LEVEL REGULATING VALVE CONTROLLED BY FLUID PRESSURE DIFFERENCE TECHNICAL FIELD The present invention relates to a level regulating valve controlled by fluid pressure difference, and more particularly to a revel regulating valve controlled by fluid pressure difference, which includes an inlet hole for guiding inlet of fluid, an outlet hole for guiding outlet of the fluid, a valve sheet formed vertically in the outlet hole for coffering the fluid, a diaphragm formed at a top of the valve sheet, and a hydraulic chamber formed by the diaphragm and a valve body above the diaphragm so that the diaphragm shrinks or expands due to the change of hydraulic pressure in the hydraulic chamber in order to control the Row of fluid, in which the level regulating valve further includes an inlet conduit for connecting the hydraulic chamber and the inlet hole; an outlet conduit for connecting the hydraulic chamber to outside; a regulating pin having a pin body inserted into the outlet conduit and a pin head elastically supported by a spring inserted into a regulating chamber formed by the valve body, the pin head continuously exerting a downward force through the regulating chamber, the pin head being used for opening or closing a channel of the outlet conduit ; and a control cam unit having a cam contacted with the regulating pin at a

lower end of the pin body of the regulating pin and a float connected to the cam via an arm so that the buoyancy of the float is transferred to the rotational movement of the cam according to the water level in a water tank to move the regulating pin in a vertical direction, wherein a hydraulic pressure in the hydraulic chamber is converted by the control cam unit according to the water level in the water tank to shrink or expand the diaphragm, thus controlling channels of the inlet hole and the outlet hole, thereby controlling the level in the water tank BACKGROUND ART Generally, a level regulating valve controlled by fluid pressure difference has a valve sheet and a diaphragm for opening or closing a fluid path between an inflow hole for guiding inflow of fluid and an outflow hole for guiding outflow of the fluid.

The valve is commonly classified into an electrical type and a mechanical type. The electrical valve controls a channel by means of operation of an electrically controlled diaphragm by forming a solenoid valve in a chamber formed by the diaphragm and a valve body.

The mechanical valve is also classified variously. For example, a spring may be inserted into the chamber formed by the diaphragm and the valve body in order to use elasticity of the spring and hydraulic balance of the fluid.

The mechanical valve may be subdivided into a level regulating valve controlled by in direct acting type fluid pressure difference and a level regulating valve controlled by pilot type fluid pressure difference.

All of the level regulating valves control a channel by transmitting a position change of a float in a water tank into a mechanical behavior.

The direct valve includes a coffering valve and a gear valve. The coffering valve has a coffering disk valve in a direction opposite to a water advancing direction so that the disk rotates according to buoyancy of the float to cut off the channel. The gear valve uses gear tooth.

The various kinds of valves introduced above are broadly known and used, but they have some problems that a level regulating function of the electric valve is interrupted by an electricity failure and there is required a high cost in manufacturing.

In addition, in case of the mechanical valve, the coffering valve may be worn when they are used for a long time, and its opening/closing operation is not smooth under high hydraulic pressure since the buoyancy of the float is not capable of enduring the hydraulic pressure. Moreover, the gear valve has a problem that it may malfunction in its opening/closing function since impurities in the fluid get gammed between gear teeth. The pilot valve needs so high costs for manufacturing.

DISCLOSURE OF INVENTION The present invention is designed to solve such problems of the prior art, and therefore an object of the invention is to provide a level regulating valve which keeps a desired water level in a water tank by inducing pressure change within a hydraulic chamber formed by a diaphragm and a valve body so that the diaphragm may expand or shrink by means of the pressure change in the hydraulic chamber.

Another object of the present invention is to provide a level regulating valve controlled by fluid pressure difference, which coffers dirt flowing into the valve with a simple control structure, thus reducing a manufacturing cost and ensuring a long life cycle.

In order to accomplish the above object, the present invention provides a level regulating valve, which includes an inlet hole for guiding inlet of fluid, an outlet hole for guiding outlet of the fluid, a valve sheet formed vertically in the outlet hole for coffering the fluid, a diaphragm formed at a top of the valve sheet, and a hydraulic chamber formed by the diaphragm and a valve body above the diaphragm so that the diaphragm shrinks or expands due to the change of hydraulic pressure in the hydraulic chamber in order to control the flow of fluid, in which the level regulating valve further includes an inlet conduit for connecting the hydraulic chamber and the inlet hole; an outlet conduit

for connecting the hydraulic chamber to outside ; a regulating pin having a pin body inserted into the outlet conduit and a pin head elastically supported by a spring inserted into a regulating chamber formed by the valve body, the pin head continuously exerting a downward force through the regulating chamber, the pin head being used for opening or closing a channel of the outlet conduit; and a control cam unit having a cam contacted with the regulating pin at a lower end of the pin body of the regulating pin and a float connected to the cam via an arm so that the buoyancy of the float is transferred to the rotational movement of the cam according to the water level in a water tank to move the regulating pin in a vertical direction, wherein a. hydraulic pressure in the hydraulic chamber is converted by the control cam unit according to the water level in the water tank to shrink or expand the diaphragm, thus controlling channels of the inlet hole and the outlet hole, thereby controlling the level in the water tank.

Preferably, there are provided two inlet conduits so as to prevent the inlet conduits from clogging at the same time by dirt flowing in through the inlet hole.

In addition, the inlet hole may have a filtering net for preventing dirt from flowing into the valve.

Preferably, the outlet conduit forms a rectangular through hole and the pin body of the regulating pin has a cylindrical shape inserted

into the outlet conduit so that there is formed a gap between the rectangular hole of the outlet conduit and the circular section of the pin body.

Also preferably, the regulating chamber forms a rectangular through hole or a circular through hole having a groove so as to be communication with the hydraulic chamber through a channel formed at a lower end, and the pin head of the regulating pin has a circular shape, whereby the fluid flows through a gap formed between the regulating chamber and the pin head to an upper portion of the pin head so that the regulating pin is pressed downward continuously by an elastic force of the spring and a hydraulic pressure in the regulating chamber.

BRIEF DESCRIPTION OF THE DRAWINGS These and other features, aspects, and advantages of preferred embodiments of the present invention will be more fully described in the following detailed description, taken accompanying drawings. In the drawings: FIG. 1 is a sectional view showing a level regulating valve controlled by fluid pressure difference according to a preferred embodiment of the present invention; FIG. 2 shows a fluid path in the level regulating valve controlled

by fluid pressure difference according to the present invention, in which (a) shows a fluid path when the valve is closed and (b) shows a fluid path when the valve is open ; and FIG. 3 is an enlarged sectional view showing an outlet conduit and a regulating pin of the level regulating valve controlled by fluid pressure difference according to the present invention.

BEST MODES FOR CARRYING OUT THE INVENTION Hereinafter, a preferred embodiment of the present invention is described in detail with reference to the attached drawings.

FIG. 1 is a sectional view showing a level regulating valve controlled by fluid pressure difference according to the present invention, FIG. 2 show a fluid path in the level regulating valve controlled by fluid pressure difference according to the present invention, and FIG. 3 is an enlarged view showing an outlet conduit and a regulating pin of the level regulating valve controlled by fluid pressure difference according to the present invention.

Referring to FIG. 1, the level regulating valve of the present invention includes inlet and outlet holes 10 and 20 for guiding inflow or outflow of fluid, a valve sheet 110 formed vertically, a diaphragm 200 positioned at a top of the valve sheet 110, and a hydraulic chamber C formed by the diaphragm 200 and a valve body 100.

In addition, the level regulating valve has an inlet conduit 150 for connecting the hydraulic chamber C to the inlet hole 10, an outlet conduit 180 for connecting the hydraulic chamber C to outside, a regulating pin 350 and a control cam unit 500. At this time, the regulating pin 350 includes a pin body 352 inserted into the outlet conduit 180, and a pin head 351 elastically supported by a spring 310 inserted into a regulating chamber 300 and guided by the regulating chamber 300 to continuously exert a downward force and open/close a channel of the outlet conduit 180. In addition, the control cam unit 500 has a cam 520 contacted with the regulating pin 350 at a lower end of the pin body 352, and a float 530 connected to the cam 520 via an arm 510. Thus, when a water level rises, the buoyancy of the float 530 changing according to the water level in the water tank is transferred to rotational behavior of the cam 520 to ascend the regulating pin 350.

Hereinafter, operation of the level regulating valve controlled by fluid pressure difference according to the present invention is described with reference to FIGs. 1 and 2.

(a) of FIG. 2 shows a fluid path when the valve is closed, while (b) of FIG. 2 shows a fluid path when the valve is open.

A fluid path along which a man stream of the fluid passes (hereinafter, referred to as'a flow path') is configured with the inlet hole 10, a space formed by a lower end of the diaphragm 200 and the valve

sheet 110, and the outlet hole 20.

The fluid on the flow path is controlled by opening or closing the valve sheet 110 according to shrinkage or expansion of the diaphragm 200.

The diaphragm 200 forms a hydraulic chamber C together with the valve body 100. At this time, the inlet conduit 150 for connecting a channel to the inlet hole 10 is formed in the hydraulic chamber C so that fluid may flow in.

However, if the fluid flowed in the hydraulic chamber C has a high hydraulic pressure, the diaphragm 200 expands and closes the flow path, while if the hydraulic pressure is low, the diaphragm 200 shrinks and opens the flow path.

At this time, the hydraulic pressure in the hydraulic chamber C is compared with a hydraulic pressure generated at a lower end of the diaphragm 200, i. e. a hydraulic pressure in the flow path, thereby causing the shrinkage or expansion of the diaphragm 200.

In addition, the hydraulic pressure in the hydraulic chamber C is controlled according to the existence of fluid flow.

As described above, the hydraulic chamber C has the outlet conduit 180 communicated with outside of the valve, and the regulating pin 250 is inserted into the outlet conduit 180. The regulating pin 350 also has the pin body 352 inserted into the outlet conduit 180 and the

pin head 351 for opening or closing a channel of the outlet conduit 180.

The spring 310 inserted into the regulating chamber 300 formed by the valve body 100 is positioned at a top of the pin head 351 and elastically supports the pin head 351 to exert a downward force continuously.

Thus, without a mechanical change of the regulating pin 350, the regulating pin 350 always closes the outlet conduit 180.

As mentioned above, the cam 520 of the control cam unit 500 is formed in contact with the regulating pin 350 at a lower end of the pin body 352 of the regulating pin 350. If the cam 520 rotates as the float 530 of the control cam unit 500 ascends according to the water level in the water tank, the regulating pin 350 changes its position along a curved surface of the cam 520 and ascends.

In more detail, the cam 520 of the control cam unit 500 ascends the regulating pin 350 when the float 530 descends according to the level. On the while, if the float 530 ascends, the regulating pin 350 descends.

Thus, when the water level in the water tank is a full water level, the regulating pin 350 descends so that the outlet conduit 180 is closed by the pin head 351 of the regulating pin 350. In addition, the hydraulic pressure of the hydraulic chamber C increases larger than that of the flow path, so the diaphragm 200 becomes expanded.

A hydraulic pressure of the fluid is determined based on Bernoulli's Equation teaching that the hydraulic pressure is low as a flow rate is rapid and the hydraulic pressure is high as a flow rate is slow. In particular, since the valve sheet 110 is perpendicularly protruded in the valve, the hydraulic pressure is focused only on a circumference of the valve sheet 110, i. e. a lower circumference of the diaphragm 200 when the diaphragm 200 is expanded and seated on the valve sheet 110. Thus, since the area to which the hydraulic pressure of the flow path is applied is small, the flow path is stably closed.

If the water level in the water tank descends, the regulating pin 350 also descends by means of the rotation of the cam 520 of the control cam unit 500, whereby the fluid in the hydraulic chamber C is discharged outside through the outlet conduit 180.

In other words, the hydraulic pressure in the hydraulic chamber C is lowered owing to the rate of the fluid, and the fluid flow on the lower circumference of the diaphragm 200 is stopped so as to increase the pressure. Therefore, the diaphragm 200 shrinks.

Now, the regulating pin 350 is described in detail with reference to FIGs. 2 and 3.

As shown in FIGs. 2 and 3, the regulating pin 350 is elastically supported by the spring 310 inserted into the regulating chamber 300 formed by the valve body 100.

At this time, if the regulating chamber 300 is formed as a circular through hole having grooves or as a rectangular through hole, and if the pin head 351 ascending or descending through the regulating chamber 300 is fonned in a cylindrical shape, the fluid may flow into the regulating chamber 300 through a gap A formed by the grooves or between the rectangular chamber and the circular pin head.

In other words, since the lower end of the regulating chamber 300 is communication with the hydraulic chamber C, the fluid may flow into the regulating chamber 300 through the lower end of the regulating chamber 300 and the gap A.

This fluid has a hydraulic pressure in the regulating chamber 300 identical to the hydraulic pressure in the hydraulic chamber C. Thus, the pin head 351 of the regulating pin 350 is pressed due to the hydraulic pressure, so the outlet conduit 180 may keep its closed state stably.

In addition, the outlet conduit 180 forms a rectangular through hole and the pin body 352 of the regulating pin 350 has a cylindrical shape with a circular section so that there is formed a gap B between the pin body 352 and the outlet conduit 180.

Thereby, though the pin head 351 ascends to be spaced apart just a little, the fluid may flow through the gap B of the outlet conduit 180, improving the control efficiency.

By using the level regulating valve according to the present invention as described above, the water level in a water tank is converted into the pressure change in the hydraulic chamber, thus automatically keeping a still water level.

A main concept of the present invention is in that the operation of the valve is controlled by the fluid flowed into the hydraulic chamber C.

Thus, the flow of fluid passing through the hydraulic chamber C in the valve plays an essential role, and impediment of the fluid flow may be a cause of breakdowns.

However, the inlet conduit 150 and the outlet conduit 180 commonly have a small diameter. Thus, if dirt is flowed in together with the fluid, the inlet conduit 150 or the outlet conduit 180 is apt to clog, thus causing a breakdown.

The level regulating valve of the present invention may have a filtering net 130 at the inlet hole 10 so as to prevent dirt from flowing into the valve. In addition, there may be provided two inlet conduit 150 in order to prevent breakdown of the valve in advance which may happen by small sized dirt.

According to the present invention, the valve opens or closes a channel of the fluid by means of shrinkage or expansion of the diaphragm caused by the difference between the hydraulic pressure in the hydraulic chamber and the hydraulic pressure in the flow channel.

Thus, the hydraulic pressure in the hydraulic chamber may be controlled by means of the water level in the water tank sensed by the control cam unit. To improve the control efficiency, there is also formed a gap between the regulating chamber and the outlet conduit.

Therefore, the water level in the water tank is fed back to the hydraulic chamber, and the level regulating valve may always keep a still water level.

In addition, since there is provided a means for filtering dirt flowing into the hydraulic chamber in advance, the level regulating valve may prevent breakdown in advance.

INDUSTRIAL APPLICABILITY The level regulating valve of the present invention described as above is advantageous in that breakdown of the valve is prevented by filtering dirt flowing in the valve and the level change in the water tank is converted into the behavior of the valve to keep the water level in the water tank constantly.

In addition, the level regulating valve of the present invention may improve its control efficiency by using the gaps formed between the outlet conduit and the regulating chamber.

The present invention has been described in detail. However, it should be understood that the detailed description and specific

examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description.