Negative pressure tank and automatic overpressure relief device for negative pressure tank

Abstract

The application discloses a kind of negative pressure tank overpressure automatic pressure relief device, including main support, action piston and elastic mechanism;Main support includes concentrically arranged outer cylinder and inner cylinder, and, the upper end of outer cylinder and inner cylinder is connected together sealingly by connecting ring, the center of connecting ring is provided with guide block, the through hole for the piston rod of action piston is provided on guide block, through hole is located in the center of inner cylinder, the plug body of action piston is adapted with the inner wall of inner cylinder;Gap is present between guide block and connecting ring, the lower part of inner cylinder has vent hole;Elastic mechanism one end is connected with the upper end of guide block, the other end is connected with the upper end of the piston rod of action piston.The application passes through the channel of emergency start external air to enter, to prevent further reduction of negative pressure in tank, to prevent equipment damage.When negative pressure is abnormally too low, start pressure relief action and issue alarm sound to remind operator.Action component whole course limits its movement track channel, improve equipment reliability.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of negative pressure storage tanks, in particular to a negative pressure tank and an automatic overpressure relief device of the negative pressure tank. BACKGROUND

[0002] Negative pressure conveying is one of pneumatic conveying, pneumatic conveying is also called airflow conveying, which is a specific application of fluidization technology, conveying particulate materials in a closed pipeline along the airflow direction by using the energy of airflow. The structure of the pneumatic conveying device is simple, and it is convenient to operate. It can be used for horizontal, vertical or inclined conveying, and some physical operations or certain chemical operations such as heating, cooling, drying and airflow classification of materials can be carried out at the same time during the conveying process.

[0003] At present, the ash storage tank is equipped for the pneumatic ash conveying device, and the ash storage tank is connected with the ash conveying pipeline and the negative pressure fan. In the running process, the negative pressure of the ash storage tank is easily abnormally low due to various reasons. At present, the negative pressure in the negative pressure tank is generally adjusted by setting a pressure regulating mechanism to adjust the pressure in the tank. However, the adjustment range of this adjustment method is very limited. In actual production, the ash storage tank is deformed due to the excessively low negative pressure, and serious safety accidents occur from time to time.

[0004] Therefore, the prior art still needs to be improved. SUMMARY

[0005] To solve the above technical problems, the embodiments of the present application propose a negative pressure tank and an automatic overpressure relief device of the negative pressure tank to solve the technical problem that the pressure regulating mechanism of the prior art cannot meet the pressure regulating demand of the negative pressure tank.

[0006] To solve the above technical problems, some embodiments of the present application disclose an automatic overpressure relief device of a negative pressure tank, which comprises a main support, a moving piston and an elastic mechanism.

[0007] The main support comprises an outer cylinder and an inner cylinder arranged concentrically, and a connecting ring sealingly connecting the upper ends of the outer cylinder and the inner cylinder. A guide block is arranged at the center of the connecting ring, and a through hole for the piston rod of the moving piston to pass through is arranged on the guide block. The through hole is located at the center of the inner cylinder, and the plug body of the moving piston is matched with the inner wall of the inner cylinder.

[0008] In addition, there is a gap between the guide block and the connecting ring, and the lower part of the inner cylinder has a vent hole.

[0009] One end of the elastic mechanism is connected to the upper end of the guide block, and the other end is connected to the upper end of the piston rod of the moving piston.

[0010] In some embodiments, the elastic mechanism is a compression spring, and the compression spring is sleeved on the piston rod.

[0011] When the pressure of the negative pressure tank is normal, the plug body is located at the upper part of the inner cylinder, and the vent hole is in communication with the space below the plug body.

[0012] When the pressure of the negative pressure tank exceeds the predetermined value, the plug body is located at the lower part of the inner cylinder, and the vent hole is partially or entirely in communication with the space above the plug body.

[0013] In some embodiments, the outer cylinder is sealingly connected to the pressure relief port of the negative pressure tank.

[0014] In some embodiments, the outer cylinder is sealingly connected to the pressure relief port of the negative pressure tank through a connecting device.

[0015] The connecting device comprises a connecting portion, a connecting cylinder and a connecting step, the connecting portion and the connecting step are respectively arranged at two ends of the connecting cylinder, and the connecting step is sealingly connected to the lower end of the outer cylinder.

[0016] In some embodiments, the length of the inner cylinder is greater than the length of the outer cylinder, and the free end of the inner cylinder does not exceed one end of the connecting portion connected to the connecting cylinder.

[0017] The middle part of the connecting portion is open and in communication with the inside of the tank body of the negative pressure tank.

[0018] In some embodiments, the vent hole is in the shape of an oblong, and the long side of the oblong is consistent with the length direction of the inner cylinder.

[0019] In some embodiments, the vent hole is four, and is uniformly arranged at the lower part of the inner cylinder.

[0020] In some embodiments, there is a gap between the inner wall of the connecting cylinder and the outer wall of the inner cylinder.

[0021] In some embodiments, the connecting portion is a threaded connection or a flange connection.

[0022] Alternatively, the outer wall of the connecting step is threadedly connected to the inner wall of the lower end of the outer cylinder.

[0023] In another aspect, some embodiments of the present application also disclose a negative pressure tank comprising the foregoing negative pressure tank overpressure automatic pressure relief device, and the outer cylinder is sealingly connected to the pressure relief port of the negative pressure tank.

[0024] By adopting the technical scheme, the present application has at least the following beneficial effects:

[0025] The negative pressure tank and the negative pressure tank overpressure automatic pressure relief device provided by the present application solve the technical problem of excessively high negative pressure of a dust storage tank for pneumatic dust conveying, and prevent further reduction of the negative pressure in the tank and damage to the equipment by starting an air passage for external air. When the negative pressure is excessively low, an alarm sound is emitted to remind the operator. The movement track of the action component is limited by the passage, thereby improving the reliability of the equipment. BRIEF DESCRIPTION OF DRAWINGS

[0026] In order to make the technical solutions in the embodiments of the present application or the prior art clearer, the accompanying drawings needed in the embodiments or prior art description will be briefly introduced. Obviously, the accompanying drawings in the following description only only some embodiments of the present application, and for those skilled in the art, other drawings can be obtained without creative work based on these drawings.

[0027] Figure 1 Structure diagram of the automatic overpressure relief device of the negative pressure tank according to some embodiments of the present application;

[0028] Figure 2 Structure diagram of the main support of the automatic overpressure relief device of the negative pressure tank according to some embodiments of the present application;

[0029] Figure 3 Structure diagram of the main support of the automatic overpressure relief device of the negative pressure tank according to some embodiments of the present application;

[0030] Figure 4 Structure diagram of the action piston of the automatic overpressure relief device of the negative pressure tank according to some embodiments of the present application;

[0031] Figure 5 Structure diagram of the connecting device of the automatic overpressure relief device of the negative pressure tank according to some embodiments of the present application;

[0032] Figure 6 Structure diagram of the automatic overpressure relief device of the negative pressure tank when the pressure is normal according to some embodiments of the present application;

[0033] Figure 7 Structure diagram of the automatic overpressure relief device of the negative pressure tank when the pressure exceeds the predetermined value according to some embodiments of the present application;

[0034] Figure 8 Air inflow path diagram of the automatic overpressure relief device of the negative pressure tank when the pressure exceeds the predetermined value according to some embodiments of the present application.

[0035] Explanation of reference signs:

[0036] 1, main support; 2, action piston; 3, elastic mechanism; 4, connecting device;

[0037] 11, inner cylinder; 12, outer cylinder; 13, connecting ring; 14, guide block; 15, air hole; 16, through hole; 21, piston rod; 22, plug body; 41, connecting part; 42, connecting cylinder; 43, connecting step. DETAILED DESCRIPTION

[0038] The embodiments of the present disclosure will be described in further detail below with reference to the drawings and examples. The following detailed description of the examples and the accompanying drawings are provided for the purpose of illustrating the principles of the present disclosure, and are not intended to limit the scope of the present disclosure, which can be embodied in a variety of different forms, not limited to the specific examples disclosed herein, but include all technical solutions falling within the scope of the claims.

[0039] The present disclosure provides these examples in order to make the present disclosure more thorough and complete, and to fully convey the scope of the present disclosure to those skilled in the art. It should be noted that: unless otherwise specified, the relative arrangement of components and steps, the components of materials, numerical expressions and values set forth in these examples should be interpreted as merely exemplary, and not as a limitation.

[0040] It should be noted that, in the description of the present disclosure, unless otherwise specified, the meaning of "a plurality of" is greater than or equal to two; the orientation or positional relationship indicated by the terms "upper", "lower", "left", "right", "inner", "outer" and the like is only for the purpose of facilitating the description of the present disclosure and simplifying the description, and does not indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation to the present disclosure. When the absolute position of the described object changes, the relative positional relationship may also change accordingly.

[0041] In addition, "first", "second", and similar words used in the present disclosure do not indicate any order, number, or importance, but are only used to distinguish different parts. "Vertical" is not strictly vertical, but within the allowable range of error. "Parallel" is not strictly parallel, but within the allowable range of error. "Include" or "contain" and similar words mean that the elements before the word cover the elements listed after the word, and do not exclude the possibility of also covering other elements.

[0042] It should also be noted that, in the description of the present disclosure, unless otherwise specified and limited, the terms "mounting", "connecting", "connection" should be interpreted broadly, for example, it can be fixedly connected, or it can be detachably connected, or integrally connected; it can be directly connected, or indirectly connected through an intermediate medium. For those skilled in the art, the specific meaning of the above terms in the present disclosure can be understood according to the specific circumstances. When it is described that a specific device is located between a first device and a second device, there can be an intermediate device between the specific device and the first device or the second device, or there can be no intermediate device.

[0043] All terms used herein are intended to have the same meaning as understood by one of ordinary skill in the art to which this disclosure pertains, unless otherwise specifically defined herein. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.

[0044] Techniques, methods, and apparatus known to those of ordinary skill in the relevant art can not be discussed in detail herein, but should be considered as part of the specification, where appropriate.

[0045] As shown in Figures 1 to 8 Some embodiments of the present application disclose an automatic overpressure relief device for negative pressure tank, comprising a main support 1, a moving piston 2 and an elastic mechanism 3. The main support 1 can be sealingly connected with the relief port of the negative pressure tank, and the automatic relief is realized through the elastic force matching of the moving piston 2 and the elastic mechanism 3. The main support 1 can comprise an outer cylinder 12 and an inner cylinder 11 arranged concentrically, and a connecting ring 13 sealingly connecting the upper ends of the outer cylinder 12 and the inner cylinder 11 together. A guide block 14 is arranged at the center of the connecting ring 13, and a through hole 16 is arranged on the guide block 14 for the piston rod 21 of the moving piston 2 to pass through. The through hole 16 is located at the center of the inner cylinder 11, and the plug body 22 of the moving piston 2 is matched with the inner wall of the inner cylinder 11. In addition, there is a gap between the guide block 14 and the connecting ring 13, and the lower part of the inner cylinder 11 has a vent hole 15. One end of the elastic mechanism 3 is connected with the upper end of the guide block 14, and the other end is connected with the upper end of the piston rod 21 of the moving piston 2. Figure 2 As shown in

[0046] In use, as the negative pressure in the negative pressure tank increases, the pressure in the tank overcomes the elastic force of the elastic mechanism 3, a pressure difference is formed between the upper surface and the lower surface of the plug body 22, the plug body 22 is driven to move towards the lower part of the inner cylinder 11, until the vent hole 15 on the inner cylinder 11 is communicated with the upper surface of the plug body 22, air can enter the inner cylinder 11 through the gap between the guide block 14 and the connecting ring 13, and then enter the tank body of the negative pressure tank through the vent hole 15, to compensate the negative pressure in the negative pressure tank, realize pressure relief, and avoid damage to the negative pressure tank caused by excessive pressure.

[0047] The automatic overpressure relief device of the negative pressure tank disclosed by some embodiments of the present application, on the basis of the above embodiments, the elastic mechanism 3 can be a compression spring, which is sleeved on the piston rod 21 during use; one end of the compression spring abuts against the guide block 14, and the other end abuts against the handle at the end of the piston rod 21; when the pressure of the negative pressure tank is normal, the plug body 22 is located at the upper part of the inner cylinder 11, and the vent hole 15 is in communication with the space at the lower part of the plug body 22; when the pressure of the negative pressure tank exceeds the predetermined value, the plug body 22 is located at the lower part of the inner cylinder 11, and the vent hole 15 is partially or entirely in communication with the space at the upper part of the plug body 22. The negative pressure range in the tank body of the negative pressure tank is related to the compression force of the compression spring.

[0048] The automatic overpressure relief device of the negative pressure tank disclosed by some embodiments of the present application, on the basis of the above embodiments, the outer cylinder 12 is sealingly connected with the relief port of the negative pressure tank, the upper surface of the plug body 22 bears the atmospheric pressure from the outside and the elastic force of the spring, the lower surface of the plug body 22 bears the pressure from the inside of the negative pressure tank, when the two are balanced, the action piston 2 remains stationary, when the negative pressure in the negative pressure tank is too large, the plug body 22 moves towards the negative pressure tank until the vent hole 15 is in communication with the upper surface of the plug body 22, the atmosphere enters the negative pressure tank, and the relief of the negative pressure tank is realized, with the entry of the atmosphere, the negative pressure in the negative pressure tank gradually decreases, under the action of the spring elastic force, the action piston 2 moves, the plug body 22 moves to the upper part of the inner cylinder 11, and the communication between the vent hole 15 and the atmosphere is closed.

[0049] The outer cylinder 12 and the relief port of the negative pressure tank can be sealingly connected through the connecting device 4; the connecting device 4 can include a connecting portion 41, a connecting cylinder 42 and a connecting step 43, the connecting portion 41 and the connecting step 43 are respectively arranged at the two ends of the connecting cylinder 42, the connecting step 43 is sealingly connected with the lower end of the outer cylinder 12, and the connecting portion 41 is sealingly connected with the relief port of the negative pressure tank. This connection mode can make the connection stability between the relief device and the negative pressure tank better.

[0050] The automatic overpressure relief device of the negative pressure tank disclosed by some embodiments of the present application, on the basis of the above embodiments, in order to further remind the staff of the situation of the negative pressure tank during relief, generally, the length of the inner cylinder 11 is greater than the length of the outer cylinder 12, the free end of the inner cylinder 11 does not exceed one end of the connecting portion 41 connected with the connecting cylinder 42, and the middle opening of the connecting portion 41 is in communication with the inside of the tank body of the negative pressure tank. Under this structure, during relief, the atmosphere first enters the inside of the inner cylinder 11 through the gap between the guide block 14 and the connecting ring 13, then comes out through the vent hole 15 at the lower part of the inner cylinder, then enters the negative pressure tank through the middle opening of the connecting portion 41 of the connecting cylinder 42. The whole gas path is tortuous, so that a sharp sound can be emitted during relief, thereby reminding the staff.

[0051] The automatic overpressure relief device of the negative pressure tank disclosed by some embodiments of the present application, on the basis of the above embodiments, in order to ensure the smooth sliding of the plug body 22 in the inner cylinder 11, the vent hole 15 can be set as an oblong shape, and the long side of the oblong shape is consistent with the length direction of the inner cylinder 11. This setting method makes the negative pressure tank communicate with the outside while not interfering with the movement of the plug body 22. Generally, the vent hole 15 can be set as four, uniformly arranged in the lower part of the inner cylinder 11.

[0052] The automatic overpressure relief device of the negative pressure tank disclosed by some embodiments of the present application, on the basis of the above embodiments, the inner wall of the connecting cylinder 42 and the outer wall of the inner cylinder 11 have a slit. By setting the slit, the airflow enters from the upper part of the inner cylinder 11, enters the slit through the oblong vent hole 15, and finally enters the negative pressure tank from the middle of the connecting part 41, so that the internal negative pressure of the pressure is no longer continuously small, thereby protecting the negative pressure tank from being deformed by air extrusion due to too low negative pressure. In this process, the ambient air bends the path through the device and thus makes a sound, thereby reminding personnel to pay attention.

[0053] Some embodiments of the present application also disclose a negative pressure tank comprising the aforementioned automatic overpressure relief device, comprising a main support 1, a moving piston 2 and an elastic mechanism 3; the main support 1 can be sealingly connected with the relief port of the negative pressure tank, and automatic relief is realized through the elastic force matching of the moving piston 2 and the elastic mechanism 3. The main support 1 can comprise an outer cylinder 12 and an inner cylinder 11 arranged concentrically, and the upper ends of the outer cylinder 12 and the inner cylinder 11 are sealingly connected together through a connecting ring 13, the center of the connecting ring 13 is provided with a guide block 14, the guide block 14 is provided with a through hole 16 through which a piston rod 21 of the moving piston 2 passes, the through hole 16 is located at the center of the inner cylinder 11, and a plug body 22 of the moving piston 2 is matched with the inner wall of the inner cylinder 11; and the guide block 14 and the connecting ring 13 have a gap therebetween, and the lower part of the inner cylinder 11 has a vent hole 15; one end of the elastic mechanism 3 is connected with the upper end of the guide block 14, and the other end is connected with the upper end of the piston rod 21 of the moving piston 2. When the main support 1 is installed on the negative pressure tank, the threaded connection mode can be used, for example, the outer cylinder 12 is provided with external threads at the lower end, and the internal threads at the relief port of the negative pressure tank are matched, and sealing pads or the like can be further arranged at the joint of the two to ensure the air tightness. When in use, when the negative pressure in the tank body is normal, the plug body 22 is located in the upper region of the inner cylinder 11, at this time the vent hole 15 is located below the plug body 22 (the end of the plug body 22 far away from the piston rod 21), the vent hole 15 is communicated with the inside of the tank body, and as the negative pressure in the negative pressure tank increases, the attraction of the negative pressure tank to the plug body 22 increases, so that the plug body 22 moves to the inside of the tank of the negative pressure tank, and the plug body 22 overcomes the elastic force of the elastic mechanism 3 during the movement, and the whole movement process keeps the negative pressure in the tank and the elastic force of the elastic mechanism 3 adaptive. Until the plug body 22 moves to the vent hole 15 partially exposed above the plug body 22, the vent hole 15 makes the inside of the tank body and the upper part of the plug body 22 (the end of the plug body 22 connected with the piston rod 21) communicated, and due to the negative pressure in the tank, the airflow enters the vent hole 15 through the gap between the guide block 14 and the inner cylinder 11, and finally enters the tank body, so that the negative pressure in the tank body decreases. In this process, if the negative pressure in the tank body is still greater than the elastic force of the elastic mechanism 3, the plug body 22 continues to advance into the tank body, until the vent hole 15 is completely exposed above the plug body 22, and the speed of the atmosphere entering the tank body reaches the maximum. Generally, the length of the inner cylinder 11 should keep the plug body 22 advanced to the lowermost end in the inner cylinder 11. As the gas enters the tank, the negative pressure in the tank gradually decreases, and under the action of the elastic force, the plug body 22 retreats upward until the vent hole 15 is completely located below the plug body 22, and a sealed space is reformed in the tank body.

[0054] Some embodiments of the application also disclose a negative pressure tank comprising the aforementioned automatic pressure relief device for negative pressure tank, and the pressure relief device is connected to the pressure relief port of the negative pressure tank through a connecting device 4, specifically, the connecting device 4 can comprise a connecting part 41, a connecting cylinder 42 and a connecting step 43, the connecting part 41 and the connecting step 43 are arranged at two ends of the connecting cylinder 42 respectively, the connecting step 43 is sealingly connected to the lower end of the outer cylinder 12, and the connecting part 41 is sealingly connected to the pressure relief port of the negative pressure tank. The outer wall of the connecting step 43 can be threadedly connected to the inner wall of the lower end of the outer cylinder 12. Meanwhile, the connecting part 41 and the pressure relief port of the negative pressure tank can be connected by flange connection or threaded connection, and such a connection mode can make the connection stability between the pressure relief device and the negative pressure tank better. The action pressure of the pressure relief device can be adjusted by adjusting the elastic force of the elastic mechanism 3. The piston rod 21 moves inside the inner cylinder 11 of the main body support 1, when the negative pressure in the tank reaches a set value, the upper end surface pressure of the plug body 22 of the action piston 2 is greater than the lower end surface pressure, the external air pushes the action piston 2 to move downward, when the plug body 22 exceeds the air hole 15 of the main body support 1. The external air enters the negative pressure tank through the air hole 15 around the guide block 14, so that the internal negative pressure no longer continues to decrease, thereby preventing the negative pressure tank from being deformed due to being squeezed by air caused by the negative pressure being too low, and the action piston 2 moves up and down like a track by means of the inner wall of the inner cylinder 11, thereby improving the stability of operation and reducing the failure of the equipment, and the device is more stable and reliable than the existing scheme in the market. In this process, the external air passes through the path of the device and is bent, thereby emitting a sound, thereby reminding personnel to pay attention.

[0055] In summary, the negative pressure tank and the automatic pressure relief device for negative pressure tank disclosed by the embodiments of the application solve the technical problem that the negative pressure of the ash storage tank for pneumatic ash conveying is too high, the channel for external air to enter is started in an emergency, so that the negative pressure in the tank is prevented from further decreasing, thereby preventing the equipment from being damaged. When the negative pressure is abnormally too low, an alarm sound is emitted to remind the operator when the pressure relief action is started. The action component has a channel limiting the movement track thereof throughout the process, thereby improving the reliability of the equipment.

[0056] So far, the embodiments of the present disclosure have been described in detail. In order to avoid obscuring the concept of the present disclosure, some details known in the art are not described. Those skilled in the art can fully understand how to implement the technical solutions disclosed herein according to the above description.

[0057] Although some specific embodiments of the present disclosure have been described in detail by way of examples, one skilled in the art should understand that the above examples are only for illustration, and are not intended to limit the scope of the present disclosure. One skilled in the art should understand that the above embodiments can be modified or equivalent replacements can be made to some technical features without departing from the scope and spirit of the present disclosure. In particular, the technical features mentioned in each embodiment can be combined in any manner as long as there is no structural conflict.

Claims

1. A negative pressure tank overpressure automatic relief device, characterized by, The device comprises a main body bracket (1), a moving piston (2) and an elastic mechanism (3). The main body bracket (1) comprises an outer cylinder (12) and an inner cylinder (11) arranged concentrically, and a connecting ring (13) sealingly connecting the upper ends of the outer cylinder (12) and the inner cylinder (11) together, the connecting ring (13) is provided with a guide block (14) at the center, the guide block (14) is provided with a through hole (16) for the piston rod (21) of the moving piston (2) to pass through, the through hole (16) is located at the center of the inner cylinder (11), the plug body (22) of the moving piston (2) is matched with the inner wall of the inner cylinder (11); And, there is a gap between the guide block (14) and the connecting ring (13), the lower part of the inner cylinder (11) is provided with a vent hole (15); The elastic mechanism (3) is connected to the upper end of the guide block (14) at one end, and connected to the upper end of the piston rod (21) of the moving piston (2) at the other end; The outer cylinder (12) and the pressure relief port of the negative pressure tank are sealingly connected through a connecting device (4); The connecting device (4) comprises a connecting part (41), a connecting cylinder (42) and a connecting step (43), the connecting part (41) and the connecting step (43) are respectively arranged at both ends of the connecting cylinder (42), and the connecting step (43) is sealingly connected with the lower end of the outer cylinder (12); The inner wall of the connecting cylinder (42) and the outer wall of the inner cylinder (11) have a gap; The elastic mechanism (3) is a compression spring, which is sleeved on the piston rod (21); When the pressure of the negative pressure tank is normal, the plug body (22) is located at the upper part of the inner cylinder (11), and the vent hole (15) is in space communication with the lower part of the plug body (22); When the pressure of the negative pressure tank exceeds a predetermined value, the plug body (22) is located at the lower part of the inner cylinder (11), and the vent hole (15) is partially or entirely in space communication with the upper part of the plug body (22); The length of the inner cylinder (11) is greater than the length of the outer cylinder (12), and the free end of the inner cylinder (11) does not exceed one end of the connecting cylinder (42) connected to the connecting part (41); The middle part of the connecting part (41) is open and in communication with the inside of the tank body of the negative pressure tank.

2. The negative pressure tank overpressure automatic pressure relief device according to claim 1, characterized by, The vent hole (15) is an oblong shape, and the long side of the oblong shape is consistent with the length direction of the inner cylinder (11).

3. The negative pressure tank overpressure automatic pressure relief device according to claim 2, characterized by The vent hole (15) is four, which are evenly arranged at the lower part of the inner cylinder (11).

4. The negative pressure tank overpressure automatic pressure relief device according to claim 1, characterized by, The connecting part (41) and the pressure relief port are threadedly connected or flange connected. Alternatively, the outer wall of the connecting step (43) is threadedly connected with the inner wall of the lower end of the outer cylinder (12).

5. A negative pressure tank characterized by, The device comprises a main body bracket (1), a moving piston (2) and an elastic mechanism (3). The main body bracket (1) comprises an outer cylinder (12) and an inner cylinder (11) arranged concentrically, and a connecting ring (13) sealingly connecting the upper ends of the outer cylinder (12) and the inner cylinder (11) together, the connecting ring (13) is provided with a guide block (14) at the center, the guide block (14) is provided with a through hole (16) for the piston rod (21) of the moving piston (2) to pass through, the through hole (16) is located at the center of the inner cylinder (11), the plug body (22) of the moving piston (2) is matched with the inner wall of the inner cylinder (11); And, there is a gap between the guide block (14) and the connecting ring (13), the lower part of the inner cylinder (11) is provided with a vent hole (15); The elastic mechanism (3) is connected to the upper end of the guide block (14) at one end, and connected to the upper end of the piston rod (21) of the moving piston (2) at the other end; The outer cylinder (12) and the pressure relief port of the negative pressure tank are sealingly connected through a connecting device (4); The connecting device (4) comprises a connecting part (41), a connecting cylinder (42) and a connecting step (43), the connecting part (41) and the connecting step (43) are respectively arranged at both ends of the connecting cylinder (42), and the connecting step (43) is sealingly connected with the lower end of the outer cylinder (12); The inner wall of the connecting cylinder (42) and the outer wall of the inner cylinder (11) have a gap; The elastic mechanism (3) is a compression spring, which is sleeved on the piston rod (21); The plug body (22) is located at the upper part of the inner cylinder (11), and the vent hole (15) is in space communication with the lower part of the plug body (22); The plug body (22) is located at the lower part of the inner cylinder (11), and the vent hole (15) is partially or entirely in space communication with the upper part of the plug body (22); The length of the inner cylinder (11) is greater than the length of the outer cylinder (12), and the free end of the inner cylinder (11) does not exceed one end of the connecting cylinder (42) connected to the connecting part (41); The middle part of the connecting part (41) is open and in communication with the inside of the tank body of the negative pressure tank. The vent hole (15) is an oblong shape, and the long side of the oblong shape is consistent with the length direction of the inner cylinder (11). The vent hole (15) is four, which are evenly arranged at the lower part of the inner cylinder (11). The connecting part (41) and the pressure relief port are threadedly connected or flange connected. Alternatively, the outer wall of the connecting step (43) is threadedly connected with the inner wall of the lower end of the outer cylinder (12).

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