CN217081442U

CN217081442U - Energy-saving six-eccentric metal sealing butterfly valve

Info

Publication number: CN217081442U
Application number: CN202123009618.9U
Authority: CN
Inventors: 邵力亭; 周军; 王泓鉴; 郑小静; 邵淳; 孙河锋; 何界; 黄辉
Original assignee: Zhejiang Beize Valve Technology Co ltd
Current assignee: Beize Valve Group Co ltd
Priority date: 2021-11-30
Filing date: 2021-11-30
Publication date: 2022-07-29
Anticipated expiration: 2031-11-30

Abstract

The utility model provides an energy-saving six eccentric metal seal butterfly valves, including the valve body, the valve rod, disk seat and butterfly plate, form the valve body runner in the valve body, disk seat and butterfly plate set up in the valve body runner, the one end of valve rod stretches into the valve body runner and is connected with the butterfly plate, set up six eccentric seal structure and disk seat seal structure on the valve body, six eccentric seal structure include eccentricity structure and eccentric angle structure, the eccentricity structure includes first eccentricity E1 and second eccentricity E2, the eccentric angle structure includes first eccentricity beta, first eccentricity E1 forms between valve rod and valve body runner, second eccentricity E2 forms between valve rod and valve body, form first eccentricity beta between disk seat and the valve body, the utility model discloses both remain present conventional three eccentric butterfly valve sealing performance reliable, long service life, open and close advantages such as sealed frictionless, also require simultaneously to open and close the stroke short, the on-off time still less, The energy-saving six-eccentric butterfly valve has the advantages of small pressure loss, lower energy loss and better economic performance.

Description

Energy-saving six-eccentric metal sealing butterfly valve

Technical Field

The utility model relates to a butterfly valve technical field, concretely relates to six eccentric metal seal butterfly valves of energy-saving.

Background

The butterfly valve is a valve which uses a disc type opening and closing piece to rotate back and forth by about 90 degrees to open, close or adjust the medium flow. The butterfly valve has the advantages of simple structure, small volume, light weight, less material consumption, small installation size, small driving moment, simple and convenient operation and rapidness, and simultaneously has good flow regulation function and sealing closing characteristic, thereby being one of the fastest valve varieties developed in the last ten years. Butterfly valves are widely used, and their variety and number of uses continue to expand, and have been developed toward high temperature, high pressure, large caliber, high sealing, long life, excellent regulation characteristics, and one-valve multiple functions. The reliability and other performance indexes of the composite material reach higher levels.

The excellent performance of the butterfly valve is closely related to the continuous eccentricity, evolution and development of the butterfly valve. In order to meet the requirements of various working conditions, the butterfly valve is subjected to evolution from concentricity to multiple eccentricities such as single eccentricity, double eccentricity, triple eccentricity, quadruple eccentricity and the like.

The multi-eccentric butterfly valve is used as the crystal of the latest technology of the valve, the length of various valves is increased, the length of various valves is avoided, the maximum pressure grade can reach 2500 pounds, the temperature can be resisted as low as minus 196 ℃, the temperature can reach as high as 700 ℃, the sealing reaches 0 leakage, and the regulation and control ratio can reach more than 100: 1. The standard caliber can be DN6000, and can correspond to clamps, lugs, flanges, ring joints, butt welds, jackets, various structural lengths and the like, and can also freely correspond to high and low temperatures and various corrosive media such as acid, alkali and the like due to large material selection margin. Especially in the case of large calibers, the shut-off valve is constantly replacing the thick gate and ball valves due to its zero leakage advantage. Butterfly valves are also continuously replacing heavy shut-off valves as control valves with their excellent control functions.

However, the opening and closing of the conventional butterfly valve is performed by 90 ° rotation of the valve stem, and thus, the opening and closing stroke of the conventional butterfly valve is one quarter of a circle, i.e., 90 °. For a large-diameter butterfly valve, a large torque is needed for opening and closing the butterfly valve, in order to easily open the butterfly valve at a hand wheel input torque end, the speed ratio of a worm gear device matched with the butterfly valve is large, the number of turns of a hand wheel or an electric actuator is large, so that the opening and closing time is long, sometimes, the opening or closing of one butterfly valve needs about half an hour or even longer, and the butterfly valve is time-consuming and labor-consuming.

In addition, the diameter of the valve seat of the conventional butterfly valve is smaller than the inner diameter of the flow passage openings at the two ends of the valve body, the thickness of the butterfly plate and the diameter of the valve shaft can occupy about 1/3 flow passage area when the butterfly plate is opened, and the flow area of a medium actually flowing through the valve seat only occupies 2/3 or even less. The reduction of the area of the flow passage inevitably leads to larger pressure loss of the butterfly valve, large energy consumption loss of the whole pipeline, increased use cost and great non-economy.

In view of the disadvantages of time and labor waste and huge cost in the opening and closing process and the use process, an energy-saving butterfly valve with short opening and closing stroke, short opening and closing time, small pressure loss, low energy consumption and good economical efficiency is especially needed to be designed.

Disclosure of Invention

In view of this, the utility model aims to overcome conventional butterfly valve prior art defect, provide one kind and had both remain present conventional three eccentric butterfly valve sealing performance reliable, long service life, open and close sealed advantage such as frictionless, also require simultaneously to open and close the stroke short, the on-off time still less, loss of pressure is little, energy loss is lower, the better energy-saving six eccentric butterfly valves of economic performance.

In order to achieve the above object, the utility model provides a following technical scheme:

the utility model provides an energy-saving six eccentric metal seal butterfly valves, includes valve body, valve rod, disk seat and butterfly plate, form the valve body runner in the valve body, disk seat and butterfly plate set up in the valve body runner, the one end of valve rod stretches into the valve body runner and is connected with the butterfly plate, set up six eccentric seal structure and disk seat seal structure on the valve body, six eccentric seal structure include that the eccentricity is apart from structure and eccentric angle structure, the eccentricity includes first eccentricity E1 and second eccentricity E2, the eccentric angle structure includes first eccentric angle beta, first eccentricity E1 forms between valve rod and valve body runner, the second eccentricity forms between valve rod and valve body apart from E2, form first eccentric angle beta between disk seat and the valve body.

Preferably, the perpendicular distance between the center line of the valve rod and the horizontal center line of the valve body flow passage forms a first eccentricity E1, and the perpendicular distance between the center line of the valve rod and the symmetrical center line of the valve body structure length forms a second eccentricity E2.

Preferably, the valve seat sealing structure is a sealing ring arranged on the butterfly plate, the butterfly plate is provided with a butterfly plate sealing surface, a sealing ring groove is formed in the butterfly plate sealing surface, the sealing ring is arranged in the sealing ring groove, and a first eccentric angle beta is formed between a radial plane of the valve seat and a central plane of the valve body structure length.

Preferably, the eccentric angle structure further comprises a second eccentric angle α, and an included angle between a central line of the oblique elliptic cone of the butterfly plate sealing surface and a central line of the butterfly plate forms the second eccentric angle α.

The preferred, the valve body is split type structure, the valve body includes left valve body and right valve body, form the disk seat mounting groove between left side valve body and the right valve body, the slope of disk seat mounting groove sets up, the disk seat sets up in the disk seat mounting groove, just the disk seat corresponds the disk seat mounting groove and is the slope structure setting.

Preferably, the left valve body is provided with a left end flange and a first middle flange, the right valve body is provided with a right end flange and a second middle flange, the valve seat mounting groove is formed between the first middle flange and the second middle flange, the first middle flange and the second middle flange are connected to form a middle flange, the middle flange is arranged in an inclined mode, and beta angles are formed between two ends of the middle flange and the corresponding left end flange and right end flange.

Preferably, a medium inlet and a medium outlet are correspondingly formed at two ends of the valve body flow passage, the valve body flow passage comprises an inlet portion close to the medium inlet, a middle chamber portion and an outlet portion close to the medium outlet, the inner diameters of the inlet portion and the outlet portion are the same, and the inner diameter of the middle chamber portion is larger than the inner diameters of the inlet portion and the outlet portion.

Preferably, the eccentricity structure further comprises a third eccentricity E3 and a fourth eccentricity E4, the distance between the central line of the valve rod and the plane of the sealing ring is perpendicular to form the third eccentricity E3, and the distance between the central line of the valve rod and the outer circle central line of the butterfly plate is formed the fourth eccentricity E4.

Preferably, the first eccentricity E1 is 1/10-1/8 × DN mm, and the second eccentricity E2 is 1/10-1/8 × DN mm.

Preferably, the first eccentric angle β is 45 ° to 55 °, and the second eccentric angle α is 8 ° to 12.

The beneficial effects of the utility model reside in that: the utility model discloses form six eccentric full metal hard to hard seal structure with whole sealing system. The six eccentricities are respectively the distances from a first eccentricity E1, a second eccentricity E2, a third eccentricity E3, a fourth eccentricity E4, a second eccentricity angle alpha and a first eccentricity angle beta. The third eccentricity E3 ensures that the valve stem does not penetrate the seal ring, making the seal ring a continuous and complete seal ring. The fourth eccentricity E4 enables the center of the valve rod to deviate from the center of the butterfly plate to form a cam effect, and the sealing ring and the valve seat have no interference and friction in the opening and closing processes of the butterfly plate. The first eccentricity E1 makes the valve rod offset in valve body runner center one side, and the butterfly plate is in valve body runner center basically when full-open, guarantees that upper and lower laminar flow is even steady and no torrent when the medium passes through the butterfly plate, and the pressure drop is minimum, and the energy consumption loss is minimum. The second eccentricity E2 makes the valve rod bias in one side of the valve body structure length symmetric center, and the butterfly plate is in the middle cavity position of the valve body expansion when fully opened, so as to ensure that the flow area reaches the maximum, the pressure loss is minimum when fully opened, and the energy loss is minimum. The second eccentric angle alpha enables the sealing surface of the valve seat and the sealing ring to form a conical surface which is completely attached and obliquely cut, and according to the cam effect, the sealing ring does not interfere with the valve seat and has no friction phenomenon in the opening and closing process of the sealing ring around the valve rod along with the butterfly plate; between sealing washer and the disk seat, close and laminate promptly, open and leave promptly, simultaneously, pressure is big more, seals tightly more. After the valve seat and the sealing ring are inclined by the first eccentric angle beta, the opening angle of the butterfly valve is changed into 90-beta, the opening and closing angle is changed into 45-55 degrees, the stroke is at least about 1/2 of the conventional butterfly valve, the opening and closing time is shortened by half at least, the time, the labor and the energy of the valve butterfly valve are saved, and the valve butterfly valve has good economic performance.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to these drawings without creative efforts.

FIG. 1 is a schematic structural view of the present invention;

FIG. 2 is a schematic sectional view of the structure of FIG. 1 at A-A in a fully open state;

FIG. 3 is a schematic cross-sectional view of the structure of FIG. 1, wherein A-A is in a fully closed state.

Reference numerals:

1. the valve comprises a valve body, 2, a valve rod, 3, a valve seat, 4, a butterfly plate, 5, a valve body flow passage, 6, a sealing ring, 7, a butterfly plate sealing surface, 8, a sealing ring groove, 9, a pressing ring, 10, a screw, 11, an actuating mechanism, 12, a left valve body, 13, a right valve body, 14, a valve seat mounting groove, 15, a middle flange, 16, a left end flange, 17, a first middle flange, 18, a right end flange, 19, a second middle flange, 20, a medium inlet, 21, a medium outlet, 22, an inlet part, 23, a middle cavity part, 24, an outlet part, E1, a first eccentric distance, E2, a second eccentric distance, E3, a third eccentric distance, E4, a fourth eccentric distance, alpha, a second eccentric angle, beta and a first eccentric angle.

Detailed Description

The technical solutions in the embodiments of the present invention will be described clearly and completely with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments in the present invention, all other embodiments obtained by a person skilled in the art without creative work belong to the protection scope of the present invention.

The invention will be further described with reference to the accompanying drawings.

The utility model provides a following technical scheme:

as shown in the accompanying drawings 1-3, the utility model discloses an energy-saving six eccentric metal seal butterfly valves, including valve body 1, valve rod 2, disk seat 3 and butterfly plate 4, form valve body runner 5 in the valve body 1, disk seat 3 and butterfly plate 4 set up in valve body runner 5, the one end of valve rod 2 stretches into valve body runner 5 and is connected with butterfly plate 4, set up six eccentric seal structure and valve seat seal structure on the valve body 1, six eccentric seal structure include that the eccentricity is apart from structure and eccentric angle structure, the eccentricity includes first eccentricity E1, second eccentricity E2, third eccentricity E3 and fourth eccentricity E4, the eccentricity structure includes first eccentricity angle beta and second eccentricity angle alpha. Concretely, this design is through setting up six eccentric seal structure, make the butterfly valve guarantee conventional eccentric butterfly valve sealing performance reliable through setting up third eccentricity E3, fourth eccentricity E4 and second eccentric angle alpha, long service life, when opening and close sealed frictionless advantage, through increasing first eccentricity E1, second eccentricity E2 and first eccentric angle beta make becoming of butterfly valve open and close the stroke short, the on-off time is still less, loss of pressure is little, energy loss is lower, the better energy-saving six eccentric butterfly valves of economic performance.

The vertical distance between the central line of the valve rod 2 and the horizontal central line of the valve body flow passage 5 forms a first eccentricity E1, the first eccentricity E1 is 1/10-1/8 multiplied by DN mm, the vertical distance between the central line of the valve rod 2 and the symmetrical central line of the structural length of the valve body 1 forms a second eccentricity E2, and the second eccentricity E2 is 1/10-1/8 multiplied by DN mm. Specifically, the valve rod 2 is offset to one side of the center of the valve body flow channel 5 by the first eccentricity E1, and the butterfly plate 4 is basically positioned at the center of the valve body flow channel 5 when being fully opened, so that the upper and lower fluid layers are uniform and stable and have no turbulence when a medium passes through the butterfly plate 4, the pressure drop is minimum, and the energy consumption loss is minimum; the second eccentricity E2 makes the valve rod 2 offset to one side of the symmetrical center of the structural length of the valve body 1, the butterfly plate 4 is positioned at the position of the enlarged middle cavity part 23 of the right valve body 13 when fully opened, the flow passage area occupied by the butterfly plate 4 and the valve rod 2 is removed, the flow passage area actually passed by the medium is larger than or equal to the area of two ports (the inlet part 22 and the outlet part 24), the pressure loss is minimum when fully opened, the energy consumption loss is minimum, and the energy consumption of a pipeline system is greatly saved. The eccentric shaft can ensure that the integral valve body 1 has symmetrical structure and shortest length so as to save installation space and cost.

The valve seat sealing structure is a sealing ring 6 arranged on the butterfly plate 4, the butterfly plate 4 is provided with a butterfly plate sealing surface 7, a sealing ring groove 8 is formed in the butterfly plate sealing surface 7, the sealing ring 6 is arranged in the sealing ring groove 8, a first eccentric angle beta is formed by the included angle between the radial plane of the valve seat 3 and the central plane of the structural length of the valve body 1, the first eccentric angle beta is 45-55 degrees, a second eccentric angle alpha is formed by the included angle between the inclined elliptic cone central line of the butterfly plate sealing surface 7 and the central line of the butterfly plate 4, and the second eccentric angle alpha is 8-12 degrees. Specifically, after the first eccentric angle β inclines the conventional vertical valve seat 3 by a corresponding angle (i.e., the second eccentric angle β), the opening angle of the butterfly plate 4 is changed to 90 ° - β. The opening and closing angle is 45-55 degrees, the stroke is only about conventional 1/2 degrees, the opening and closing time is shortened by half, the medium is quickly cut off, and the safety of a pipeline system is ensured. Time-saving, labor-saving and energy-saving, and has good economic performance; the second eccentric angle alpha enables the sealing surfaces of the valve seat 3 and the sealing ring 6 to form a beveled elliptic conical surface, and the sealing ring 6 does not have interference and friction phenomena in the whole opening and closing process along with the rotation of the butterfly plate 4 around the valve rod 2 in the opening and closing motion process. The sealing ring 6 is attached to the valve seat 3 when closed, and is separated when opened. And no friction and abrasion exist between the sealing pairs, so that the sealing reliability and the long service life are ensured.

In the design, the sealing ring 6 is fixed on the butterfly plate 4 through a pressing ring 9 and a screw 10; the valve rod 2 penetrates through shaft holes in the butterfly plate 4 and the right valve body 13, the valve rod 2 is fixedly connected with the butterfly plate 4 through a flat key, the valve rod 2 is sealed and positioned at one shaft end of the valve body 1 through a shaft end cover, and the other end of the valve rod penetrates out of the valve body 1 and then is connected with the executing mechanism 11 on the support. The valve rod 2 rotates in the shaft hole of the valve body 1 under the driving action of the actuating mechanism 11, and meanwhile, the valve rod 2 is connected with the butterfly plate 4 and the sealing ring 6 through the flat key to drive the butterfly plate and the sealing ring to rotate as a whole so as to realize the opening and closing process. The radial plane of the sealing pair of the butterfly plate 4 and the sealing ring 6 is parallel to the radial plane of the valve seat 3, therefore, the butterfly plate 4 and the sealing ring 6 are also in an inclined state when being closed, and form an angle beta with the vertical plane at the center of the valve body 1, and the opening and closing stroke is only 90-beta degrees, namely 45-55 degrees.

Valve body 1 is split type structure, valve body 1 includes left valve body 12 and right valve body 13, form disk seat mounting groove 14 between left side valve body 12 and the right valve body 13, disk seat mounting groove 14 slope sets up, disk seat 3 sets up in disk seat mounting groove 14, just disk seat 3 corresponds disk seat mounting groove 14 and is the slope structure setting. The valve body 1 is of a two-piece split structure and consists of a left valve body 12 and a right valve body 13. Specifically, the left valve body 12 and the right valve body 13 are connected into a whole valve body 1 through a middle flange 15 and bolts. The middle flange 15 is obliquely arranged and forms a beta angle with the corresponding left end flange 16 and right end flange 18, so that the stroke of the opening and closing angle of the butterfly plate 4 is reduced by the beta angle, and the opening and closing time is shortened. The two valve bodies 1 are positioned and sealed through the valve seat 3 and the sealing gasket to form a static sealed whole.

The left valve body 12 is provided with a left end flange 16 and a first middle flange 17, the right valve body 13 is provided with a right end flange 18 and a second middle flange 19, the valve seat mounting groove 14 is arranged between the first middle flange 17 and the second middle flange 19, the first middle flange 17 and the second middle flange 19 are connected to form a middle flange 15, the middle flange 15 is obliquely arranged, and beta angles are formed between two ends of the middle flange 15 and the corresponding left end flange 16 and right end flange 18. Specifically, the valve seat 3 is clamped and fixed in a valve seat mounting groove 14 of an inclined middle flange 15 between the left valve body 12 and the right valve body 13, the planes on two sides of the valve seat 3 and the valve body 1 form static seal through a gasket, and the inclined first middle flange 17 and the inclined second middle flange 19 are fixedly connected through bolts. The sealing ring 6 is fixedly connected to the butterfly plate 4 through a clamping ring 9 and a screw 10. When the valve is closed, the radial planes of the sealing ring 6, the butterfly plate 4 and the valve seat 3 are kept in parallel and consistent, namely, the radial planes and the vertical plane of the structural length center of the valve body 1 form an inclined state with an angle beta, and the opening and closing stroke of the butterfly plate 4 is 90-beta. The sealing ring 6 is movably connected with the valve seat 3, so that the replacement on site is ensured, the maintenance is easy, and the use cost is low. The inclined valve seat 3 is designed, the whole opening and closing angle is 45-55 degrees, and the lowest stroke is even 1/2 of a common butterfly valve. The opening and closing time is short, and the energy-saving effect is obvious.

The two ends of the valve body flow passage 5 are correspondingly provided with a medium inlet 20 and a medium outlet 21, the valve body flow passage 5 comprises an inlet part 22 close to the medium inlet 20, a middle cavity part 23 and an outlet part 24 close to the medium outlet 21, the inner diameters of the inlet part 22 and the outlet part 24 are the same, and the inner diameter of the middle cavity part 23 is larger than the inner diameters of the inlet part 22 and the outlet part 24. Specifically, compared with the inlet part 22 and the outlet part 24 at two ends, the inner volume of the middle cavity part 23 of the valve body flow passage 5 is larger, the volume of the enlarged middle cavity part 23 is larger than 40% of the volume of the inlet part 22 and the outlet part 24, after the butterfly plate 4 is opened, the flow cross section area passing through the valve seat 3 is equal to or larger than the cross section area of the inlet part 24 and the outlet part 24 of the valve, the medium almost has no pressure drop after passing through the butterfly plate 4, the head loss is minimized, and the lowest energy consumption is realized.

The vertical distance between the central line of the valve rod 2 and the plane of the sealing ring 6 forms a third eccentricity E3, the third eccentricity E3 is 1/2 multiplied by the shaft diameter of the valve rod +20mm, the distance between the central line of the valve rod 2 and the outer circle central line of the butterfly plate 4 forms a fourth eccentricity E4, and the fourth eccentricity E4 is 2-12 mm. Specifically, the third eccentricity E3 can ensure that the valve rod 2 does not pass through the sealing ring 6, so that the sealing ring 6 becomes a continuous and complete sealing ring; and the fourth eccentricity E4 makes the center of the valve rod 2 deviate from one side of the center of the butterfly plate 4 to form a cam effect, so that the sealing ring 6 and the valve seat 3 have no interference and friction action in the opening and closing process of the butterfly plate 4.

The previous description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the invention. Thus, the present invention is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. The utility model provides an energy-saving six eccentric metal seal butterfly valves which characterized in that: including valve body, valve rod, disk seat and butterfly plate, form the valve body runner in the valve body, disk seat and butterfly plate set up in the valve body runner, the one end of valve rod stretches into the valve body runner and is connected with the butterfly plate, set up six eccentric seal structures and disk seat seal structure on the valve body, six eccentric seal structures include the eccentricity structure and the eccentric angle structure, the eccentricity structure includes first eccentricity E1 and second eccentricity E2, the eccentric angle structure includes first eccentric angle beta, first eccentricity E1 forms between valve rod and valve body runner, the second eccentricity E2 forms between valve rod and valve body, form first eccentric angle beta between disk seat and the valve body.

2. The energy-saving six-eccentric center metal seal butterfly valve of claim 1, wherein: the vertical distance between the central line of the valve rod and the horizontal central line of the valve body flow passage forms a first eccentricity E1, and the vertical distance between the central line of the valve rod and the symmetrical central line of the valve body structure length forms a second eccentricity E2.

3. The energy-saving six-eccentric center metal seal butterfly valve of claim 1, wherein: the valve seat sealing structure is a sealing ring arranged on the butterfly plate, the butterfly plate is provided with a butterfly plate sealing surface, a sealing ring groove is formed in the butterfly plate sealing surface, the sealing ring is arranged in the sealing ring groove, and a first eccentric angle beta is formed between the radial plane of the valve seat and the central plane of the valve body structure length.

4. The energy-saving six-eccentric center metal seal butterfly valve of claim 3, wherein: the eccentric angle structure further comprises a second eccentric angle alpha, and an included angle formed by the central line of the inclined elliptic cone of the butterfly plate sealing surface and the central line of the butterfly plate forms the second eccentric angle alpha.

5. The energy-saving six-eccentric center metal seal butterfly valve of claim 1, wherein: the valve body is split type structure, the valve body includes left valve body and right valve body, form the disk seat mounting groove between left side valve body and the right valve body, the slope of disk seat mounting groove sets up, the disk seat sets up in the disk seat mounting groove, just the disk seat corresponds the disk seat mounting groove and is the slope structure setting.

6. The energy-saving six-eccentric center metal seal butterfly valve of claim 5, wherein: the left valve body is provided with a left end flange and a first middle flange, the right valve body is provided with a right end flange and a second middle flange, the valve seat mounting groove is formed between the first middle flange and the second middle flange, the first middle flange and the second middle flange are connected to form a middle flange, the middle flange is arranged in an inclined mode, and beta angles are formed between the two ends of the middle flange and the corresponding left end flange and the right end flange.

7. The energy-saving six-eccentric center metal seal butterfly valve of claim 1, wherein: the two ends of the valve body flow passage are correspondingly provided with a medium inlet and a medium outlet, the valve body flow passage comprises an inlet part close to the medium inlet, a middle cavity part and an outlet part close to the medium outlet, the inner diameters of the inlet part and the outlet part are the same, and the inner diameter of the middle cavity part is larger than the inner diameters of the inlet part and the outlet part.

8. The energy-saving six-eccentric center metal seal butterfly valve of claim 3, wherein: the eccentricity structure further comprises a third eccentricity E3 and a fourth eccentricity E4, the distance between the center line of the valve rod and the plane of the sealing ring is perpendicular to the plane of the sealing ring to form the third eccentricity E3, and the distance between the center line of the valve rod and the center line of the outer circle of the butterfly plate forms the fourth eccentricity E4.

9. The energy-saving six-eccentric center metal seal butterfly valve of claim 1, wherein: the first eccentricity E1 is 1/10-1/8 XDN mm, and the second eccentricity E2 is 1/10-1/8 XDN mm.

10. The energy-saving six-eccentric center metal seal butterfly valve of claim 4, wherein: the first eccentric angle beta is 45-55 degrees, and the second eccentric angle alpha is 8-12 degrees.