CN209818755U

CN209818755U - Double-valve-rod automatic butterfly valve

Info

Publication number: CN209818755U
Application number: CN201920407122.0U
Authority: CN
Inventors: 谢志鹏; 苏海荣; 谢江炎
Original assignee: Shijiazhuang Nest Machinery Valve Industry Co Ltd
Current assignee: Shijiazhuang Nest Machinery Valve Industry Co Ltd
Priority date: 2019-03-28
Filing date: 2019-03-28
Publication date: 2019-12-20
Anticipated expiration: 2029-03-28

Abstract

The utility model relates to the technical field of butterfly valve accessories, in particular to a double-valve rod automatic butterfly valve, which improves the adjusting precision, can still be controlled after a driving device is damaged, and improves the use reliability; the valve comprises a valve body, a valve clack and a driving device, wherein the valve clack is rotatably arranged in the valve body; still include the box, the apparatus further comprises a rotating shaft, the gag lever post, hand lead screw, the mounting panel, the drive shaft, first valve rod, the second valve rod, first ball bearing, second ball bearing, the fluted disc, third ball bearing, fourth ball bearing, the worm, first cone pulley, the second cone pulley, fifth ball bearing, sixth ball bearing, seventh ball bearing, third cone pulley and fourth cone pulley, the third cone pulley is located the left side of second cone pulley, and third cone pulley and second cone pulley meshing, be provided with horizontal bar hole on the rear side wall of box, the fourth cone pulley be located the right side of first cone pulley and leave the clearance between the first cone pulley.

Description

Double-valve-rod automatic butterfly valve

Technical Field

The utility model relates to a technical field of butterfly valve auxiliary device especially relates to an automatic butterfly valve of double-stem.

Background

As is well known, a butterfly valve, also called a flap valve, is a regulating valve with a simple structure, and can be used for on-off control of a low-pressure pipeline medium, namely a butterfly valve, wherein a closing member (a valve clack or a butterfly plate) is a disc and rotates around a valve shaft to achieve opening and closing; the existing butterfly valve comprises a valve body, a valve clack and a driving device, wherein the valve clack is rotatably arranged in the valve body, the driving device is arranged at the top end of the valve body, and the output end of the driving device is connected with the valve clack; when the existing butterfly valve is used, the valve clack is driven to rotate through the driving device, so that the pipeline is opened and closed, and the flow is regulated; the existing butterfly valve is found to have low adjusting precision in use, and once the driving device is damaged and stops working, the butterfly valve cannot be controlled, so that the use reliability is low.

SUMMERY OF THE UTILITY MODEL

In order to solve the technical problem, the utility model provides an improve its regulation precision to after drive arrangement damages, still can control the butterfly valve, improve the automatic butterfly valve of double-valve-rod who uses the reliability.

The utility model relates to a double-valve-rod automatic butterfly valve, which comprises a valve body, a valve clack and a driving device, wherein the valve clack is rotatably arranged in the valve body; the valve comprises a valve body, a through hole, a rotating shaft, a limiting rod, a hand-operated lead screw, a mounting plate, a driving shaft, a first valve rod and a second valve rod, wherein the valve body is internally provided with a through hole which is through from front to back, a first mounting groove is arranged on the inner bottom wall of the through hole, a first ball bearing is fixedly arranged in the first mounting groove, a through hole which is through from top to bottom is arranged in the middle of the valve clack, a first mounting through hole which is communicated with the through hole is arranged at the top end of the valve body, a second ball bearing is fixedly arranged in the first mounting through hole, the valve body is arranged at the top end of the valve body, a working cavity is arranged in the valve body, the bottom end of the rotating shaft penetrates through the through hole from the top end of the valve clack and is inserted into the first ball bearing, the rotating shaft and the valve clack, the fluted disc is positioned in the working cavity, the middle part of the left side wall and the middle part of the right side wall of the working cavity are respectively provided with a second mounting groove and a third mounting groove, the second mounting groove and the third mounting groove are oppositely arranged left and right, a third ball bearing and a fourth ball bearing are respectively and fixedly mounted in the second mounting groove and the third mounting groove, the left end of the driving shaft is inserted into the third ball bearing, the right end of the driving shaft is inserted into the fourth ball bearing, the middle part of the driving shaft is provided with a worm, the worm is meshed with the fluted disc, the left end and the right end outside the driving shaft are respectively provided with a first conical wheel and a second conical wheel, the rear end of the right side wall of the working cavity is provided with a fourth mounting groove, a fifth ball bearing is fixedly mounted in the fourth mounting groove, the left side wall of the box body is provided with a second mounting through hole, the second mounting through hole is opposite, and a sixth ball bearing is fixedly installed in the second installation through hole, the upper half area of the installation plate is provided with a left and right through threaded hole, the right end of the hand screw passes through the threaded hole from the left end of the installation plate and is inserted into the interior of the fifth ball bearing, the left end of the hand screw passes through the sixth ball bearing from the working cavity to the outside of the box body, the lower half area of the installation plate is provided with a left and right through limiting hole, the left end of the limiting rod is connected with the left side wall of the working cavity, the right end of the limiting rod passes through the limiting hole from the left end of the installation plate and is connected with the right side wall of the working cavity, the driving device is installed on the right side of the rear end of the installation plate, the rear end of the first valve rod passes through the installation plate from the front end of the installation plate and is in transmission connection with the front side output end of the driving device, the front end of the first valve rod is provided with, and third cone pulley and second cone pulley meshing are provided with horizontal bar hole on the rear wall of box, the left half region of mounting panel is provided with the third installation through-hole that link up around, and fixed mounting has seventh ball bearing in the third installation through-hole, the front end of second valve rod passes seventh ball bearing to the front side of mounting panel from the rear end of mounting panel, and the rear end of second valve rod passes bar hole to the rear of box in the working chamber to install the fourth cone pulley at the front end of second valve rod, the fourth cone pulley be located the right side of first cone pulley and leave the clearance between the first cone pulley.

The utility model discloses an automatic butterfly valve of double-stem still includes the slide, the top and the bottom of slide are provided with horizontal last spout and lower chute respectively, the interior roof in bar hole and interior diapire slide respectively and set up in last spout and lower chute to the fifth installation through-hole that link up around being provided with at the middle part of slide, fixed mounting has eighth ball bearing in the fifth installation through-hole, the rear end of second valve rod passes eighth ball bearing to the rear of slide from the front end of slide.

The utility model discloses an automatic butterfly valve of double-valve-rod still includes the swiveling wheel is installed to the rear end of second valve rod.

The utility model discloses a double-valve-rod automatic butterfly valve works as when the fourth cone pulley just meshed with first cone pulley, the third cone pulley still meshes with second cone pulley, and when the fourth cone pulley was fully meshed with first cone pulley, the third cone pulley broke away from with second cone pulley.

The utility model discloses an automatic butterfly valve of double-stem, the number of teeth of the unnecessary second cone of the number of teeth of first cone, the number of teeth of fourth cone is less than the number of teeth of third cone.

The utility model discloses an automatic butterfly valve of double-valve-rod, the top of box is provided with circular scale mark to be provided with the calibrated scale in the centre of circular scale mark, the calibrated scale is connected with the top of fluted disc.

The utility model discloses an automatic butterfly valve of double-stem, the valve clack includes two sets of valve blocks and the sealing washer between two sets of valve blocks, the sealing washer is the polytetrafluoroethylene material.

The utility model discloses an automatic butterfly valve of double-stem, be connected between the left end of slide and the left side wall in bar hole and be provided with left dustproof cloth, be provided with right dustproof cloth between the right-hand member of slide and the right side wall in bar hole.

Compared with the prior art, the beneficial effects of the utility model are that: the mounting plate moves rightwards by rotating the hand-operated lead screw, the third conical wheel is fully meshed with the second conical wheel, the fourth conical wheel is separated from the first conical wheel at the moment, the first valve rod and the third conical wheel are driven to rotate by the driving device, the second conical wheel is driven to rotate by the third conical wheel, so that the driving shaft is driven to rotate, the fluted disc and the rotating shaft are driven to rotate by the matching of the worm on the driving shaft and the fluted disc, so that the valve clack is rotated, the mounting plate moves leftwards by reversely rotating the hand-operated lead screw, the fourth conical wheel is meshed with the first conical wheel, the third conical wheel is still meshed with the second conical wheel, the hand-operated lead screw is continuously rotated until the fourth conical wheel is fully meshed with the first conical wheel, the third conical wheel is separated from the second conical wheel at the moment, the fourth conical wheel is driven to rotate by manually rotating the second valve rod, the fourth conical wheel drives the first conical wheel and the driving shaft to rotate, the driving shaft drives the fluted disc to rotate, the adjusting precision of the fluted disc is improved through manual adjustment, and after the driving device is damaged, the butterfly valve can be still controlled, and the use reliability is improved.

Drawings

Fig. 1 is a schematic structural diagram of the present invention;

FIG. 2 is a schematic top view of the interior of the case of the present invention;

FIG. 3 is a schematic top view of the exterior of the case of the present invention;

in the drawings, the reference numbers: 1. a valve body; 2. a valve flap; 3. a drive device; 4. a box body; 5. a rotating shaft; 6. a limiting rod; 7. manually shaking a lead screw; 8. mounting a plate; 9. a drive shaft; 10. a first valve stem; 11. a second valve stem; 12. a first ball bearing; 13. a second ball bearing; 14. a fluted disc; 15. a third ball bearing; 16. a fourth ball bearing; 17. a worm; 18. a first conical wheel; 19. a second conical wheel; 20. a fifth ball bearing; 21. a sixth ball bearing; 22. a third conical wheel; 23. a strip-shaped hole; 24. a seventh ball bearing; 25. a fourth cone wheel; 26. a slide plate; 27. an eighth ball bearing; 28. a rotating wheel; 29. circular scale lines; 30. a dial scale; 31. a left dust cloth; 32. and (4) right dustproof cloth.

Detailed Description

The following detailed description of the embodiments of the present invention is provided with reference to the accompanying drawings and examples. The following examples are intended to illustrate the invention, but are not intended to limit the scope of the invention.

As shown in fig. 1 to 3, the double-stem automatic butterfly valve of the present invention comprises a valve body 1, a valve flap 2 and a driving device 3, wherein the valve flap 2 is rotatably installed in the valve body 1; the valve comprises a valve body 1, a rotating shaft 5, a limiting rod 6, a hand-operated lead screw 7, a mounting plate 8, a driving shaft 9, a first valve rod 10 and a second valve rod 11, wherein a through hole which is through from front to back is arranged in the valve body 1, a first mounting groove is arranged on the inner bottom wall of the through hole, a first ball bearing 12 is fixedly mounted in the first mounting groove, a through hole which is through from top to bottom is arranged in the middle of the valve clack 2, a first mounting through hole which is communicated with the through hole is arranged at the top end of the valve body 1, a second ball bearing 13 is fixedly mounted in the first mounting through hole, the valve body 4 is mounted at the top end of the valve body 1, a working cavity is arranged in the valve body 4, the bottom end of the rotating shaft 5 penetrates through the through hole from the top end of the valve clack 2 and is inserted into the first ball bearing 12, the rotating shaft 5 is fixedly connected with the, a fluted disc 14 is arranged at the top end of the rotating shaft 5, the fluted disc 14 is positioned in the working cavity, a second mounting groove and a third mounting groove are respectively arranged on the middle part of the left side wall and the middle part of the right side wall of the working cavity, the second mounting groove and the third mounting groove are oppositely arranged at the left and the right, a third ball bearing 15 and a fourth ball bearing 16 are respectively and fixedly arranged in the second mounting groove and the third mounting groove, the left end of the driving shaft 9 is inserted into the third ball bearing 15, the right end of the driving shaft 9 is inserted into the fourth ball bearing 16, a worm 17 is arranged in the middle part of the driving shaft 9, the worm 17 is meshed with the fluted disc 14, a first conical wheel 18 and a second conical wheel 19 are respectively arranged at the left end and the right end of the outer side of the driving shaft 9, a fourth mounting groove is arranged at the rear end of the right side wall of the working cavity, a fifth ball bearing 20 is fixedly arranged, the second mounting through hole is opposite to the fourth mounting groove in the left-right direction, a sixth ball bearing 21 is fixedly mounted in the second mounting through hole, a threaded hole which is communicated with the left side and the right side is formed in the upper half area of the mounting plate 8, the right end of the hand-operated lead screw 7 penetrates through the threaded hole from the left end of the mounting plate 8 in a screw mode and is inserted into the fifth ball bearing 20, the left end of the hand-operated lead screw 7 penetrates through the sixth ball bearing 21 from the working cavity to the outside of the box body 4, a limiting hole which is communicated with the left side and the right side is formed in the lower half area of the mounting plate 8, the left end of the limiting rod 6 is connected with the left side wall of the working cavity, the right end of the limiting rod 6 penetrates through the limiting hole from the left end of the mounting plate 8 and is connected with the right side wall of the working cavity, the driving device 3 is mounted on the right side of the rear end of the mounting plate 8, the rear end of the first valve rod, the third cone pulley 22 is positioned on the left side of the second cone pulley 19, the third cone pulley 22 is meshed with the second cone pulley 19, a transverse strip-shaped hole 23 is formed in the rear side wall of the box body 4, a third mounting through hole which penetrates through the front and back is formed in the left half area of the mounting plate 8, a seventh ball bearing 24 is fixedly mounted in the third mounting through hole, the front end of the second valve rod 11 penetrates through the seventh ball bearing 24 from the rear end of the mounting plate 8 to the front side of the mounting plate 8, the rear end of the second valve rod 11 penetrates through the strip-shaped hole 23 from the working cavity to the rear of the box body 4, a fourth cone pulley 25 is mounted at the front end of the second valve rod 11, and the fourth cone pulley 25 is positioned on the right side of the first cone pulley 18 and has a gap with the first cone pulley 18; the mounting plate moves rightwards by rotating the hand-operated lead screw, the third conical wheel is fully meshed with the second conical wheel, the fourth conical wheel is separated from the first conical wheel at the moment, the first valve rod and the third conical wheel are driven to rotate by the driving device, the second conical wheel is driven to rotate by the third conical wheel, so that the driving shaft is driven to rotate, the fluted disc and the rotating shaft are driven to rotate by the matching of the worm on the driving shaft and the fluted disc, so that the valve clack is rotated, the mounting plate moves leftwards by reversely rotating the hand-operated lead screw, the fourth conical wheel is meshed with the first conical wheel, the third conical wheel is still meshed with the second conical wheel, the hand-operated lead screw is continuously rotated until the fourth conical wheel is fully meshed with the first conical wheel, the third conical wheel is separated from the second conical wheel at the moment, the fourth conical wheel is driven to rotate by manually rotating the second valve rod, the fourth conical wheel drives the first conical wheel and the driving shaft to rotate, the driving shaft drives the fluted disc to rotate, the adjusting precision of the fluted disc is improved through manual adjustment, and after the driving device is damaged, the butterfly valve can be still controlled, and the use reliability is improved.

The utility model discloses a double-valve-rod automatic butterfly valve, still include slide 26, slide 26's top and bottom are provided with horizontal upper chute and lower chute respectively, and the interior roof and the interior diapire of bar hole 23 slide respectively and set up in upper chute and lower chute, and be provided with the fifth installation through-hole that link up from beginning to end in slide 26's middle part, and fixed mounting has eighth ball bearing 27 in the fifth installation through-hole, and the rear end of second valve stem 11 passes eighth ball bearing 27 to slide 26's rear from slide 26's front end; fix the second valve rod through the slide, improve the steadiness of second valve rod to the slide can be along strip-shaped hole horizontal slip along the mounting panel.

The utility model discloses a double-valve-rod automatic butterfly valve, which also comprises a rotating wheel 28 arranged at the rear end of the second valve rod 11; the second valve rod is convenient to rotate through the rotating wheel, and the use reliability is improved.

The utility model discloses a double-valve-rod automatic butterfly valve, when fourth cone pulley 25 just meshed with first cone pulley 18, third cone pulley 22 still meshes with second cone pulley 19, when fourth cone pulley 25 fully meshes with first cone pulley 18, third cone pulley 22 breaks away from second cone pulley 19; the condition that the third cone pulley and the second cone pulley are separated and the fourth cone pulley and the first cone pulley are separated at the same time can not occur, the rotating condition of the driving shaft under the action of medium pressure is avoided, and the practicability is improved.

The utility model discloses a double-valve-rod automatic butterfly valve, the number of teeth of the first cone-shaped wheel 18 is more than the number of teeth of the second cone-shaped wheel 19, and the number of teeth of the fourth cone-shaped wheel 25 is less than the number of teeth of the third cone-shaped wheel 22; the adjusting precision of the second valve rod is higher than that of the first valve rod, the first valve rod can be driven to be adjusted through the driving device at ordinary times, then the second valve rod is switched to be adjusted, and the adjusting precision is guaranteed.

In the double-valve-rod automatic butterfly valve of the utility model, the top end of the box body 4 is provided with a circular scale mark 29, a dial 30 is arranged in the middle of the circular scale mark 29, and the dial 30 is connected with the top end of the fluted disc 14; the rotation angle of the fluted disc is conveniently observed through the circular scale marks and the dial, so that the rotation angle of the valve clack is observed, and the practicability is improved.

The utility model discloses a double-valve-rod automatic butterfly valve, the valve clack 2 comprises two groups of valve plates and a sealing ring between the two groups of valve plates, and the sealing ring is made of polytetrafluoroethylene material; the sealing performance between the valve clack and the valve body is improved.

In the double-valve-rod automatic butterfly valve of the utility model, a left dustproof cloth 31 is connected and arranged between the left end of the sliding plate 26 and the left side wall of the strip-shaped hole 23, and a right dustproof cloth 32 is arranged between the right end of the sliding plate 26 and the right side wall of the strip-shaped hole 23; prevent through left dustproof cloth and right dustproof cloth that external dust from getting into the work intracavity through the bar hole.

The utility model discloses a double-valve-rod automatic butterfly valve, when it works, before accomplishing the above-mentioned action, install it at the position that the user needs at first, through rotating hand lead screw, make the mounting panel move to the right, and make third cone pulley and second cone pulley fully mesh, at this moment fourth cone pulley breaks away from with first cone pulley, drive first valve rod and third cone pulley rotation through drive arrangement, third cone pulley drives second cone pulley rotation, thereby drive the drive shaft rotation, through the cooperation of the worm on the drive shaft and fluted disc, make fluted disc and pivot rotate, thereby rotate the valve clack, through reverse rotation hand lead screw, make the mounting panel move to the left, fourth cone pulley meshes with first cone pulley, third cone pulley and second cone pulley still mesh, continue to rotate hand lead screw, until fourth cone pulley and first cone pulley fully mesh, at the moment, the third conical wheel is separated from the second conical wheel, the second valve rod is manually rotated to drive the fourth conical wheel to rotate, the fourth conical wheel drives the first conical wheel and the driving shaft to rotate, the driving shaft drives the fluted disc to rotate, the adjusting precision of the fluted disc is improved through manual adjustment, the butterfly valve can still be controlled after the driving device is damaged, the use reliability is improved, the second valve rod is fixed through the sliding plate, the stability of the second valve rod is improved, the sliding plate can slide left and right along the strip-shaped hole along with the mounting plate, the second valve rod can be conveniently rotated through the rotating wheel, the situation that the third conical wheel is separated from the second conical wheel and the fourth conical wheel is separated from the first conical wheel is avoided, the situation that the driving shaft rotates under the action of medium pressure is avoided, the adjusting precision of the second valve rod is higher than that of the first valve rod, and the first valve rod can be driven by the driving device to adjust at, then switch to the second valve rod and adjust again, guarantee the precision of regulation, cross the convenient turned angle who observes the fluted disc of circular scale mark and calibrated scale to observe the turned angle of valve clack, improve the practicality, prevent through left dustproof cloth and right dustproof cloth that external dust passes through the bar hole and gets into the work intracavity.

The foregoing is only a preferred embodiment of the present invention, and it should be noted that, for those skilled in the art, a plurality of modifications and variations can be made without departing from the technical principle of the present invention, and these modifications and variations should also be regarded as the protection scope of the present invention.

Claims

1. A double-valve-rod automatic butterfly valve comprises a valve body (1), a valve clack (2) and a driving device (3), wherein the valve clack (2) is rotatably arranged in the valve body (1); the valve is characterized by further comprising a box body (4), a rotating shaft (5), a limiting rod (6), a hand-operated lead screw (7), a mounting plate (8), a driving shaft (9), a first valve rod (10) and a second valve rod (11), wherein a through hole which is through from front to back is formed in the valve body (1), a first mounting groove is formed in the inner bottom wall of the through hole, a first ball bearing (12) is fixedly mounted in the first mounting groove, a through hole which is through from top to bottom is formed in the middle of the valve clack (2), a first mounting through hole which is communicated with the through hole is formed in the top end of the valve body (1), a second ball bearing (13) is fixedly mounted in the first mounting through hole, the box body (4) is mounted at the top end of the valve body (1), a working cavity is formed in the box body (4), the bottom end of the rotating shaft (5) penetrates through the through hole from the top end of the valve clack (, and the rotating shaft (5) is fixedly connected with the valve clack (2) through a bolt, the top end of the rotating shaft (5) penetrates through the bottom walls of the second ball bearing (13) and the box body (4) and extends into the working cavity, a fluted disc (14) is arranged at the top end of the rotating shaft (5), the fluted disc (14) is positioned in the working cavity, a second mounting groove and a third mounting groove are respectively arranged on the middle part of the left side wall and the middle part of the right side wall of the working cavity, the second mounting groove and the third mounting groove are oppositely arranged at the left and right sides, a third ball bearing (15) and a fourth ball bearing (16) are respectively and fixedly mounted in the second mounting groove and the third mounting groove, the left end of the driving shaft (9) is inserted into the third ball bearing (15), the right end of the driving shaft (9) is inserted into the fourth ball bearing (16), a worm (17) is arranged in the middle part of the driving shaft (9), and the worm (, the left end and the right end outside the driving shaft (9) are respectively provided with a first cone pulley (18) and a second cone pulley (19), the rear end of the right side wall of the working cavity is provided with a fourth mounting groove, a fifth ball bearing (20) is fixedly mounted in the fourth mounting groove, the left side wall of the box body (4) is provided with a second mounting through hole, the second mounting through hole is opposite to the fourth mounting groove in the left-right direction, a sixth ball bearing (21) is fixedly mounted in the second mounting through hole, the upper half area of the mounting plate (8) is provided with a threaded hole which is through in the left-right direction, the right end of the hand screw (7) penetrates through the threaded hole from the left end of the mounting plate (8) and is inserted into the fifth ball bearing (20), the left end of the hand screw (7) penetrates through the sixth ball bearing (21) to the outside of the box body (4) from the working cavity, the lower half area of the mounting plate (8) is provided with a, the left end of gag lever post (6) is connected with the left side wall of working chamber, and the right-hand member of gag lever post (6) passes spacing hole and is connected with the right side wall of working chamber from the left end of mounting panel (8), drive arrangement (3) are installed in the rear end right side of mounting panel (8), the rear end of first valve rod (10) passes mounting panel (8) and is connected with the front side output transmission of drive arrangement (3) from the front end of mounting panel (8), and third cone wheel (22) is installed to the front end of first valve rod (10), third cone wheel (22) are located the left side of second cone wheel (19) to third cone wheel (22) and second cone wheel (19) meshing are provided with horizontal bar hole (23) on the rear side wall of box (4), the left half region of mounting panel (8) is provided with the third installation through-hole that link up from beginning to end to fixed mounting has seventh ball bearing (24) in the third installation through-hole, the front end of second valve rod (11) passes seventh ball bearing (24) to the front side of mounting panel (8) from the rear end of mounting panel (8), and the rear end of second valve rod (11) passes bar hole (23) to the rear of box (4) in the working chamber to install fourth cone pulley (25) at the front end of second valve rod (11), fourth cone pulley (25) be located the right side of first cone pulley (18) and leave the clearance with between first cone pulley (18).

2. The automatic butterfly valve with the double valve rods according to claim 1, further comprising a sliding plate (26), wherein the sliding plate (26) is provided with a transverse upper chute and a transverse lower chute at the top end and the bottom end, the inner top wall and the inner bottom wall of the strip-shaped hole (23) are slidably arranged in the upper chute and the lower chute, a fifth through hole penetrating from front to back is arranged in the middle of the sliding plate (26), an eighth ball bearing (27) is fixedly arranged in the fifth through hole, and the rear end of the second valve rod (11) passes through the eighth ball bearing (27) from the front end of the sliding plate (26) to the rear end of the sliding plate (26).

3. A dual stem automatic butterfly valve according to claim 2, further comprising a rotary wheel (28) mounted to the rear end of said second stem (11).

4. A dual stem automatic butterfly valve according to claim 3, wherein said third cone (22) is still engaged with said second cone (19) when said fourth cone (25) is just engaged with said first cone (18), and wherein said third cone (22) is disengaged from said second cone (19) when said fourth cone (25) is fully engaged with said first cone (18).

5. A dual stem automatic butterfly valve according to claim 4, wherein the first cone (18) has a number of teeth which is greater than the number of teeth of the second cone (19), and the fourth cone (25) has a number of teeth which is less than the number of teeth of the third cone (22).

6. A double stem automatic butterfly valve according to claim 5, characterised in that the top of the box (4) is provided with a circular graduation mark (29) and in the middle of the circular graduation mark (29) is provided with a dial (30), the dial (30) being connected with the top of the fluted disc (14).

7. A double stem automatic butterfly valve according to claim 6, characterized in that the flap (2) comprises two valve plates and a seal between the two valve plates, the seal being made of Teflon.

8. The automatic butterfly valve with the double valve rods according to claim 7, wherein a left dustproof cloth (31) is connected between the left end of the sliding plate (26) and the left side wall of the strip-shaped hole (23), and a right dustproof cloth (32) is connected between the right end of the sliding plate (26) and the right side wall of the strip-shaped hole (23).