Explosion-proof electric control box

Abstract

This invention discloses an explosion-proof electrical control box, comprising: a box body, the box body including an explosion-proof outer shell and a front cover, the explosion-proof outer shell being a hollow shell structure with one open end, the front cover being closable at the opening, and when the front cover is closed at the opening, an explosion-proof joint structure is provided between the explosion-proof outer shell and the front cover, the explosion-proof joint structure being used to form a bent and extended explosion-proof channel to cool explosive gases and block the outward propagation of flames; a modular mounting plate for mounting electrical modules, slidably disposed within the explosion-proof outer shell, capable of being pulled out after the front cover is opened and realizing power-off interlocking in maintenance mode; and a pressure relief structure disposed on the explosion-proof outer shell, used to directionally release pressure and prevent flame propagation when there is overpressure inside the box. This application achieves comprehensive technical effects of safe maintenance, controllable pressure relief, reliable explosion-proof, and stable temperature.

Description

Technical Field

[0001] This invention relates to the field of explosion-proof electrical equipment technology, and in particular to an explosion-proof electrical control box. Background Technology

[0002] Explosion-proof electrical control boxes are key explosion-proof electrical equipment widely used in explosive gas environments (such as petroleum, chemical, natural gas, and other IIA / IIB / IIC level hazardous locations). Their core function is to prevent flames and high-temperature gases from igniting external explosive mixtures in the event of electrical faults, arcs, or deflagrations inside the box, while ensuring the reliable operation of internal electrical components.

[0003] Existing traditional explosion-proof control boxes mainly rely on thick-walled cast steel or welded shells, flat / stop explosion-proof joint surfaces, conventional cable entry devices, and internal fixed installation structures to achieve basic explosion-proof functions. However, existing explosion-proof control boxes cannot simultaneously meet the comprehensive requirements of high explosion-proof rating, easy maintenance, controllable pressure, and stable heat dissipation.

[0004] Therefore, it is necessary to propose an explosion-proof electrical control box to solve at least one of the above problems.

[0005] It should be noted that the above introduction to the technical background is only for the purpose of providing a clear and complete explanation of the technical solutions of this application and facilitating understanding by those skilled in the art. It should not be assumed that these technical solutions are known to those skilled in the art simply because they have been described in the background section of this application. Summary of the Invention

[0006] To address the shortcomings of existing technologies, this invention provides an explosion-proof electrical control box that achieves comprehensive technical benefits including safe maintenance, controllable pressure relief, reliable explosion protection, and stable temperature.

[0007] The specific technical solution of the embodiments of the present invention is as follows: An explosion-proof electrical control box includes: a box body comprising an explosion-proof outer shell and a front cover; the explosion-proof outer shell being a hollow shell structure with one open end; the front cover being closable at the opening; when the front cover is closed at the opening, an explosion-proof engagement structure is provided between the explosion-proof outer shell and the front cover; the explosion-proof engagement structure is used to form a bent and extended explosion-proof channel to cool explosive gases and block the outward propagation of flames; a modular mounting plate for mounting electrical modules; the modular mounting plate is slidably disposed within the explosion-proof outer shell and can be pulled out after the front cover is opened to achieve power-off interlocking in maintenance mode; and a pressure relief structure disposed on the explosion-proof outer shell for directional pressure release and flame propagation prevention when overpressure occurs inside the box body.

[0008] Furthermore, the explosion-proof joint structure includes a multi-level stepped joint surface.

[0009] Furthermore, let the initial flame temperature be T0, and the allowable outer temperature be T. ign The effective length of the explosion-proof joint structure should satisfy the thermal attenuation relationship based on the composite attenuation coefficient α. ; The composite attenuation coefficient α is determined based on the average convective heat transfer coefficient hp of the wall surface to the high-temperature gas, the wall heat transfer area As per unit length, and the gas mass flow rate per unit length through the channel. and the relationship between the specific heat capacity (cp) of gases Make an estimate; Where As is equivalent to the channel perimeter P within the explosion-proof joint structure, hp, The dimensions of the enclosure are calibrated through testing or numerical simulation based on the on-site medium and the dimensions of the enclosure.

[0010] Furthermore, the modular mounting plate is installed inside the explosion-proof housing via a slide rail and a limit lock. The limit lock is configured to trigger a warning power-off when the modular mounting plate is pulled out of the first stroke, and to trigger a forced full power-off when the modular mounting plate is pulled out of the second stroke, wherein the first stroke is less than the second stroke.

[0011] Furthermore, the modular mounting plate is divided into an electrical control area, an actuator drive area, a power supply area, and a grounding busbar area. The back of the modular mounting plate is electrically connected to a busbar and a pluggable connector. When the modular mounting plate is pulled out, the busbar is disconnected from the pluggable connector.

[0012] Furthermore, the explosion-proof enclosure is provided with an air vent on the side wall or top, and the pressure relief structure is disposed at the air vent. The pressure relief structure includes: a pressure relief shell, which has an inlet end and an outlet end opposite to each other. The inlet end is connected to the air vent. Along the direction from the inlet end to the outlet end, a pressure relief diaphragm and a flame arrestor are sequentially disposed inside the pressure relief shell. A pressure buffer cavity is formed between the pressure relief diaphragm and the outlet end. The pressure buffer cavity is used to reduce the instantaneous pressure peak after the pressure relief diaphragm ruptures.

[0013] Furthermore, the pressure relief diaphragm is provided with a pre-crack groove, and the pressure relief diaphragm can only rupture unidirectionally from the inlet end to the outlet end.

[0014] Furthermore, the thickness of the pressure relief diaphragm is 0.3mm–0.8mm; The burst pressure of the pressure relief diaphragm is according to Sure, Where K is an empirical coefficient, a dimensionless coefficient, and its value ranges from 0.2 to 2.0; P burst The desired blast pressure; σ allow The allowable stress or yield strength of the pressure relief diaphragm material; t is the thickness of the pressure relief diaphragm; 'a' represents the radius or characteristic dimension of the pressure relief diaphragm.

[0015] Furthermore, the fire-resistant mesh comprises a multi-layered stainless steel mesh structure with a mesh size ≤0.3mm, used to block the outward spread of flames at the moment of pressure relief.

[0016] Furthermore, the explosion-proof electrical control box also includes a temperature control unit, which includes a temperature sensor and a temperature adjustment mechanism. The temperature control unit can form a linkage control with the modular mounting plate. The temperature control unit is configured such that: when the modular mounting plate is pulled out, the temperature adjustment mechanism stops working; after the modular mounting plate is pushed in, the temperature adjustment mechanism automatically resumes temperature adjustment.

[0017] Furthermore, the explosion-proof housing is also provided with an explosion-proof cable opening structure, which includes a bimetallic sleeve, a clamping ring, and a flame-arresting clamping component. The bimetallic sleeve includes an explosion-proof layer with a first predetermined thickness on the outer side and a heat-conducting layer with a second predetermined thickness on the inner side. A first connecting portion is provided on the periphery of one end of the explosion-proof layer. The clamping ring includes an inner ring and an outer ring. The outer ring is provided with a second connecting portion, which forms a detachable structure with the first connecting portion. An adjusting cone angle is provided on the inner ring. The flame-arresting clamping component is provided with a flame-arresting groove, which is a segmented labyrinth microchannel structure used to block flame propagation and achieve cable sealing.

[0018] The technical solution of the present invention has the following significant beneficial effects: The explosion-proof electrical control box provided in this application, by setting an explosion-proof joint structure between the explosion-proof shell and the front cover that can form a bent explosion-proof channel, can effectively cool and quench the high-temperature and high-pressure gas generated by the explosion, reliably block the spread of flames to the outside, and improve explosion-proof safety. The modular mounting plate can be easily pulled out after opening the front cover and realizes automatic power-off interlock during maintenance, which not only facilitates the inspection and replacement of internal electrical components, but also avoids safety hazards such as electric arcs and electric shocks during maintenance operations, while maintaining the integrity of the explosion-proof shell. The pressure relief structure can realize the directional release of pressure and flame blocking when the internal pressure of the box rises abnormally, preventing the shell from deforming or cracking due to pressure impact, and improving the safety of the equipment under fault conditions. Through the synergistic cooperation of the above structures, the present invention can simultaneously achieve the comprehensive technical effects of stable explosion-proof, safe maintenance, and controllable pressure release, effectively improving the overall reliability and safety of the explosion-proof electrical control box.

[0019] Specific embodiments of the invention are disclosed in detail below with reference to the description and accompanying drawings, indicating how the principles of the invention can be employed. It should be understood that the embodiments of the invention are not therefore limited in scope. Features described and / or shown for one embodiment may be used in the same or similar manner in one or more other embodiments, combined with features in other embodiments, or substituted for features in other embodiments. Attached Figure Description

[0020] The accompanying drawings described herein are for illustrative purposes only and are not intended to limit the scope of the invention in any way. Furthermore, the shapes and proportions of the components in the drawings are merely illustrative to aid in understanding the invention and do not specifically limit the shapes and proportions of the components. Those skilled in the art, guided by the teachings of this invention, can select various possible shapes and proportions to implement the invention according to specific circumstances.

[0021] Figure 1 This is a schematic diagram of the overall structure of an explosion-proof electrical control box provided in the embodiments of this application; Figure 2 This is a schematic diagram showing the location of the explosion-proof joint structure of an explosion-proof electrical control box provided in the embodiments of this application; Figure 3 This is a schematic diagram of a modular mounting plate for an explosion-proof electrical control box provided in the embodiments of this application; Figure 4 This is a schematic diagram of a pressure relief structure for an explosion-proof electrical control box provided in the embodiments of this application; Figure 5 This is a schematic diagram of the explosion-proof cable port structure of an explosion-proof electrical control box provided in the embodiments of this application; Figure 6 This is a schematic diagram of the temperature control unit of an explosion-proof electrical control box provided in the embodiments of this application.

[0022] The reference numerals in the above figures are as follows: 1. Explosion-proof enclosure; 10. Opening; 11. Explosion-proof joint structure; 2. Front cover; 3. Modular mounting plate; 31. Electrical control area; 32. Actuator drive area; 33. Power supply area; 34. Limit lock; 35. Grounding busbar area; 36. Slide rail; 4. Pressure relief structure; 40. Pressure relief casing; 41. Pressure relief diaphragm; 42. Fire-resistant mesh; 43. Pressure-relieving chamber; 5. Explosion-proof cable outlet structure; 51. Bimetallic sleeve; 52. Pressure ring; 53. Flame arrestor clamping parts; 6. Electrical modules; 7. Temperature control unit; 71. Fan; 72. Heater. Detailed Implementation

[0023] The details of the present invention can be more clearly understood by referring to the accompanying drawings and the description of specific embodiments. However, the specific embodiments of the present invention described herein are for illustrative purposes only and should not be construed as limiting the invention in any way. Under the teachings of this invention, those skilled in the art can conceive of any possible modifications based on the invention, all of which should be considered within the scope of the invention. It should be noted that when an element is referred to as being "set on" another element, it can be directly on the other element or there may be an intervening element. When an element is referred to as being "connected" to another element, it can be directly connected to the other element or there may be an intervening element. The terms "mounted," "connected," and "connected" should be interpreted broadly, for example, they can refer to mechanical or electrical connections, or internal communication between two elements, and can be direct or indirect connections through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms according to the specific circumstances. The terms "vertical," "horizontal," "upper," "lower," "left," "right," and similar expressions used herein are for illustrative purposes only and do not represent the only embodiments.

[0024] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein in the specification of this application is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0025] In practical use, existing explosion-proof control boxes generally have the following technical defects: The internal installation structure is fixed, making maintenance and repair inconvenient: most of the electrical components inside the box are installed on fixed panels. When repairing, replacing or wiring, the entire box needs to be disassembled, which is cumbersome and time-consuming. In addition, the disassembly process can easily damage the precision of the explosion-proof mating surface, reducing the explosion-proof safety.

[0026] The lack of a directional pressure relief channel poses a high safety risk: When a faulty electric arc inside the enclosure causes a deflagration, the internal pressure rises rapidly. Traditional enclosures lack a controllable pressure relief structure, which can easily lead to shell deformation, cracking of joint surfaces, and even irregular spread of the explosion shock wave, threatening the safety of on-site equipment and personnel.

[0027] Insufficient sealing and fire-retardant performance of cable entry devices: Conventional explosion-proof cable opening structures are simple, have poor adaptability to cables of different diameters, and uneven clamping force can easily lead to sealing gaps; moreover, the fire-retardant path at the cable opening position is short and the heat dissipation capacity is weak, making it a weak link in explosion protection.

[0028] The sealed interior has poor heat dissipation and is prone to temperature runaway: The explosion-proof shell has high sealing performance, but the heat generated by the internal electrical components is difficult to dissipate. Long-term high-temperature operation accelerates the aging of the components, which can easily lead to malfunctions, insulation failures, or even short circuits and fires, further increasing the risk of explosion.

[0029] This invention provides an explosion-proof electrical control box that achieves comprehensive technical effects such as safe maintenance, controllable pressure relief, reliable explosion protection, and stable temperature.

[0030] Please refer to the following for comprehensive information. Figures 1 to 4 This application specification provides an explosion-proof electrical control box, which may include: a box body, the box body including an explosion-proof outer shell 1 and a front cover 2, the explosion-proof outer shell 1 being a hollow shell structure with an opening 10 at one end, the front cover 2 being closable at the opening 10, and when the front cover 2 is closed at the opening 10, an explosion-proof joint structure 11 is provided between the explosion-proof outer shell 1 and the front cover 2, the explosion-proof joint structure 11 being used to form a bent and extended explosion-proof channel to cool explosive gases and block the outward propagation of flames; a modular mounting plate 3, the modular mounting plate 3 being used to install electrical modules 6, the modular mounting plate 3 being slidably disposed inside the explosion-proof outer shell 1, and being able to be pulled out after the front cover 2 is opened to achieve power-off interlocking in maintenance mode; and a pressure relief structure 4, the pressure relief structure 4 being disposed on the explosion-proof outer shell 1, for directional pressure release and flame propagation when there is overpressure inside the box body.

[0031] The explosion-proof electrical control box provided in this application mainly includes: an explosion-proof shell 1, a front cover 2, a modular mounting plate 3, and a pressure relief structure 4. Static explosion-proof is achieved through a bent explosion-proof channel, maintenance safety is achieved through a pull-out mounting plate, and deflagration safety is achieved through the pressure relief structure 4. These three components together constitute a complete safety system, fundamentally solving the problems of difficult maintenance, uncontrollable pressure relief, and unreliable explosion-proof design of traditional explosion-proof boxes. In addition, the explosion-proof electrical control box may also include: an explosion-proof cable port structure 5, an electrical module 6, and a temperature control unit 7, etc.

[0032] The present application will now be described in detail with reference to the accompanying drawings and embodiments.

[0033] The explosion-proof housing 1 is a thick-walled cast steel or welded housing with an opening 10 at one end, and the front cover 2 is closable and disposed at the opening 10 of the explosion-proof housing 1. When the front cover 2 is closed, an explosion-proof joint structure 11 is formed between the explosion-proof housing 1 and the front cover 2. The explosion-proof joint structure 11 is used to form a bent and extended explosion-proof channel to cool the explosive gas and block the outward propagation of the flame.

[0034] like Figure 2As shown, specifically, the explosion-proof joint structure 11 includes a multi-level stepped joint surface, which allows the explosion-proof joint structure 11 to form a multi-level stepped bent explosion-proof channel, thereby achieving flame cooling and quenching by extending the flame path and increasing the heat exchange area.

[0035] The effective length of the explosion-proof joint structure 11 is determined based on the flame thermal decay model, and can be specifically calibrated by simulation or experiment based on the medium, box size, heat transfer coefficient, and gas flow rate.

[0036] Specifically, assuming the initial flame temperature is T0 and the allowable outer temperature is Tign, ​​the effective length of the explosion-proof joint structure 11 should satisfy the thermal attenuation relationship based on the composite attenuation coefficient α. ; The composite attenuation coefficient α is determined based on the average convective heat transfer coefficient hp of the wall surface to the high-temperature gas, the wall heat transfer area As per unit length, and the gas mass flow rate per unit length through the channel. and the relationship between the specific heat capacity (cp) of gases Make an estimate; Where As is equivalent to the channel perimeter P within the explosion-proof joint structure 11, hp, The dimensions of the enclosure are calibrated through testing or numerical simulation based on the on-site medium and the dimensions of the enclosure.

[0037] Where: h p The average convective heat transfer coefficient of the wall surface to the high-temperature gas (W / (m²)) 2 ·K), depends on the channel size and flow conditions; A s Let A be the wall heat transfer area per unit length (m² / m). If the channel width is b and the channel height is h, then for the perimeter P, A... s =P; The mass flow rate of gas per unit length through the channel (kg / (sm)) can be estimated based on the initial mass flow rate of the gas or by the ignition impact flow rate. c p is the specific heat capacity of the gas (J / (kg·K)).

[0038] In one specific implementation, with a housing depth of 200mm–400mm and natural gas operation, a 3–5-level stepped explosion-proof design is adopted, with a total equivalent explosion-proof length of 30mm–60mm, to ensure that the external temperature is lower than the ignition temperature of the combustible gas.

[0039] Overall, the aforementioned labyrinth-structured explosion-proof joint structure 11 provides: a longer flame transmission path; multi-stage temperature attenuation; and an overall pressure resistance of 0.7–1.2 MPa for the explosion-proof enclosure 1.

[0040] In this embodiment, the explosion-proof enclosure 1 adopts a thick-walled metal structure, preferably made of Q235B steel or 304 stainless steel, with a shell thickness of 10-16 mm to meet the explosion-proof strength requirements. The mating end faces of the enclosure (including the mating surfaces between the front cover 2 and the explosion-proof enclosure 1) are machined into a multi-level stepped labyrinth-type explosion-proof structure. The explosion-proof labyrinth groove includes at least three steps, each step having a depth of 8-12 mm, and the explosion-proof gap is set to 0.08-0.10 mm, thereby ensuring that the explosion flame is completely extinguished when passing through the labyrinth groove.

[0041] To further enhance airtightness and impact resistance, evenly distributed high-strength bolts (M10-M12, 8-12 locations) can be installed at the fastening points of the front cover 2, and stainless steel clamping rings and 52-type washers can be used to ensure uniform clamping of the mating surfaces. Thickened stiffening plates can be installed on the outer wall of the enclosure, depending on the installation conditions, to enhance the shell's impact resistance. The modular mounting plate 3 can be directly accessed after the front cover 2 is opened. The entire enclosure meets ExdIIBT6 or higher explosion-proof requirements.

[0042] The modular mounting plate 3 is used to install the electrical module 6. The modular mounting plate 3 is slidably disposed inside the explosion-proof housing 1, and can be pulled out after the front cover 2 is opened to achieve power-off interlocking in maintenance mode.

[0043] like Figure 3 As shown, the modular mounting plate 3 can be installed inside the explosion-proof housing 1 via a slide rail 36 and a limiting latch 34. The limiting latch 34 is configured to trigger a warning power-off when the modular mounting plate 3 is pulled out for a first stroke, and to trigger a forced full power-off when the modular mounting plate 3 is pulled out for a second stroke, wherein the first stroke is shorter than the second stroke. In specific use, by setting the limiting latch 34, the modular mounting plate 3 can trigger a warning power-off when it is pulled out 10–25 mm, and trigger a forced full power-off when it is pulled out 30–60 mm. This achieves graded safety protection, providing early warning power-off at the start of maintenance and complete power-off after full extraction, avoiding electric arcs during live operation and significantly improving operational safety in the explosion-proof environment.

[0044] Specifically, the modular mounting plate 3 can be installed in the cabinet via a double-layer stainless steel ball bearing slide rail 36, with a load-bearing capacity of ≥25kg and an extraction stroke of 70–100% of the cabinet depth.

[0045] The limiting latch 34 may include a block, a spring, a limiting hole, etc. Of course, the specific combination and structure of the limiting latch 34 are not limited to the above configuration, and this application does not make a unique limitation.

[0046] In one embodiment, the modular mounting plate 3 is divided into an electrical control area 31, an actuator drive area 32, a power supply area 33, and a grounding busbar area 35. The back of the modular mounting plate 3 is electrically connected to a busbar and a pluggable connector. When the modular mounting plate 3 is pulled out, the busbar is disconnected from the pluggable connector.

[0047] In this embodiment, the modular mounting plate 3 adopts a drawer-type structure. The slide rails 36 on the left and right sides cooperate with the inner wall of the outer shell, so that the mounting plate can be pulled out horizontally after the front cover 2 is opened, which facilitates maintenance, replacement and wiring operations.

[0048] The modular mounting plate 3 may include an electrical control area 31, an actuator drive area 32, a power supply area 33, a limit lock 34, and a grounding busbar area 35. The electrical control area 31 is used to house the PLC, small relays, temperature control unit 7, and terminal blocks. The actuator drive area 32 is used to house actuator drive modules (such as motor drives, electromagnet drivers, etc.). The power supply area 33 is used to house the main incoming terminal, disconnecting switches, and short-circuit protection devices. The limit lock 34 controls the locking state of the drawer-type mounting plate. When the mounting plate is pulled out to the maintenance position, the limit lock 34 automatically activates, cutting off the power interlock of the temperature regulation mechanism (heater 72, fan 71, etc.) to prevent electric shock or arcing risks caused by misoperation. The grounding busbar is used to unify the wiring of the grounding module, ensuring reliable grounding of the structural components, housing, and external shielding wires of the modular mounting plate 3.

[0049] Overall, the modular mounting plate 3 physically isolates different functional zones, making the wiring inside the box neater, maintenance more convenient, and improving system security.

[0050] The modular mounting plate 3 features clear functional partitions, which helps reduce electrical interference and facilitates inspection and maintenance. The rear plug-in connection enables maintenance without disconnection, significantly shortening maintenance time and reducing the risk of wiring errors. Furthermore, when the modular mounting plate 3 uses a busbar + plug-in connector connection on the back, the busbar and connector automatically disconnect when pulled out, eliminating the need for wiring removal during maintenance.

[0051] In this embodiment, the explosion-proof housing 1 is provided with an air vent on the side wall or top, and the pressure relief structure 4 is provided at the air vent to achieve three-level protection: first pressure relief, then flame arrest, and finally buffering. The pressure relief chamber 43 effectively reduces the instantaneous pressure peak, avoids impact damage to the housing or external equipment, and achieves safe, directional, and stable exhaust.

[0052] like Figure 4As shown, specifically, the pressure relief structure 4 may include: a pressure relief shell 40, which has an inlet end and an outlet end, the inlet end being connected to the vent hole, and a pressure relief diaphragm 41 and a flame arrestor mesh 42 being sequentially arranged inside the pressure relief shell 40 along the direction from the inlet end to the outlet end, a pressure relief diaphragm 41 and a flame arrestor mesh 42 being formed between the pressure relief diaphragm 41 and the outlet end, the pressure relief cavity 43 being used to reduce the instantaneous pressure peak after the pressure relief diaphragm 41 ruptures.

[0053] The pressure relief diaphragm 41 is provided with a pre-crack groove, and the pressure relief diaphragm 41 can only rupture unidirectionally from the inlet end to the outlet end.

[0054] The burst pressure of the pressure relief diaphragm 41 can be determined based on its thickness t, characteristic dimension a, allowable stress of the material, and empirical coefficients. In other words, the burst pressure of the pressure relief diaphragm 41 is related to the diaphragm thickness, material properties, and structural dimensions.

[0055] The burst pressure of the pressure relief diaphragm 41 is according to Sure, Where K is an empirical coefficient, a dimensionless coefficient, and its value ranges from 0.2 to 2.0; Pburst is the desired burst pressure; σallow is the allowable stress or yield strength of the pressure relief diaphragm 41 material; t is the thickness of the pressure relief diaphragm 41; a is the radius or characteristic dimension of the pressure relief diaphragm 41.

[0056] The thickness of the pressure relief diaphragm 41 is 0.3mm–0.8mm.

[0057] In one specific embodiment, the pressure relief diaphragm 41 can be made of SUS304 stainless steel with a thickness of 0.3–0.8 mm. The diaphragm burst pressure P burst Related to diaphragm thickness t, characteristic radius a, and allowable material stress σ allow Approximately satisfies semi-empirical relation , Where: P burst The desired burst pressure (Pa); σ allow The allowable stress or yield strength (Pa) of the pressure relief diaphragm 41 material; t is the thickness (m) of the pressure relief diaphragm 41; a is the radius or characteristic dimension (m) of the pressure relief diaphragm 41; K is an empirical coefficient related to boundary conditions / stress distribution (dimensionless, needs to be calibrated by FEM or experiment, usually in the range of 0.2–2.0).

[0058] The empirical coefficient K is related to the support and groove shape of the diaphragm (usually determined by finite element simulation or prototype testing). During the design, the diaphragm thickness can be obtained by substituting the above relationship into the required burst pressure (e.g., 0.2–0.4 MPa) and diaphragm size, combined with a safety factor; the range of 0.3–0.8 mm given in this embodiment is an empirically recommended value under common chamber and burst pressure conditions.

[0059] Take a typical dimension 'a' (e.g., 5–20 mm, depending on the vent diameter and cavity design), and substitute it with commonly used materials (the allowable stress of stainless steel 304 is approximately 200–250 MPa). By selecting a reasonable K (e.g., a conservative value of 0.5) and the design burst pressure (0.2–0.4 MPa), 't' can be obtained in the range of several hundred micrometers to several millimeters.

[0060] Example: Let a = 10 mm, P = 0.3 MPa, σ allow =200MPa, K=0.5, then

[0061] The value is in the range of 0.3–0.8 mm, which illustrates the engineering feasibility of this thickness selection (the numerical example is for design reference only, and the value of K needs to be calibrated by FEM / experiment).

[0062] Furthermore, the flame arrestor mesh 42 includes a multi-layer stainless steel mesh stacked structure, wherein the mesh size of the stainless steel mesh is ≤0.3mm, which is used to block the outward spread of flames at the moment of pressure relief.

[0063] Whether a flame can propagate through a small gap depends on the quenching gap of the gas being tested. For common flammable gases (such as methane, propane, etc.) or gas mixtures, the quenching gap is typically in the range of 0.5–1.0 mm (depending on the gas, pressure, and temperature). This means that when the characteristic dimension of the channel is below this value, the flame is unlikely to propagate continuously. The flame arrestor mesh 42 uses a multi-layered structure of SUS316 stainless steel, with a mesh size preferably ≤0.3 mm. This conservative strategy (considering both manufacturing feasibility and the risk of clogging) is employed. This mesh size is much smaller than the flame quenching gap value for common flammable gases, effectively blocking flame propagation during depressurization and pressure relief, increasing the flame arrestor safety margin. To prevent the flame arrestor mesh 42 from being clogged by particles, a removable protective screen and filter element are installed on the outside for easy on-site cleaning and maintenance.

[0064] like Figure 5As shown, the explosion-proof housing 1 is further provided with an explosion-proof cable opening structure 5. The explosion-proof cable opening structure 5 includes a bimetallic sleeve 51, a clamping ring 52, and a flame-arresting clamping member 53. The bimetallic sleeve 51 includes an explosion-proof layer with a first predetermined thickness on the outer side and a heat-conducting layer with a second predetermined thickness on the inner side. A first connecting portion is provided on the periphery of one end of the explosion-proof layer. The clamping ring 52 includes an inner ring and an outer ring. The outer ring is provided with a second connecting portion, which forms a detachable structure with the first connecting portion. An adjusting cone angle is provided on the inner ring. The flame-arresting clamping member 53 is provided with a flame-arresting groove, which is a segmented labyrinth microchannel structure used to block flame propagation and achieve cable sealing.

[0065] In this embodiment, the explosion-proof cable opening structure 5 is a composite explosion-proof cable opening structure 5, which is used to realize the functions of explosion-proof, sealing and mechanical fixation at the cable entry point, so as to adapt to various cable specifications in the range of Φ8 to Φ26 mm.

[0066] In this embodiment, the explosion-proof cable opening structure 5 may include a bimetallic sleeve 51, a clamping ring 52, and a flame-arresting clamping member 53.

[0067] The bimetallic sleeve 51 adopts a double-layer composite structure, with an outer explosion-proof layer and an inner thermally conductive and flame-retardant layer, balancing structural strength and heat dissipation / flame-retardant performance. The outer layer uses 45# steel or 304 stainless steel to provide sufficient impact resistance, while the inner layer uses T2 copper to improve thermal conductivity and flame-retardant capability. The flame-retardant clamping component 53 can be an integral or segmented structure, formed by a copper alloy skeleton and an EPDM / FKM elastic sealing layer. Its outer surface has a conical structure that matches the inner conical surface of the clamping ring 52. During the tightening of the clamping ring 52, the flame-retardant clamping component 53 contracts radially, thus adapting to cables of different diameters and generating uniform clamping force on the cable sheath, forming a stable and reliable sealing channel and multi-stage flame-retardant path. The total length of the flame-retardant path is not less than 20mm, effectively blocking the propagation of electric arc and flame. A locking nut is provided on the outside of the cable opening structure, and torque control ensures the clamping structure achieves optimal sealing performance. The entire cable opening structure meets the Exd structural requirements and has undergone airtightness testing, tensile testing, and fire resistance performance verification.

[0068] Specifically, the outer layer can be a steel explosion-proof layer, and the inner layer is a copper heat-conducting layer. The clamping ring 52 is equipped with an adjusting cone surface and is detachably connected to the sleeve. The flame-arresting clamping component 53 is equipped with a segmented labyrinth microchannel flame-arresting groove to achieve reliable flame arrest and sealing, and is compatible with cables of different diameters.

[0069] In one specific embodiment, the outer layer of the bimetallic sleeve 51 can be made of 45# steel, and its thickness can be 2–4 mm to ensure good explosion-proof performance. The inner layer can be made of T2 copper to ensure good thermal conductivity and flame-retardant performance. The thickness of the inner layer can be 0.7–2 mm.

[0070] The thickness of the outer steel layer is determined by the formula for the circumferential strength of a thin-walled cylinder under the rapid pressure increase caused by gas deflagration:

[0071] in: t s The thickness of the steel layer; P r Design pressure for transient deflagration (generally designed at 1.0–1.6 MPa). D is the inner diameter of the sleeve; σ s The allowable stress for 45# steel is approximately 250–350 MPa. S f For a safety factor of (2.0–3.0) Substituting the typical cable port structure (D≈15–30mm), we can obtain t s =1.8~3.6mm.

[0072] The main function of the inner copper layer is to quickly absorb the heat of the flame, so that the gas temperature drops below the quenching temperature (Tq).

[0073]

[0074] in: t c The thickness of the copper layer; L is the length of the fire-resistant path (L≥12mm); T0 is the flame temperature (≈1200–2000℃); T q The quenching temperature is approximately 200–300℃. c c、 ρ c These are the specific heat and density of copper, respectively. T m This refers to the allowable temperature near the melting point of copper (≈600℃). Substituting the typical values, we get: t c ≈0.8–1.5 mm.

[0075] In this embodiment, the clamping ring 52 is a tapered clamping ring 52, which can meet the needs of adjusting the clamping force for cables of different diameters (Φ8–Φ26). Specifically, the clamping ring 52 can ensure uniform clamping without damaging the cable insulation or destroying the explosion-proof gap.

[0076] The clamping force can be estimated using the following contact pressure formula:

[0077] The tapered structure makes:

[0078] Wherein, θ is the 52-cone angle of the clamping ring (typically 6–12°), which can be continuously adjusted from Φ8 to Φ26.

[0079] The clamping ring 52 and the bimetallic sleeve 51 can be connected by threads. For example, the first connecting part on the outer side of the explosion-proof layer is an external thread, and the second connecting part on the inner side of the outer ring of the clamping ring 52 is an internal thread. The internal thread and the external thread cooperate to form a threaded connection mechanism.

[0080] In this embodiment, the flame-arresting clamping member 53 is provided with a flame-arresting groove, which is a segmented labyrinth microchannel structure. Specifically, the flame-arresting groove may include any one or a combination of the following: a U-shaped groove, a V-shaped groove, and a stepped labyrinth groove, etc. The groove depth is 3–6 mm, the groove width is 1–2 mm, the gap is 0.05–0.15 mm, and the number of stages is 2–3 segments, with multiple segments connected in series to form a flame-arresting path ≥12 mm.

[0081] The flame arrestor achieves reliable flame arrest through multiple synergistic mechanisms: the explosive gas expands and depressurizes within the tank, making full contact with the copper wall, and the heat is rapidly absorbed, reducing the temperature; the flame is forced to change direction multiple times within the labyrinthine channels, significantly reducing its propagation speed and suppressing its propagation trend; the copper wall continuously absorbs a large amount of heat and rapidly dissipates it, causing the flame temperature to drop rapidly below the quenching temperature; the channel gaps are controlled within the flame quenching gap, preventing the flame from maintaining continuous propagation; combined with the multi-stage tank series structure, the residual flame energy is attenuated step by step, ultimately achieving the effect of completely extinguishing the flame and blocking its outward propagation.

[0082] like Figure 6 As shown, in one embodiment, the explosion-proof electrical control box may further include a temperature control unit 7, which includes a temperature sensor and a temperature adjustment mechanism. The temperature control unit 7 can form a linkage control with the modular mounting plate 3. The temperature control unit 7 is configured such that: when the modular mounting plate 3 is pulled out, the temperature adjustment mechanism stops working; after the modular mounting plate 3 is pushed in, the temperature adjustment mechanism automatically resumes temperature adjustment.

[0083] In this embodiment, the explosion-proof electrical control box is also equipped with a temperature control unit 7, which is used to realize automatic temperature detection, adjustment and overheat protection inside the box, and ensure that the electrical components operate stably within a safe temperature range. The temperature control unit 7 mainly includes: an explosion-proof temperature sensor, an explosion-proof cooling fan 71, a heater 72 and a temperature controller, and forms a mechanical-electrical composite linkage protection with the limit lock 34 of the modular mounting plate 3.

[0084] The temperature controller is installed in the electrical control area 31 of the modular mounting plate 3. The entire structure utilizes an explosion-proof enclosure 1, or is electrically isolated via an intrinsically safe barrier, to meet the requirements for use in flammable and explosive hazardous environments. At least one Pt100 temperature probe is installed inside the enclosure for real-time acquisition of the internal ambient temperature. To further improve detection reliability, a second temperature probe can be installed in parallel outside the enclosure to monitor the surface temperature of the explosion-proof enclosure 1. The temperature probe is equipped with a stainless steel protective tube with a diameter of Φ4mm and a length of 60mm. The sensor cable is introduced into the enclosure through a composite explosion-proof cable port and is shielded and grounded to enhance anti-interference capabilities and operational safety.

[0085] The temperature control unit 7 adopts a PID control algorithm to achieve high-precision automatic temperature control, with a temperature measurement and control accuracy of ±1℃. The specific control logic is as follows: when the internal temperature of the chamber is higher than 45℃, the explosion-proof heat dissipation fan 71 or other heat dissipation structures are automatically started for forced heat dissipation; when the internal temperature of the chamber is lower than 5℃, the heater 72 is automatically started for low-temperature heating to avoid condensation, icing and abnormal device startup.

[0086] To ensure safe maintenance operations, this invention provides a mechanical-electric composite limit lock 34 at the junction of the modular mounting plate 3 and the explosion-proof enclosure 1, and meets the following technical requirements: the limit lock 34 must be arranged at the mating position of the modular mounting plate 3 and the explosion-proof enclosure 1; when the modular mounting plate 3 is pulled out by 10–25 mm, a warning-level power-off logic is immediately triggered; when the modular mounting plate 3 is further pulled out to 30–60 mm (approximately 20% of the total pull-out stroke), a forced full power-off must be triggered to completely cut off the dangerous potential.

[0087] The purpose of the above-mentioned limit interlock design is to: prevent the risk of explosion caused by electric arc generated during live extraction operation; prevent the heater 72 from continuing to work during maintenance, which could lead to the risk of electric shock or burns due to high temperature; and strictly adhere to the core safety principle of explosion-proof electrical equipment: disconnect power first, then open the cover / perform maintenance.

[0088] The limit lock 34 is linked with the temperature control unit 7 and the electrical control system for protection. When the lock is triggered, the system synchronously performs the following actions: Cut off heater 72 and the high-voltage circuit to achieve electrical safety power disconnection; The temperature controller automatically enters maintenance mode and pauses automatic PID adjustment. The cooling fan 71 continues to run and delays for 20 seconds to force the internal residual heat to dissipate; Output a maintenance interlock signal to the main controller to prevent accidental power supply during maintenance.

[0089] In this embodiment, the system's reliability, safety, and adaptability are improved through internal status monitoring and intelligent optimization control. Specifically, this includes enclosure pressure monitoring, electrical anomaly monitoring, intelligent temperature control algorithm, dual-probe redundant control, fault self-recovery, and modular mounting plate 3-linkage logic.

[0090] The explosion-proof electrical control box can also be equipped with a pressure monitoring device to collect internal pressure information in real time and form a linkage protection with the pressure relief structure 4. When a sudden pressure change occurs in the pressure relief chamber 43 or the pressure value exceeds the preset threshold, the system automatically determines that it is an internal abnormal state, and simultaneously realizes audible and visual alarms, fault reporting, and automatic power cut-off of the main circuit to avoid safety risks caused by continuous pressure increase.

[0091] The explosion-proof electrical control box is also equipped with current and power supply abnormality monitoring functions to detect the circuit current, voltage and load status in real time, so as to prevent abnormal internal heating caused by actuator overload, short circuit, phase loss, overcurrent and other faults; at the same time, it provides real-time protection for heater 72 circuit to avoid the risks of heater 72 short circuit, overheating and dry burning, and improve the safety and service life of electrical system.

[0092] The temperature control unit 7 provided in this application embodiment can adopt a fuzzy PID and adaptive weight control algorithm. According to the changes in internal load, running time, ambient temperature and heat dissipation status of the chamber, it can automatically adjust the PID parameters online, so that the temperature control response is faster, the overshoot is smaller, the stability is higher, and the temperature oscillation is significantly reduced, so that the temperature inside the chamber is maintained in a more stable range.

[0093] The temperature control unit 7 employs a dual-probe redundancy configuration with an internal Pt100 temperature probe and a shell temperature probe. It processes the two temperature signals using a weighted fusion and bias voting algorithm to achieve higher accuracy and reliability in temperature detection. This algorithm can be used to: detect anomalies such as temperature probe failure, wire breakage, and drift; predict over-temperature trends in advance for proactive control; and pre-adjust the heater 72 to avoid significant temperature fluctuations.

[0094] The explosion-proof electrical control box provided in this application embodiment also has complete fault self-diagnosis and automatic recovery logic: when the temperature probe fails or becomes inaccurate, it automatically enters the safety protection mode; triggers the heater 72 to cut off power and the fan 71 to force cooling; completes fault location, recording and prompting; after the fault is cleared, the system can automatically complete self-test and resume normal operation.

[0095] Among them, the temperature control unit 7 and the modular mounting plate 3 form a deep mechanical-electric linkage to realize automatic mode switching: after the modular mounting plate 3 is pulled out, it automatically enters the maintenance mode: the heater 72 is immediately forced to shut off; the PID automatically stops adjusting; the cooling fan 71 maintains delayed cooling to ensure that the internal residual heat is fully dissipated; the system locks the output and marks it as an unoperable state to prevent accidental closing.

[0096] After the modular mounting plate 3 is pushed in, the system automatically resumes operation mode: the system performs a power-on self-test; checks the status and calibration validity of the dual temperature probes; automatically resumes the fuzzy PID adaptive temperature control algorithm; and after confirming that there are no abnormalities, resumes normal heating / heat dissipation control.

[0097] The explosion-proof electrical control box provided in this embodiment of the invention achieves a four-in-one safety guarantee system of static explosion-proof, dynamic pressure relief, safety maintenance, and intelligent temperature control through the overall coordinated cooperation of the multi-level tortuous explosion-proof joint structure 11, the pull-out modular mounting plate 3, the directional pressure relief structure 4, the composite explosion-proof cable port structure 5, and the temperature control interlocking unit.

[0098] During normal operation, the enclosure remains fully enclosed and explosion-proof, the modular mounting plate 3 is locked and positioned, the pressure relief structure 4 is in standby mode, and the temperature control unit 7 automatically maintains a stable internal temperature to ensure long-term safe and reliable operation of the equipment.

[0099] During maintenance, the inspection can be completed simply by opening the front cover 2 and pulling out the modular mounting plate 3. The explosion-proof housing 1 remains intact and undamaged. At the same time, the limit lock 34 triggers the power-off interlock according to the stroke level, strictly following the explosion-proof safety principle of "power off first, maintenance later", thus avoiding the risks of electric arc, electric shock and high temperature from the source.

[0100] When a fault arc or deflagration occurs inside the enclosure, the multi-stage tortuous explosion-proof joint surface extends the flame path and enhances heat exchange, causing the high-temperature gas to cool and extinguish rapidly, preventing the flame from spreading outward. If the internal pressure exceeds the limit, the pressure relief diaphragm 41 ruptures precisely in one direction according to the set pressure. After the high-temperature gas flow completely blocks the flame through the flame arrestor mesh 42, it enters the pressure relief chamber 43 to reduce the pressure peak, achieving safe, directional, and controllable pressure relief. The composite explosion-proof cable port simultaneously plays a role in sealing, explosion resistance, heat conduction, and flame arrest, and together with the linkage protection of the temperature control unit 7, further improves the overall safety and operational stability.

[0101] All articles and references disclosed herein, including patent applications and publications, are incorporated herein by reference for various purposes. The term “substantially constitutes…” used to describe a combination should include the identified element, component, part, or step, as well as other elements, components, parts, or steps that do not substantially affect the essential novelty of the combination. The use of the terms “comprising” or “including” to describe combinations of elements, components, parts, or steps herein also contemplates embodiments substantially constituted by such elements, components, parts, or steps. The use of the term “may” herein is intended to indicate that any described attribute included by “may” is optional. Multiple elements, components, parts, or steps can be provided by a single integrated element, component, part, or step. Alternatively, a single integrated element, component, part, or step can be divided into multiple separate elements, components, parts, or steps. The use of the disclosure “a” or “an” to describe an element, component, part, or step is not intended to exclude other elements, components, parts, or steps.

[0102] The various embodiments described in this specification are presented in a progressive manner, with each embodiment focusing on its differences from the others. Similar or identical parts between embodiments can be referred to interchangeably. The above embodiments are only for illustrating the technical concept and features of the present invention, and are intended to enable those skilled in the art to understand the content of the invention and implement it accordingly. They should not be construed as limiting the scope of protection of the present invention. All equivalent changes or modifications made according to the spirit and essence of the present invention should be included within the scope of protection of the present invention.

Claims

1. An explosion-proof electrical control box, characterized in that, The explosion-proof electrical control box includes: The enclosure includes an explosion-proof shell and a front cover. The explosion-proof shell is a hollow shell structure with one end open. The front cover is designed to be openable and closable at the opening. When the front cover is closed at the opening, an explosion-proof joint structure is provided between the explosion-proof shell and the front cover. The explosion-proof joint structure is used to form a bent and extended explosion-proof channel to cool the explosive gas and block the flame from spreading outward. A modular mounting plate is used to install electrical modules. The modular mounting plate is slidably disposed inside the explosion-proof housing and can be pulled out after the front cover is opened to achieve power-off interlocking in maintenance mode. A pressure relief structure is provided on the explosion-proof enclosure to release pressure in a directional manner and prevent flame propagation when there is overpressure inside the enclosure.

2. The explosion-proof electrical control box as described in claim 1, characterized in that, The explosion-proof joint structure includes a multi-level stepped joint surface.

3. The explosion-proof electrical control box as described in claim 2, characterized in that, Let the initial flame temperature be T0 and the allowable outer temperature be T. ign The effective length of the explosion-proof joint structure should satisfy the thermal attenuation relationship based on the composite attenuation coefficient α. ; The composite attenuation coefficient α is determined based on the average convective heat transfer coefficient hp of the wall surface to the high-temperature gas, the wall heat transfer area As per unit length, and the gas mass flow rate per unit length through the channel. and the relationship between the specific heat capacity (cp) of gases Make an estimate; Where As is equivalent to the channel perimeter P within the explosion-proof joint structure, hp, The dimensions of the enclosure are calibrated through testing or numerical simulation based on the on-site medium and the dimensions of the enclosure.

4. The explosion-proof electrical control box as described in claim 1, characterized in that, The modular mounting plate is installed inside the explosion-proof housing via a slide rail and a limit lock. The limit lock is configured to trigger a warning power-off when the modular mounting plate is pulled out of the first stroke, and to trigger a forced full power-off when the modular mounting plate is pulled out of the second stroke, wherein the first stroke is less than the second stroke.

5. The explosion-proof electrical control box as described in claim 1 or 4, characterized in that, The modular mounting plate is divided into an electrical control area, an actuator drive area, a power supply area, and a grounding busbar area. The back of the modular mounting plate is electrically connected to a busbar and pluggable connectors. When the modular mounting plate is pulled out, the busbars are disconnected from the pluggable connectors.

6. The explosion-proof electrical control box as described in claim 1, characterized in that, The explosion-proof enclosure has an air vent on its side wall or top. The pressure relief structure is located at the air vent. The pressure relief structure includes a pressure relief shell with an inlet end and an outlet end. The inlet end is connected to the air vent. Along the direction from the inlet end to the outlet end, a pressure relief diaphragm and a flame arrestor are sequentially arranged inside the pressure relief shell. A pressure-reducing cavity is formed between the pressure relief diaphragm and the outlet end. The pressure-reducing cavity is used to reduce the instantaneous pressure peak after the pressure relief diaphragm ruptures.

7. The explosion-proof electrical control box as described in claim 6, characterized in that, The pressure relief diaphragm is provided with a pre-crack groove, and the pressure relief diaphragm can only rupture unidirectionally from the inlet end to the outlet end.

8. The explosion-proof electrical control box as described in claim 6, characterized in that, The thickness of the pressure relief diaphragm is 0.3mm–0.8mm; The burst pressure of the pressure relief diaphragm is according to Sure, Where K is an empirical coefficient, a dimensionless coefficient, and its value ranges from 0.2 to 2.0; P burst The desired blast pressure; σ allow The allowable stress or yield strength of the pressure relief diaphragm material; t is the thickness of the pressure relief diaphragm; 'a' represents the radius or characteristic dimension of the pressure relief diaphragm.

9. The explosion-proof electrical control box as described in claim 6, characterized in that, The fire-resistant mesh comprises a multi-layered stainless steel mesh structure with a mesh size ≤0.3mm, used to block the outward spread of flames at the moment of pressure relief.

10. The explosion-proof electrical control box as described in claim 1, characterized in that, The explosion-proof electrical control box also includes a temperature control unit, which includes a temperature sensor and a temperature adjustment mechanism. The temperature control unit can form a linkage control with the modular mounting plate. The temperature control unit is configured such that: when the modular mounting plate is pulled out, the temperature adjustment mechanism stops working; after the modular mounting plate is pushed in, the temperature adjustment mechanism automatically resumes temperature adjustment.

11. The explosion-proof electrical control box as described in claim 1, characterized in that, The explosion-proof housing is also provided with an explosion-proof cable port structure, which includes a bimetallic sleeve, a clamping ring, and a flame-arresting clamping component. The bimetallic sleeve includes an explosion-proof layer with a first predetermined thickness on the outer side and a heat-conducting layer with a second predetermined thickness on the inner side; a first connecting portion is provided on the periphery of one end of the explosion-proof layer. The clamping ring includes an inner ring and an outer ring. The outer ring is provided with a second connecting part, which forms a detachable structure with the first connecting part. The inner ring is provided with an adjusting cone angle. The flame-arresting clamping component is provided with a flame-arresting groove, which is a segmented labyrinth microchannel structure used to block the spread of flames and achieve cable sealing.

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