Tandem spring type flame suppressor

Abstract

The invention aims to provide the serial spring type flame suppressor which has the advantages that the valve is not easy to damage, the reliability is high, and the service life is longer. The series spring type flame suppressor comprises: a housing; the overpressure valve is arranged in the shell; the negative pressure valve is arranged outside the shell; the overpressure valve and the negative pressure valve are installed on the fixing shaft in the mode that the overpressure valve and the negative pressure valve can slide in the axis direction, and an inner limiting spring and an outer limiting spring which can stretch out and draw back in the axis direction are arranged on the fixing shaft in a series connection mode. The internal limiting spring is used for abutting against the overpressure valve to limit the sliding range of the overpressure valve on the fixing shaft, and the external limiting spring is used for abutting against the negative pressure valve to limit the sliding range of the negative pressure valve on the fixing shaft.

Description

Technical Field

[0001] The invention relates to a series spring type flame arrester, which can be used in a fuel system of a civil transport aircraft, for example. Background Art

[0002] Flame arresters are used in the ventilation system of fuel tanks of civil aircraft to prevent external flames from entering the fuel tanks. At the same time, they need to protect the fuel tanks from overpressure and negative pressure to prevent the fuel tank structure from being damaged by excessive positive or negative pressure. Flame arresters are generally installed above the vent of the fuel tank. Existing flame arresters are of the following two types: Figure 1 The external spring-loaded flame arrester shown and Figure 2 External rocker-arm flame arrestor shown.

[0003] However, the above two types of flame arresters may be subjected to excessive positive and negative pressures when subjected to complex air flow fields, causing the valves to have excessive actuation frequencies or amplitudes that exceed the tolerance of the device itself, thus causing strength damage. Figure 1 In the external spring-loaded flame arrester shown, excessive swing of the rocker arm or excessive frequency may cause damage to the external spring-loaded valve. Figure 2 In the external rocker arm flame arrester shown, when the swing amplitude of the rocker arm is too large or the frequency is too high, the fixing plate of the flame arrester valve plate may be damaged or even fall off.

[0004] That is, valve damage problems of flame suppressors mostly occur in the moving parts, and the variable flow field during flight can easily cause it to be subjected to excessive positive and negative pressures, too frequent periodic fluctuations, and repeated deflection and impact of the moving surface of the spring or rocker arm, which can easily cause fatigue damage and damage.

[0005] In summary, whether it is an external spring-type flame suppressor or an external rocker-arm type flame suppressor, the valve is relatively easy to be damaged. At present, there is no mature improvement plan to solve the problem of damage to the actuating valve of the flame suppressor. In order to ensure that the valve of the flame suppressor can have high reliability and long life, optimization and improvement are urgently needed. Summary of the invention

[0006] In view of the above problems, an object of the present invention is to provide a series spring type flame arrester with a valve that is not easily damaged, high reliability and long service life.

[0007] In order to achieve the above-mentioned purpose of the present invention, the present invention provides a series spring type flame suppressor, comprising: a shell; an overpressure valve arranged inside the shell; a negative pressure valve arranged outside the shell; and a fixed shaft fixedly installed on the shell, the overpressure valve and the negative pressure valve are installed on the fixed shaft in a manner that can slide along the axial direction, and an internal limit spring and an external limit spring that can be extended and retracted along the axial direction are arranged on the fixed shaft in a series connection manner, the internal limit spring is used to abut against the overpressure valve to limit the sliding range of the overpressure valve on the fixed shaft, and the external limit spring is used to abut against the negative pressure valve to limit the sliding range of the negative pressure valve on the fixed shaft.

[0008] According to the series spring flame arrester of the present invention, a fixed axis, i.e., a fixed axis, is used to ensure that the movement trajectories of the overpressure valve and the negative pressure valve as well as the internal limit spring and the external limit spring are controlled and along the axial direction. That is, in the case of overpressure and negative pressure in the fuel tank, the movement of the overpressure valve and the negative pressure valve is carried out along the axial direction, which is simple and reliable and will not cause damage. In addition, by limiting the sliding range of the overpressure valve and the negative pressure valve respectively through the internal limit spring and the external limit spring, excessive movement of the overpressure valve and the negative pressure valve can be prevented, and damage to the overpressure valve and the negative pressure valve will not be caused, thereby improving reliability and equipment life.

[0009] Preferably, a sealing ring for an overpressure valve is installed on the overpressure valve, and a sealing ring for a negative pressure valve is installed on the negative pressure valve. The overpressure valve sealing ring is located between the overpressure valve and the inner surface of the outer shell to seal the overpressure valve and the inner surface of the outer shell, and the negative pressure valve sealing ring is located between the negative pressure valve and the outer surface of the outer shell to seal the negative pressure valve and the outer surface of the outer shell.

[0010] According to the series spring type flame arrester of the present invention, the sealing ring for the overpressure valve and the sealing ring for the negative pressure valve can prevent the gap between the overpressure valve and the negative pressure valve and the fixed shaft from causing gas leakage, and the overpressure valve and the negative pressure valve can be sealed on the shell while ensuring free movement. In addition, the precise vertical positioning of the axis direction of the fixed shaft can ensure that the seal with the surface of the shell is intact.

[0011] Preferably, the sealing ring for the overpressure valve is composed of two sealing rings, an inner sealing ring and an outer sealing ring, which are embedded in the sealing groove of the valve plate of the overpressure valve itself, and the sealing ring for the negative pressure valve is composed of two sealing rings, an inner sealing ring and an outer sealing ring, which are embedded in the sealing groove of the valve plate of the negative pressure valve itself.

[0012] According to the series spring type flame arrester of the present invention, in order to avoid the external leakage caused by the inevitable movement gap between the valve plate and the fixed shaft of the overpressure valve and the negative pressure valve, the overpressure valve seal ring and the negative pressure valve seal ring are controlled by the inner and outer double seal rings composed of two seal rings, the inner and outer seal rings, to control the flame arrester inside the valve body of the overpressure valve and the negative pressure valve, and prevent the flame arrester from leaking outside the valve body of the overpressure valve and the negative pressure valve, thereby ensuring the air tightness of the series spring type flame arrester. Therefore, the sealing and complete fixation of the overpressure valve seal ring and the negative pressure valve seal ring can be ensured.

[0013] Preferably, ventilation holes are respectively arranged at positions of the shell corresponding to the overpressure valve and the negative pressure valve, the ventilation holes are composed of four sector-shaped surfaces, and an axis mounting hole is formed in the center of the four sector-shaped surfaces. The fixed shaft passes through the axis mounting hole and is installed on the shell, and the fixed shaft is connected to the shell by the cross spacing parts between the four sector-shaped surfaces.

[0014] According to the series spring type flame arrester of the present invention, air is taken in or exhausted through the four sector-shaped surfaces of the vent hole, and the fixed shaft is firmly connected to the outer shell by means of the cross spacing part between the four sector-shaped surfaces. Therefore, it is possible to ensure the strength and flatness of the mounting part of the fixed shaft while ensuring the air intake or exhaust volume, thereby being able to meet the requirements of the air intake or exhaust volume and the requirements of the mounting flatness at the same time.

[0015] Preferably, the four sector-shaped surfaces of the vent hole and the shaft mounting hole are formed by laser cutting.

[0016] The series spring type flame arrester according to the present invention can ensure that the installation plane of the fixed shaft and the housing remain in the same plane without deviation.

[0017] Preferably, an external limit spring fixing portion is arranged on the outside of the position of the outer shell corresponding to the negative pressure valve, and the external limit spring fixing portion is formed into a half I-shape, is located outside the negative pressure valve and the external limit spring, and is for the fixed shaft to pass through, and the external limit spring fixing portion is formed as a fixed end of the external limit spring.

[0018] According to the series spring type flame arrester of the present invention, since the external limit spring fixing portion is formed as the fixed end of the external limit spring, the negative pressure valve and the end of the fixed shaft can be protected from deformation due to external force during manufacturing, installation and transportation.

[0019] Preferably, the external limit spring fixing portion is integrally formed with the housing.

[0020] The series spring type flame arrester according to the present invention can ensure that the shell is not easily deformed and can accurately position the fixed shaft to ensure that the axis of the fixed shaft is perpendicular to the plane of the shell.

[0021] Preferably, the overpressure valve, the negative pressure valve and the fixed shaft are made of self-lubricating metal material.

[0022] The series spring type flame arrester according to the present invention can reduce the sliding friction loss to the greatest extent and improve the reliability and service life of the product. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a perspective view showing the structure of a conventional external spring type flame arrester.

[0024] Figure 2 It is a perspective view showing the structure of a conventional external rocker arm type flame arrester.

[0025] Figure 3 1 is a schematic diagram schematically showing the structure of a series spring type flame arrester according to an embodiment of the present invention.

[0026] Figure 4 It is an exploded schematic diagram schematically showing the structure of each part of the series spring type flame arrester according to an embodiment of the present invention.

[0027] Figure 5 It is a schematic diagram schematically showing the serial spring type flame arrester in the overpressure exhaust state according to the embodiment of the present invention.

[0028] Figure 6 It is a schematic diagram schematically showing the series spring type flame arrester according to the embodiment of the present invention in a negative pressure suction state.

[0029] Figure 7 1 is a perspective view showing the structure of a series spring type flame arrester according to an embodiment of the present invention, wherein a rectangular opening is cut out on the oblique left side to facilitate viewing of the internal structure.

[0030] Figure 8 1 is a perspective view showing the structure of a housing of a series spring type flame arrester according to an embodiment of the present invention, wherein a rectangular opening is cut out on the oblique right side to facilitate viewing of the internal structure.

[0031] Fig. 9 It is a side view showing the structure of the housing of the series spring type flame arrester according to the embodiment of the present invention.

[0032] Fig.10 This is a front view showing the structure of a series spring type flame arrester according to an embodiment of the present invention, wherein a rectangular opening is cut out on the front side to facilitate viewing of the internal structure.

[0033] (Explanation of symbols)

[0034] 100 Series Spring-Loaded Flame Arrestor

[0035] 1 Housing

[0036] 11 Installation bottom

[0037] 12 Housing body

[0038] 121 Ventilation hole

[0039] 122 Shaft mounting hole

[0040] 123 Fireproof Honeycomb

[0041] 124 External limit spring fixing part

[0042] 2 Overpressure valve

[0043] 3 Negative pressure valve

[0044] 4 Fixed axis

[0045] 5 Internal limit spring

[0046] 6 External limit spring

[0047] 7 Sealing ring for overpressure valve

[0048] 8 Sealing ring for negative pressure valve DETAILED DESCRIPTION

[0049] Various embodiments of the present invention will now be described in detail, examples of which are shown in the accompanying drawings and are described below. Although the present invention will be described in conjunction with the exemplary embodiments, it should be appreciated that this specification is not intended to limit the present invention to those exemplary embodiments. On the contrary, the present invention is intended to cover not only these exemplary embodiments, but also various alternative forms, modifications, equivalent forms and other embodiments that may be included within the spirit and scope of the present invention as defined by the appended claims.

[0050] Next, combine Figures 3 to 10 A series spring type flame arrester 100 according to an embodiment of the present invention will be described. Figure 3 FIG. 1 is a schematic diagram schematically showing the structure of a series spring type flame arrester 100 according to an embodiment of the present invention. Figure 4 1 is an exploded schematic diagram schematically showing the structure of each part of the series spring type flame arrester 100 according to the embodiment of the present invention. Figure 5 Schematic diagram showing the serial spring type flame arrester 100 according to the embodiment of the present invention in an overpressure exhaust state. Figure 6Schematic diagram showing the serial spring type flame arrester 100 according to the embodiment of the present invention in a negative pressure suction state. Figure 7 It is a three-dimensional diagram showing the structure of a series spring type flame arrester 100 according to an embodiment of the present invention, wherein a rectangular opening K is cut on the oblique left side for the convenience of viewing the internal structure (it should be noted that the rectangular opening K does not actually exist and is only cut for the convenience of viewing the internal structure). Figure 8 1 is a perspective view showing the structure of the housing 1 of the series spring type flame arrester 100 according to the embodiment of the present invention, wherein a rectangular opening K is cut out on the oblique right side for the convenience of viewing the internal structure. Fig. 9 1 is a side view showing the structure of the housing 1 of the series spring type flame arrester 100 according to the embodiment of the present invention. Fig.10 1 is a front view showing the structure of a series spring type flame arrester 100 according to an embodiment of the present invention, wherein a rectangular opening K is cut out on the front side to facilitate viewing of the internal structure.

[0051] The series spring type flame arrester 100 of the embodiment of the present invention is used, for example, in the fuel tank of a civil aircraft to prevent external flames from entering the fuel tank, and at the same time to protect the fuel tank from overpressure and negative pressure, so as to prevent the fuel tank from being damaged by excessive positive or negative pressure. The series spring type flame arrester 100 of the embodiment of the present invention is installed, for example, above the vent of the fuel tank.

[0052] (Overall structure of the series spring type flame arrester 100)

[0053] like Figures 3 to 10 As shown, the serial spring type flame arrester 100 of the embodiment of the present invention comprises a housing 1, an overpressure valve 2 arranged inside the housing 1, a negative pressure valve 3 arranged outside the housing 1, and a fixed shaft 4 fixedly mounted on the housing 1. The overpressure valve 2 and the negative pressure valve 3 are mounted on the fixed shaft 4 in a manner that they can slide along the axial direction. An internal limit spring 5 and an external limit spring 6 that can be extended and retracted along the axial direction are arranged on the fixed shaft 4 in a serially connected manner, the internal limit spring 5 is used to abut against the overpressure valve 2 to limit the sliding range of the overpressure valve 2 on the fixed shaft 4, and the external limit spring 6 is used to abut against the negative pressure valve 3 to limit the sliding range of the negative pressure valve 3 on the fixed shaft 4.

[0054] Specifically, if Figure 5 As shown, the overpressure valve 2 on the left is used to move to the right by squeezing the internal limit spring 5 to discharge gas when the pressure in the fuel tank is too high. Figure 6 As shown, the negative pressure valve 3 on the right is used to move to the right by squeezing the external limit spring 6 when the pressure in the fuel tank is too low, so as to achieve the function of inhaling gas.

[0055] Therefore, in the serial spring type flame arrester 100 of the embodiment of the present invention, a fixed axis, i.e., a fixed axis 4, is used to ensure that the movement trajectory of the overpressure valve 2 and the negative pressure valve 3 as well as the internal limit spring 5 and the external limit spring 6 is controlled and along the axial direction. That is, in the case of overpressure and negative pressure in the fuel tank, the movement of the overpressure valve 2 and the negative pressure valve 3 is carried out along the axial direction, which is simple and reliable and will not cause damage. In addition, by limiting the sliding range of the overpressure valve 2 and the negative pressure valve 3 respectively through the internal limit spring 5 and the external limit spring 6, excessive movement of the overpressure valve 2 and the negative pressure valve 3 can be prevented, and damage to the overpressure valve 2 and the negative pressure valve 3 will not be caused, which can improve reliability and equipment life.

[0056] Furthermore, the internal limit spring 5 and the external limit spring 6 are fixed by using a fixed shaft 4, which can save space and weight.

[0057] In addition, in the series spring type flame suppressor 100 of the embodiment of the present invention, a sealing ring 7 for an overpressure valve is installed on the overpressure valve 2, and a sealing ring 8 for a negative pressure valve is installed on the negative pressure valve 3. The sealing ring 7 for the overpressure valve is located between the overpressure valve 2 and the inner surface of the outer shell 1 to seal the overpressure valve 2 and the inner surface of the outer shell 1, and the sealing ring 8 for the negative pressure valve is located between the negative pressure valve 3 and the outer surface of the outer shell 1 to seal the negative pressure valve 3 and the outer surface of the outer shell 1.

[0058] Thus, the sealing ring 7 for the overpressure valve and the sealing ring 8 for the negative pressure valve can prevent gas leakage caused by the gap between the overpressure valve 2 and the negative pressure valve 3 and the fixed shaft 4, and the overpressure valve 2 and the negative pressure valve 3 can be sealed on the housing 1 while ensuring free movement. In addition, the precise vertical positioning of the axial direction of the fixed shaft 4 can ensure that the seal with the surface of the housing 1 is intact.

[0059] Preferably, in this embodiment, if Figure 3 , Figure 4 As shown, the sealing ring 7 for the overpressure valve is composed of two sealing rings, an inner sealing ring and an outer sealing ring, which are embedded in the sealing groove of the valve plate of the overpressure valve 2 itself, and the sealing ring 8 for the negative pressure valve is composed of two sealing rings, an inner sealing ring and an outer sealing ring, which are embedded in the sealing groove of the valve plate of the negative pressure valve 3 itself.

[0060] In order to avoid external leakage caused by the inevitable movement gap between the valve disc and the fixed shaft 4 of the overpressure valve 2 and the negative pressure valve 3, the overpressure valve seal ring 7 and the negative pressure valve seal ring 8 are used to control the leakage inside the valve body of the overpressure valve 2 and the negative pressure valve 3, and the leakage will not leak outside the valve body of the overpressure valve 2 and the negative pressure valve 3, thereby ensuring the airtightness of the series spring type flame arrester 100. In this way, the sealing and complete fixation of the overpressure valve seal ring 7 and the negative pressure valve seal ring 8 can be ensured.

[0061] In addition, preferably, an inner sealing ring (not shown) smaller than the inner circumferential sealing ring of the overpressure valve sealing ring 7 and the negative pressure valve sealing ring 8 is also provided inside the overpressure valve 2 and the negative pressure valve 3 respectively.

[0062] In summary, in the series spring type flame arrester 100 of the present invention, the middle fixed shaft 4 is fixed on the left and right fixed planes of the outer shell 1, and is connected to the structure of the outer shell 1 as a whole, and the overpressure valve 2 and the negative pressure valve 3 can slide freely along the axis. It can ensure that the outer shell 1 is always in the same plane, and ensure the precise positioning of the fixed shaft 4 to meet the requirements of the sealing ring 7 for the overpressure valve and the sealing ring 8 for the negative pressure valve to seal two surfaces at the same time. The series spring type flame arrester 100 of the present invention can prevent the excessive movement of the valve plates of the overpressure valve 2 and the negative pressure valve 3, improve the life of the equipment, and achieve a good seal with the outer shell 1.

[0063] (Specific structure of the series spring type flame arrester 100)

[0064] In this embodiment, for example Figure 8 as well as Fig. 9 As shown, the housing 1 includes a mounting bottom surface 11 and a housing body 12 vertically disposed on the mounting bottom surface 11, and the housing body 12 is formed into a substantially rectangular parallelepiped shape. The series spring type flame arrester 100 of the embodiment of the present invention is installed above the vent of the fuel tank of a civil aircraft through the mounting bottom surface 11, for example.

[0065] Vent holes 121 are respectively provided at positions corresponding to the overpressure valve 2 and the negative pressure valve 3 of the housing 1 (specifically, the housing body 12). The vent hole 121 is composed of four sector-shaped surfaces, and a shaft mounting hole 122 is formed in the center of the four sector-shaped surfaces. The fixed shaft 4 passes through the shaft mounting hole 122 and is mounted on the housing 1. The fixed shaft 4 is connected to the housing 1 (specifically, the housing body 12) by the cross spacing between the four sector-shaped surfaces. Thus, the fixed shaft 4 is fixed between the two side wall surfaces of the housing body 12 and is sealed with the housing 1. For example, it can be sealed by local welding or gluing, so as to prevent the gas in the housing 1 from leaking to the outside.

[0066] Thus, air is taken in or out through the four sectors of the vent hole 121, and the fixed shaft 4 is firmly connected to the housing body 12 by means of the cross intervals between the four sectors. While ensuring the air intake or exhaust volume, the strength and flatness of the mounting portion of the fixed shaft 4 can be ensured, thereby meeting the requirements of the air intake or exhaust volume and the requirements of the mounting flatness at the same time.

[0067] Preferably, the four sector surfaces of the vent hole 121 and the shaft mounting hole 122 are formed by laser cutting, thereby ensuring that the mounting plane of the fixed shaft 4 and the side wall surface of the housing body 12 remain in the same plane without deviation.

[0068] A fireproof honeycomb 123 is provided in the upper region of the housing body 12 to prevent flames from entering the fuel tank.

[0069] In addition, an external limit spring fixing portion 124 is provided outside the position of the housing 1 (specifically, the housing body 12) corresponding to the negative pressure valve 3. The external limit spring fixing portion 124 is formed in a half I-shape, for example, and is located outside the negative pressure valve 3 and the external limit spring 6, and is passed through by the fixed shaft 4. The external limit spring fixing portion 124 is formed as a fixed end of the external limit spring 6 to protect the ends of the negative pressure valve 3 and the fixed shaft 4 from being deformed by external forces during manufacturing, installation, and transportation.

[0070] Preferably, the external limit spring fixing portion 124 is integrally formed with the housing body 12. Thus, it can be ensured that the housing 1 is not easily deformed, the fixed shaft 4 can be accurately positioned, and the fixed shaft 4 that passes through the housing body 12 is fixed on the external limit spring fixing portion 124 to ensure that the axis of the fixed shaft 4 is perpendicular to the side wall of the housing body 12, and the moving trajectories of the overpressure valve 2 and the negative pressure valve 3 are along the axis direction, so that the overpressure valve 2 and the negative pressure valve 3 are less likely to be damaged.

[0071] The overpressure valve 2 and the negative pressure valve 3 are formed in a circle, and the overpressure valve sealing ring 7 and the negative pressure valve sealing ring 8 are also formed in a circle. The outer shapes of the overpressure valve 2 and the negative pressure valve 3 are slightly larger than the outer shapes of the outer peripheral sealing rings of the overpressure valve sealing ring 7 and the negative pressure valve sealing ring 8.

[0072] Preferably, the overpressure valve 2, the negative pressure valve 3 and the fixed shaft 4 are made of self-lubricating metal materials, which can minimize sliding friction losses and improve the reliability and life of the product.

[0073] (Variation Example)

[0074] The present invention is described above by way of example in conjunction with the accompanying drawings. It is obvious that the specific implementation of the present invention is not limited to the above-mentioned embodiments.

[0075] (1) In the above embodiment, the serial spring type flame arrester 100 of the present invention is used in a fuel tank of a civil aircraft. However, the serial spring type flame arrester 100 of the present invention can also be used in any part where flames need to be blocked, such as a fuel tank of other equipment.

[0076] (2) In the above-mentioned embodiment, the structure for sealing the overpressure valve 2 and the negative pressure valve 3 respectively using the sealing ring 7 for the overpressure valve and the sealing ring 8 for the negative pressure valve is described, but the structure for sealing the overpressure valve 2 and the negative pressure valve 3 is not particularly limited, and other sealing forms may also be used.

[0077] In addition, the structure in which the sealing ring 7 for the overpressure valve and the sealing ring 8 for the negative pressure valve are respectively installed on the overpressure valve 2 and the negative pressure valve 3 in a snap-fit ​​manner is described, but the sealing ring 7 for the overpressure valve and the sealing ring 8 for the negative pressure valve can also be installed in other forms.

[0078] (3) In the above embodiment, the case where the external limit spring fixing portion 124 is formed into a half I-shape is described, but the shape of the external limit spring fixing portion 124 is not particularly limited, and other shapes such as a box shape may also be adopted. In addition, the external limit spring fixing portion 124 may also be formed separately from the housing 1.

[0079] (4) In the above-mentioned embodiment, the case where the overpressure valve 2, the negative pressure valve 3 and the fixed shaft 4 are made of self-lubricating metal materials is described, but the overpressure valve 2, the negative pressure valve 3 and the fixed shaft 4 can also be made of ordinary metal materials and lubricating oil, etc. can be added therebetween.

[0080] Although the structure and working principle of the present invention are described above in conjunction with the preferred embodiments, it should be recognized by those skilled in the art that the above examples are only for illustration and cannot be used as limitations of the present invention. Therefore, the present invention can be modified and varied within the spirit of the claims, and these modifications and variations will fall within the scope required by the claims of the present invention.

Claims

1. A series spring type flame arrester, characterized in that: include: shell; an overpressure valve disposed inside the housing; a negative pressure valve disposed outside the housing; as well as a fixed shaft fixedly mounted on the housing, The overpressure valve and the negative pressure valve are mounted on the fixed shaft in a manner that they can slide along the axial direction. An internal limit spring and an external limit spring which can be extended and retracted along the axial direction are arranged on the fixed shaft in a serially connected manner. The internal limit spring is used to abut against the overpressure valve to limit the sliding range of the overpressure valve on the fixed shaft. The external limit spring is used to abut against the negative pressure valve to limit the sliding range of the negative pressure valve on the fixed shaft.

2. The series spring type flame arrester according to claim 1, characterized in that: A sealing ring for an overpressure valve is installed on the overpressure valve, and a sealing ring for a negative pressure valve is installed on the negative pressure valve. The overpressure valve sealing ring is located between the overpressure valve and the inner surface of the shell to seal the overpressure valve and the inner surface of the shell. The sealing ring for the negative pressure valve is located between the negative pressure valve and the outer surface of the shell to seal the negative pressure valve and the outer surface of the shell.

3. The series spring type flame arrester according to claim 2, characterized in that: The sealing ring for the overpressure valve is composed of two sealing rings, an inner sealing ring and an outer sealing ring, which are embedded in the sealing groove of the valve plate of the overpressure valve. The sealing ring for the negative pressure valve is composed of two sealing rings, an inner peripheral sealing ring and an outer peripheral sealing ring, which are embedded in the sealing groove of the valve plate of the negative pressure valve.

4. The series spring type flame arrester according to claim 1, characterized in that: Ventilation holes are respectively arranged at positions of the shell corresponding to the overpressure valve and the negative pressure valve. The vent hole is composed of four sector-shaped surfaces, and an axis mounting hole is formed in the center of the four sector-shaped surfaces. The fixed axis passes through the axis mounting hole and is mounted on the shell. The fixed axis is connected to the shell by the cross spacing parts between the four sector-shaped surfaces.

5. The series spring type flame arrester according to claim 4, characterized in that: The four sector-shaped surfaces of the vent hole and the shaft mounting hole are formed by laser cutting.

6. The series spring type flame arrester according to claim 1, characterized in that: An external limit spring fixing portion is arranged on the outside of the position of the shell corresponding to the negative pressure valve. The external limit spring fixing portion is formed into a half I-shape and is located outside the negative pressure valve and the external limit spring, and is passed through by the fixed shaft. The external limit spring fixing portion is formed as a fixed end of the external limit spring.

7. The series spring type flame arrester according to claim 6, characterized in that: The external limit spring fixing portion is integrally formed with the housing.

8. The series spring type flame arrester according to claim 1, characterized in that: The overpressure valve, the negative pressure valve and the fixed shaft are made of self-lubricating metal material.

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