Technical Field The present invention relates to a water gate, more specifically an automatic water gate, which is installed in an underwater dam or a canal such as an irrigation canal of a river or a relatively small reservoir so as to maintain a stored water level within a certain extent.

Background Art An underwater dam is a concrete structure constructed along a width of a river to maintain a water level of an upper stream over a certain extent, and drainage through the underwater dam is achieved by overflowing over an upper end of the underwater dam.

Therefore, in the underwater dam, an upper part of stored water remains continuously and substances such as various heavy metals in water are piled up so that a red tide or green tide is occurred. Also, since the underwater dam itself disturbs a smooth draining in flood, a river may overflows and a riverbank may be washed away.

Meanwhile, to solve the above problem of the underwater dam and manage the water level of a reservoir, a water gate is installed in the underwater dam or a canal of a reservoir/river.

However, the water gate of prior art installed in the underwater or a canal of a reservoir/river mostly, has an elevation-adjusting handle for moving the water gate up and down at an upper part thereof, and is opened and closed by rotating the elevation- adjusting handle. However, when this water gate is opened and closed by human power,

much strength is needed. Also when the water gate is not opened and closed properly, water overflow is caused or water over a proper amount is discharged.

Disclosure of Invention The present invention is contemplated to solve the aforementioned problem, and it is an object of the present invention to provide an provide the automatic water gate, in which according to the water level detection of a sensor, the opening and closing operation is performed automatically by a cylinder and winch so that the stored water level is maintained within a certain extent and a lower part of the stored water is drained easily in opened state, the opening and closing operation is performed easily even if a sand and gravel are piled up on the bottom of a water stored side adjacent to the water gate body, the draining operation is carried out rapidly, and especially the water gate body damage due to the impact of stones and trees is prevented.

To accomplish the above object, it is provided an automatic water gate comprising: a pair of walls constructed with a predetermined distance to both sides of a canal; a supporter fixed uprightly to the canal side surface of each wall; a water gate body having a hollow or vacuumed rectangular shape and a rotation shaft provided with both upper sides thereof, the water gate body being disposed between each wall in order that a stored water sided surface forms a right angle or an acute angle to a bottom of the canal, the rotation shaft being coupled in the supporter rotatively ; a cylinder for moving up and down the water gate body about the rotation shaft, an upper part of the cylinder being coupled rotatively to a side surface of the supporter, a lower part of the cylinder being coupled rotatively to a side surface of the water gate body; and a sensor for detecting a water level of the stored water,

In the present invention the water gate body rotates about the rotation shaft and is opened and closed automatically by expanding and retracting a rod in the cylinder. according to the water level detection of the sensor.

Brief Description of Drawings The features and advantages of the present invention will be more described specifically in the following description of preferred embodiments of the invention with reference to the accompanying drawings wherein: FIG. 1 is a perspective view of an automatic water gate according to the first embodiment of the present invention; FIG. 2 is a side view of a closed state of the automatic water gate according to the first embodiment of the present invention; FIG. 3 is a side view of a opened state of the automatic water gate according to the first embodiment of the present invention; FIG. 4 is a detailed view of a frame and packing of the present invention; FIG. 5 is a perspective view of the automatic water gate according to the second embodiment of the present invention; and FIG. 6 is a side view of closed state of the automatic water gate according to the second embodiment of the present invention.

Best Mode for Carrying Out the Invention Reference will now be made in detail to the embodiment of the present invention and examples of which are illustrated in the accompanying drawings. In explaining the present invention, the same names and reference numerals will be given to the same

components, and explanations in the same will be omitted.

FIG. 1 illustrates a perspective view of an automatic water gate according to the first embodiment of the present invention, and FIG. 2 and FIG. 3 illustrate a side view of the automatic water gate WG according to the first embodiment of the present invention.

A reference numeral 1 is a concrete structure built with a predetermined distance to both sides of a irrigation canal (referred to as"a canal"below) of a small reservoir or river, or a wall having a shortened length in the underwater dam.

A supporter 2 is fixed uprightly to support a water gate body 3 described below to a canal side surface of the wall 1.

The water gate body 3 in the supporter 2 is material having buoyancy, or is a hollow or vacuumed rectangular shape even if it is not made of material having a buoyancy. Also, a rotation shaft 3a is provided with both upper sides, and a packing 3b is fixed to an end portion of a stored water sided surface.

The water gate body 3 is disposed in the supporter 2 so that the stored water sided surface forms a right angle or an acute angle to a bottom of the canal, and the rotation shaft 3a is coupled in the supporter 2 rotatively. In closed state of the water gate body 3. the packing 3b provided with the end portion in the stored water sided surface of the water gate body 3. is stuck to a frame 4 for sealing operation.

The water gate body 3 is opened and closed by a cylinder 5, rotating about the rotation shaft 3a. An upper part of the cylinder 5 is hinged rotatively to the upper part of the supporter 2, and a lower part of the cylinder 5 is coupled rotatively to a side part of the water gate body 3.

Due to the structure described above, with expanding or retracting the cylinder 5, a lower part of the water gate 3 is opened and closed by rotating about the rotation shaft

3a.

A reference numeral 6 is a sensor for detecting the water level of the stored water.

The operation that the water level is adjusted automatically by the automatic water gate (WG) of the first embodiment is as follows.

When the stored water level is low, the cylinder 5 maintains expanded state as shown in FIG. 2, and at the same time closed state in which the lower part of the water gate body 3 is in contact with the bottom of the canal is maintained so that water storing process is initiated.

When the water level approaches the height of the wall 1 with the continuous water string process, the cylinder 5 is retracted as shown in FIG. 3, and the lower part of the water gate body 3 rotates upwardly to a draining water side about the rotation shaft 3a so that the water draining operation is performed. In opened state of the water gate body 3, a draining area which is formed between the stored water sided surface of the water gate body 3 and the bottom of the canal, is maximized so that drainage is performed rapidly, and stones, trees and the like pass beneath the water gate body 3, so that the water gate body 3 is not damaged. In addition, as the water gate body 3 is opened by rotating upwardly to a water draining side, the opening operation of the water gate body 3 is not disturbed anyway, although a sand and gravel are piled up on the bottom of the stored water sided canal adjacent to the water gate body 3.

In the first embodiment described above, the operation of the cylinder 5 is carried out by the water level detection of the sensor 6 provided with the water stored side, and maintains the stored water level within a certain extent by opening and closing the water gate body 3 repeatedly.

The first embodiment of the present discloses only the preferred one, and does

not limit the spirit of the present invention.

That is, as shown in FIG. 5, in the present invention a groove 32 is formed in the upper side part of the water gate body 30, a cylinder 50 is accommodated in the groove 32, an upper and a lower part of the cylinder 50 is coupled rotatively to the side part of the supporter 2 and water gate body 30, and the groove 32 is closed to be opend and closed by a cover member 33. Also, a rotation shaft 31 is provided to an upper part of the water gate body 30, and this rotation shaft 31 is coupled to the supporter 2 rotatively. It is apparent that these modifications fall into the scope of the present invention.

Additionally, a rubber cover is mounted to the outside of the cylinder 50 as the means for protecting the cylinder and rod, so that the cylinder is not worn by the sand and gravel.

The water gate WG'according to the modification of the present invention maintains the stored water level within a certain extent constantly by the repeated opening and closing operation similar to that of the first embodiment, and also increases the durability of the cylinder 50 as the cylinder 50 is accommodated and protected in the groove 32 of the water gate body 30.

Further, in constructing a apparatus for opening and closing the water gate by rotating the rotation shaft provided to both sides of the water gate, apparatus for opening and closing the water gate is constructed in order that the draining operation is performed through the lower part of the water gate. using various known means such as a rotary actuator. Therefore, although other means are applied to rotate the water gate, this is included within the scope of the present invention.

Also, there are various means for opening and closing the water gate which installed in a right or acute angle, by a hydraulic cylinder, or other hydraulic means using

a screw and rack gear. Therefore, all other water gate, which drains water to the extent flowing in through the lower part thereof, is included in the scope of the present invention apparently.

The Industrial Applicability In the present invention, the water gate body is disposed in the wall constructed in the canal to form an acute angle to the canal bottom, the upper part of the water gate is coupled rotatively, and the lower part thereof moves up and down about the rotation shaft by the cylinder. Also, the cylinder operates by the detection of the water level in the sensor provided to the water stored side.

Therefore, in the water gate of the present invention, the opening and closing operation is performed automatically by the water level detection of the sensor. Also, since a lower part of the stored water is drained easily through the drain area formed between the stored water sided surface of the water gate body and the bottom of the canal in the opened state, the red tide and green tide is prevented.

As the water gate body of the present invention is opened by rotating upwardly to a water draining side, the opening operation is performed easily, although a sand and gravel are piled up on the bottom of the stored water sided canal adjacent to the water gate body.

Since water is drained through the lower part of the water gate, a draining area is maximized so that drainage is performed rapidly and the water gate body is not damaged by the impact of stones, trees and the like.

Due to the draining operation of water through the lower part of the water gate, contaminants of light specific gravity is thrust by contaminants of heavy specific gravity

located in the lower part of the water gate and floats around the upper end of the water gate. During that, contaminants are resolved by photosynthesis of the sun light, friction effect of the convention layer, resolving effect of a microbe, and dissolved oxygen, and resolved contaminants is drained selectively.

As proved in a Bernoulli's theorem, the material of the light specific gravity is swept way together with the material of heavy specific gravity, which flows rapidly.

That is, the contaminants resolved naturally is swept way in drained water which has heavy specific gravity relatively and is less contaminated so that the secondary resolving effect is occurred.