ensure that the traversing assembly does l~ot follow the line in both dilections of the up-down cycle of the line. The h~dludyllalll;c drag of any ballast used should be as low as possible so that it and the liDe moves in concelt with the buoyant membel.
In the embodiment illustrated, utilizing one one-way clutch, when th~
assembly reaches a predetermined position the one-way clutch is disengaged by actuator 18 (see Fig. 4(b) so that the instrument assembly is free to travel in the directioD determined by its buoyancy. In anothel emhodiment, wherein two one-way clutches are employed, the actuator arm 18 revelses the cr.6~.6~ l-l or /lic~n~ment status of each clutch.
As indicated above, the ill~LIulll.,.it assembly can have either positive or negative buoyancy. In the former case, the action of the waves is used to drive the assembly dowDward while the buoyancy folce can be utilized to bring the 21 6~60~
assembly up to the upper position. In the later case, the action of the waves isused to drive the assembly upward while the negative buoyancy force can be utilized to bring the assembly down to the lower position.
In another embodiment of the invention, in wllich the traversing assembly 6 has sl~hstAnhz~lly neutral buoyancy, the assembly employs two one-way clutches. I
this; ~odiu.~ one clutch would be engaged while the other is tliC~n~Ag~d for each direction of travel, and both clutches would be reversed for the opposite direction of travel.
Since the power for raising and lowering the ill;,llu~ l is provided by wave energy, the plesent profiler can be made to operate unattended fol relatively long periods of time. Still longer operation can be obtained by utilizing ocean wave, current, wind or solar energy for chalging a battely for the electlonic -ol~ used for data acquisition and lld~ iOll and system control.
E:xample A prototype similal to that illustrated in the dlawings was constructed and tested. The device was provided with a single one-way clutch to drive the instrument assembly downward under the action of waves, and used positive buoyancy to retuln the instrument to the surface. The i.l~l-ull,~ assembly was 2.24 m long, 0.26 m in diameter, had a mass of 100 kg, and a positi~e buoyancy of 2.27 kg. The tests were run on a buoy/mooring which was forced at 0.43 hz witl peak to peak amplitude of 0.24 m by the waves. These values were determined by doing a spectral analysis of the data obtained by a motion sensing i..~llu~Clll attached to the buoy. The waves pl-oduced a descent speed of about 12 to 14 m/min. The ascent speed, under the buoyancy force with one-way clutch disengaged, was 30 m/min.

Claims

What is claimed is:

1. A wave-powered ocean profiler, comprising:
a) an instrument for collecting oceanographic profile data;
b) a buoyant member for riding the waves on a body of water;
c) a line suspended from a lower end of the buoyant member;
d) a line traversing assembly operatively disposed on the line for supporting the instrument and conveying the instrument along the line; said traversing assembly including a disengagable one-way clutch, operative, while engaged, to allow travel incrementally along the line in one direction as the line rises and falls under the action of waves, and to prevent travel along the line in the opposite direction; and e) actuating means for the one-way clutch, responsive to a condition representative of a desired travel limit of the traversing assembly along the line, and operative for selectively engaging or disengaging the one way clutch.

The apparatus of Claim 1 wherein the traversing assembly includes an enclosure having a specific gravity different from that of the body of water to provide a force urging the assembly for travel along the line, while the one-way clutch is disengaged, in a direction opposite to that provided by the action of waves while the one-way clutch is engaged.

3. The apparatus of Claim 1 further comprising a second one-way clutch which is actuated opposite to that of the other one-way clutch, upon reaching a predetermined travel position for travel in the opposite direction.

4. The apparatus of Claim 1 further comprising line tightening means to provide that the line is taut and moves up and down with the buoyant member

5. The apparatus of Claim 4 wherein the line tightening means comprises ballast means attached to a lower end of the line.

6. The apparatus of Claim 4 wherein the line tightening means comprises an elastic member interconnecting a lower end of the line and the ocean bottom.

7. The apparatus of Claim 1 further comprising anchoring means connected at a lower end of said line to restrict horizontal travel of the buoyant member while allowing the buoyant member, line to ride up and down with the action of waves.

8. The apparatus of Claim 1 further comprising telemetering means for transmitting data from the instrument.

9. The apparatus of Claim 1 further comprising control means for control of the actuating means.