Low-temperature triple-eccentric multilayer metal hard sealing butterfly valve

Abstract

The invention discloses a low-temperature triple-eccentric multi-layer metal hard sealing butterfly valve which comprises a valve body, a valve rod, a butterfly plate, a valve cover, a driving mechanism, a sealing ring, a clamping mechanism, a rotating head, a rotating rod, a rotating gear, an upper rack, a lower rack and limiting teeth, the valve rod and the butterfly plate are rotationally arranged in the valve body, and the bottom end of the valve rod is hinged to the side wall of the butterfly plate; the top end of the valve rod penetrates through the outer upper portion of the valve body to be connected with a valve cover, a driving mechanism is detachably installed on the outer portion of the upper portion of the valve rod and used for driving the valve rod to rotate so as to drive the butterfly plate to rotate in the valve body, and a sealing ring is detachably installed on the outer side face of the butterfly plate. The outer wall of the sealing ring is tightly attached to the inner wall of the valve body, a clamping mechanism matched with the sealing ring is arranged on the butterfly plate, the sealing ring can be conveniently mounted and dismounted, meanwhile, the sealing performance is higher, rotation of the valve rod is controlled by the driving mechanism, and operation is more convenient.

Description

Technical Field

[0001] The invention relates to the technical field of butterfly valves, in particular to the technical field of low-temperature three-eccentric multi-layer metal hard-sealed butterfly valves. Background Art

[0002] A butterfly valve is a valve whose closing disc or butterfly plate is a disc-shaped butterfly plate, which rotates around the valve shaft to achieve opening and closing. The butterfly valve can be used to control the flow of various types of fluids such as air, water, steam, various corrosive media, mud, oil, liquid metal and radioactive media. It mainly plays a cutting and throttling role in the pipeline.

[0003] With the development of industrial technology, ordinary butterfly valves can no longer meet industrial needs. In order to meet various working conditions, butterfly valves have undergone the evolution of concentric, single eccentric, double eccentric and triple eccentric. Among them, the three eccentricities of the triple eccentric butterfly valve refer to: 1. An offset formed by the center of the valve shaft and the sealing surface of the valve plate, 2. An offset formed by the center of the valve shaft and the center line of the valve body, 3. An offset formed by the center line of the valve body sealing surface and the center line of the valve.

[0004] However, the current triple-eccentric butterfly valve is a metal hard-sealed butterfly valve with three geometric eccentric structures. It uses torque sealing and is used in harsh working conditions. For longer valve stems and micro-leakage conditions, the valve stem is prone to rod jumping, and the wear between the sleeve and the packing is a very serious problem, resulting in increased opening and closing torque, noise and wear, and valve stem jamming.

[0005] In order to solve the problems raised in the background technology, for example, application number CN201621391571.3 discloses a three-eccentric butterfly valve, including: a brake device; a valve body located on one side of the brake device; a groove on the upper surface of the valve body is provided which is concentric with the valve stem and is located on the outer periphery of the valve stem; an annular metal valve seat is fixed in the valve body; a disc-shaped valve plate is installed in the metal valve seat, and a valve stem is radially penetrated in the valve plate to control the valve stem to jump in the valve body; and a bracket is provided to provide support for the valve stem with a longer length, and self-centering is formed by the step on the lower support plate, and the upper support plate adopts a countersunk hole structure and a shaft sleeve to provide the valve stem with a third point support and positioning. The three-eccentric butterfly valve of the utility model well controls the jumping of the valve stem during the opening and closing process, reduces the friction between the valve stem and the shaft sleeve, and between the valve stem and the packing, reduces the probability of the valve stem being stuck, and improves the service life, but the structure still has the following defects: Although the above structure can control the bouncing of the valve stem during the opening and closing process and reduce the friction between the valve stem and the shaft sleeve, and the valve stem and the packing, the valve seat in this structure is generally installed in the valve body, and the reverse pressure-bearing capacity is weak, and it cannot adapt to the working conditions with high requirements for bidirectional sealing leakage level. When the reverse medium pressure of the three-eccentric butterfly valve is high, the higher-pressure fluid medium acts on the valve plate surface on the retaining ring side. Due to the existence of radial eccentricity, the additional torque generated by the fluid pressure makes the valve plate tend to open. As the medium pressure increases, the minimum sealing pressure ratio required between the valve plate sealing ring and the valve seat increases, while in fact the sealing pressure ratio between the two gradually decreases, which is prone to leakage due to the low sealing pressure ratio.

[0006] In order to solve the problems raised in the above-mentioned technology, for example, application number CN201822191709.0 discloses a three-eccentric butterfly valve, including: a valve body, a limit ring, a valve seat, a valve plate, a valve stem, an elastic element and a valve plate sealing ring. The valve body is provided with a limit convex portion, the limit ring is fixed in the valve body, and an axially movable valve seat is adopted. The displacement of the valve seat is limited by the elastic element, so that the sealing pressure on the valve seat gradually increases with the increase of the medium pressure, and the sealing pressure ratio between the valve plate sealing ring and the valve seat increases with the increase of the medium pressure, thereby improving the self-adaptation ability of the valve seat to the change of the reverse fluid pressure, ensuring the required minimum sealing pressure ratio, and avoiding the leakage of the valve seat. However, the structure still has the following defects: 1. In the above structure, the sealing ring is installed on the valve plate by bolts, which makes it difficult to disassemble and install the sealing ring when it is damaged after long-term use, resulting in cumbersome operation; 2. In the above structure, the rotation of the valve stem is controlled by the staff, which results in time-consuming and labor-intensive operation and low work efficiency. Summary of the invention

[0007] The purpose of the present invention is to solve the problems in the prior art and to propose a low-temperature three-eccentric multi-layer metal hard-sealed butterfly valve, which can facilitate the installation and disassembly of the sealing ring and has stronger sealing performance. The rotation of the valve stem is controlled by a driving mechanism, and the operation is more convenient.

[0008] To achieve the above-mentioned purpose, the present invention proposes a low-temperature three-eccentric multi-layered metal hard-sealed butterfly valve, including a valve body, a valve stem, a butterfly plate, a valve cover, a driving mechanism, a sealing ring, a clamping mechanism, a rotating head, a rotating rod, a rotating gear, an upper rack, a lower rack, and a limiting tooth. The valve body is internally rotatably provided with a valve stem and a butterfly plate, the bottom end of the valve stem is hinged to the side wall of the butterfly plate, the top end of the valve stem passes through the upper outer portion of the valve body and is connected to a valve cover, a driving mechanism is detachably installed on the upper outer portion of the valve stem, the driving mechanism is used to drive the valve stem to rotate, so as to drive the butterfly plate to rotate in the valve body, the outer side surface of the butterfly plate is detachably installed with a sealing ring, and the sealing ring The outer wall of the butterfly plate fits tightly with the inner wall of the valve body, and the butterfly plate is provided with a clamping mechanism that cooperates with the sealing ring. The clamping mechanism includes a rotating head, a rotating rod, a rotating gear, an upper rack, a lower rack and a limiting tooth. The rotating head is rotatably arranged on the outer surface of the butterfly plate, and the middle part of the rotating head is rotatably connected with a rotating rod. The end of the rotating rod passes through the interior of the butterfly plate and is rotatably provided with a rotating gear. The interior of the butterfly plate is provided with a accommodating cavity, and the upper rack and the lower rack are respectively located at the upper and lower ends of the accommodating cavity, and the rotating gear is meshed and connected with the upper rack and the lower rack, and limiting teeth are provided on one end of the upper rack and the lower rack close to the sealing ring.

[0009] Preferably, the inner side wall of the sealing ring is provided with two limiting grooves matched with the limiting teeth, and the limiting teeth are used to be embedded in the limiting grooves to achieve limiting fixation of the sealing ring, and the limiting teeth and the limiting grooves are both triangular structures.

[0010] Preferably, both upper and lower ends of the accommodating cavity are provided with sliding grooves, and sliding blocks are slidably provided in the sliding grooves, and one end of the two sliding blocks is respectively connected to one side of the upper rack and the lower rack.

[0011] Preferably, the driving mechanism includes a housing, a driving motor, a main shaft, a driving gear and a secondary gear. The driving motor is installed on the inner top wall of the housing by bolts. The output end of the driving motor is rotatably connected to the main shaft. The lower end outer wall of the main shaft is rotatably provided with a driving gear. The secondary gear is rotatably installed on the upper outer wall of the valve stem, and the secondary gear is meshed with the driving gear.

[0012] Preferably, a packing pad and a sealing ring are pressed between the upper inner wall of the valve body and the outer wall of the valve stem, and the packing pad and the sealing ring are pressed in sequence along the axial direction of the valve stem.

[0013] Preferably, a sealing groove matched with a sealing ring is provided in an annular shape on the inner wall of the valve body, and the sealing ring is located in the sealing groove.

[0014] Preferably, a control mechanism is also installed inside the shell, and a control switch matching the control mechanism is installed outside the shell. The control mechanism includes a controller, a rotating shaft, an outer gear and a lower gear. The input end of the controller is connected to the rotating shaft. The controller is used to transmit the number of rotations of the rotating shaft to the control switch. The outer wall at the end of the rotating shaft is rotatably provided with an outer gear. The lower gear is rotatably installed below the secondary gear. The lower gear is meshed with the outer gear, and the output end of the controller is connected to the drive motor through wires.

[0015] Beneficial effects of the present invention: The invention can facilitate the installation and removal of the sealing ring by cooperating with the clamping mechanism, the limiting groove, the sliding groove and the sliding block. When the sealing ring needs to be installed, firstly, two limiting grooves corresponding to the limiting teeth are opened on the inner side wall of the sealing ring, and then the sealing ring is installed to the outer side surface of the butterfly plate and clamped into the sealing groove. Then, the rotating head is rotated, the rotating head drives the rotating rod to rotate, the rotating rod drives the rotating gear to rotate, the rotating gear drives the upper rack and the lower rack to move in the direction of the sealing ring respectively, and at the same time, the sliding block on the upper rack and the lower rack moves in the sliding groove, and then drives the limiting teeth to be embedded in the limiting groove on the sealing ring to realize the limiting fixation of the sealing ring. When the sealing ring needs to be removed, the rotating head is rotated in the opposite direction, the rotating head drives the rotating rod to reverse, the rotating rod drives the rotating gear to reverse, so that the upper rack and the lower rack are close to each other, and then drives the limiting teeth to disengage from the limiting groove, and then the sealing ring can be taken out, thereby realizing the rapid installation and removal of the sealing ring, greatly improving the processing efficiency, and solving the problem that the sealing ring is not convenient to remove and install when it is damaged after long-term use, resulting in more cumbersome operation. 2. The present invention can automatically rotate the valve stem through the coordinated use of the driving mechanism, the control mechanism and the control switch. When the driving motor drives the main shaft to rotate, the main shaft drives the active gear to rotate, and the active gear drives the secondary gear to rotate, thereby driving the valve stem to rotate. During the rotation process, the valve stem drives the butterfly plate to rotate, thereby realizing the opening and closing of the butterfly valve. When the valve stem rotates, it also drives the lower gear to rotate, thereby driving the outer gear to rotate, and the outer gear drives the rotating shaft to rotate, thereby feeding back the number of rotations of the rotating shaft to the controller, and recording the number of rotations when the butterfly plate is fully opened. Therefore, when the butterfly plate is fully opened, the controller controls the driving motor to cut off the power, so that the butterfly plate will not continue to rotate in the original rotation direction. Therefore, the valve stem will not turn too much, resulting in the inability to accurately judge whether the butterfly plate assembly is in an open or closed state. The operation is simpler, which solves the problem that the rotation of the valve stem is controlled by the staff, which leads to time-consuming and labor-intensive operation and low work efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 This is a front view of the low-temperature three-eccentric multi-layer metal hard-sealed butterfly valve of the present invention; Figure 2 It is a cross-sectional view of the valve body of the low-temperature three-eccentric multi-layer metal hard-sealed butterfly valve of the present invention; Figure 3 It is an enlarged schematic diagram of point A of the low-temperature three-eccentric multi-layer metal hard-sealed butterfly valve of the present invention; Figure 4 It is a schematic diagram of the driving mechanism of the low-temperature three-eccentric multi-layer metal hard-sealed butterfly valve of the present invention; Figure 5 It is a side view of the low-temperature three-eccentric multi-layer metal hard-sealed butterfly valve of the present invention; Figure 6 It is an enlarged schematic diagram of point B of the low-temperature three-eccentric multi-layer metal hard-sealed butterfly valve of the present invention; In the figure: 1-valve body, 2-valve stem, 3-butterfly plate, 31-accommodating chamber, 311-slide groove, 312-sliding block, 4-valve cover, 5-driving mechanism, 51-housing, 52-driving motor, 53-main shaft, 54-driving gear, 55-secondary driving gear, 6-sealing ring, 61-limiting groove, 7-clamping mechanism, 71-rotating head, 72-rotating rod, 73-rotating gear, 74-upper rack, 75-lower rack, 76-limiting tooth, 8-packing pad, 9-sealing ring, 10-sealing groove, 11-control mechanism, 111-controller, 112-rotating shaft, 113-external gear, 114-lower gear, 12-control switch. DETAILED DESCRIPTION

[0017] See also Figure 1 and Figure 4The low-temperature three-eccentric multi-layer metal hard-sealed butterfly valve provided in this embodiment includes a valve body 1, a valve stem 2, a butterfly plate 3, a valve cover 4, a driving mechanism 5, a sealing ring 6, a clamping mechanism 7, a rotating head 71, a rotating rod 72, a rotating gear 73, an upper rack 74, a lower rack 75, and a limiting tooth 76. The valve body 1 is internally rotatably provided with a valve stem 2 and a butterfly plate 3. The bottom end of the valve stem 2 is hinged to the side wall of the butterfly plate 3. The top end of the valve stem 2 passes through the outer upper part of the valve body 1 and is connected to the valve cover 4. The driving mechanism 5 is detachably installed on the upper outer part of the valve stem 2. The driving mechanism 5 is used to drive the valve stem 2 to rotate so as to drive the butterfly plate 3 to rotate in the valve body 1. The outer side surface of the butterfly plate 3 is detachably installed with a sealing ring 6, and the outer wall of the sealing ring 6 is connected to the inner wall of the valve body 1. Tightly fitting, the butterfly plate 3 is provided with a clamping mechanism 7 that cooperates with the sealing ring 6, and the clamping mechanism 7 includes a rotating head 71, a rotating rod 72, a rotating gear 73, an upper rack 74, a lower rack 75 and a limiting tooth 76. The rotating head 71 is rotatably set on the outer surface of the butterfly plate 3, and the middle part of the rotating head 71 is rotatably connected with the rotating rod 72. The end of the rotating rod 72 passes through the interior of the butterfly plate 3 and is rotatably provided with a rotating gear 73. The interior of the butterfly plate 3 is provided with a accommodating chamber 31, and the upper rack 74 and the lower rack 75 are respectively located at the upper and lower ends of the accommodating chamber 31. The rotating gear 73 is meshed and connected with the upper rack 74 and the lower rack 75. The upper rack 74 and the lower rack 75 are both provided with limiting teeth 76 at one end close to the sealing ring 6.

[0018] The working principle and beneficial effects of the above scheme are as follows: when the rotating head 71 is rotated, the rotating head 71 drives the rotating rod 72 to rotate, and the rotating rod 72 drives the rotating gear 73 to rotate, and the rotating gear 73 drives the upper rack 74 and the lower rack 75 to move respectively in the direction of the sealing ring 6. At the same time, the sliding blocks 312 on the upper rack 74 and the lower rack 75 move in the sliding groove 311, thereby driving the limiting tooth 76 to embed into the limiting groove 61 on the sealing ring 6 to achieve the limiting fixation of the sealing ring 6. When the sealing ring 6 needs to be removed, the rotating head 71 is rotated in the opposite direction, the rotating head 71 drives the rotating rod 72 to reverse, and the rotating rod 72 drives the rotating gear 73 to reverse, so that the upper rack 74 and the lower rack 75 are close to each other, thereby driving the limiting tooth 76 to disengage from the limiting groove 61, and then the sealing ring 6 is taken out, thereby realizing the rapid installation and removal of the sealing ring 6.

[0019] In this embodiment, see Figure 2 and Figure 3 The inner side wall of the sealing ring 6 is provided with two limiting grooves 61 matched with the limiting teeth 76. The limiting teeth 76 are used to be embedded in the limiting grooves 61 to achieve the limiting fixation of the sealing ring 6, and the limiting teeth 76 and the limiting grooves 61 are both triangular structures.

[0020] The working principle and beneficial effects of the above solution are as follows: the limiting teeth 76 are embedded into the limiting grooves 61 , thereby achieving the limiting fixation of the sealing ring 6 .

[0021] In this embodiment, see Figure 2 and Figure 3 The upper and lower ends of the accommodating cavity 31 are both provided with sliding grooves 311, and sliding blocks 312 are slidably provided in the sliding grooves 311, and one end of the two sliding blocks 312 is respectively connected to one side of the upper rack 74 and the lower rack 75.

[0022] The working principle and beneficial effects of the above solution are as follows: when the upper rack 74 and the lower rack 75 move, the sliding block 312 is driven to move in the sliding groove 311 , thereby reducing the moving friction between the upper rack 74 and the lower rack 75 .

[0023] In this embodiment, see Figure 4 The driving mechanism 5 includes a housing 51, a driving motor 52, a main shaft 53, a driving gear 54 and a secondary gear 55. The driving motor 52 is installed on the inner top wall of the housing 51 by bolts. The output end of the driving motor 52 is rotatably connected with the main shaft 53. The lower end outer wall of the main shaft 53 is rotatably provided with a driving gear 54. The secondary gear 55 is rotatably installed on the upper outer wall of the valve stem 2, and the secondary gear 55 is meshed with the driving gear 54.

[0024] The working principle and beneficial effects of the above scheme are as follows: when the driving motor drives the main shaft 53 52 to rotate, the main shaft 3 drives the driving gear 54 to rotate, the driving gear 54 drives the secondary gear 55 to rotate, and then drives the valve stem 2 to rotate. During the rotation process, the valve stem drives the butterfly plate 3 to rotate, thereby realizing the opening and closing of the butterfly valve.

[0025] In this embodiment, see Figure 5 and Figure 6 A packing pad 8 and a sealing ring 9 are pressed between the upper inner wall of the valve body 1 and the outer wall of the valve stem 2 , and the packing pad 8 and the sealing ring 9 are pressed in sequence along the axial direction of the valve stem 2 .

[0026] The working principle and beneficial effects of the above scheme: by providing the packing pad 8 and the sealing ring 9, it is possible to prevent the low temperature in the valve body 1 from leaking from between the upper inner wall of the valve body 1 and the outer wall of the valve stem 2, thereby achieving a sealing effect.

[0027] In this embodiment, see Figure 2 The inner wall of the valve body 1 is provided with a sealing groove 10 matched with the sealing ring 6 in an annular shape, and the sealing ring 6 is located in the sealing groove 10 .

[0028] The working principle and beneficial effects of the above solution: the sealing performance of the sealing ring 6 can be further enhanced by providing the sealing groove 10 .

[0029] In this embodiment, see Figure 4 A control mechanism 11 is also installed inside the housing 51, and a control switch 12 matched with the control mechanism 11 is installed outside the housing 51. The control mechanism 11 includes a controller 111, a rotating shaft 112, an outer gear 113 and a lower gear 114. The input end of the controller 111 is connected to the rotating shaft 112. The controller 111 is used to transmit the number of rotations of the rotating shaft 112 to the control switch 12. The outer wall of the end of the rotating shaft 112 is rotatably provided with an outer gear 113. The lower gear 114 is rotatably installed below the secondary gear 55. The lower gear 114 is meshed and connected with the outer gear 113. The output end of the controller 111 is connected to the drive motor 52 through an electric wire.

[0030] The working principle and beneficial effects of the above scheme are as follows: when the valve stem 2 rotates, the lower gear 114 is driven to rotate at the same time, thereby driving the outer gear 113 to rotate, and the outer gear 113 drives the rotating shaft 112 to rotate, so that the number of rotations of the rotating shaft 112 is fed back to the controller 111, and the number of rotations when the butterfly plate 3 is fully opened is recorded. Therefore, when the butterfly plate 3 is fully opened, the controller 111 controls the drive motor 52 to cut off the power, so that the butterfly plate 3 will not continue to rotate in the original rotation direction, so the valve stem 2 will not turn too much and make it impossible to accurately judge whether the butterfly plate assembly is in the open or closed state.

[0031] Working process of the present invention: During the operation of the low-temperature three-eccentric multi-layer metal hard-sealed butterfly valve of the present invention, when the sealing ring 6 needs to be installed, firstly, two limiting grooves 61 corresponding to the limiting teeth are opened on the inner side wall of the sealing ring 6, and then the sealing ring 6 is installed to the outer side of the butterfly plate 3 and inserted into the sealing groove 10, and then the rotating head 71 is rotated, the rotating head 71 drives the rotating rod 72 to rotate, the rotating rod 72 drives the rotating gear 73 to rotate, and the rotating gear 73 drives the upper rack 74 and the lower rack 75 to move toward the direction of the sealing ring 6 respectively, and at the same time, the sliding teeth on the upper rack 74 and the lower rack 75 are The movable block 312 moves in the slide groove 311, thereby driving the limiting tooth 76 to embed into the limiting groove 61 on the sealing ring 6, thereby realizing the limiting fixation of the sealing ring 6. When the sealing ring 6 needs to be removed, the rotating head 71 is rotated in the opposite direction, and the rotating head 71 drives the rotating rod 72 to reverse, and the rotating rod 72 drives the rotating gear 73 to reverse, so that the upper rack 74 and the lower rack 75 approach each other, thereby driving the limiting tooth 76 to disengage from the limiting groove 61, and then the sealing ring 6 can be taken out, thereby realizing the rapid installation and removal of the sealing ring 6, greatly improving the processing efficiency.

[0032] When the driving motor drives the main shaft 53 of 52 to rotate, the main shaft 3 drives the driving gear 54 to rotate, and the driving gear 54 drives the secondary driving gear 55 to rotate, thereby driving the valve stem 2 to rotate. During the rotation process, the valve stem drives the butterfly plate 3 to rotate, thereby realizing the opening and closing of the butterfly valve. When the valve stem 2 rotates, it also drives the lower gear 114 to rotate, thereby driving the outer gear 113 to rotate, and the outer gear 113 drives the rotating shaft 112 to rotate, thereby making the number of rotations of the rotating shaft 112 fed back to the controller 111, and recording the number of rotations when the butterfly plate 3 is fully opened. Therefore, when the butterfly plate 3 is fully opened, the controller 111 controls the driving motor 52 to cut off the power, so that the butterfly plate 3 will not continue to rotate in the original rotation direction, so the valve stem 2 will not turn too much, resulting in the inability to accurately judge whether the butterfly plate assembly is in the open or closed state.

[0033] The control method of the present invention is to control by manually starting and closing the switch. The wiring diagram of the power element and the provision of power supply are common knowledge in the field, and the present invention is mainly used to protect mechanical devices, so the present invention will no longer explain the control method and wiring layout in detail.

[0034] The above embodiments are intended to illustrate the present invention, not to limit the present invention. Any solution that is a simple transformation of the present invention belongs to the protection scope of the present invention.

Claims

1. Low temperature three-eccentric multi-layer metal hard seal butterfly valve, characterized by: The valve body (1) comprises a valve stem (2), a butterfly plate (3), a valve cover (4), a driving mechanism (5), a sealing ring (6), a clamping mechanism (7), a rotating head (71), a rotating rod (72), a rotating gear (73), an upper rack (74), a lower rack (75), and a limiting tooth (76). The valve body (1) is internally rotatably provided with a valve stem (2) and a butterfly plate (3). The bottom end of the valve stem (2) is hingedly connected to the side wall of the butterfly plate (3). The top end of the valve stem (2) passes through the upper outer portion of the valve body (1) and is connected to the valve cover (4). The upper outer portion of the valve stem (2) is detachably provided with a driving mechanism (5). The driving mechanism (5) is used to drive the valve stem (2) to rotate so as to drive the butterfly plate (3) to rotate in the valve body (1). The outer side surface of the butterfly plate (3) is detachably provided with a sealing ring (6). The outer wall of the sealing ring (6) is tightly fitted with the inner wall of the valve body (1). 3) is provided with a clamping mechanism (7) matched with the sealing ring (6), the clamping mechanism (7) comprising a rotating head (71), a rotating rod (72), a rotating gear (73), an upper rack (74), a lower rack (75) and a limiting tooth (76), the rotating head (71) is rotatably arranged on the outer surface of the butterfly plate (3), the middle part of the rotating head (71) is rotatably connected with the rotating rod (72), the end of the rotating rod (72) penetrates the inside of the butterfly plate (3) and is rotatably provided with a rotating gear (73), the inside of the butterfly plate (3) is provided with a accommodating chamber (31), the upper rack (74) and the lower rack (75) are respectively located at the upper and lower ends of the accommodating chamber (31), the rotating gear (73) is meshedly connected with the upper rack (74) and the lower rack (75), and the upper rack (74) and the lower rack (75) are both provided with limiting teeth (76) at one end close to the sealing ring (6).

2. The low-temperature three-eccentric multi-layer metal hard-sealed butterfly valve according to claim 1, characterized in that: The inner side wall of the sealing ring (6) is provided with two limiting grooves (61) adapted to the limiting teeth (76); the limiting teeth (76) are used to be embedded in the limiting grooves (61) to achieve limiting fixation of the sealing ring (6); and the limiting teeth (76) and the limiting grooves (61) are both triangular structures.

3. The low-temperature three-eccentric multi-layer metal hard-sealed butterfly valve according to claim 1, characterized in that: The upper and lower ends of the accommodating cavity (31) are both provided with sliding grooves (311), and sliding blocks (312) are slidably arranged in the sliding grooves (311), and one end of the two sliding blocks (312) is respectively connected to one side of the upper rack (74) and the lower rack (75).

4. The low-temperature three-eccentric multi-layer metal hard-sealed butterfly valve according to claim 1, characterized in that: The driving mechanism (5) comprises a housing (51), a driving motor (52), a main shaft (53), a driving gear (54) and a secondary gear (55); the driving motor (52) is mounted on the inner top wall of the housing (51) by means of bolts; the output end of the driving motor (52) is rotatably connected to the main shaft (53); the lower end outer wall of the main shaft (53) is rotatably provided with a driving gear (54); the secondary gear (55) is rotatably mounted on the upper outer wall of the valve stem (2); the secondary gear (55) is meshingly connected to the driving gear (54).

5. The low-temperature three-eccentric multi-layer metal hard-sealed butterfly valve according to claim 1, characterized in that: A packing pad (8) and a sealing ring (9) are pressed between the upper inner wall of the valve body (1) and the outer wall of the valve stem (2), and the packing pad (8) and the sealing ring (9) are pressed in sequence along the axial direction of the valve stem (2).

6. The low-temperature three-eccentric multi-layer metal hard-sealed butterfly valve according to claim 1, characterized in that: The inner wall of the valve body (1) is provided with a sealing groove (10) in an annular shape and matched with the sealing ring (6); the sealing ring (6) is located in the sealing groove (10).

7. The low-temperature three-eccentric multi-layer metal hard-sealed butterfly valve according to claim 4, characterized in that: A control mechanism (11) is also installed inside the housing (51), and a control switch (12) matched with the control mechanism (11) is installed outside the housing (51). The control mechanism (11) comprises a controller (111), a rotating shaft (112), an external gear (113) and a lower gear (114). The input end of the controller (111) is connected to the rotating shaft (112). The controller (111) is used to transmit the number of rotations of the rotating shaft (112) to the control switch (12). The outer wall of the end of the rotating shaft (112) is rotatably provided with an external gear (113). The lower gear (114) is rotatably installed below the secondary gear (55). The lower gear (114) is meshedly connected with the external gear (113). The output end of the controller (111) is connected to the drive motor (52) via an electric wire.

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