Pneumatic safety valve with pressure protection

Abstract

The utility model discloses a pneumatic safety valve with pressure protection specifically related to the field of industrial safety equipment, including valve body, the valve body is installed with gland, is provided with the valve clack and valve rod in the valve body inner chamber, the valve clack is connected with valve rod, still includes a set of tight single -layer air cylinder and normally closed pilot control loop, single -layer air cylinder sets up in the top of gland, and the piston rod of single -layer air cylinder is connected with the upper end of valve rod through double -end bolt, when the piston rod goes up and down, can drive valve rod and valve clack synchronous movement, the utility model discloses a tight single -layer air cylinder replaces the traditional multilayer big cylinder diameter air cylinder or huge spring assembly, combines with normally closed pilot logic, makes the whole valve structure very compact, and axial and radial size all significantly reduces, this makes it can be easily installed on the pipeline system or equipment interface of narrow space, and the adaptability is stronger.

Description

Technical Field

[0001] This utility model relates to the field of industrial safety equipment technology, and more specifically, to a pneumatic safety valve with pressure protection. Background Technology

[0002] Safety valves are crucial safety protection devices in industrial systems. Their function is to automatically open and release pressure when the pressure of the medium in pressure-bearing equipment such as pipelines and containers exceeds a predetermined value, and automatically close after the pressure returns to normal, thereby preventing accidents caused by overpressure and protecting life and property. Based on the different power sources and control methods, safety valves are mainly divided into two categories: direct-load type (such as spring type) and pilot-operated type.

[0003] Patent application CN117537125A discloses a "high-temperature back pressure valve device." This device is used on a compressor test bench to control the flow and pressure of high-temperature, high-pressure gas. It includes a valve body, valve core, valve stem, inlet pipe, and outlet pipe. The valve body internally has a valve disc moving chamber and a piston moving chamber. The valve core is spindle-shaped, with the front end being the valve disc structure and the rear end being the piston structure. By introducing low-temperature balancing gas into the piston moving chamber to balance the pressure difference on both sides of the valve disc, the valve stem operating force is reduced, achieving smooth valve opening and back pressure regulation. This invention effectively solves the problems of valve jamming, sealing, and high operating force under high-temperature, high-pressure environments. It features a compact structure and self-sealing and pressure balancing characteristics.

[0004] However, the device described in patent CN117537125A is essentially a "back pressure valve" or "control valve" for flow and pressure regulation. Its design aims to achieve precise back pressure regulation and reliable operation at high temperatures. Its opening and closing are typically actively controlled processes (e.g., driven by an external actuator), rather than a protective action automatically triggered by system pressure. It is not a "safety valve" in the traditional sense, meaning it is not primarily used for automatic, rapid, and full-volume venting to protect the system when it is overpressured. Its pilot or balancing air path is mainly used to reduce operating force, prevent jamming, and achieve regulation functions, rather than precisely sensing system pressure and directly driving the valve to achieve protective opening.

[0005] Currently, the most widely used type of safety valve in the industrial safety valve field is still the direct-load spring safety valve. Its basic principle is to use the preload of the spring to balance the force of the medium acting on the valve disc. When the medium pressure exceeds the spring preload, the valve disc opens to release pressure. Although simple in structure and low in cost, it has several inherent defects: First, the spring preload directly determines the opening pressure of the safety valve. Under long-term exposure to high pressure, frequent opening and closing, and environmental corrosion, the spring is prone to relaxation, fatigue, or corrosion, leading to changes in its stiffness. This, in turn, causes opening pressure drift, reduced protection accuracy, and may even result in premature or delayed opening, posing a significant safety hazard. Second, during valve opening and reseating, the valve disc impacts the valve seat at high speed, causing severe impact wear on the sealing surface, easily leading to seal failure and internal leakage. This impact also easily triggers valve disc "flutter" (high-frequency opening and closing phenomenon), which not only exacerbates wear but also generates noise and pipeline vibration, seriously threatening the safe and stable operation of equipment. Furthermore, traditional pneumatic control valves often employ multi-layered or large-diameter cylinders to achieve greater driving force, resulting in a bulky and cumbersome overall structure that is difficult to install in space-constrained environments. In addition, under low-pressure conditions, the control accuracy and sensitivity of traditional pneumatic control methods are often poor.

[0006] Therefore, it is necessary to develop a new type of safety valve that can inherit the advantages of high precision and low back pressure influence of pilot-operated control, while overcoming the disadvantages of traditional spring-loaded safety valves such as easy pressure drift during opening, easy seal damage, and large size. At the same time, it should clearly define its core function as an automatic overpressure protection device to meet the increasingly higher requirements of modern industry, especially for safety equipment under harsh working conditions such as high pressure, large diameter, zero leakage, and limited space. Utility Model Content

[0007] In order to overcome the above-mentioned defects of the prior art, the present invention provides a pneumatic safety valve with pressure protection, which solves the problems of opening pressure drift, easy impact damage to the sealing surface, large size and poor control accuracy under low pressure that exist in the spring direct load type safety valves widely used in the prior art.

[0008] To achieve the above objectives, this utility model provides the following technical solution: a pneumatic safety valve with pressure protection, including a valve body, a pressure cap installed on the valve body, a valve disc and a valve stem disposed in the inner cavity of the valve body, the valve disc being connected to the valve stem, and also including a set of tightly closed single-layer cylinder and a normally closed pilot control circuit; A single-layer cylinder is located on the top of the gland. The piston rod of the single-layer cylinder is connected to the upper end of the valve rod by a double-headed bolt. When the piston rod moves up and down, it can drive the valve rod and valve disc to move synchronously. The normally closed pilot control circuit is the core of this valve's pressure sensing and logic control. The pilot control circuit includes a pilot valve and a filter to protect the pilot valve. The inlet of the pilot valve is connected to the medium pressure sensing port inside the valve body, thereby enabling real-time sensing of the pressure of the protected system. The filter is located at the medium pressure sensing port to filter impurities in the medium drawn from the valve body, ensuring that the precision components inside the pilot valve are not blocked and improving the reliability of the control circuit. The outlet of the pilot valve is connected to a single-layer cylinder. The single-layer cylinder is connected to the atmosphere or a low-pressure vent. The pilot valve is set as a normally closed valve. When it senses that the system pressure is lower than the set value, it remains closed, allowing the system medium pressure to be introduced and act on the upper chamber of the single-layer cylinder, pushing the valve stem to move downward and thus keeping the valve disc closed. When the system pressure reaches or exceeds the set value, the pilot valve opens to release the pressure in the upper chamber of the single-layer cylinder, and the valve disc opens to release pressure under the action of the medium. When the valve is closed, it relies on the medium pressure acting on the upper chamber of the single-layer cylinder, the emptying state of the single-layer cylinder itself, and the self-sealing force of the medium acting on the valve disc to form a triple sealing guarantee. In the closed state, the first layer is the normally closed pilot valve logic that ensures that the pressure continues to act on the upper chamber of the cylinder; the second layer is that the lower chamber of the single-layer cylinder is always emptied, and there is no reverse force; the third layer is the self-sealing force generated by the system medium pressure acting directly on the valve disc. These three factors together constitute a reliable triple sealing guarantee, providing a foundation for achieving the goal of zero leakage. A high-precision filter is installed at the inlet of the pilot valve, and a force-balanced structure design is adopted to make its opening pressure setpoint stable and unaffected by changes in valve back pressure, thus protecting the sensitivity and reliability of the pilot valve.

[0009] Furthermore, the single-layer cylinder is connected to the gland via a cylinder connector, which is fixed to the single-layer cylinder with an internal hexagon screw. The cylinder connector is also fixed to the gland with a round nut. A sealing gasket is provided at the connection between the gland and the top of the valve body to improve the strength and stability of the connection structure.

[0010] Furthermore, the valve stem passes through the gland and the cylinder connecting seat. A dynamic sealing assembly is provided between the valve stem and the valve disc. The dynamic sealing assembly includes a sealing pressure ring and a sealing ring arranged in sequence. A sealing ring II and a sealing ring III are provided between the valve disc and the inner wall of the valve body to ensure that there is no external leakage at the connection.

[0011] Furthermore, the valve body is equipped with a valve seat that mates with the valve disc. The sealing surfaces of the valve disc and the valve seat are made of hard alloy material through welding or inlay to form a hard seal that is resistant to erosion and wear. A sealing ring IV is provided at the connection between the outer wall of the valve seat and the valve disc to ensure that there is no external leakage at the connection.

[0012] Furthermore, a sealing shaft is provided on one side of the valve body. The sealing shaft and the valve disc together form the main valve disc. The sealing shaft is fixed to the valve body by a cap nut.

[0013] Furthermore, the valve body is equipped with a drain connector, which is normally sealed with a cap nut. It is used to drain residual media in the valve cavity during valve maintenance or testing. The inner wall of the drain connector away from the valve body is equipped with a sealing ring I, and a bottom plug is also provided at the bottom of the valve body.

[0014] The technical effects and advantages of this utility model are as follows: This utility model uses a compact single-layer cylinder to replace the traditional multi-layer large-diameter cylinder or bulky spring assembly. Combined with normally closed pilot logic, the entire valve structure is very compact, and the axial and radial dimensions are significantly reduced. This makes it easy to install in narrow pipeline systems or equipment interfaces, making it more adaptable. This invention employs a triple sealing mechanism: normally closed pilot logic pressure holding, normally open atmospheric venting in the lower cylinder chamber, and self-sealing by the medium force. Under normal operating conditions, the valve disc withstands a strong net closing force, and combined with the hard alloy sealing surface, it can achieve bubble-level sealing or even zero leakage, making it perfectly suitable for fields such as petrochemicals, natural gas, and nuclear power where leakage is extremely critical. The pilot control circuit of this utility model is a valve that automatically senses the dangerous pressure in the system and triggers the release. Its cylinder power comes entirely from the system medium itself and does not require an external air source. It conforms to the essential attributes of a safety valve as an automatic and passive safety protection device. It avoids the severe mechanical impact of traditional spring valves, opens and closes more smoothly, eliminates the risk of chatter, and is more friendly to pipeline systems. Attached Figure Description

[0015] To more clearly illustrate the embodiments of this utility model or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings in the following description are merely exemplary, and those skilled in the art can derive other embodiments based on the provided drawings without creative effort.

[0016] The structures, proportions, sizes, etc. illustrated in this specification are only for the purpose of assisting those skilled in the art in understanding and reading the content disclosed herein, and are not intended to limit the implementation conditions of this utility model. Therefore, they have no substantial technical significance. Any modifications to the structure, changes in the proportions, or adjustments to the size, without affecting the effects and objectives that this utility model can produce, should still fall within the scope of the technical content disclosed in this utility model.

[0017] Figure 1 This is a schematic diagram of the overall structure of this utility model.

[0018] Figure 2 This is a cross-sectional view of the overall structure of this utility model.

[0019] Figure 3 For the present utility model Figure 2 Enlarged view of the structure of section A in the middle.

[0020] The attached figures are labeled as follows: 1 Single-layer cylinder, 2 Cylinder connecting seat, 3 Round nut, 4 Pressure cap, 5 Sealing ring, 6 Sealing ring, 7 Valve stem, 8 Sealing ring I, 9 Drain connector, 10 Cap nut, 11 Valve body, 12 Lower plug, 13 Hex socket head cap screw, 14 Double-ended bolt, 15 Sealing gasket, 16 Sealing ring II, 17 Valve disc, 18 Sealing ring III, 19 Sealing shaft, 20 Valve seat, 21 Sealing ring IV. Detailed Implementation

[0021] The following specific embodiments illustrate the implementation of this utility model. Those skilled in the art can easily understand other advantages and effects of this utility model from the content disclosed in this specification. Obviously, the described embodiments are only some, not all, of the embodiments of this utility model. Based on the embodiments of this utility model, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of this utility model.

[0022] This utility model provides a pneumatic safety valve with pressure protection, including a valve body 11, a pressure cap 4 installed on the valve body 11, a valve disc 17 and a valve stem 7 arranged in the inner cavity of the valve body 11, the valve disc 17 being connected to the valve stem 7, and also including a tight single-layer cylinder 1 and a normally closed pilot control circuit. A single-layer cylinder 1 is located on top of the pressure plate 4, and the piston rod of the single-layer cylinder 1 is connected to the upper end of the valve rod 7 by a double-headed bolt 14; The pilot control circuit includes a pilot valve and a filter; the inlet of the pilot valve is connected to the medium pressure sensing port inside the valve body 11, and the filter is set at the medium pressure sensing port to filter impurities in the medium drawn from the valve body and prevent the pilot valve from being blocked; the outlet of the pilot valve is connected to the single-layer cylinder 1; the single-layer cylinder 1 is connected to the atmosphere or a low-pressure relief port. The pilot valve adopts a normally closed, force-balanced structure (such as a pilot safety valve or a pilot relief valve). Its set pressure can be precisely calibrated by adjusting the internal spring preload. When it senses that the system pressure is lower than the set value, it remains closed, allowing the system medium pressure to be introduced and act on the upper chamber of the single-layer cylinder 1, pushing the valve stem 7 downward to keep the valve disc 17 closed. When the system pressure reaches or exceeds the set value, the pilot valve opens to release the pressure in the upper chamber of the single-layer cylinder 1, and the valve disc 17 opens to release pressure under the action of the medium. When the valve is closed, it relies on the medium pressure acting on the upper chamber of the single-layer cylinder 1, the venting state of the single-layer cylinder 1 itself, and the self-sealing force of the medium acting on the valve disc 17 to form a triple sealing guarantee. The pilot valve adopts a force-balanced structural design, which makes its opening pressure setpoint stable and unaffected by changes in valve back pressure.

[0023] The single-layer cylinder 1 and the pressure plate 4 are connected by a cylinder connecting seat 2. The cylinder connecting seat 2 and the single-layer cylinder 1 are fixed by an internal hex screw 13. The cylinder connecting seat 2 and the pressure plate 4 are fixed by a round nut 3. A sealing gasket 15 is provided at the connection between the pressure plate 4 and the top of the valve body 11 to improve the strength and stability of the connection structure. The valve stem 7 passes through the gland 4 and the cylinder connecting seat 2. A dynamic sealing assembly is provided between the valve stem 7 and the valve disc 17. The dynamic sealing assembly includes a sealing pressure ring 5 and a sealing ring 6 arranged in sequence. A sealing ring II 16 and a sealing ring III 18 are provided between the valve disc 17 and the inner wall of the valve body 11. A valve seat 20 that mates with the valve disc 17 is provided inside the valve body 11. The sealing surfaces of the valve disc 17 and the valve seat 20 are made of hard alloy material to form a hard sealing pair. A sealing ring IV 21 is provided at the connection between the outer wall of the valve seat 20 and the valve disc 17. A sealing shaft 19 is provided on one side of the valve body 11. The sealing shaft 19 and the valve disc 17 together form the main valve disc. The sealing shaft 19 is fixed to the valve body 11 by a cap nut 10. A drain connector 9 is provided on the valve body 11 for draining residual media in the valve cavity during valve maintenance or testing. A sealing ring I8 is provided on the inner wall of the drain connector 9 at the end away from the valve body 11. A lower plug 12 is also provided at the bottom of the valve body 11.

[0024] The specific implementation method is as follows: the pilot valve is preset to a normally closed state; its working principle is as follows: Normal operating (closed) state: When the medium pressure of the protected system is lower than the set pressure value of the safety valve, the pilot valve remains normally closed. At this time, the system medium pressure is blocked by the closed pilot valve, but through the control logic inside the pilot valve (or bypass damping orifice, depending on the specific design of the pilot valve), the pressure is maintained and transmitted into the upper chamber of the single-layer cylinder 1. Since the area of ​​the piston rod is larger than the effective sealing area of ​​the valve disc 17 (or through lever ratio design), the medium pressure acting above the cylinder piston will generate a downward net force, which is transmitted through the piston rod and valve rod 7, pressing the valve disc 17 tightly onto the valve seat 20 to achieve a reliable seal. At this time, the lower chamber of the single-layer cylinder 1 is open to the atmosphere without resistance. Overpressure relief (open) state: When the pressure of the protected system rises and reaches or exceeds the set pressure value of the pilot valve, the sensing element (such as diaphragm, piston) inside the pilot valve is activated, driving the valve core to open rapidly; once the pilot valve is opened, the upper chamber of the single-layer cylinder 1 is connected to the low-pressure relief zone (usually the atmosphere) through the pilot valve, and the pressure in the upper chamber is quickly released; due to the sudden drop in pressure in the upper chamber, the force of the system medium acting on the valve disc 17 instantly overcomes the remaining resistance, pushing the valve disc 17, valve stem 7 and piston rod assembly to move rapidly upward, the valve is fully opened, the medium is discharged at high speed, and the system pressure drops; Reseating closed state: When the system pressure drops to the reseating pressure value set by the pilot valve due to depressurization (usually slightly lower than the start-up pressure), the pilot valve closes again; the system pressure is re-established through the closed pilot valve and introduced into the upper chamber of the single-layer cylinder 1, pushing the piston rod to move downward, causing the valve disc 17 to close again and press against the valve seat 20.

[0025] Although the present invention has been described in detail above with general descriptions and specific embodiments, some modifications or improvements can be made to it, which will be obvious to those skilled in the art. Therefore, all such modifications or improvements made without departing from the spirit of the present invention fall within the scope of protection claimed by the present invention.

Claims

1. A pneumatic safety valve with pressure protection, comprising a valve body (11), a pressure cap (4) mounted on the valve body (11), a valve disc (17) and a valve stem (7) disposed in the inner cavity of the valve body (11), the valve disc (17) being connected to the valve stem (7), characterized in that: It also includes a compact single-layer cylinder (1) and a normally closed pilot control circuit; The single-layer cylinder (1) is located on the top of the pressure plate (4), and the piston rod of the single-layer cylinder (1) is connected to the upper end of the valve rod (7) by a double-headed bolt (14); The pilot control circuit includes a pilot valve and a filter; the inlet of the pilot valve is connected to the medium pressure sensing port inside the valve body (11), and the filter is located at the medium pressure sensing port; the outlet of the pilot valve is connected to the single-layer cylinder (1); the single-layer cylinder (1) is connected to the atmosphere or low-pressure relief port.

2. The pneumatic safety valve with pressure protection according to claim 1, characterized in that: The single-layer cylinder (1) is connected to the pressure cap (4) by a cylinder connecting seat (2). The cylinder connecting seat (2) is fixed to the single-layer cylinder (1) by an internal hexagon screw (13). The cylinder connecting seat (2) is fixed to the pressure cap (4) by a round nut (3). A sealing gasket (15) is provided at the connection between the pressure cap (4) and the top of the valve body (11).

3. A pneumatic safety valve with pressure protection according to claim 2, characterized in that: The valve stem (7) passes through the pressure cap (4) and the cylinder connecting seat (2). A dynamic sealing assembly is provided between the valve stem (7) and the valve disc (17). The dynamic sealing assembly includes a sealing pressure ring (5) and a sealing ring (6) arranged in sequence. A sealing ring II (16) and a sealing ring III (18) are provided between the valve disc (17) and the inner wall of the valve body (11).

4. A pneumatic safety valve with pressure protection according to claim 1, characterized in that: The valve body (11) is provided with a valve seat (20) that cooperates with the valve disc (17). The sealing surfaces of the valve disc (17) and the valve seat (20) are made of hard alloy material to form a hard sealing pair. A sealing ring IV (21) is provided at the connection between the outer wall of the valve seat (20) and the valve disc (17).

5. A pneumatic safety valve with pressure protection according to claim 1, characterized in that: A sealing shaft (19) is provided on one side of the valve body (11). The sealing shaft (19) and the valve disc (17) together form the main valve disc. The sealing shaft (19) and the valve body (11) are fixed by a cap nut (10).

6. A pneumatic safety valve with pressure protection according to claim 1, characterized in that: The valve body (11) is provided with a drain connector (9) for discharging residual media in the valve cavity during valve maintenance or testing. The drain connector (9) is provided with a sealing ring I (8) on the inner wall of the end away from the valve body (11). The bottom of the valve body (11) is also provided with a bottom plug (12).

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