Background Art A butterfly valve is installed on a conveying line such as a large-sized pipeline for conveying waste water generated in an industry, exhaust gas generated in steel works, raw material such as resin used in an injection molding company, cement, grain such as rice, and the like

(hereinafter referred as"fluid") and a vertical pipeline of a storing hopper for storing the fluid to control the flow of the fluid. FIG. 1 schematically shows such a conventional butterfly valve.

As shown in FIG. 1, by allowing a rotational disk 120 connected to a rotational shaft rotating in a longitudinal direction of the valve to contact a valve seat 140 mounted on a ring-shape along an inner circumference of a valve body 130, the flow of the fluid 150 can be controlled. In order to make one understand problems that will be described hereinafter with reference to FIG. 1, the fluid is referred to as grain granules.

That is, when the rotational shaft 110 is rotated by mechanical manipulation or manual manipulation, the rotational disk 120 is integrally rotated to allow seat contacting ends 120a thereof to contact or non-contact the valve seat 140 to control the flow of the fluid 150.

DISCLOSURE OF THE INVENTION Technical-Problem However, in the conventional butterfly valve 100, as shown in FIG. la, the moment the one side seat contacting end 120a of a rotational disk 30 closely contacts the valve seat 140 by the rotation of the rotational disk 120 by the rotation of the rotational shaft 110 to check the flow of 5 the fluid 150, as shown in FIG. lb, foreign objects (foreign objects contained in the waste water, foreign objects contained in the exhaust gas, resin material for the injection molding, granules contained in the cement, or grain granules) contained in the fluid flowing along the 10 conveying line or the vertical pipeline 160 get into between the seat contacting end 120a and the valve seat 140.

For example, the moment the one side seat contacting end 120a closely contacts the valve seat 140 by the rotation of the rotational disk 120, when it is assumed that the 15 fluid is grains, grains 150a (initially introduced into between the seat contacting end 120a and the valve seat 140 by the rotation of the rotational disk 120 or other foreign objects 150a mixed in the grains are jammed, by which a minute gap may be formed between the seat contacting end 20 120a of the rotational disk 120 moving in a circular-motion and the valve seat 140.

However, the fluid is subject to pressure in the line, the initial fluid (or foreign object) 150a is not easily removed from a space between the seat contacting end 120a and the valve seat 140, rather allowing the following fluid or foreign objects to be continuously pushed and jammed between the seat contacting end 120a and the valve seat 140.

As a result, as shown in FIG. lb, in the conventional butterfly valve 100, when the fluid such as granules, grains, powder or other foreign objects flowing along the conveying line or the vertical pipeline 160 is jammed between the valve seat 140 and the seat contacting end 120a of the rotational disk 120, the flow of the fluid cannot be completely checked. When the fluid is emission, the exhaust gas leakage accident may be incurred and an air leakage depressing the fluid may be incurred.

In addition, when the rotation disk 120 repeatedly rotates in a state where the grains or other objects 150a are jammed, the valve seat 140 may be damaged, thereby deteriorating the sealing property of the valve. Sometimes, there will be a need to exchange the valve or the whole body of the valve.

Technical-Solution Accordingly, the present invention has been made in an effort to solve the above-described problems of the prior art. An object of the invention is to provide a butterfly 5 valve improved in sealing, which is designed to improve the seal between a rotational disk and a valve seat by preventing fluid granules or other foreign objects from getting into between the valve seat and a seat contacting end of the rotational disk and to improve its operation and 10 service life by effectively preventing the damage of the valve seat and the leakage of the fluid including air.

To achieve the above object and other advantages and in accordance with the purpose of the invention, as embodied and broadly described herein, there is provided a butterfly 15 valve improved in sealing, comprising a valve body through which fluid passes; a rotational disk provided on a longitudinal rotational shaft of the valve body; and a valve seat installed on an inner circumference of the valve body and designed to check fluid flow when contacting the 20 rotational disk, wherein the rotational disk comprises space-forming means defining a space to which the fluid or

foreign objects jammed between a seat contacting end of the rotation disk and the valve seat are directed.

Preferably, the space-forming means is formed of a semi-circular plate detachably attached on the rotational disk to define the space.

Alternatively, the space-forming means is formed of an integral elevated member integrally formed on the rotational disk to define the space.

Preferably, the butterfly valve is an eccentric butterfly valve, and the space-forming means is formed on at least one side of the rotational disk.

Alternatively, wherein the butterfly valve is a concentric butterfly valve, and the space-forming means is formed on at least one side of the rotational disk.

At this point, the rotational disk is further projected in a radial direction beyond the space-forming means to prevent the valve seat from being damaged by the space-forming means.

Further preferably, the valve seat is an expansion/contraction type valve seat that is expanded by compressing fluid supplied through a fluid passage provided in the valve and contracted when the fluid is exhausted.

At this point, the butterfly valve is an eccentric butterfly valve, and the fluid passage is formed to allow the fluid to flow through a valve body and a seat ring 5 mounted in the valve body to fix the valve seat.

Alternatively, the butterfly valve is a concentric butterfly valve, and the fluid passage is formed to allow the fluid to flow through the valve body.

Further preferably, the fluid used for expanding and 10 contracting the expansion/contraction type valve seat is one of air and oil.

Description Of Drawings FIG. la is a plan view of a butterfly valve according 15 to an embodiment of the prior art, in which a valve is closed; FIG. 1b is a plan view of a butterfly valve depicted in FIG. la, in which foreign objects are jammed in a closing operation; 20 FIG. 2 is an exploded perspective view of a butterfly valve according to an embodiment of the present invention; FIG. 3 is a front view of a butterfly valve depicted in FIG. 2; FIG. 4a is a perspective view of a major portion of a rotational disk having space-forming means preventing 5 foreign objects from being jammed in a butterfly valve according to an embodiment of the present invention, in which the space-forming means is formed in an integral structure; FIG. 4b is a perspective view of a major portion of a 10 rotational disk having space-forming means preventing foreign objects from being jammed in a butterfly valve according to an embodiment of the present invention, in which the space-forming means is formed in a separated structure; 15 FIG. 5a is a view illustrating an operation of a conventional butterfly valve ; FIG. 5b is a view illustrating an operation of a butterfly valve according to the present invention; FIG. 5c is a view illustrating a major part of FIG.

20 5b; FIG. 6 is a schematic view of an operation of an eccentric butterfly valve with space-forming means formed on one side of a rotational disk according to an embodiment of the present invention; FIG. 7 is a schematic view of an operation of an 5 eccentric butterfly valve with space-forming means formed on both sides of a rotational disk according to an embodiment of the present invention; FIG. 8a is a plan view of a conventional concentric butterfly valve; 10 FIG. 8b is a plan view of a concentric butterfly valve according to another embodiment of the present invention; FIG. 9a is a view of a major part of a concentric butterfly valve depicted in FIG. 8b, illustrating a state just before the valve is closed ; 15 FIG. 9b is a view of a major part of a concentric butterfly valve depicted in FIG. 8b, illustrating a state where the valve is closed; FIG. 10a is a plan view of an eccentric butterfly valve with an expansion/contraction-type valve seat that can 20 expand and contract by fluid such as air or oil according to another embodiment of the present invention, in which space- forming means is provided on one side of a rotational disk; FIG. 10b is a plan view of an eccentric butterfly valve with an expansion/contraction-type valve seat that can expand and contract by fluid such as air or oil according to 5 another embodiment of the present invention, in which space- forming means is provided on both sides of a rotational disk; FIG. 10c is a view of a major part of FIG. 10a ; FIG. lla is a plan view of a concentric butterfly 10 valve with an expansion/contraction-type valve seat that can expand and contract by fluid such as air or oil according to another embodiment of the present invention, in which space- forming means is provided on one side of a rotational disk; FIG. llb is a plan view of a concentric butterfly 15 valve with an expansion/contraction-type valve seat that can expand and contract by fluid such as air or oil according to another embodiment of the present invention, in which space- forming means is provided on both sides of a rotational disk; and 20 FIG. llc is a view of a major part of FIG. lla.

Best Mode The present invention will be described more in detail in conjunction with the accompanying drawings.

FIGS. 2 and 3 show a butterfly valve 1 according to an 5 embodiment of the present invention. The butterfly valve 1 of this embodiment is an eccentric butterfly valve or a shaft-eccentric type butterfly valve where a rotational disk 30 is eccentric with respect to a rotational shaft 20.

The butterfly valve 1 includes a valve body 10, the 10 rotational disk 30 and a valve seat 40. The valve seat 40 is fixed by a seat ring 60 and a cover 70.

That is, the valve body 10 is a housing having an opening which functions as a passage of a variety of fluid (80 in FIG. 5b) such as waste water, emission generated in, 15 for example, a steel maker, resin used for injection molding, cement, and grains such as rice.

As shown in FIGS. 2 and 3, the rotational shaft 20 is mounted on the valve body 10 such that it can be manipulated by human power of other mechanical tools through a center of 20 the valve body 10. The disk-shaped rotational disk 30 is eccentrically mounted on the rotational shaft 20. That is,

as shown in FIG. 4, the rotational disk 30 is eccentrically coupled to the rotational shaft by an attaching member 32 attached on one side surface of the rotational disk 30.' As shown in FIGS. 2 and 3, the valve seat 40 is mounted on an inner circumference of the valve body 10 to check the flow of the fluid by closely contacting a seat contacting end 30a of the rotational disk 30. At this point, the seat ring 60 and the cover 70 that support the valve seat 40 are fixed onto the valve body 10.

At this point, as shown in FIGS. 2 and 4, the rotational disk 30 is provided with space-forming means 50 for forming a space A to which foreign objects 80a jammed between the seat contacting end 30a and the valve seat 40 are directed.

As shown in FIGS. 5a and 5b, the conventional butterfly valve 100 and the inventive butterfly valve 1 will be compared with each other hereinafter to describe the space-forming means 50 provided on the inventive butterfly valve 1 in more detail.

As shown in FIG. 5a, in the conventional butterfly valve 100, the rotational disk 120 rotates by the rotational shaft 110. When a left side seat contacting end 120a of the rotational disk 120 contacts the valve seat 140, initial fluid or foreign objects mixed in the fluid are jammed between the seat contacting end 120a and the valve seat 140 5 and the following fluid is consecutively jammed between the seat contacting end 120a and the valve seat 140.

Since the fluid is subject to pressure in the conveying line or the vertical pipeline, when the initial fluid or foreign objects 150a are jammed between the seat 10 contacting end of the rotational disk and the valve seat, thereby forming a gap. Other fluid or foreign objects are further jammed in the gap.

At this point, foreign objects contained in the waste water or emission, resin, cement, or grains are also jammed 15 to form a gap through which pressurized air or fluid is leaked.

However, as shown in FIG. 5b, in the inventive butterfly valve 1, when the seat contacting end 30a of the rotational disk 30 contacts the valve seat 40 by the 20 rotation of the rotational disk 30, the space-forming means 50 provided on the rotational disk 30 allows the initial

fluid or foreign objects 80a to flow into the space A defined by the space-forming means 50.

A this point, the foreign objects 80a directed into the space A of the space-forming means 50 are smoothly transferred by the rotation of the rotation disk 30 since the pressure is not applied to the fluid, thereby preventing the jam of the following fluid.

Accordingly, the foreign objects are smoothly transferred in the space A of the space-forming means 50, as a result of which the seat contacting end 30a of the rotational disk 30 can maintain the close contact state with the valve seat 40.

Meanwhile, the space-forming means 50, as shown in FIG.

4b, may be formed of a semi-circular plate detachably attached on the rotational disk 30 to define the space A allowing the foreign objects 80a to be induced there into.

The outer circumference of the semi-circular plate is concaved to define the space A to which the initial fluid or foreign objects 80a are introduced.

The semi-circular plate of the space-forming means 50 schematically shown in the drawing may be attached on the

rotational disk 30 by welding or bolts.

As shown in FIG. 4a, the space-forming means 50 of the present invention may be formed of an elevated member integrally formed on the rotational disk 30 to define the space A. In this case, the rotational disk 30 with the integral elevated member may be formed through a metal cast process. The butterfly valve 1 with the space-forming means 50 of the integral elevated member is preferably applied to a large-sized pipeline.

As shown in FIG. 5c, in the inventive eccentric butterfly valve 1, the seat contacting end 30a of the rotational disk 30 is further projected beyond an end 50a of the space-forming means 50 so that a gap can be formed there between.

That is, when the rotational disk 30 rotates in a direction where the valve seat 40 and the seat contacting end 30a of the rotational disk 30 contact each other, if the end 50a of. the space-forming means 50 is projected to be identical to the seat contacting end 30a, the valve seat 40 may be damaged by the end 50a of the space-forming means 50.

Furthermore, in order to provide a secure seal, the valve

seat should be depressed on the rotational disk. In this case, the possibility of the valve seat damage will be further increased.

As shown in FIG. 6, since the foreign objects 80a are generally jammed at the one side seat contacting end 30a even when the space-forming means 50 is installed on only the seat contacting end 30a side of the rotational disk 30, the problems of the prior art described with reference to FIGS. 1b and 5a are solved. However, as shown in FIG. 7, it is also possible that the space-forming means 50 may be formed of the semi-circular plates or integral elevated members detachably attached on both sides of the rotational disk 30.

That is, as shown in FIG. 6, since the other side seat contacting end of the rotational disk 30 is not applied with pressure from a rear side in the rotational direction, the initial fluid or foreign objects 80a, the fluid or foreign objects are not easily jammed between the right side seat contacting end and the valve seat 40. However, as shown in FIG. 6 in case where the valve is applied to the conveying line subject to fluid pressure from both sides, the space-

forming means 50 is preferably installed on the both sides of the rotational disk 30. In this case, although the manufacturing costs of the valve will be increased, the secure seal can be obtained.

Accordingly, in the eccentric butterfly valve 1, the space-forming means 50 provided on the rotational disk 30 may be provided on one or both sides of the rotational disk 30.

The operation of the space-forming means 50 of the inventive butterfly valve 1 will be described hereinafter with reference to FIGS. 6 and 7. When the rotational disk 50 rotates by the rotation of the rotational shaft 20, the fluid or foreign objects 80a jammed between at least one of both sides of the seat contacting ends 30a and 30b and the valve seat 40 flow into the space A of the space-forming means 50. At this point, the foreign objects 80a in the space A is not subject to the pressure, they are not compressed by the rotation of the rotational disk 30 but smoothly move in the rotational direction of the rotational disk 30.

Accordingly, when compared with a prior case where the

foreign objects 150a are jammed between the seat contacting end 120a of the rotational disk 120 and the valve seat 140 (see FIG. 5a), as shown in FIGS. 6 and 7, the foreign objects 80a are not jammed between the seat contacting end 30a of the disk and the valve seat, thereby improving the sealing property between the rotational disk and the valve seat, preventing the wear of the valve seat to save the costs.

FIGS. 8 and 9 show a butterfly valve according to another embodiment of the present invention. The butterfly valve of this embodiment is a concentric butterfly valve or a shaft-concentric type butterfly valve.

As shown in FIGS. 8 and 9, the concentric butterfly valve 1 of this embodiment has a rotational shaft 20 penetrating a center of the rotational disk 30.

At this point, as shown in FIG. 8a, initial fluid or foreign objects (150a in FIG. 5a) may be jammed between the seat contacting end 120a and the valve seat 140 in the conventional concentric butterfly valve.

However, as shown in FIGS. 8 and 9, in the concentric butterfly valve 1 of the present invention, the space-

forming means 50 may be provided on one side or both sides of the rotational disk 30 as in the butterfly valve depicted in FIGS. 6 and 7.

At this point, as in the butterfly valve depicted FIG.

4, the concentric butterfly valve 1 of this embodiment is also designed such that the semicircular plate is detachably attached on the rotational disk 30 or the integrate elevated member may be integrally formed with the rotational disk through the steel cast process.

At this point, as shown in FIG. 9, when the butterfly valve is the concentric butterfly valve 1, the end of the space-forming means 50 is formed to be shorter than the seat contacting end 30a (or 30b) of the rotational disk to prevent the wear of the valve seat.

That is, as shown in FIG. 9b, it is preferable that a gap is formed between the seat contacting end 30a of the rotation disk and the end 50a of the space-forming means 50.

FIGS. 10 and 11 show a butterfly valve according to another embodiment of the present invention. In this embodiment, the butterfly valve is formed of the concentric or eccentric butterfly valve, in which a valve seat is formed of an expansion/contraction type valve seat 40'that is expanded and contracted by pressure fluid such as air or oil. Accordingly, the sealing property between the rotational disk and the valve seat is improved and the wear 5 and damage of the valve seat can be minimized.

That is, the valve seat 40'is elastically contracted when fluid is exhausted. The valve seat 40'is contracted when the rotation disk is in a close position where it completely checks or cuts off the flow of the fluid.

10 Accordingly, the wear and damage of the valve seat 40'can be prevented.

Accordingly, the butterfly valve 1'depicted in FIGS.

10 and 11 is designed to increase the service life of the valve seat by preventing the wear and damage of the valve 15 seat and to prevent the initial fluid or foreign objects from being jammed between the valve seat and the rotational disk by the space-forming means 50.

FIG. 10 shows the eccentric butterfly valve 1', in which a fluid passage for compressing and exhausting the 20 fluid toward and from the valve seat 40'is formed through the valve body 10 and a seat ring 60 coupled to the valve

body to fix the valve seat 40'.

At this point, as shown in FIG. 10c, the fluid passage 90 is comprised of a first passage 92 formed on the valve body 10 and provided with a nipple 98 to which an air tube or an oil tube is coupled, a circular passage 94 formed on an outer circumference of the seat ring 60 to communicate with the first passage 92, and second passage 96 formed on the state ring 60 to be spaced away from each other at a predetermined distance and communicate with the circular passage 94.

Accordingly, when the fluid such as air and oil is fed to the first passage 92 and directed to the circular passage 94, it flows in the circumferential direction along the seat ring and expands the valve seat 40'through the second passages 96. When the valve seat is expanded, the rotational disk is located in the valve close position where the valve seat closely contacts the rotational disk.

When the valve is opened, the fluid is exhausted through the fluid passage 90 just before the rotational disk 30 rotates, thereby contracting the valve seat 40'and forming a minute gap between the rotational body 30 and the

valve seat 40'. As a result, the rotational disk is rotated to the opening position without wearing and damaging the valve.

As a result, as shown in FIGS. 10a and 10b, by the rotational disk 30 with the space-forming means 50 on at least one of both sides, the fluid granules or foreign objects 80a are not jammed between the disk and the valve seat and the wear and damage of the valve seat can be prevented.

FIG. 11 shows the concentric butterfly valve 1'with the expansion/contraction type valve seat 40'.

That is, as shown in FIG. llc, a fluid passage 90 is provided through a valve body 10 coupled to a valve seat 40' and a nipple 98 is provided on an inlet side of the fluid passage 90 and coupled to an air or oil tube.

Accordingly, when the compressed fluid is supplied through the fluid passage 90, the expansion/contraction valve seat 40'is expanded to increase the frictional force with the rotation disk 30, thereby improving the sealing property of the valve. When the fluid is exhausted, the valve seat 40 is contracted to prevent the valve seat from

being worn and damaged.

As a result, as shown in FIGS. lla and llb, by the rotational disk 30 with the space-forming means 50 on at least one of both sides, the fluid granules or foreign objects 80a are not jammed between the disk and the valve seat and the wear and damage of the valve seat can be prevented.

Meanwhile, as shown in FIGS. 10c and llc, in the butterfly valve 1'with the expansion/contraction valve seat 40', there is no need for a gap between the end 50a of the space-forming means 50 and the seat contacting end 30a (or 30b) of the disk since the valve seat expands and contracts by itself.

However, in order to standardize the space-forming means so that the space-forming means can be applied to both valves respectively having the normal valve seat 40 and the expansion/contraction valve seat 40', as shown in FIG. 5c and 9, it is preferable that a gap is formed between the end 50a of the space-forming means 50 and the seat contacting end 30a of the disk.

As described above, the butterfly valve is designed to improve the seal between a rotational disk and a valve seat by preventing fluid granules or other foreign objects from getting into between the valve seat and a seat contacting end of the rotational disk and to improve its operation and 5 service life by effectively preventing the damage of the valve seat and the leakage of the fluid including air.

Furthermore, when the valve seat is formed of an expansion/contraction valve seat, the wear of the valve seat can be further prevented.

10 Industrial Applicability In the butterfly valve of the present invention, by forming the space-forming means for defining a side space on the rotational disk checking the fluid flow by contacting 15 the valve seat, the fluid jammed between the valve seat and the rotational disk are removed when the rotational disk rotates, thereby effectively preventing the damage of the valve seat and the fluid leakage to increase the service life and improve the valve operation.

20 In addition, by using the expansion/contraction valve seat, the wear and damage of the valve seat can be minimized.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it will be understood by those of ordinary skill in the art that various changes in form and details may be made therein without departing from the spirit and scope of the present invention as defined by the following claims.