Background Art Conventional high-speed water pumps have been operated by electricity or oil. In such a conventional electric water pump or a water pump run by oil, electricity or oil has to be supplied whenever operated.

In addition, a high-speed water pump operated using oil discharges pollutants, raising concerns about environmental contamination. In addition, use of such an electric water pump or a water pump run by oil causes global warming.

Disclosure of the Invention The present invention provides a gravity water pump pumping a various kinds of fluids, including water such as a waterfall, river water and drizzle, and gases heavier than air, using gravity, saving 100% of electricity or oil. The gravity water pump can continuously pump water when a fixed amount of fluid is reserved in a tank and circulated. In addition, the kinetic energy and potential energy of fluid generated by pumping can be utilized as an energy source, thereby eliminating concerns about environmental contamination or global warming.

The present invention will be described with reference to the appended drawings.

As shown in FIGS. 1 H, 2A, and 2B, a gravity water pump according to an embodiment of the present invention includes a piston (10) and a switch (1), which are coupled together such that fluid does not leak through a binding portion between a base plate (20) of the piston (10) and a base plate (12) of the switch (1).

A larger piston or a smaller piston may be coupled to the switch (1) depending on the volume of fluid to be pumped. In other words, a larger piston may be coupled to the switch (1) when pumping a large volume of fluid. A smaller piston may be coupled to the switch (1) when pumping a small volume of fluid.

As shown in FIGS. 1A, 2A, and 2B, the base plate (13) of the switch (1) coupled to the piston (10) has a plurality of drainage holes (3) and an opening (12). Grooves (59) are formed in bearings (16), which are disposed along opposing edges of the opening (12), and a lever (56) having a hole (57) is placed within the opening (12) and is supported by a shaft (19) received in the grooves (59). A packing (72) is placed on the base plate (13) of the switch (1), and a rotary lid (15) with an annular protrusion (37) thereon is mounted on the packing (72) such that it can be smoothly opened and closed. The hole (57) of the lever (56) is connected to a hook (58) of the rotary lid (15) by a link (63), and a string (17) is tied to a hole (38) formed in the annular protrusion (37).

A packing (76) is placed underneath the base plate (13) of the switch (1) and the base plate (20) of the piston (10). An annular fixing plate (78) with a protective frame (70), which is positioned below a water-impervious flexible sag (65), is placed below the base plate (13) of the switch (1) and the base plate (20) of the piston (10) and fixed thereto using bolts.

A floatable lid (62,62", 62"') having an internal space (74,74') is

installed between the packing (76) and the protective frame (70). A floatable lid having no internal space and made of a material having a low specific gravity may be used.

An annular floatable plate (81) is mounted on a bottom surface of the fixing plate (78) such that the piston (10) and the switch (1) float on fluid when placed in a cylinder (2).

FIG. 2C is a top view of the piston (10) and the switch (1) coupled to each other. As shown in FIG. 2C, an upper inner wall of the piston (10) is connected to an upper outer wall of the switch (1) by a support bar (64). A support rod (29) is fitted to an upper inner wall of the switch (1), and a support bar (24) having a hole (60) is connected between a middle portion of the support rod (29) and the upper inner wall of the switch (1). Fluid is allowed to enter the piston (10) and the switch (1) through a space (75) surrounded by the support bars (64,24) and the upper inner wall of the piston (10) and a space (87) inside the switch (1).

Strings (30) and (31) are tied to both ends of the support rod (64), which is fitted between the upper inner wall of the piston (10) and the upper outer wall of the switch (1), or to both ends of the support rod (29).

When only the switch (1) is used as illustrated in FIG. 2D, the strings (30) and (31) may be tied to both ends of the support bar (29). When both the piston (10) and the switch (1), coupled to each other, are used, the strings (30) and (31) may be tied to both ends of the support bar (29) or the support bar (64). A longer distance between the two ends of the support bar (29) or (64), to which the strings (30) and (31) are tied, provides a more stable connection structure. However, the distance between the two ends of the support bar (29,64), to which the strings (30,31) are tied, may be varied freely if necessary.

A switching block (28) is tightly coupled to the hole 60 of the support bar (24), which is fitted between the middle portion of the

support bar (29) supported against the upper inner wall of the switch (1) and the upper inner wall of the switch (1).

As shown in FIGS. 2D, 1 H, and 2A, the hole (57,57') of the lever (56, 56') supported by the shaft (19,19') received in the grooves (59) of the bearings (26), which are formed along opposing edges of the opening (12, 12') in the base plate (13,13') of the switch (1, 1'), is connected to the hook (58,58') of the rotary lid (15,15') by the link (63, 63'). In a state where the packing (72, 72') is placed on the base plate (13,13') of the switch (1, 1'), the rotary lid (15,15') with the annular protrusion (37,37') is mounted on the packing (72,72') such that it can be smoothly opened or closed, and the string (17, 17') is tied to the hole (38, 38') of the annular protrusion (37,37').

The annular fixing plate (78,78') with the protective frame (70, 70') is interposed between the packing (76, 76') and the bellows (68,68'), which underlie the base plate (13,13') of the switch (1, 1'), and the bellows (68,68') and the annular fixing plate (78,78') with the protective frame (70,70') are fixed to the base plate (13,13') using bolts. The floatable lid (62, 62', 62", 62"') with the internal space (74,74') is positioned between the packing (76,76') and the protective frame (70, 70'). As described above, a floatable lid having no internal space and made of a material having a smaller specific gravity than fluid may be used.

The bellows (68,68') and the switch (1, 1') are installed in the cylinder (2,2'), and a drainage hole (69, 69') of the bellows (68,68') is interconnected with a drainage tube (4,4'). A packing (6,6') and a ball (7, 7') are sequentially placed on an annular protrusion (5,5') formed around a lower inner wall of the drainage tube (4,4') connected to a lower side portion of the cylinder (2,2'). Another annular protrusion (79, 79') for retaining the ball (7, 7') is formed on the inner wall of the

drainage tube (4, 4') above the annular protrusion (5,5'). A hose is connected to an upper end of the drainage tube (4, 4').

As shown in FIGS. 1A, 1B, 1D, 1E, 1F, 1G, 1H, 2A, and 2B, the gravity water pump according to the present invention includes a set of water pumping units A and B. The gravity water pump is made of a strong, anticorrosive or rustproof material. The gravity water pump includes a rigid support frame (35, 35') having a front support plate (55, 55'), a rear support plate (18,18'), four legs (36,36', 36", 36"'), which are attached to the front support plate (55,55') or the rear support plate (18,18'), a cross bar (34) connecting the legs (36,36"), and a cross bar (34') connecting the legs (36', 36"').

Bearings (39,39', 41,41') are fixed to beams (71, 71') connecting the front support plate (55, 55') and the rear support plate (18,18'), and pulleys (32, 32', 23, 23') are coupled to the bearings (39, 39', 41,41') by shafts (33,33', 21,21'), respectively.

As shown in FIGS. 1A and 1F, one ends of the strings (30,30'), the other ends of which are tied to the front end portions of the support rod (29,29'), fixed to the upper portions of the switches (1, 1'), are tied together and hang from recesses of the pulleys (32, 32'). One ends of the strings (31,31'), the other ends of which are tied to the rear end portions of the support rods (29,29'), are tied together and hang from recesses of the pulleys (23, 23'). The piston (10) and the switch (1) hang below the pulleys (32,23), and the piston 10'and the switch (1') hang below the pulleys (32', 23').

Drainage holes (27, 27') are formed in a bottom surface of a fluid tank (8,8') placed on the support frames (35,35') having the front support plates (55,55') and the rear support plates (18,18'). Annular downward protrusions (9,9') are formed around the drainage holes (27, 27'), respectively. Packings (42, 42') are placed around the drainage holes (27,27') opposite to the annular downward protrusions (9,9'),

respectively, and valves (80,80') with handles (26, 26') are placed thereon, respectively, such that intermediate slant portions (53,53') and end slant portions (52, 52'), which extend from the handles (26, 26'), respectively, of the valves (80,80'), protrude downward the drainage holes (27, 27'). The valves (80,80') are capped with protective covers (67,67'), respectively, and edges of the protective covers (67, 67') are fixed to an inner bottom surface of the fluid tank (8,8').

The cylinders (2,2'), in which the piston (10) and the switch (1), and the piston (10') and the switch (1') are hung by the strings (30,31, 30', 31'), are fixed below the fluid tank (8,8'), aligned therewith, and one ends of hoses connected to the upper ends of the drainage tubes (4,4') are connected to the fluid tank (8,8') or any place (not shown) where fluid is required (not shown). As described above, the packings (6,6') and the balls (7, 7') are respectively placed on the annular protrusions (5, 5') formed around the lower inner walls of the drainage tubes (4,4') connected to the bottoms or the lower side portions of the cylinders (2, 2'). Additional annular protrusions (79,79') for retaining the balls (7, 7') are formed on the inner walls of the drainage tubes (4,4') above the annular protrusions (5,5').

As shown in FIGS. 1H, 2A, and 2E, the hole (57,57') of the lever (56,56') supported by the shaft (19,19') received in the grooves (59, 59') of the bearings (16,16') formed along opposing edges of the opening (12,12'), which is formed in the base plate (13,13') of the switch (1, 1') together with the plurality of drainage holes (3, 3'), and a lower end of a rod (25,25') with a hook (22,22') is connected by the string (17,17') passing through a hole (83,83') of the flexible lid (14,14').

Here, the hole (83,83') through which the string (17,17') passes is sealed to prevent leakage of fluid therethrough.

The base plate (20,20') of the piston (10,10') is coupled to the base plate (13,13') of the switch (1, 1') such that fluid does not leak

through their binding portion. A larger piston may be coupled to the switch (1, 1') when pumping a large volume of fluid. A smaller piston may be coupled to the switch (1, 1') when pumping a small volume of fluid. In other words, the size of the piston (10, 10)'coupled to the switch (1, 1') may be varied depending on situations.

In a state where the packing (76,76') is disposed underneath the base plate (20,20') of the piston (10, 10') and the base plate (13,13') of the switch (1, 1') and the annular fixing plate (78, 78') with the protective frame (70,70') is placed underneath the flexible sag (65,65'), the base plate (20,20') of the piston (10,10') and the base plate (13,13') of the switch (1, 1') are coupled using bolts. As described above, the floatable lid (62, 62', 62", 62"') having the internal space (74,74') is placed between the packing (76,76') and the protective frame (70,70').

As described above, a floatable lid having no internal space and made of a material having a low specific gravity may be used.

The annular floatable plate (81,81') is mounted on the bottom surface of the fixing plate (78,78') such that the piston (10,10') and the switch (1, 1') floats smoothly on fluid in the cylinder (2,2').

The water-impervious flexible sag (65,65') is put inside the cylinder (2,2') such that an upper end portion of the flexible sag (65,65') folds back on itself and hooks over an upper end of the cylinder (2,2'), and a cylindrical extension (66, 66') is fitted to the upper end of the cylinder (2,2'). A lower end portion of the flexible sag (65, 65') overlaps the base plate (13,13') of the switch (1, 1') and the base plate (20, 20') of the piston (10,10'). The annular fixing plate (78, 78') is placed underneath the lower. end portion of the flexible sag (65) contacting the base plates (13,13', 20,20') and fixed to the base plates (13,13', 20,20') using bolts. As a result, when the piston (10,10') and the switch (1, 1') move up and down in the cylinder (2,2') and the cylindrical extension (66,66'), fluid does not leak, and friction is

minimized because an outer wall of the piston (10,10') does not contact the inner walls of the cylinder (2,2') and the cylindrical extension (66, 66').

To prevent leakage of fluid through the binding portion between the base plate (20,20') of the piston (10,10') and the base plate (13, 13') of the switch {1, 1'), a hole (54, 54') is formed in a lower portion of the switch (1, 1') to allow fluid in the piston (10, 10') to flow into the switch (1, 1) through the hole (54, 54').

According to general pumping principls, which are applied to the gravity water pump according to the present invention, the amount of fluid which stays in the cylinder (2, 2') when the flexible lid (14, 14') or the rotary lid (15,15') and the floatable lid (62,62') are removed from the plurality of drainage holes (3, 3') and the opening (12, 12') formed in the base plate (13, 13') of the switch (1, 1') should be greater than the amount of fluid pumped out through the drainage tube (4, 4).

An end of the string (17, 17'), tied to the hole (57, 57') of the lever (56, 56'), is tied to a lower end of the rod (25,25') with the hook (22,22').

A lever (77, 77') coupled to an upper bearing (48, 48') of the switching block (28, 28'), which is fitted to the hole (60,60') of the support rod (24, 24'), by a shaft (47, 47') swings about the shaft (47, 47') within an internal space (73, 73') of the switching block (28, 28').

The lever (77, 77') supported by the shaft (47, 47') includes a hook (40,40') on a lower end, a weight {44, 44') on a side opposite to the hook (44,44'), and a horizontal lever (51,51') with an elliptical hole (61, 61') on an upper end. The hook (40, 40') swings about the shaft (47,47') due to the weight of the weight (44, 44') and is pushed in a direction opposite to the weight (44,44') and catches on the hook (22, 22') on the upper end of the rod 825, 25'), which moves up and down in the internal space (73,73') of the switching block (28,28').

A-spring (not shown) instead of the weight (44, 44') may be installed such that an end of the horizontal lever (51,51') can swing about the shaft (47, 47') and be lifted.

As a string (50, 50') tied to an upper end of the rod (25, 25') with the hook (22, 22') and passing through the elliptical hole (61,61') of the horizontal lever {51, 51') is pulled upward, the hook {22, 22') of the rod (25, 25') moving up and down in the internal space (73, 73') of the switching block (28, 28') is lifted and catches on the hook (40,40').

Meanwhile, when the horizontal lever (51, 51') is pushed down, the hook (40,40') swinging about the shaft (47,47') is released from the hook (20, 20').

The string (50,50') is tied to a hole (43, 43') formed in a lower end portion of a bolt shaft (46, 46') received in a shaft holder (45, 45') fixed-to a bottom of the beam (71, 71'), and an adjusting nut (49,49') having gauges is coupled to a threaded portion of the bolt shaft (46, 46*) passing through a center hole of the shaft holder (45, 45').

FIG. 1A is a perspective view of a gravity water pump according to an embodiment of the present invention, which has the structure illustrated in FIG. 2E. A gravity water pump according to another embodiment of the present invention is illustrated in FIG. 2F. The structure of the gravity water pump of FIG. 2F is mostly the same as the gravity water pump of FIG. 2E, except that the hole (57, 57') of the lever (56, 56'), supported by the shaft (19, 19') received in the grooves (59, 59') of the bearing (16,16'), in the opening (12,12') of the base plate (13, 13') coupled to the base plate (20,20') of the piston (10, 10') is connected to the hook (58, 58') of the rotary lid (15,15'), with the packing (72,72') on the base plate (13,13') of the switch (1,1'). The rotary lid (15,15') with the annular protrusion (37,37') is positioned on the packing (72,72') such that it can be smoothly opened or closed. An end of the string (17,17'), tied to the hole (38,38') of the annular

protrusion (37, 37'), is tied to the lower end portion of the rod (25,25') with the hook (22, 22'). Descriptions on other elements of the gravity water pump of FIG. 2F, which are the same as in the gravity water pump of FIG. 2E, will not be provided here.

A gravity water pump according to another embodiment of the present invention is illustrated in FIG. 2G. The structure of the gravity water pump of FIG. 2G is mostly the same as the gravity water pump of FIG. 2E, except that, instead of the flexible sag (65, 65') and the cylindrical extension (66, 66'), a U-packing (11, 11') is fitted in a circumferential groove of the piston (10, 10'). In the gravity water pump of FIG. 2G, as the switch (1, 1') and the piston (10,10') with the U-packing (11, 11') moves down along the cylinder (2,2'), the U-packing (11,11') rubs against the inner wall of the cylinder (2, 2') and prevents leakage of fluid above the piston (10,10'), thereby maintaining a pressure on fluid in the cylinder (2, 2') for more efficient pumping.

Descriptions on other elements of the gravity water pump of FIG. 2G, which are the same as in the gravity water pump of FIG. 2E, will not be provided here.

The operational principles of a gravity water pump according to the present invention will be described. While fluid is contained in the cylinder (2,2') and fluid is supplied to the fluid tank (8,8'), the end slant portion (52) of the handle (26) is turned clockwise to open the valve (80) of the water pumping unit A so that fluid contained in the fluid tank (8,8') falls into the piston (10) and the switch (1), and the piston (10) and the switch (1) move down and enter the cylinder (2) due to the weight of the fluid dropping from the fluid tank (8,8').

When the piston (10) and the switch (1) move down into the cylinder (2), maintaining a pressure on the fluid contained in the cylinder (2), fluid does not leak because of the water-impervious flexible sag (65), and friction is minimal because the outer wall of the piston (10) does not

contact the inner wall of the cylinder (2).

As the fluid contained in the cylinder (2) is pushed by the piston (10) and the switch (1) moving down along the cylinder (2), the fluid rises along the drainage tube (4), pushing up the ball (7), and is discharged through the hose connected to the upper end of the drainage tube (4).

Here, the discharged fluid may be supplied to a place where fluid is required.

As the piston (10) and the switch (1) move down to pump fluid, the piston (10') and the switch (1'), which are hung by the strings (31', 30') passing over the pulleys (23,23'), are lifted.

When the piston (10) and the switch (1) reach the lower limit, the slack string (50) tied to the hole (42), formed in the lower end portion of the bolt shaft (46), becomes taut. The piston (10) and the switch (1) move down, even when the rod (25) cannot drop anymore, so that the flexible lid (14) is lifted, as illustrated by dashed lines, and the lever (56) turns about the shaft (19) clockwise, thereby allowing a lower end (82) of the lever (56) to push down and open the floatable lid (62).

When the flexible lid (14) and the floatable lid (62) are opened, the hook (22) of the rod (25), to which the string (50) is tied, catches on the hook (40) of the lever (77) moving down together with the switch (1), so that the flexible lid (14) and the floatable lid (62) remain open.

While the flexible lid (14) and the floatable lid (62) are opened, the fluid in the piston (10) and the switch (1) is allowed to enter the cylinder (2) and combine with fluid already in the cylinder (2) so that a stronger buoyant force acts on the annular floatable plate (81) to lift the piston (10) and the switch (1,) fixed thereto.

Meanwhile, when the piston (10') and the switch (1') of the other water pumping unit B, which are hung by the strings (31', 30) passing over the pulleys (23, 23', 32,32'), rise and reach the upper limit, an end of the horizontal lever (51) on the lever (77') pushes the end slant

portion (52') of the handle (26') of the valve (80') fitted to the drainage hole (27') of the fluid tank (8,8') so that the end of the horizontal lever (51') turns clockwise about the shaft (47') and the hook (40') of the lever (77'), which turns clockwise about the shaft (47'), is released from the hook (22) of the rod (25'). As a result, the flexible lid (24') and the lever (56') return to their initial positions, and the floatable lid (62') floats on the fluid in the cylinder (2'), thereby closing the opening in the base plate (13') of the switch (1').

The piston (10) and the switch (1) reach the lower limit, and the piston (10') and the switch (1') reach the upper limit simultaneously. In other words, the flexible lid (14) and the floatable lid (62) are opened and the flexible lid (14') and the floatable lid (62') are closed simultaneously.

However, after the flexible lid (14) and the floatable lid (62) are opened as the piston (10) and the switch (1) reach the lower limit, the piston (10) and the switch (1) drop further due to the weight of the fluid contained therein untill the upper end of the rod (25), to which the string (50) is tied, reaches a bottom of the horizontal lever (51). A distance by which the rod (25) moves down further after the flexible lid (14) and the floatable lid (62) are opened can be varied freely by adjusting the length of a lower portion of the bolt shaft (46), which protrudes out of the center hole of the shaft holder (45), by turning the adjusting nut (49).

By turning the adjusting nut (49,49') coupled to the bolt shaft (46), the position of the bolt shaft (46,46'), to which the string (50,50') is tied, and the position of the rod (25,25') with the hook (22, 22'), to which the string (17,17') is tied, can be precisely adjusted so that the upper and lower limits of the piston (10,10') and the switch (1,1') when the flexible lid (14,14') or the rotary lid (15,15') and the floatable lid 62 are opened and closed can be controlled.

As described above, since the piston (10) and the switch (1) drop

further after having reached the lower limit so that the flexible lid (14) and the floatable lid (62) are opened, the piston (10') and the switch (1') of the other water pumping unit rise further after having reached the upper limit so that the flexible lid (14') and the floatable lid (62') are closed.

As the piston (10') and the switch (1') rise further while the upper end of the horizontal lever (51') contacting the support bar (24') pushes the end slant portion (52') of the handle (26'), the end slant portion (52') turns counterclockwise, thereby opening the valve (80') and allowing fluid contained in the fluid tank (8,8') to fall into the piston (10') and the switch 1'.

However, when fluid initially falls into the piston (10') and the switch (1'), the piston (10) and the switch (1) of the other water pumping unit still move down so that the piston (10') and the switch (1') cannot stop rising and the upper end of the horizontal lever (51') forces the end slant portion (52') of the handle (26') aside such that the intermediate slant portion (53') is vertically disposed, and continues upward adjacent to the intermediate slant portion (53'). In this state, the valve (80') is in its most open state.

As the upper end of the horizontal lever (51') contacting the piston (10') and the support bar (24') of the switch (1') continues upward adjacent to the intermediate slant portion (53'), the valve (80') remains open so that a maximum volume of fluid in the fluid tank (8') is allowed to enter the piston (10') and the switch (1').

When the upper bearing (48') of the switching block (28'), which is fitted to the hole (60') of the support bar (24') on the top of the switch (1'), contacts the shaft holder (45') fixed to the bottom of the beam (71'), the piston (10') and the switch (1') cannot rise further.

When the piston (10) and the switch (1) stop falling, the ball (7) sticks to the packing (6) in the drainage tube (4) to prevent the fluid in

the drainage tube (4) and the hose from flowing back into the cylinder (2).

The piston (10) and the switch (1) can stop dropping at the lower limit when the bottom of the horizontal lever (51) contacts the upper end of the rod (25) and the string (50) tied to the rod (51) becomes taut.

In this state, when the fluid contained in the piston (10') and the switch (1') is heavier than the fluid contained in the piston (10) and the switch (1), the piston (10') and the switch (1') fall due to the weight of the fluid therein, thereby maintaining a pressure on the fluid contained in the cylinder (2'), pushing up the ball (7') in the drainage tube (4'), and pumping the fluid toward the hose connected to the upper end of the drainage tube (4').

Then, the piston (10) and the switch (1) hung by the strings (30, 31) rise easily while the flexible lid (14) and the floatable lid (62) remain open, since a larger amount of fluid than that pumped up along the discharge tube (4') enters the cylinder (2) from the piston (10) and the switch (1).

Meanwhile, as the piston (10') and the switch (1') continue to drop, maintaining a pressure on the fluid contained in the cylinder (3'), fluid is pumped continuously.

The piston (10') and the switch (1') fall according to the same mechanism as the piston (10) and the switch (1). The piston (10) and the switch (1) rise according to the same mechanism as the piston (10') and the switch (1').

As described above, externally supplied fluid is pumped up as a set of the piston (10) and the switch (1) and a set of the piston (10') and the switch (1') alternately fall and rise due to a difference in the weight of fluid contained therein. Kinetic energy is generated when the pistons (10,10') and the switches (1, 1') rise and fall to pump fluid and potential energy is generated by the pumped fluid.

When free ends of the hoses connected to the upper ends of the drainage tubes (4,4') are guided into the fluid tank (8, 8') reservinga fixed volume of fluid, kinetic and potential energy can be generated continuously according to the above-described pumping mechanism as the fluid circulates through the fluid tank (8,8').

The operational principles of the gravity water pump illustrated in FIG. 2F are the same as the operational principles of the gravity water pump illustrated in FIG. 2E, except that a stronger force is required for opening the rigid rotary lid (15,15') in FIG. 2F than opening the flexible lid (14,14'). Therefore, detailed descriptions on the operational principles of the gravity water pump according to the present invention illustrated in FIG. 2F will be omitted.

The operational principles of the gravity water pump illustrated in FIG. 2G are the same as the operational principles of the gravity water pump illustrated in FIG. 2E, except that the U-packing (11) fitted in the circumferential groove of the cylinder (2) rubs against the inner wall of the cylinder (2) when the piston (10) and the switch (1) fall into the cylinder (2) due to the weight of fluid entering the piston (10) and the switch (1). As a result, fluid does not leak above the cylinder (2) and a pressure on the fluid is maintained, thereby pushing up the ball (7) and pumping the fluid up along the drainage tube (4) and the hose connected to the upper end of the drainage tube (4).

In the gravity water pump illustrated in FIG. 2G, friction is generated since the U-packing (11) fitted in the circumferential groove of the piston (10) rubs against the inner wall of the cylinder (2) when the piston (10) rises or falls along the cylinder (2). However, the manufacturing costs can be reduced with the structure of the gravity water pump illustrated in FIG. 2G, and it is easy to assemble and repair the gravity water pump of FIG. 2G. Furthermore, the gravity water pump of FIG. 2G has a large cylinder volume, and thus enables efficient

pumping. Since the operational principles of the gravity water pump of FIG. 2G are almost the same as those of the gravity water pump of FIG.

2E as described above, detailed descriptions thereof will be omitted.

FIG. 2D illustrates a gravity water pump according to another embodiment of the present invention. In particular, the gravity water pump of the present embodiment includes a part pushing the fluid contained in the cylinder (2, 2') to maintain a pressure on the cylinder.

The operational principles of the gravity water pump of FIG. 2D are the same as those of the gravity water pumps of FIGS. 2E, 2F, and 2G, except that the bellows (68) is folded as the switch (1) falls into the cylinder (2) due to the weight of fluid entering the switch (1) such that a pressure is applied to the fluid contained in the bellows (68) and the ball (7) in the drainage hole (4) is pushed up during pumping. Energy loss is minimal when using the gravity water pump of FIG. 2D. However, use of the bellows (68) raises the manufacturing costs.

Energy loss during pumping is smaller when the bellows (68,68') is folded or unfolded than when the flexible bag (65,65') is braced or loosened and is much smaller than the energy loss due to friction occurring when the U-packing (11, 11') rubs against the inner wall of the cylinder (2, 2') as the piston (10,10') with the U-packing (11, 11') falls or rises along the cylinder (2,2').

Effects of the Invention Unlike conventional water pumps utilizing electricity or oil as a driving source, a water pump according to the present invention utilizes gravity as a driving source, saving 100% of electricity or oil. ln addition, when using the gravity water pump according to the present invention, there is no concern about the discharge of contaminants produced when using conventional fossil energy sources such as oil. Furthermore, the kinetic energy generated during pumping and the potential energy of the

pumped fluid are considered to be pollution-free, clean energy sources.

Unlike exhaustible fossil energy sources that have to be produced, transported, and stored for usage, gravity used as a driving source in the water pump according to the present invention is an inexhaustible energy source available at any place without requiring separate production, transportation, and storage processes. A minimum investment as well as manufacturing equipment are required to produce fossil energy sources, whereas the kinetic and potential energy generated when using the gravity water pump according to the present invention are produced by gravity as long as the gravity water pump operates properly.

Brief Description of the Drawings FIG. 1A is a perspective view of a gravity water pump according to the present invention; FIG. 1B is a perspective view of an automatic switch unit used in the gravity water pump according to the present invention; FIG. 1C is a perspective view of a rotary lid used in the gravity water pump according to the present invention; FIG. 1 D is a perspective view of a protective frame and a floatable lid used in the gravity water pump according to the present invention; FIG. 1Eis a perspective view of a precise adjustment unit used in the gravity water pump according to the present invention; FIG. 1 F is a perspective view of a support frame on which pulleys are mounted used in the gravity water pump according to the present invention ; FIG. 1 G is a perspective view of an annular floatable plate used in the gravity water pump according to the present invention; FIG. 1 H is a perspective view of a binding structure of a base plate of a piston and a base plate of a switch in the gravity water pump

according to the present invention; FIG. 2A is a plan view of the binding structure of the base plate of the piston and the base plate of the switch in the gravity water pump according to the present invention; FIG. 2B is an enlarged, vertical sectional view of the binding structure of the base plate of the piston and the base plate of the switch in the gravity water pump according to the present invention; FIG. 2C is a top view of the piston and the switch coupled together in the gravity water pump according to the present invention; FIG. 2D is a vertical sectional view illustrating a main part of a gravity water pump using a bellows, according to an embodiment of the present invention, and operational principles thereof; FIG. 2E is a vertical sectional view illustrating a gravity water pump using a flexible sag, according to another embodiment of the present invention, and operational principles thereof; FIG. 2F is a vertical sectional view illustrating a gravity water pump using a rotary lid, according to another embodiment of the present invention, and operational principles thereof; and FIG. 2G is a vertical sectional view illustrating a gravity water pump using a U-packing, according to another embodiment of the present invention, and operational principles thereof.

Best Mode for Carrying Out the Invention According to the operational principles of a gravity water pump described with reference to FIGS. 2E, 2F, and 2G, when a free end of the hose connected to the upper end of the discharge tube 4 (4') is guided into the fluid tank 8 (8') reserving a fixed amount of fluid and connected to the gravity water pump such that pumped fluid can be circulated through the fluid tank 8 (8'), kinetic and potential energy can be generated continuously by operating the gravity water pump, without

requiring a supply of fluid from an external source. Therefore, the gravity water pump according to the present invention can cope with concerns about energy shortage, environmental contamination, and global warming.

Industrial Applicability According to the operational principles of a gravity water pump described with reference to FIGS. 2E, 2F, and 2G, when a free end of the hose connected to the upper end of the discharge tube (4,4') is guided into the fluid tank (8,8') reserving a fixed amount of fluid and connected to the gravity water pump such that pumped fluid can be circulated through the fluid tank (8,8'), kinetic and potential energy can be generated continuously by operating the gravity water pump, without requiring a supply of fluid from an external source. The generated kinetic and potential energy of the fluid can be used as a clean energy source in various industrial fields.