阅读说明：本技术 一种三偏心双向蝶阀密封结构 (Three-eccentric bidirectional butterfly valve sealing structure ) 是由 徐国奇 金伟 于 2021-08-31 设计创作，主要内容包括：本发明公开了一种三偏心双向蝶阀密封结构,包括管道,所述管道的外部固定安装有阀体,所述阀体的外部固定安装有固定板,所述管道的内部固定安装有阀座,所述管道的内部转动安装有与阀座配合的蝶板,所述固定板的内部设有用于带动蝶板转动的驱动机构,所述蝶板与阀座之间设有用于提高管道的密封性的密封机构,所述管道的内部于阀体的两侧均开设有导流口。本发明通过电机带动蜗杆套转动,然后带动蝶板对管道的内部进行密封后,使其不易发生松动,从而提高蝶板的稳定性,并使得流体难以对环形储液囊进行冲击,进而提高蝶板以及阀座之间的密封性,再减缓流体对蝶板的冲击,延长蝶板的使用寿命。(The invention discloses a three-eccentric two-way butterfly valve sealing structure which comprises a pipeline, wherein a valve body is fixedly arranged outside the pipeline, a fixing plate is fixedly arranged outside the valve body, a valve seat is fixedly arranged inside the pipeline, a butterfly plate matched with the valve seat is rotatably arranged inside the pipeline, a driving mechanism for driving the butterfly plate to rotate is arranged inside the fixing plate, a sealing mechanism for improving the sealing performance of the pipeline is arranged between the butterfly plate and the valve seat, and flow guide ports are formed in the pipeline and arranged on two sides of the valve body. According to the butterfly valve, the worm sleeve is driven to rotate by the motor, and then the butterfly plate is driven to seal the interior of a pipeline, so that the butterfly plate is not easy to loosen, the stability of the butterfly plate is improved, fluid is difficult to impact the annular liquid storage bag, the sealing performance between the butterfly plate and the valve seat is improved, the impact of the fluid on the butterfly plate is relieved, and the service life of the butterfly plate is prolonged.)

1. The utility model provides a three eccentric two-way butterfly valve seal structure, includes pipeline (1), its characterized in that: a valve body (2) is fixedly arranged outside the pipeline (1), a fixing plate (3) is fixedly arranged outside the valve body (2), a valve seat (11) is fixedly arranged in the pipeline (1), a butterfly plate (9) matched with the valve seat (11) is rotatably arranged in the pipeline (1), a driving mechanism for driving the butterfly plate (9) to rotate is arranged in the fixed plate (3), a sealing mechanism for improving the sealing performance of the pipeline (1) is arranged between the butterfly plate (9) and the valve seat (11), flow guide openings (13) are respectively formed in the pipeline (1) at two sides of the valve body (2), buffer tubes (14) are respectively connected with the outer parts of the two flow guide openings (13) in a threaded manner, the interior of the pipeline (1) is provided with a buffer mechanism which is matched with a buffer tube (14) and is used for reducing the impact of fluid on the butterfly plate (9).

2. A three-eccentric center bidirectional butterfly valve sealing structure according to claim 1, characterized in that: actuating mechanism is including offering device groove (12) in fixed plate (3) one side, the internally mounted of device groove (12) has motor (4), device chamber (5) have still been seted up to the inside of fixed plate (3), the output dress tip of motor (4) runs through the lateral wall of device groove (12) and extends to the inside and fixed mounting of device chamber (5) and has worm cover (6), the internally mounted of device chamber (5) installs pivot (8), the upper end of pivot (8) has worm wheel (7) in the inside fixed mounting of device chamber (5), worm wheel (7) and worm cover (6) meshing, the lower extreme of pivot (8) runs through the diapire of device chamber (5) and extends to the inside of pipeline (1) and with one side fixed connection of butterfly plate (9).

3. A three-eccentric center bidirectional butterfly valve sealing structure according to claim 2, characterized in that: the sealing mechanism comprises an annular liquid storage bag (10) fixedly installed at the edge of the butterfly plate (9), and electrorheological fluid is filled in the annular liquid storage bag (10).

4. A triple offset bidirectional butterfly valve seal structure according to claim 3, wherein: the electric rheological fluid device is characterized in that a controller is arranged outside the pipeline (1), the controller is electrically connected with the motor (4), and the controller is also electrically connected with the electric rheological fluid through a lead.

5. A three-eccentric center bidirectional butterfly valve sealing structure according to claim 1, characterized in that: the buffer mechanism includes a first balloon (16) fixedly mounted on top within a buffer tube (14), a first sliding plug (15) is arranged inside the buffer tube (14) in a sliding way, the lower end of the first air bag (16) is fixedly connected with the upper end of the first sliding plug (15), a plurality of sliding cavities (17) have been seted up to the inner wall of pipeline (1) equidistant circumference still, every the equal slidable mounting in inside of sliding cavity (17) has slide (19), every equal fixed mounting has second gasbag (18), and is a plurality of between a lateral wall of slide (19) and sliding cavity (17) the equal fixed mounting of a lateral wall of slide (19) has baffle (20), and is a plurality of the one end of baffle (20) runs through another lateral wall of a plurality of sliding cavities (17) respectively and extends to the inside of pipeline (1), and is a plurality of second gasbag (18) all are linked together with the inside of first gasbag (16).

6. A three-eccentric center bidirectional butterfly valve sealing structure according to claim 1, characterized in that: and a sealing ring is arranged at the joint of the buffer tube (14) and the diversion port (13).

Technical Field

The invention relates to the technical field of valves, in particular to a three-eccentric bidirectional butterfly valve sealing structure.

Background

The butterfly valve is a regulating valve with simple structure, can be used for controlling the flow of various fluids such as air, water, steam, various corrosive media, slurry, oil, liquid metal, radioactive media and the like, mainly plays the roles of cutting off and throttling on a pipeline, and can be divided into a center sealing butterfly valve, a single eccentric butterfly valve, a double eccentric butterfly valve and a triple eccentric butterfly valve according to the structure.

In the prior art (No. CN208605652U), a sealing structure of a bidirectional sealing triple offset butterfly valve comprises a butterfly plate and a valve seat, the butterfly plate and the valve seat are in sealing fit to form a sealing pair, the valve seat is fixed on the butterfly plate through a gland and a screw gland, the screw gland is in threaded connection with the butterfly plate, the screw pitch of the screw gland is smaller than that of the butterfly plate, a screw gap exists between the screw gland and the butterfly plate after the screw gland is connected with the butterfly plate, the axial end face of the screw gland protrudes out of the surface of the butterfly plate after the screw gland is installed in the butterfly plate, the pressure plate presses the screw gland tightly to enable the screw gland to axially displace, the valve seat is squeezed when the screw gland axially displaces, and the pressure plate is fixed on the butterfly plate through screws.

However, the utility model also has certain defects: 1. the plate seat can produce the friction with the disk seat when the butterfly plate rotates, influences the leakproofness of sealing ring, and 2, sealing ring nature easily changes under the high low temperature condition, loses original tension, reduces the leakproofness of butterfly plate.

Therefore, a three-eccentric two-way butterfly valve sealing structure is provided.

Disclosure of Invention

The invention aims to provide a three-eccentric two-way butterfly valve sealing structure, which is characterized in that a worm sleeve is driven to rotate by a motor, and then a butterfly plate is driven to seal the inside of a pipeline, so that the butterfly plate is not easy to loosen, the stability of the butterfly plate is improved, fluid is difficult to impact an annular liquid storage bag, the sealing property between the butterfly plate and a valve seat is further improved, the impact of the fluid on the butterfly plate is relieved, the service life of the butterfly plate is prolonged, and the problems in the background art are solved.

In order to achieve the purpose, the invention provides the following technical scheme:

the utility model provides a three eccentric two-way butterfly valve seal structure, includes the pipeline, the outside fixed mounting of pipeline has the valve body, the outside fixed mounting of valve body has the fixed plate, the inside fixed mounting of pipeline has the disk seat, the inside of pipeline is rotated and is installed with disk seat complex butterfly plate, the inside of fixed plate is equipped with and is used for driving butterfly plate pivoted actuating mechanism, be equipped with the sealing mechanism who is used for improving the leakproofness of pipeline between butterfly plate and the disk seat, the inside of pipeline has all seted up the water conservancy diversion mouth in the both sides of valve body, two the equal threaded connection in outside of water conservancy diversion mouth has the buffer tube, the inside of pipeline is equipped with and is used for reducing the buffer tube complex buffer gear of fluid to the impact of butterfly plate.

Drive the worm cover through the motor and rotate, then drive the butterfly plate and carry out the sealed back to the inside of pipeline, make its difficult emergence not hard up to improve the stability of butterfly plate, and make the fluid be difficult to strike annular reservoir, and then improve the leakproofness between butterfly plate and the disk seat, slow down the impact of fluid to the butterfly plate again, prolong the life of butterfly plate.

Preferably, actuating mechanism is including seting up the device groove in fixed plate one side, the internally mounted in device groove has the motor, the device chamber has still been seted up to the inside of fixed plate, the output shaft end of motor runs through the lateral wall in device groove and extends to the inside and the fixed mounting in device chamber and have the worm cover, the internal rotation in device chamber installs the pivot, the upper end of pivot has the worm wheel in the inside fixed mounting in device chamber, the worm wheel meshes with the worm cover, the lower extreme of pivot runs through the diapire in device chamber and extends to the inside of pipeline and with one side fixed connection of butterfly plate.

The motor is controlled to rotate through the controller, then the worm sleeve in the cavity of the device is driven to rotate through the motor, then the worm sleeve can drive the rotating shaft to rotate through the worm wheel, and further the butterfly plate in the pipeline is driven to rotate.

Preferably, the sealing mechanism comprises an annular liquid storage bag fixedly installed at the edge of the butterfly plate, and electrorheological fluid is filled in the annular liquid storage bag.

After long-time use, there may be wearing and tearing between the contact surface of butterfly plate and disk seat, and then produce the gap and lead to the fluid seepage, when butterfly plate and disk seat contacted each other, the inside of annular reservoir is equipped with the electrorheological fluids, the electrorheological fluids deformation, and seal between the contact surface to butterfly plate and disk seat, and be the inside that liquid electrorheological fluids can crowd the gap fast, and then carry out good sealing to gap department, and ordinary sealing washer is because unable inside to the gap is sealed, so the leakproofness of annular reservoir has apparent promotion with comparing ordinary sealing washer.

Preferably, a controller is arranged outside the pipeline, the controller is electrically connected with the motor, and the controller is also electrically connected with the electrorheological fluid through a lead.

After the butterfly plate seals the interior of the pipeline, the controller can be used for supplying power to the interior of the annular liquid storage bag, the electrorheological fluid is subjected to an electric field and shows the characteristic of non-Newtonian fluid, and the free flowing liquid is converted into solid in millisecond time, namely the electrorheological fluid can show certain solid-phase property and cannot flow, namely the electrorheological fluid is changed from liquid to solid and shows strong rigidity, so that the fluid is difficult to impact the annular liquid storage bag, and the sealing performance between the butterfly plate and the valve seat is improved.

Preferably, buffer gear includes the first gasbag at top in the buffer tube of fixed mounting, the inside slidable mounting of buffer tube has first sliding plug, the lower extreme of first gasbag and the upper end fixed connection of first sliding plug, a plurality of smooth chambeies, every have still been seted up to equidistant circumference of the inner wall of pipeline the equal slidable mounting in inside of smooth chamber has the slide, every equal fixed mounting has the second gasbag, and is a plurality of between a lateral wall of slide and smooth chamber equal fixed mounting has the baffle, and is a plurality of the one end of baffle runs through another lateral wall of a plurality of smooth chambeies respectively and extends to the inside of pipeline, and is a plurality of the second gasbag all is linked together with the inside of first gasbag.

When the butterfly plate is suddenly closed, fluid can produce the impact to the butterfly plate, this kind of phenomenon is called "water hammer effect", close the back at the butterfly plate, fluid can dash the inside of buffer tube, and extrude first gasbag through first sliding plug, first gasbag deformation afterwards, and with the inside second gasbag of smooth chamber of gas extrusion, then drive the baffle through the slide and remove, make a plurality of baffles present the gathering form to centre of a circle department in the inside of pipeline, and then slow down the impact of fluid to the butterfly plate, the life of extension butterfly plate.

Preferably, a sealing ring is installed at the joint of the buffer tube and the diversion port.

Because the outside buffer tube of water conservancy diversion mouth does not need dismouting frequently, so ordinary sealing washer just can prevent the fluid seepage of junction, and then guarantees the inside leakproofness of pipeline.

Compared with the prior art, the invention has the beneficial effects that:

1. the rotation of the motor is controlled through the controller, so that the rotating shaft inside the pipeline and the butterfly plate are not easy to loosen, and the stability of the butterfly plate is improved.

2. After the butterfly plate seals the inside of the pipeline, the controller can be used for supplying power to the inside of the annular liquid storage bag, after long-time use, abrasion can exist between contact surfaces of the butterfly plate and the valve seat, further a gap is generated, and fluid leakage is caused, when the butterfly plate and the valve seat are contacted with each other, as the annular liquid storage bag is internally provided with electrorheological fluid, the electrorheological fluid deforms and seals between the contact surfaces of the butterfly plate and the valve seat, and the electrorheological fluid in a liquid state can be rapidly extruded to the inside of the gap, the electrorheological fluid is subjected to an electric field and shows the characteristic of non-Newtonian fluid, and freely flowing liquid is changed into solid within millisecond-level time, namely the electrorheological fluid can show certain solid-phase property and can not flow, namely, the liquid state is changed into a solid state and shows strong rigidity, and further good sealing is carried out on the gap, and because ordinary sealing washer can't seal up the inside in gap, so the leakproofness of annular reservoir has apparent promotion with comparing ordinary sealing washer for the fluid is difficult to strike annular reservoir, and then improves the leakproofness between butterfly plate and the valve seat.

3. When the butterfly plate is suddenly closed, fluid can produce the impact to the butterfly plate, and this kind of phenomenon is called "water hammer effect", and after the butterfly plate was closed, a plurality of baffles presented the gathering form to centre of a circle department in the inside of pipeline, and then slowed down the impact of fluid to the butterfly plate, prolonged the life of butterfly plate.

Drawings

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

FIG. 2 is a schematic view of the internal structure of the present invention;

FIG. 3 is a schematic view of the internal structure of the fixing plate according to the present invention;

FIG. 4 is a top view of the internal structure of the fixing plate of the present invention;

FIG. 5 is a top view of the internal structure of the present invention;

FIG. 6 is a side view of the internal structure of the present invention;

fig. 7 is an enlarged view of the structure at a in fig. 2 according to the present invention.

In the figure: 1. a pipeline; 2. a valve body; 3. a fixing plate; 4. a motor; 5. a device cavity; 6. a worm sleeve; 7. a worm gear; 8. a rotating shaft; 9. a butterfly plate; 10. an annular reservoir; 11. a valve seat; 12. a device slot; 13. a flow guide port; 14. a buffer tube; 15. a first spool; 16. a first air bag; 17. a slide chamber; 18. a second air bag; 19. a slide plate; 20. and a baffle plate.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

In the description of the present invention, it is to be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", and the like, indicate orientations and positional relationships based on those shown in the drawings, and are used only for convenience of description and simplicity of description, and do not indicate or imply that the device or element being referred to must have a particular orientation, be constructed and operated in a particular orientation, and thus, should not be considered as limiting the present invention.

Furthermore, the terms "first", "second" and "first" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, features defined as "first", "second", may explicitly or implicitly include one or more of the described features. In the description of the present invention, "a plurality" means two or more unless specifically defined otherwise. Furthermore, the terms "mounted," "connected," and "connected" are to be construed broadly and may, for example, be fixedly connected, detachably connected, or integrally connected; can be mechanically or electrically connected; they may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The specific meanings of the above terms in the present invention can be understood in specific cases to those skilled in the art.

Referring to fig. 1 to 7, the present invention provides a sealing structure of a triple eccentric bidirectional butterfly valve, which has the following technical scheme:

the utility model provides a three eccentric two-way butterfly valve seal structure, including pipeline 1, pipeline 1's outside fixed mounting has valve body 2, valve body 2's outside fixed mounting has fixed plate 3, pipeline 1's inside fixed mounting has disk seat 11, pipeline 1's inside rotation install with disk seat 11 complex butterfly plate 9, the inside of fixed plate 3 is equipped with and is used for driving butterfly plate 9 pivoted actuating mechanism, be equipped with the sealing mechanism who is used for improving pipeline 1's leakproofness between butterfly plate 9 and the disk seat 11, water conservancy diversion mouth 13 has all been seted up in valve body 2's both sides in pipeline 1's inside, the equal threaded connection in outside of two water conservancy diversion mouths 13 has buffer tube 14, pipeline 1's inside is equipped with and buffer tube 14 complex is used for reducing the buffer gear of the impact of fluid to butterfly plate 9.

Referring to fig. 1, 3 and 4, as an embodiment of the present invention, the driving mechanism includes a device groove 12 formed on one side of the fixing plate 3, the motor 4 is installed inside the device groove 12, the device cavity 5 is further formed inside the fixing plate 3, the end of the output shaft of the motor 4 penetrates through the side wall of the device groove 12 and extends into the device cavity 5, and is fixedly installed with a worm sleeve 6, a rotating shaft 8 is rotatably installed inside the device cavity 5, a worm wheel 7 is fixedly installed at the upper end of the rotating shaft 8 in the device cavity 5, the worm wheel 7 is meshed with the worm sleeve 6, and the lower end of the rotating shaft 8 penetrates through the bottom wall of the device cavity 5 and extends into the pipeline 1 and is fixedly connected with one side of the butterfly plate 9.

Rotate through controller control motor 4, then drive the worm cover 6 of device 5 inside in chamber through motor 4 and rotate, worm cover 6 will drive pivot 8 through worm wheel 7 afterwards and rotate, and then drive the butterfly plate 9 of pipeline 1 inside and rotate, because the transmission of worm wheel and worm has self-locking function, in order to only can rotate back through worm cover 6 drive worm wheel 7 at motor 4 and rotate, but worm wheel 7 can not drive worm cover 6 and rotate, and then drive butterfly plate 9 in pivot 8 and carry out the sealed back to pipeline 1's inside, make it difficult the emergence not hard up, thereby improve butterfly plate 9's stability.

Referring to fig. 5, as an embodiment of the present invention, the sealing mechanism includes an annular reservoir 10 fixedly installed at an edge of the butterfly plate 9, and an interior of the annular reservoir 10 is filled with an electro-rheological fluid.

After long-time use, there may be wearing and tearing between the contact surface of butterfly plate 9 and valve seat 11, and then produce the gap and lead to the fluid seepage, when butterfly plate 9 and valve seat 11 contacted each other, the inside of annular reservoir 10 is equipped with the electrorheological fluids, the electrorheological fluids deformation, and seal between the contact surface of butterfly plate 9 and valve seat 11, and be the inside that liquid electrorheological fluids can crowd the gap fast, and then carry out good sealing to gap department, and ordinary sealing washer is because can't seal up the inside in gap, have apparent promotion with comparing ordinary sealing washer with the leakproofness of annular reservoir 10.

Referring to fig. 1, as an embodiment of the present invention, a controller is disposed outside a pipe 1, and the controller is electrically connected to a motor 4, and is also electrically connected to an electrorheological fluid through a lead.

After the butterfly plate 9 seals the inside of the pipeline 1, the controller can be used for supplying power to the inside of the annular liquid storage bag 10, the electrorheological fluid inductor is subjected to an electric field and shows the characteristic of non-Newtonian fluid, and the free flowing liquid is converted into solid in millisecond time, namely the electrorheological fluid can show certain solid-phase property and cannot flow, namely the electrorheological fluid is converted from liquid to solid and shows strong rigidity, so that the fluid is difficult to impact the annular liquid storage bag 10, and the sealing performance between the butterfly plate 9 and the valve seat 11 is further improved.

As an embodiment of the present invention, referring to fig. 2, 5 and 7, the buffering mechanism includes a first air bag 16 fixedly installed at the top inside a buffer tube 14, a first sliding plug 15 is slidably installed inside the buffer tube 14, the lower end of the first air bag 16 is fixedly connected with the upper end of the first sliding plug 15, a plurality of sliding cavities 17 are further circumferentially opened on the inner wall of the pipeline 1 at equal intervals, a sliding plate 19 is slidably installed inside each sliding cavity 17, a second air bag 18 is fixedly installed between each sliding plate 19 and one side wall of the sliding cavity 17, a baffle 20 is fixedly installed on one side wall of each sliding plate 19, one end of each baffle 20 penetrates through the other side wall of each sliding cavity 17 and extends into the pipeline 1, and each second air bag 18 is communicated with the inside of the first air bag 16.

When the butterfly plate 9 is suddenly closed, the fluid can impact the butterfly plate 9, which is called a "water hammer effect", and after the butterfly plate 9 is closed, the fluid can rush to the inside of the buffer tube 14 and extrude the first air cell 16 through the first sliding plug 15, then the first air cell 16 deforms and extrudes gas into the second air cell 18 inside the sliding cavity 17, and then the sliding plate 19 drives the baffle plate 20 to move, so that the plurality of baffle plates 20 are gathered towards the center of the circle inside the pipeline 1, the impact of the fluid on the butterfly plate 9 is further slowed, and the service life of the butterfly plate 9 is prolonged.

Referring to fig. 1-2, a seal ring is mounted at the junction of the buffer tube 14 and the diversion port 13 as an embodiment of the present invention.

Since the buffer tube 14 outside the diversion port 13 does not need to be frequently disassembled and assembled, the fluid leakage at the joint can be prevented by using a common sealing ring, and the sealing performance inside the pipeline 1 is further ensured.

The working principle is as follows: the motor 4 is controlled to rotate through the controller, then the motor 4 drives the worm sleeve 6 in the device cavity 5 to rotate, then the worm sleeve 6 drives the rotating shaft 8 to rotate through the worm wheel 7, and further drives the butterfly plate 9 in the pipeline 1 to rotate, the worm wheel 7 can only be driven to rotate through the worm sleeve 6 after the motor 4 rotates due to the self-locking function of worm and gear transmission, but the worm wheel 7 cannot drive the worm sleeve 6 to rotate, so that the butterfly plate 9 is not easy to loosen after the rotating shaft 8 drives the butterfly plate 9 to seal the inside of the pipeline 1, the stability of the butterfly plate 9 is improved, the inside of the annular liquid storage bag 10 can be powered through the controller after the butterfly plate 9 seals the inside of the pipeline 1, after long-time use, abrasion can exist between the contact surfaces of the butterfly plate 9 and the valve seat 11, and further gaps can be generated and cause fluid leakage, when the butterfly plate 9 and the valve seat 11 are contacted with each other, because the annular liquid storage bag 10 is internally filled with electrorheological fluid, the electrorheological fluid deforms and seals between the contact surfaces of the butterfly plate 9 and the valve seat 11, and the liquid electrorheological fluid can be rapidly squeezed into the gap, the electrorheological fluid is subjected to an electric field and shows the characteristic of non-Newtonian fluid, and is converted from free flowing liquid into solid within millisecond-scale time, namely the electrorheological fluid can show a certain solid phase property and cannot flow, namely the electrorheological fluid is converted from liquid into solid and shows strong rigidity, so as to well seal the gap, while a common sealing ring can not seal the gap, the sealing performance of the annular liquid storage bag 10 is obviously improved compared with that of a common sealing ring, so that the fluid is difficult to impact the annular liquid storage bag 10, and further the sealing performance between the butterfly plate 9 and the valve seat 11 is improved, when the butterfly plate 9 is suddenly closed, the fluid can impact the butterfly plate 9, which is called a "water hammer effect", and after the butterfly plate 9 is closed, the fluid can rush to the inside of the buffer tube 14 and extrude the first air cell 16 through the first sliding plug 15, then the first air cell 16 deforms and extrudes gas into the second air cell 18 inside the sliding cavity 17, and then the sliding plate 19 drives the baffle plate 20 to move, so that the plurality of baffle plates 20 are gathered towards the center of the circle inside the pipeline 1, the impact of the fluid on the butterfly plate 9 is further slowed, and the service life of the butterfly plate 9 is prolonged.

Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that changes, modifications, substitutions and alterations can be made in these embodiments without departing from the principles and spirit of the invention, the scope of which is defined in the appended claims and their equivalents.