WO2002075185A1

WO2002075185A1 - Butterfly valve

Info

Publication number: WO2002075185A1
Application number: PCT/KR2002/000452
Authority: WO
Inventors: Jong Chul Lee; Young Choi; Hong Tae Yeo
Original assignee: K. B. Co., Ltd.
Priority date: 2001-03-19
Filing date: 2002-03-15
Publication date: 2002-09-26

Abstract

Disclosed is a butterfly valve where the sealing structure made between a rigid metal seat (130) and a rigid valve disc (126) is improved such that the valve disc (126) is closely contacted with the metal seat (130) with a zero point of contact and separated from the metal seat (130) from the zero point of contact, thereby ensuring that the sealing and durability thereof are greatly advanced at a high temperature and at a high pressure. The contact faces (127a, 127b) between the metal seat (130) and the valve disc (126) are straight lines BC and DE and guarantee a high sealing effect without using elastic or frictional behaviour of the valve seat or the valve disc.

Description

BUTTERFLY NALNE

Technical Field

The present invention relates to a butterfly valve, and more particularly, to a butterfly valve where the sealing structure made between a metal seat and a valve disc is improved such that the valve disc is closely contacted with the metal seat with a zero point of contact and separated from the metal seat from the zero point of contact, thereby ensuring that the sealing and durability thereof are greatly advanced at a high temperature and at a high pressure.

Background Art

FIG. 1 shows a configuration of a sealing portion in a conventional butterfly valve, where a sheet type of metal seat 2 is secured on the side of a valve body 10 by means of an insert ring 4 such that the inside of the metal seat 2 becomes in contact with the outside of a valve disc 3, with the elasticity thereof. As a result, when the valve disc 3 rotates for closing the butterfly valve, the valve disc 3 comes in contact with the inside of the metal seat 2 by the elasticity produced from the metal seat 2. FIG. 2 shows another configuration of the sealing portion in the conventional butterfly valve, where there is provided a round seat ring 16 between a valve body 11 and a seat retainer 15 such that by using the elasticity of the seat ring 16, a valve disc 13 becomes in contact with the seat ring 16 upon closing the valve.

FIG. 3 shows still another configuration of the sealing portion in the conventional butterfly valve, where several angle rings 21 are provided between a retainer 22 and a valve disc 23 such that one of the angle rings 21 becomes in contact with a seat 25 on a valve body 24 side.

However, each of the sealing ways embodied in the conventional butterfly valve in FIGS. 1 to 3 has some defects in the conditions of high temperature and pressure for a substantially long period of time.

Referring first to FIGS. 1 and 2, the sealing effect is achieved by using the elasticity of the metal itself such as the sheet type of metal seat 2 and the round seat ring 16, with a result that the friction generated at the time when the metal seat 2 and the seat ring 16 are in contact with the valve discs 3 and 13 causes the metal seat 2 and the seat ring 16 to be worn, which makes the sealing effect undesirably deteriorated after the use of long period of time. That is to say, the sealing is obtained or released by the action of the elasticity and friction and therefore, if either the elasticity or the friction fails to exert, its inherent sealing can't be well kept. It can be hence understood that the metal seat 2 and the seat ring 16 as shown in the figures are not suitable as a desired metal seat. Especially in FIG. 2, a number of parts such as, for example, a ball 12, a set screw 14, a plate spring 17 and a back up spring 18 are added, which causes the number of assembling processes and the cost of production to be considerably raised.

Referring to FIG. 3, the configuration exhibits some durability against the abrasion. However, it suffers from some disadvantages that the production process of the angle rings 21 is implemented in complicated ways and it is difficult to have complete sealing.

Disclosure of Invention

An object of the present invention is to provide a butterfly valve where a zero point of contact between a valve disc and a metal seat is obtained, without the use of elasticity caused from the metal seat and with no friction between the valve disc and the metal seat, thereby achieving complete sealing therebetween.

Another object of the present invention is to provide a butterfly valve that is provided with a valve disc that absorbs the expansion at the atmosphere of high temperature and pressure in the butterfly valve, thereby preventing contact portions between the valve disc and a metal seat from being physically attached to each other.

To achieve these and other objects of the present invention, there is provided a butterfly valve that has a metal seat disposed in a valve body for sealing a valve disc and opens and closes a fluid passage by manipulating the valve disc by means of a rotary shaft, characterized in that the inner periphery of the metal seat is formed in such a fashion that definite straight lines A'C and DF' are integrated circumferentially, in manners to make definite straight lines OA' and OC have the same radius at one radius area thereof and to make definite straight lines OD and OF' at the other radius area thereof have the same radius, around the rotating center of the rotary shaft; the outer periphery of the valve disc is formed in such a fashion that a definite straight line BC with a point of contact B at the center of the definite straight line A'C and a definite straight line DE with a point of contact E at the center of the definite straight line DF' are divided around a centering line X of the valve disc and circumferentially integrated; and the valve disc being provided on the outer periphery thereof with separation faces with end points having smaller arc radius than the points of contact B and E of the metal seat, for the purpose of deviating the valve disc from the metal seat upon opening the valve disc.

Preferably, the definite straight lines A'C and DF' are correspondingly located on a short radius area and a long radius area relative to the rotating center of the rotary shaft. The rotating center of the rotary shaft is placed on the center line X of the fluid passage or placed eccentrically by a predetermined interval from the center line X.

Preferably, the valve disc is provided with a plurality of thermal contact preventing grooves that are adapted to prevent contact portions between the valve disc and the metal seat from being physically bonded with each other when the valve disc is closed with a zero point of contact, on the one side thereof or the both sides thereof.

Additional advantages, objects, and features of the invention will be set forth in part in the description which follows and in part will become apparent to those having ordinary skill in the art upon examination of the following or may be learned from practice of the invention. The objectives and other advantages of the invention may be realized and attained by the structure particularly pointed out in the written description and claims hereof as well as the appended drawings.

Brief Description of the Drawings

Further objects and advantages of the invention can be more fully understood from the following detailed description taken in conjunction with the accompanying drawing in which:

FIGS. 1 to 3 show various configurations of the main parts of the sealing portion in a conventional butterfly valve;

FIG. 4 shows a perspective view for a butterfly valve according to the present invention;

FIG. 5 shows a sectional view taken along the line A-A in FIG. 4 when the valve disc is closed; FIG. 6 shows the arc track of the valve disc in the contact portions between the valve disc and the metal seat in FIG. 4;

FIG. 7 shows a rear view for the valve disc applied in the present invention;

FIG. 8 shows the case where the center of the rotary shaft for manipulating the valve disc is located at the centering line of the valve disc; FIG. 9 shows a trajectory of valve disk in the eccentric state; and

FIG. 10 shows a trajectory of valve disk in the center state.

Best Mode for Carrying Out the Invention

The present invention will now be described in detail in connection with preferred embodiments with reference to the accompanying drawings. For reference, like reference characters designate corresponding parts throughout several views.

FIG. 4 shows a perspective view for a butterfly valve according to the present invention, FIG. 5 shows a sectional view taken along the line A-A in FIG. 4 when the valve disc is closed, FIG. 6 shows the arc track of the valve disc in the contact portions between the valve disc and the metal seat in FIG. 4, FIG. 7 shows a rear view for the valve disc applied in the present invention, and FIG. 8 shows the case where the center of the rotary shaft for manipulating the valve disc is located at the centering line of the valve disc. As shown in FIGS. 4 and 5, a butterfly valve according to the present invention includes a valve body 120, a rotary shaft 124 for opening and closing a fluid passage 123 in the valve body 120, and a valve disc 126 connected to the rotary shaft 124 such that the fluid passage 123 is opened and closed.

The valve body 120 is provided on the inner peripheral surface with a metal seat 130 that comes in face-contact with the outer peripheral surface of the valve disc 126, when the valve disc 126 rotates around the rotating center O of the rotary shaft 124, and thus opened and closed.

In the state where the valve disc 126 is closed, on the contact portions where the outer peripheral surface of the valve disc 126 and the inner peripheral surface of the metal seat 130 come in contact with each other, the definite straight line BC at the short radius area and the definite straight line DE at the long radius area are integrated peripherally around the rotating center O of the rotary shaft 124, as shown in FIG. 6, thereby forming shared contact faces 127a and 127b thereon.

In this case, the short radius area corresponds to the right circumference and the long radius area to the left circumference, around the center line X of the valve disc 126, as shown in FIG. 7.

The inner peripheral surface of the metal seat 130 is formed in such a fashion that definite straight lines A'C and DF' are integrated peripherally, in manners to make definite straight lines OA' and OC have the same radius at the short radius area thereof and to make definite straight lines OD and OF' at the long radius area thereof have the same radius, around the center line X of the valve disc 126.

The points A' and D have the same distance value 'd/2' from the center line X, wherein the 'd' represents a maximum diameter value of the metal seat 130.

The outer peripheral surface of the valve disc 126 is formed in such a fashion that a definite straight line BC with a point of contact B at the center of the definite straight line A'C and a definite straight line DE with a point of contact E at the center of the definite straight line DF' are divided around the centering line X of the valve disc 126 and integrated peripherally.

In addition, the valve disc 126 is provided on the outer peripheral surface thereof with separation faces 126e and 126f with end points A and F having smaller arc radius than the points of contact B and E of the metal seat 130, for the purpose of deviating the valve disc 126 from the metal seat 130 upon opening the valve disc 126.

If the rotary shaft 124 rotates counterclockwise to open the valve disc 126, as shown in FIGS. 5 and 6, the definite straight lines BC and DE are deviated from the metal seat 130 at the zero point of contact, around the rotating center O of the rotary shaft

124.

At that time, the arc track of the rotary radius (R_A) that is drawn by the point A of the one separation face 126e in the valve disc 126 is passed through the point of contact

B of the metal seat 130, and at the same time, the arc track of the rotary radius (Rp) that is drawn by the point F of the other separation face 126f in the valve disc 126 is passed through the point of contact E of the metal seat 130.

In other words, when the valve disc 126 is opened, the point A is not interfered by the point of contact B and the point F is not interfered by the point of contact E, as shown in FIG. 6. On the other hand, when the valve disc 126 is closed, the rotary radius (Re) of the valve disc 126 drawn by the definite straight line OB is larger than that of the metal seat 130 drawn by the definite straight line OB and at the same time, the rotary radius of the valve disc 126 drawn by the definite straight line OE is larger than that of the metal seat

130 drawn by the definite straight line OE, such that when the valve disc 126 is at the points of contact B, C, D and E, it can't further rotate clockwise (in a direction where the valve is closed) and has the sealing with the metal seat 130 at the zero point of contact therewith.

If the valve disc 126 is closed, there are provided the contact faces 127a and 127b where the valve disc 126 and the metal seat 130 are contacted with each other, such that they come in close contact with each other with a zero gap therebetween on the straight lines connecting the points of contact B and C and connecting the points of contact D and E existing on the contact faces 127a and 127b.

As understood from the above description, the butterfly valve according to the present invention has the geometrical contact faces between the valve disc 126 and the metal seat 130, without using the sealing components such as, for example, friction or elasticity obtained in the conventional butterfly valve, with a result that no abrasion is generated on the contact faces. Also, the valve disc 126 comes in contact with the metal seat 130 at the zero gap therewith and thus closed, thereby exhibiting an excellent sealing effect. On the other hand, the valve disc 126 is provided with a plurality of thermal contact preventing grooves 126a, as shown in FIG. 7, that are .adapted to prevent the valve disc 126 from being thermally contacted with the metal seat 130, when the valve disc 126 is expanded due to the fluid at the high temperature and pressure.

At that time, the thermal contact preventing grooves 126a may be formed on the front or rear side of the valve disc 126.

FIG. 9 illustrates a trajectory of zero point of contact substantially shown on the valve disc 126.

A reference numeral 140 that is not described yet denotes a seat retainer for fixing the metal seat 130 on the valve body side 120. In the preferred embodiment of the present invention, the rotating center O of the rotary shaft 124 is placed eccentrically from the axis X of the metal seat 130, for the purpose of improving the sealing effect of the valve disc 126. However, even if the rotating center O of the rotary shaft 124 is placed on the axis X of the metal seat 130, the valve disc 126 is closed at the zero point of contact under the above-mentioned geometrical configuration substantially as shown in FIG. 10 and opened by the operation of the separation faces 126e and 126f.

Industrial Applicability

■ As described above, the butterfly valve according to the present invention has some advantages: since a valve disc comes in contact with a metal seat with a zero gap when the valve disc is closed, a more excellent sealing effect is obtained; since the sealing is not obtained from the elasticity of the metal seat, the decrease in the sealing capability according to the reduction of the elasticity does not occur; and since the valve disc is opened and closed, without any friction with the metal seat, no abrasion is found on the contact faces between the valve disc and the metal seat and the durability thereof is greatly improved.

Additionally, the sealing between the valve disc and the metal seat is obtained, without having the friction or elasticity obtained in the conventional butterfly valve, thereby reducing the number of parts necessary for obtaining the friction or elasticity, which enables production cost to be considerably decreased.

Claims

What Is Claimed Is:

1. A butterfly valve that has a metal seat (130) disposed in a valve body

(126) for sealing a valve disc (126) and opens and closes a fluid passage (123) by manipulating said valve disc (126) by means of a rotary shaft (124), characterized in that: the inner peripheral surface of said metal seat (130) is formed in such a fashion that definite straight lines A'C and DF' are integrated peripherally, in manners to make definite straight lines OA' and OC have the same radius at the one radius area thereof and to make definite straight lines OD and OF' at the other radius area thereof have the same radius, around the center line (O) of said rotary shaft (124); the outer peripheral surface of said valve disc (126) is formed in such a fasion that a definite straight line BC with a point of contact B at the center of the definite straight line A'C and a definite straight line DE with a point of contact E at the center of the definite straight line DF' are divided around a centering line (X) of the valve disc (126) and integrated peripherally; and said valve disc (126) being provided on the outer peripheral surface thereof with separation faces (126e, 126f) with end points (A, F) having smaller arc radius than the points of contact (B, E) of the metal seat (130), for the purpose of deviating the valve disc (126) from the metal seat (130) upon opening the valve disc (126).

2. The butterfly valve according to claim 1, wherein said definite straight lines A'C and DF' are correspondingly located on a short radius area and a long radius area relative to said rotating center (O) of said rotary shaft (124).

3. The butterfly valve according to claim 1, wherein said rotating center (O) of said rotary shaft (124) is placed on the center line (X) of said fluid passage (123).

4. The butterfly valve according to claim 1, wherein said rotating center (O) of said rotary shaft (124) is placed eccentrically by a predetermined interval from said center line (X) of said fluid passage (123).

5. The butterfly valve according to claim 1, wherein said valve disc (126) is provided with a plurality of thermal contact preventing grooves (126a) that are adapted to prevent contact portions between said valve disc (126) and said metal seat (130) from being physically bonded with each other when said valve disc (126) is closed with a zero point of contact, on the one side thereof or the both sides thereof.