DEVICE FOR GENERATING ELECTRICITY USING BUOYANCY

TECHNICAL FIELD

The present in vveennttiioonn ggeenneerraallllyy rreellaatteess ttoo aann eelleeccttrriicciittyy ggeenneerraattiioonn ddeevviicce, and more particularly to a buoyancy electricity generation device for generating electric power using buoyancy of bubbles.

BACKGROUND ART

Various energy sources such as thermal power, hydraulic power, atomic power, tidal power, wind power, etc. are used to generate power. A thermal power plant utilizes combustion energy of fossil fuel such as coal and oil. An atomic power plant utilizes nuclear fission energy of radioactive substances. However, they must be located in a place far away from a residential area due to environmental pollution and radioactivity leak. A hydraulic power plant carries out electric power generation using the difference in elevation of water contained in a dam blocking a river. It should be constructed at a river having a rich rainfall or a larger flow amount in order to obtain a sufficient amount of water. A tidal power plant carries out using the difference in elevation of seawater stored in a barrier by the flux and reflux of tides. It is constructed at a coast where there is a large difference between the flux and reflux of tides. A wind power plant carries power generation by rotating a windmill by means of wind. It is constructed at a place where strong winds tend to blow.

As such, there is a problem with conventional power generation ways in that environmental pollutions occur or the location of power plants is greatly restricted. Further, since the power plants are generally far away from places demanding electric power, there is another problem in that a transmission facility should be constructed throughout a long distance from the power plants to the places demanding electric power.

Recently, in order to solve such problems of conventional power generation ways, electric power generation ways using buoyancy as energy source were proposed. As one example of such ways, there is an electric power generation way wherein a water wheel is rotated by means of the rising force of bubbles.

In case of a motion, wherein an object having a weight of 75kg falls in the atmosphere for one second by Im, is used for electric power generation in whole, electric power generation of 1 horsepower is obtained. In the meantime, bubbles rise at a speed of about 0.5m/s in water. If a bubble giving buoyancy corresponding l

to a weight of 75kg exists in water, such a bubble rises by Im for about 2 seconds. Thus, electric power, which is twice more than the above-discussed electric power generation made by the fall in the atmosphere, can be produced. This is based on a principle similar to electric power generation made by the difference in elevation of water in hydroelectric power generation. However, this means that if air can be blown at a depth corresponding to the difference of elevation, electric power generation having a better efficiency is possible over hydroelectric power generation using the difference of elevation of water. For example, a maximum theoretical output of typical hydroelectric power generation is known as P(kW)=9.8HQ (wherein Q is flow amount per seconds (m ³ /s) and H is an effective difference in elevation). However, in case of electric power generation using buoyancy, considering the rising speed of bubbles, a maximum theoretical output can become S(kW)=2d ^χ 9.8Q (wherein Q is an amount of air (m ³ ) and d is a depth).

As one example of such electricity generation devices using buoyancy, Korean Patent Application Publication No. 10-2000-14747 discloses a buoyancy electricity generation device, wherein water wheels with wings are disposed at multiple stages in a tank and air is ejected to wings of the water wheels through a nozzle placed on a bottom of the tank by means of an air compressor to thereby rotate the water wheel and drive a generator. Also, Korean Utility Model Application Publication No. 93-19971 discloses a buoyancy electricity generation device, wherein two rotary elements are disposed to be spaced vertically in a tank and a chain connecting two rotary elements is provided with a plurality of air-collecting parts and high-pressure exhaust gas from an internal combustion engine provided outside the tank is supplied to the air-collecting parts at a bottom of the tank. This allows electric power generation using buoyancy of the exhaust gas.

In such prior art buoyancy electricity generation devices, the high-pressure air or exhaust gas is ejected into water to generate bubbles. Thus, in case of increasing the depth of water to increase an amount of electric power generation, there is a need to increase the output of the compressor or the internal combustion engine so that the high-pressure air or the exhaust gas can be supplied at a higher pressure sufficiently enough to overcome increased water pressure near the bottom of the tank. However, as the depth of water increases by 10m, the water pressure rises by about 1 atmospheric pressure. For example, the water pressure at the depth of water of 100m becomes about 11 atmospheric pressures. However, conventional compressors or internal combustion engines cannot sufficiently blow air or exhaust

gas into such water under high pressure. Accordingly, there is a problem with the prior art buoyancy electricity generation device in that power generation capability is difficult to increase and the use of a high-pressure compressor requiring a large power consumption rather lowers power generation efficiency.

DISCLOSURE TECHNICAL PROBLEM

The present invention is directed to solving the foregoing problems. It is an object of the present invention to provide an electricity generation device using buoyancy as energy source.

It is another object of the present invention to provide a buoyancy electricity generation device, which is configured to facilitate air supply at a deeper depth of water to thereby lengthen a buoyancy distance and enhance power generation efficiency. It is yet another object of the present invention to provide a buoyancy electricity generation device, which can be constructed near places demanding electric power to thereby simplify the construction of a transmission facility.

TECHNICAL SOLUTION In order to achieve the above and other objects, the present invention provides a device of generating electricity using buoyancy, which comprises the following: a tank containing a liquid; an air supplying device including: a bellows- shaped air chamber having an air inlet allowing an external air to flow in and an air outlet allowing an internal air to flow out, the air inlet being openable during expansion of the air chamber and the air outlet being openable during contraction of the air chamber; and a drive shaft for expanding and contracting the air chamber by a reciprocating motion; a drive device for reciprocating the drive shaft of the air supplying device; an exhaust pipe in communication with the air outlet at one end portion thereof, the other end portion thereof being located near a bottom of the tank; motion converting means for collecting bubbles discharged from the other end portion of the exhaust pipe and converting a rise motion caused by buoyancy of the collected bubbles into a rotary motion; and a generator for generating electricity from the rotary motion caused by the motion converting means.

The motion converting means may include: a chain; a plurality of buckets disposed on the chain for collecting the bubbles; and first and second rotary means vertically spaced apart from each other, each rotary means engaging to the chain.

The generator is operatively coupled to a rotating shaft of the first rotary means.

The air supplying device may be located at a lower side of the tank. The air supplying device further includes: a housing containing the air chamber therein and maintaining an internal space of the air supplying device at a liquid-tight state; and a air supplying pipe in communication with an atmosphere outside the tank at one end portion thereof and being in communication with an internal space of the housing at the other end portion thereof. The drive device reciprocates the drive shaft by the rotary motion of the motion converting means.

The chain may include a plurality of contact members corresponding to each bucket. The drive device includes engaging and releasing means. The engaging and releasing means may engage to a closest one of the contact members being rotated together with the chain and may be then released from the closest one after being rotated at a predetermined angle along with the rotation of the chain. In such a case, the drive shaft is coupled to the engaging and releasing means and is lifted by the rotation of the engaging and releasing means.

The engaging and releasing means may comprise a rotary element having first and second arms spread at a predetermined angle. The rotary element is pivotable about a pivot shaft disposed adjacent to a lower end portion of the chain.

The first arm includes a portion engaging to the contact member and the second arm is coupled to the drive shaft.

The air chamber includes a movable frame and a fixed frame fixed within an inside of the housing. The drive shaft is coupled to the movable frame of the air chamber.

The air supplying device may further include elastically pressing means disposed on the drive shaft, the elastically pressing means pressing the drive shaft in an opposite direction to the lift of the drive shaft.

The air inlet and the air outlet may include a check valve. The air supplying device may be located outside the tank. The exhaust pipe is closed at the other end portion thereof. Further, the exhaust pipe includes: a plurality of holes disposed in proximity with the other end portion thereof, the discharged air passing through the holes; and an elastic cap wrapping the holes and opening and closing the holes.

Preferably, the exhaust pipe has a cross-sectional area corresponding to 15% of a cross-sectional area of the air chamber. Further, the present invention provides a device of generating electricity using buoyancy, which comprises the following: a tank containing a liquid; a discharging

means disposed near a bottom of the tank for flowing a portion of the liquid; an air supplying pipe in communication with an atmosphere outside the tank at one end portion thereof, the other end portion thereof being an air supplying outlet in communication with an inside of the tank; a bubble generating pipe opened at one end portion and the other end portion thereof and receiving the liquid flowing by the discharging means at the one end portion thereof, the other end portion thereof being in communication with the inside of the tank, wherein the bubble generating pipe is joined to the air supplying pipe such that the air supplying outlet is located inside the bubble generating pipe, wherein the bubble generating pipe includes a bubble generating means allowing the air supplied from the air supplying outlet to be sucked into the liquid discharged from the discharging means to generate bubbles; a motion converting means for collecting bubbles discharged from the other end portion of the bubble generating pipe and converting a rise motion caused by buoyancy of the collected bubbles into a rotary motion; and a generator for generating electricity from the rotary motion caused by the motion converting means.

The bubble generating means is a throat portion having a reduced cross- sectional area in the bubble generating pipe. The air supply outlet is located in the throat portion.

An inner diameter of the throat portion is dimensioned so that the liquid flowing by the discharging means has a pressure close to an atmospheric pressure while passing through the throat portion.

The air supplying pipe diverges into a plurality of short pipes at the other end portion thereof. Opened end portions of the short pipes form the air supplying outlet. A portion of the air supplying pipe adjacent to the other end portion thereof includes: a portion extending parallel to the bubble generating pipe from downstream of the throat portion of the bubble generating pipe upstream up to the throat portion; and a portion extending vertically from said portion to the air supplying outlet.

An air pump may be provided at the air supplying pipe. The bubble generating pipe is placed parallel to a level surface of the liquid.

Preferably, the discharging means is a submergible motor pump.

The motion converting means includes: a chain; a plurality of buckets disposed on the chain for collecting the bubbles; and first and second rotary means vertically spaced apart from each other, each rotary means engaging to the chain. The electric generator is operatively coupled to a rotating shaft of the first rotary means.

The device further comprises a governor disposed between the rotating shaft and the generator. The governor constantly maintains a velocity of the rotary motion of the motion converting means to be introduced to the generator.

Further, the present invention provides a device of generating electricity using buoyancy, which comprises the following: a tank containing a liquid; a discharging means disposed near a bottom of the tank for flowing a portion of the liquid; an air supplying pipe in communication with an atmosphere outside the tank at one end portion thereof, the other end portion thereof being an air supplying outlet in communication with an inside of the tank; a bubble generating pipe opened at one end portion and the other end portion thereof and receiving the liquid flowing by the discharging means at the one end portion thereof, the other end portion thereof being in communication with the inside of the tank, wherein the bubble generating pipe has a throat portion having a reduced cross-sectional area therein, wherein the bubble generating pipe is joined to the air supplying pipe such that the air supplying outlet is located in the throat portion, wherein the bubble generating pipe allows the air supplied from the air supplying outlet to be sucked into the liquid discharged from the discharging means to generate bubbles; a plurality of bucket assemblies, each including: a rotating shaft supported by an inner wall of the tank at both ends thereof; a plurality of arms radially extending from the rotating shaft; and a plurality of buckets disposed at distal ends of the arms; a plurality of bubble guiding members disposed between the bucket assemblies for collecting the bubbles escaping from the lower bucket assembly and guiding the collected bubbles to the upper bucket assembly; and a generator connected to one or more rotating shafts for generating electricity. An inner diameter of the throat portion is dimensioned so that the liquid flowing by the discharging means has a pressure close to an atmospheric pressure while passing through the throat portion. Such a buoyancy electricity generation device further comprises a means for interlocking the rotating shafts of the bucket assemblies. An air pump may be provided at the air supplying pipe.

ADVANTAGEOUS EFFECTS

The buoyancy electricity generation device, which is constructed in accordance with the present invention, may provide the following effects.

First, since bubbles are generated in liquid contained in a tank and power generation is made by using buoyancy of such bubbles, the buoyancy electricity generation device can be constructed in any place demanding electric power without any restriction on geographic and topographic conditions relevant to obtaining

energy source for power generation.

Second, since air can be easily supplied at a deeper depth of water, the buoyancy electricity generation device can maximize the use of buoyancy and enhance the power generation efficiency. Third, since the tank for containing liquid can be constructed near places demanding electric power, the buoyancy electricity generation device can simplify the construction of a transmission facility.

DESCRIPTION OF DRAWINGS Fig. 1 shows an inner side of a buoyancy electricity generation device according to a first embodiment of the present invention.

Fig. 2 is a side view of the buoyancy electricity generation device of Fig. 1 and showing its inner side.

Fig. 3 shows a combined structure of a discharging means, an air supplying pipe and a bubble generating pipe.

Fig. 4 shows a coupled structure of the discharging means, the air supplying pipe and the bubble generating pipe, and further shows an alternative of the bubble generating pipe.

Figs. 5 and 6 are perspective views showing air supplying outlets of the air supplying pipes.

Fig. 7 shows an alternative of the other end portion of the air supplying pipe. Fig. 8 is a front view of a unit chain and a bucket. Fig. 9 is a side view of the unit chain and the bucket. Fig. 10 shows an inner side of a buoyancy electricity generation device according to a second embodiment of the present invention.

Fig. 11 is a side view of the buoyancy electricity generation device of Fig. 11 and showing its inner side.

Fig. 12 shows an installation example of the buoyancy electricity generation device of the present invention. Fig. 13 a front view of a buoyancy electricity generation device according to a third embodiment of the present invention and showing its inner side.

Fig. 14 is a side view of the buoyancy electricity generation device of Fig. 13 and showing its inner side.

Fig. 15 is a side view of an air supplying device and showing its inner side. Fig. 16 is a cross-sectional view of the other end portion of an exhaust pipe.

Fig. 17 is a front view of a bucket.

Fig. 18 is a side view of a buoyancy electricity generation device according to a fourth embodiment of the present invention and showing its inner side.

MODE FOR INVENTION The preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

Fig. 1 shows an inner side of a buoyancy electricity generation device according to a first embodiment of the present invention. Fig. 2 is a side view of the buoyancy electricity generation device of Fig. 1 and showing its inner side. Referring to Figs. 1 and 2, the buoyancy electricity generation device 100 according to one embodiment of the present invention comprises the following: a tank 110 containing a liquid 111 therein; a bubble generating means 120, 130, 140 disposed near a bottom of the tank 110; a motion converting means 150, 161 to 164 for collecting bubbles discharged from the bubble generating means and converting a rise motion caused by buoyancy of the collected bubbles into a rotary motion; and a generator 170 coupled to the motion converting means for generating electricity from the rotary motion caused by the motion converting means.

The tank 110 is disposed on the ground. The liquid 111 is contained in the tank 110. The liquid 111 may be water or oil. A distance between a level surface Ilia of the liquid (i.e., surface of the liquid) and the bubble generating means 120, 130, 140 is about Im. The amount of liquid 111 is relevant to the capability of generator 170. An upper end of the tank 110 is opened to the atmosphere.

The bubble generating means 120, 130, 140 is disposed near a bottom of the tank 110. Where the liquid is water, a hydraulic pressure that is more than about 11 atmospheric pressures acts around the bubble generating means 120, 130, 140. The bubble generating means 120, 130, 140 is configured to supply air of an atmospheric pressure to the liquid 110, on which such a high hydraulic pressure acts, to thereby generate bubbles.

The bubble generating means 120, 130, 140 comprises the following: a discharging means 120 for discharging the liquid 111 at a predetermined flow rate; an air supplying pipe 130 disposed throughout an inner and outer sides of the tank 110 as passing through a wall of the tank 110 and supplying the air being outside the tank 110 to the liquid 111 being inside the tank 110; and a bubble generating pipe 140 allowing the air supplied through the air supplying pipe 130 to be sucked into the liquid discharged from the discharging means 120 to generate bubbles. One end 140a of the bubble generating pipe 140 is joined to an outlet of the discharging

means 120. The other end 140b of the bubble generating pipe is opened.

The motion converting means 150, 161 to 164 comprises the following: a chain-bucket assembly 150, wherein buckets 152 are disposed at a regular interval on a plurality of unit chains 151; a first rotary member 161a, 161b and a second rotary member 163a, 163b vertically spaced apart from each other, each engaging to the chain-bucket assembly 150 and being rotated with rotation of the chain-bucket assembly 150; a first rotating shaft 162 fixed to the first rotary member 161a, 161b and being rotated together with the first rotary member 161a, 161b; and a second rotating shaft 164 fixed to the second rotary member 163a, 163b and being rotated together with the second rotary member 163a, 163b. The bucket 152 is positioned such that its opened end portion is opposed to the other end 140b of the bubble generating pipe when it is placed above the other end 140b of the bubble generating pipe.

Thus, the bubbles ejected out of the other end 140b of the bubble generating pipe 140 are collected into the bucket 152 located above the other end 140b of the bubble generating pipe. The collected bubbles 112 lift the bucket 152 by their buoyancy. If one bucket 151 is lifted by buoyancy, then the next bucket 152 is then located above the other end 140b of the bubble generating pipe and the bubbles are collected in the next bucket to lift it. By such action, the chain-bucket assembly 150 is circulated along a path connecting the first rotary member 161a, 161b and the second rotary member 163a, 163b.

One end of the first rotating shaft 162 of the first rotary member 161a, 161b is rotatably supported on one wall surface of the tank 110. The other end of the first rotating shaft extends outward of the other wall of the tank 110 passing through it. The other end of the first rotating shaft is coupled to a drive shaft 170a of the generator 170, thereby carrying out electricity generation.

In the meantime, buoyancy of the bubbles can be varied due to an irregular expansion of the bubbles 112 during rise, change of water temperature, etc. In order to prevent the rotation of the drive shaft 170a of the generator 170 from being unstable due to such variation, a governor 171 may be provided between the other end of the first rotating shaft 162 and the drive shaft 170a. A typical governor for a hydraulic power facility, which serves to maintain a constant revolution number irrespective of load variation, may be used.

Fig. 3 shows a combined structure of the discharging means, the air supplying pipe and the bubble generating pipe.

Referring to Fig. 3, the discharging means 120 includes a liquid inlet 121, a

liquid discharging outlet 122, a discharging fan 123 and a motor 124.

The bubble generating pipe 140 has a throat portion 141 therein. The throat portion is a portion with a cross-sectional area reduced along a discharging direction F of the liquid. An air supplying outlet 131, which is an outlet portion of the air supplying pipe 130, is disposed in the throat portion 141.

At a point A of Fig. 3, the liquid is discharged at about 11 atmospheric pressures out of the discharging means 120. As the discharged liquid passes through the throat portion 141, its velocity becomes faster and its pressure drops near an atmospheric pressure (below an atmospheric pressure or slightly higher than an atmospheric pressure). Thus, the air of an atmospheric pressure, which is introduced into the air supplying pipe 130 through an inlet of the air supplying pipe 130, is sucked into the liquid passing through the throat portion 141 through the outlet placed in the throat portion 141. The sucked air generates bubbles in the liquid. As the liquid containing bubbles passes through a diffuser portion 142, its velocity becomes slow and its pressure is increased. An inner diameter Dc of the bubble generating pipe at a point C is the same as an inner diameter D _A at a point A. Accordingly, the liquid is discharged out of the other end 140b of the bubble generating pipe into the tank 110 after it recovers the velocity and pressure of the point A at the point C. The bubbles contained in the discharged liquid rise by buoyancy. They are collected into the bucket 152 located above the other end 140b of the bubble generating pipe and then apply a lift force caused by buoyancy to the bucket 121.

An inner diameter DB of the bubble generating pipe at a point B is determined such that a pressure of the liquid passing the point B drops near an atmospheric pressure (below an atmospheric pressure or slightly higher than an atmospheric pressure). The inner diameter D _B at the point B is relevant to the depth at which the discharging means 120 is located in the tank 110, pressure of the liquid at such a depth, kinds of the liquid, resistance in a pipe, etc.

Preferably, the other end of the air supplying pipe, which is formed with the air supplying outlet 131, is bent in the discharging direction F of the liquid.

In order to prevent the liquid in the tank 110 from flowing outward through the air supplying pipe 130 when the buoyancy electricity generation device 100 does not work, a valve mechanism 132 {see Fig. 2) is provided in a middle portion of the air supplying pipe 130. If the valve mechanism 132 is opened, when the buoyancy electricity generation device 100 is operated and the pressure of the liquid in the throat portion 141 sufficiently drops near an atmospheric pressure while the liquid is

discharged out of the discharging means 120, the air supplied out of the air supplying pipe 130 enters the liquid.

In case the air supplying pipe 130 is too long, the air cannot be sucked into the liquid to be discharged smoothly due to high resistance in the air supplying pipe 130. In order to avoid such a state, an air pump 133 {see Fig. 2) may be additionally provided between the valve mechanism 132 and the one end 130a of the air supplying pipe. Furthermore, even when the pressure of the liquid passing through the throat portion 141 is above an atmospheric pressure, the air can be sucked by means of the air pump 133. A submergible motor pump, wherein the inlet port 121 and the discharging port 122 are positioned with a slight height difference or they are positioned at the same height, may be used as the discharging means 120. For example, in case the depth from the water surface is about 100m, a submergible motor pump consuming an electric power of 60OkW may be used. Such a submergible motor pump can discharge water of 20m ³ at a velocity of 10m/s.

According to a test conducted by the present inventor, it was confirmed that air could be supplied to water up to 50% of flow amount passing through the bubble generating pipe. This is when the inner diameters of the one end and the other end of the bubble generating pipe were 10mm and the cross-sectional area of the air supplying outlet was half of that of the bubble generating pipe and water was discharged at 3~4m/s. Accordingly, in case of using a submergible motor pump discharging water of 20m ³ per second at a velocity of 10m/s, the air of 10m ³ per second under an atmospheric pressure can be supplied to the liquid. In such a case, the bubbles of Im ³ per second are generated under a hydraulic pressure of 11 atmospheric pressures.

Fig. 4 shows an alternative of the bubble generating pipe 140. The other end 140b of the bubble generating pipe is bent upwardly, thereby improving the probability that the bubbles coming out of the bubble generating pipe enter the bucket 152. In addition, the discharged liquid impinges against the bucket 152, thereby assisting the lift motion of the bucket 152.

Fig. 5 is a perspective view showing the air supplying outlet 131 of the air supplying pipe 130. The air supplying outlet 131 takes the form of a slit, which is elongated vertically. Accordingly, the flow resistance of the liquid becomes small at the air supplying outlet. This is advantageous to making the flow rate faster at the throat portion 141.

Fig. 6 shows another example of the air supplying outlet. The air supplying

pipe 131 diverges into a plurality of short pipes, thereby providing a plurality of air supplying outlets 131'. In such a case, due to the liquid that passed between the short pipes, the contact areas between the air and the liquid are increased and the efficiency of air supply is enhanced. Fig. 7 shows an alternative of the air supplying pipe. The air supplying pipe

130 has a U-shaped bent portion 130b, 130c adjacent to the outlet portion. A portion of the air supplying pipe, at which the liquid passing through the throat portion 141 impinges against the air supplying pipe 130, defines only a vertical portion 130c of the bent portion. This substantially prevents the air supplying pipe from hindering the flow of the liquid in the throat portion 141.

Fig. 8 is a front view of the assembly of the chain and the bucket. Fig. 9 is a side view thereof.

The bucket 152 has the shape of a trough with a triangular cross-section, thereby reducing the resistance applied from the liquid during the circulation of the chain-bucket assembly 150. However, the bucket 152 of the present invention may have a shape other than the above. The volume of the bubbles collected in the bucket expands as they rise to the level surface of the liquid 111. Preferably, a volume of the bucket 152 is sized to sufficiently accept such an expanding volume of the bubbles. The unit chain 151 has an insertion groove 151a at its one end and an insertion portion 151b at its other end. The unit chains are consecutively joined together in such a manner that the insertion portion 151b is inserted to the insertion groove of the adjoining other unit chain and a pin is fastened between the insertion portion and the insertion groove. The unit chain 151 has holes 151 c, to which teeth of the first and second rotary members 161a, 161b, 163a, 163 engage.

Fig. 10 shows a buoyancy electricity generation device according to a second embodiment of the present invention with its inner side shown. Fig. 1 1 is a side view of the buoyancy electricity generation device of Fig. 10, which shows its inner side. In Figs. 10 and 11, like reference numerals refer to like elements in comparison with the buoyancy electricity generation device 100 of Figs. 1 to 6.

The motion converting means 251, 255 includes a plurality of bucket assemblies 251 and a plurality of bubble guiding members 255, which are disposed vertically in the tank 110. The bucket assembly 251 has a rotating shaft 254, a plurality of arms 253 radially extending from the rotating shaft, and buckets 252 respectively located at distal ends of the arms 253. The bubbles coming out of the bubble generating pipe 140 rise by buoyancy and is collected in the bucket 252 that

is located upward. The motion of the bucket 252 caused by the buoyancy of the bubbles is converted into rotary motion around the rotating shaft 254. When the bucket 252 is turned over during passing top side, the bubbles coming out of the unit bucket 252 enters the bubble guiding member 255. The bubble guiding member 255 has an inverted funnel shape and has an outlet 255a at its top portion. The outlet 255a is disposed below the bucket of the next bucket assembly in a position where the next bucket assembly can collect the bubbles and be rotated. As such, the bucket assemblies 251 are rotated around their respective rotating shafts by the buoyancy of the collected bubbles. One end of the rotating shaft 254 of each bucket assembly 251 is rotatably supported in the inner wall of the tank 110. The other end thereof extends outwardly passing through the wall of the tank 110. A sprocket wheel or pulley 256 is coupled to the outwardly extending other end of each rotating shaft. Each sprocket wheel or pulley 256 may be connected to each other using a chain or belt 257 or a gear device so that each sprocket wheel or pulley 256 is moved together. The generator 170 can be driven by directly coupling one of the sprocket wheels or pulleys 256 to the drive shaft of the generator 170 or coupling one of the sprocket wheels or pulleys 256 to the drive shaft of the generator 170 via the governor 170.

Descriptions have been made on the buoyancy electricity generation device 100 or 200, which is configured such that buoyancy distances are determined to be about 100m. However, the present invention is certainly not limited thereto. In case that the depth of the tank 100 is deeper than 100m and the pressure of the liquid becomes several tens of atmospheric pressure near the bottom of the tank, the air of an atmospheric pressure can be supplied into the liquid of high pressure near the bottom of the tank to generate bubbles by appropriately designing the components composing the bubble generating means 120, 130, 140. Accordingly, by appropriately designing the tank 110, the bubble generating means 120, 130, 140, etc, a buoyancy electricity generation device, wherein the buoyancy distance is increased and electricity generation efficiency is thus enhanced, may be provided. Further, a small-sized buoyancy electricity generation device, which is designed such that the tank depth is low and the pressure of liquid near a bottom of the tank is slightly higher than an atmospheric pressure, may be provided. In such a case, although the interior of the bubble generating pipe is configured to be straight, bubbles can be generated in the liquid passing the bubble generating pipe in a simple manner using the pressure drop of liquid caused by a high-speed liquid discharge of the discharging means.

Fig. 12 shows an installation example of the buoyancy electricity generation device of the present invention.

In the buoyancy electricity generation device 100 or 200 of the present invention, the liquid 111 is contained in the tank 110 and bubbles are generated in the liquid 111 and buoyancy of such bubbles are used as an energy source. Accordingly, it is not needed to be constructed at a specific location where there is energy source needed for electricity generation. As shown in Fig. 10, the buoyancy electricity generation device 100 or 200 can be constructed in such a manner that the tank is installed directly on the ground or a structure 181 for covering the tank and the generator is further installed after the installation of the tank. Produced electricity is sent to a transforming facility and can be supplied to consumers 12 or factories 13 via the transforming facility 182. Accordingly, the buoyancy electricity generation device of the present invention can be constructed directly in a place demanding electric power without regard to a specific location, thereby greatly reducing the transmission facility.

Fig. 13 is a front view of a buoyancy electricity generation device constructed according to a third embodiment of the present invention and showing its inner side.

Fig. 14 is a side view of the buoyancy electricity generation device of Fig. 13. In

Figs. 13 and 14, like reference numerals refer to like elements in comparison with the buoyancy electricity generation device 100 of the first embodiment.

Referring to Figs. 13 and 14, the buoyancy electricity generation device 300 according to the third embodiment of the present invention comprises the following: a tank 110 containing liquid 111 therein; a bubble generating means 320, 330, 340 disposed near a bottom of the tank 110; a motion converting means 150, 161 to 164 for collecting bubbles discharged from the bubble generating means and converting a rise motion caused by buoyancy of the collected bubbles into a rotary motion; and a generator 170 coupled to the motion converting means for generating electricity from the rotary motion caused by the motion converting means.

The tank 110 is disposed on the ground 11. The liquid 111 such as water or oil is contained in the tank 110. The amount of liquid 111 is relevant to the capability of the generator 170. The upper end of the tank 110 is opened to an atmosphere.

The bubble generating means 320, 330, 340 is disposed near the bottom of the tank 110. The bubble generating means 320, 330, 340 is configured to supply external air to the liquid 111 to thereby generate bubbles.

The bubble generating means 320, 330, 340 comprises an air supplying pipe

320, an air supplying device 330 and a drive device 340. The air supplying pipe

320 is disposed throughout the inner and outer sides of the tank 110 as passing through the wall of the tank 110. The air supplying pipe supplies the air of an atmospheric pressure being outside the tank 110 to the inside of the tank 110. The air supplying device 330 has an expansible and contractable air chamber 332, which is connected to the air supplying pipe 320, and a drive shaft 336 for expanding and contracting the air chamber. The air supplying device 330 discharges external air via an exhaust pipe 335. The drive device 342 drives the drive shaft 336. One end

321 of the air supplying pipe 320 is opened to the atmosphere outside the tank 110. Its other end 322 is connected to the air supplying device 330. In the air supplying device 330, the lift of the drive shaft 336 causes the air chamber 332 to be contracted. Then, air is discharged via the exhaust pipe 335. The discharged air is ejected into the liquid 111 from the other end 335a of the exhaust pipe as bubbles. The drive device 342 drives the drive shaft 366 by the rotary power of the chain-bucket assembly 150.

The bucket 152 of the chain-bucket assembly 150 of the motion converting means 150, 161 to 164 is positioned such that its opened end portion is opposed to the other end 335a of the exhaust pipe when it is placed above the other end 335a of the exhaust pipe 335. The ejected bubbles are collected in the bucket 152 located upward. The bucket 352 is lifted by the buoyancy of the collected bubbles. If one bucket 152 is lifted by buoyancy, then the next bucket 152 is located above the other end 335a of the exhaust pipe and the bubbles are collected in the next bucket to lift it. By the above action, the chain-bucket assembly 150 is circulated along a path connecting the first rotary member 161a, 161b and the second rotary member 163 a, 163b. The circulation of the chain-bucket assembly 150 and the rotation of the first rotary member 162 caused thereby allow the generator 170 to generate electricity.

A brake device 372, which does not allow the first rotating shaft 162 to rotate, is provided between the first rotating shaft 162 and the drive shaft 170a of the generator 170. Further, a motor 372 for starting the buoyancy electricity generation device 300 may be provided. The motor 372 may be connected to a first rotating shaft 162 via a gear device.

Fig. 15 is a side view of the air supplying device and the drive device, which shows the inner side of the air supplying device.

The air supplying device 330 includes: a housing 331 placed at a bottom side of the tank 110 for containing the air chamber 332 therein and maintaining the internal space of the air supplying device at a water-tight state; the expansible and

contractable air chamber 332 disposed in the housing 331; the drive shaft 336 for expanding and contracting the air chamber 332 by vertical reciprocating movement; and an elastically pressing member 337 disposed between the housing 311 and the drive shaft 336 for pressing the drive shaft 336 in an opposite direction to lift the drive shaft 336.

A side of the housing 331 is formed with an inlet 331a, to which one end portion 321 of the air supplying pipe is connected. Thus, the inside of the housing 331 is maintained under an atmospheric state. On a bottom of the inside of the housing 331 is provided buffering stoppers 331b for limiting the expansion of the air chamber 332. Spring or material having a buffering function may be used as the buffering stopper 331b.

The air chamber 332 includes: a fixed frame 332a provided with an air inlet 332d and an air outlet 332; an expansion and contraction portion 332b capable of expansion and contraction in a lengthwise direction and being opened at its one and the other end portions; and a movable frame 332c joined to the opened other end portion of the expansion and contraction portion 332b. The fixed frame 332a, the expansion and contraction portion 332b and the movable frame 332c define the air chamber 332.

The fixed frame 332a is fixed to the inside of the housing 331. The one end portion of the expansion and contraction portion 332b is air-tightly joined to a lower side of a valve plate 331b and the other end portion thereof is air-tightly joined to the movable frame 332c. Bellows may be used as the expansion and contraction portion 332b.

The air inlet 332d is provided at the fixed frame 332a. The air inlet is opened when the air chamber 332 is expanded, thereby allowing the external air to flow into the air chamber 332. The air outlet 332e is provided at the fixed frame 332a. The air inlet is opened when the air chamber 332 is contracted, thereby allowing internal air to be discharged outward. The exhaust pipe 335 is in communication with the air outlet 332e and extends outward of the housing 331 to guide the air toward the bucket 352. It is preferable that a length of the exhaust pipe 335 is as short as possible and its cross-sectional area is 15% of a cross- sectional area of the air chamber 332.

The air inlet 332d and the air outlet 332e may include a check valve. The air inlet may be configured as a diaphragm, which opens in case of expansion of the air chamber 332 and is closed in case of contraction of the air chamber. In case the air outlet is a check valve, an elasticity of a spring provided in the air outlet 332e can

be determined so that the air outlet 332e is opened when the air compressed during the contraction of the air chamber 332 reaches a suitable pressure level.

The drive shaft 336 for expanding and contracting the air chamber 332 is pivotably coupled to the drive device 340 at its one end and is coupled to the fixed frame 332c at its other end. The drive shaft 336 is capable of being vertically moved inwardly and outwardly of the housing 331 through a top portion of the housing 331. The drive shaft 336 has a U-shaped air chamber support 336a coupled to the plate-like portion 332c. The air chamber support 336a is moved upward and downward through the fixed frame 332a. The drive shaft 336 has a seat 336b, on which the elastically pressing member 337 is seated, at its middle portion. The drive shaft 336 further has a seal 336c disposed outside the housing 331 to prevent the liquid 111 from flowing into the housing 331. The seal 336c may be configured as bellows disposed between the drive shaft 336 and an upper surface of the housing 331. The elastically pressing member 337 is disposed between an internal wall of the top portion of the housing 331 and the seat 336b. A compression coil spring may be used as the elastically pressing member 337.

Each unit chain 151 of the chain-bucket assembly 150 is formed with a contact member 341 {see Figs. 13 and 17) corresponding to each bucket 152. The contact member takes the form of a bar. The drive device 342 includes engaging and releasing means, which engages and is released to and from the contact member 341. The engaging and releasing means is configured such that it engages to the closest one of the contact members and is then released from the closest one after being rotated at a predetermined angle along with the rotation of the unit chain 151. The engaging and releasing means comprises: a rotary element 342 having first and second arms 342a and 342b spread at a predetermined angle; and a pivot shaft 343 for pivotably supporting the rotary element 342. The pivot shaft 343 is disposed on an end portion of a supporting post 344 so as to be in close proximity with a lower end portion of the chain-bucket assembly 150. The pivot shaft 343 may be provided on an outer portion of the housing 331 by means of a component similar to the supporting post 344 instead of using the supporting post. The first arm 342a of the rotary element 342 comprises a portion configured to be contacted to the contact member 341. The second arm 342b of the rotary element is pivotably coupled to the one end of the drive shaft 366 at its distal end. As the chain-bucket assembly 150 is circulated, the contact members 341 provided at each unit chain 141 pass by the drive device 342 while striking and

lifting the first arm 342a one after the other. While one contact member 341 being closest to the first arm 342a is engaged to and released from the first arm 342a, the first arm is pivoted upward (clockwise in Fig. 15) and the second arm 342b is also pivoted to thereby pull the drive shaft 366 upward. Thus, the fixed frame 332c coupled to the air chamber support 366a of the drive shaft 366 is pulled upward and the air chamber 332 is contracted. When the air in the air chamber 332 is compressed above a certain pressure level, the air outlet 332e is opened and the compressed air is discharged to the exhaust pipe 335. If the first arm 342a is released from the contact member 341, then the rotary element becomes free. In such a case, the drive shaft 336 is lowered by an expansion force of the elastically pressing member 337 and the rotary element 342 is pivoted downward (counterclockwise in Fig. 15). The air chamber 332 is then expanded. If the air chamber 322 is expanded, then the air outlet 332e is closed and the air inlet 332d is opened to allow the external air to flow from the inside of the housing 311 into the air chamber 322. If the contact member of the next unit chain is engaged to and released from the first arm 342a, while the rotary element 342 is upwardly and downwardly pivoted, the discharge of compressed air and the inflow of external air is carried out. The air discharged to the exhaust pipe 335 is ejected into the bucket 152 passing by above through the other end portion 335a of the exhaust pipe. Fig. 16 is a cross-sectional view of the other end portion of an exhaust pipe.

The other end portion 335a of the exhaust pipe is closed. Further, the other end portion 335a is configured such that a plurality of holes 335b is drilled near the other end portion 335a. Thus, the air is discharged from the other end portion 335a of the exhaust pipe as bubbles. Further, the other end portion 335a is provided with an elastic cap 335a, which is made from rubber and is disposed so as to wrap the other end portion 335a. The elastic cap 335c is placed on the other end portion 335a with a small space therebetween or in nearly close contact therewith. When the compressed air is discharged due to the contraction of the air chamber 332, the air is discharged as bubbles when the elastic cap 335c is slightly expanded by the pressure of such air. When the air chamber 332 is expanded, the pressure of inside of the exhaust pipe 335 drops and the elastic cap 335c closes the holes 335b accordingly, thereby preventing the liquid 111 from flowing into the exhaust pipe 335.

Fig. 17 is a front view of the unit chain and the bucket. The contact member 341 is provided at a middle portion of the unit chain 151. The length of the contact member 341 is determined such that a sufficient quantity of bubbles can be supplied to the bucket 152 out of the exhaust pipe 335, while the first arm 342a is engaged to

and released from the contact member 341.

Fig. 18 is a side view of a buoyancy electricity generation device according to a fourth embodiment of the present invention and showing its inner side. In Figs.

14 and 18, like reference numerals refer to like elements in comparison with the buoyancy electricity generation devices 100 and 300 of the first and third embodiments.

In the buoyancy electricity generation device 400 of this embodiment, the air supplying device 330' is provided at the outside the tank 110. Further, a drive device 440, which drives the drive shaft 336' of the air supplying device 330', includes a motor and a crank mechanism, thereby converting the rotary motion of the motor into linear reciprocating motion of the drive shaft 336.

Since the air supplying device 330' is placed outside the tank under an atmospheric pressure, components such as the air supplying pipe 320, the seal disposed between the drive shaft 336 and the housing 331, etc., are omitted in the air supplying device 330', unlike the air supplying device 330 of the third embodiment. Further, the air supplying device 330' may be simply configured without the housing 331 in comparison to the air supplying device 330 of the third embodiment. Further, since the drive shaft 336' is linearly reciprocated by the drive device 400, the elastically pressing member, which presses the drive shaft 336 in order to expand the air chamber 332, may be omitted. The exhaust pipe 335' extends from an exhaust valve 332e of the air supplying device 330 into the tank 110. The other end portion 335a' of the exhaust pipe is located to be opposed to the bucket 152.

The drive device 400 for driving the drive shaft 336 may include: the motor 441; a circular plate 442 coupled to a rotating shaft of the motor 441 ; and a connecting rod 443 joined to an edge portion of the circular plate and the drive shaft 336. The rotary motion of the motor 441 is converted into the vertical liner reciprocating motion of the drive shaft 336. The motor 441 may be configured to rotate the circular plate at a suitable speed by means of reduction gears.

As described above, the buoyancy electricity generation devices 300 and 400 of the third and fourth embodiments employ the motion converting means used in the buoyancy electricity generation device 100 of the first embodiment. However, the water wheel-shaped bucket assembly and the bubble guiding member, which are used in the buoyancy electricity generation device 200 of the second embodiment, may be employed as the motion converting means in the buoyancy electricity generation device 300 and 400.

While the present invention has been particularly shown and described with

reference to exemplary embodiments thereof, it will be understood by those skilled in the art that various alternations or modifications can be made without departing from the scope of the present invention.

INDUSTRIAL APPLICABILITY

The present invention provides a buoyancy electricity generation device, which utilizes buoyancy as an energy source and is not restricted by any geographic and topographic conditions as well as having a high electricity generation efficiency.