Ma protection level explosion-proof draw-out type ventilator for positive pressure protection in explosion-proof motor

Abstract

The invention belongs to the field of coal mine underground ventilation safety, and relates to an Ma protection level anti-explosion draw-out type ventilator for positive pressure protection in an explosive-proof motor, which comprises a fan flow channel, the explosive-proof motor arranged in the fan flow channel, an impeller in transmission connection with the explosive-proof motor, and a junction box for controlling the explosive-proof motor, the explosion-proof motor further comprises a pressurization sealing cavity which is communicated with the inner cavity of the explosion-proof motor and the inner cavity of the junction box, and the pressure of the pressurization sealing cavity is larger than that in the fan flow channel, so that explosive gas flowing through the fan flow channel cannot enter the pressurization sealing cavity. On the basis of a common explosion-proof draw-out type ventilator, the inner cavity of the explosion-proof motor is communicated with the inner cavity of the junction box in a sealed mode, the pressurization sealing cavity is formed, so that external explosive gas is prevented from entering the inner cavities of the explosion-proof motor and the junction box, and therefore the protection level of the common explosion-proof draw-out type ventilator is improved to the Ma protection level; the safety problem of an existing anti-explosion draw-out type ventilator is solved.

Description

Technical Field

[0001] The invention belongs to the field of underground ventilation safety in coal mines, and relates to a Ma protection level explosion-proof extraction ventilator with internal positive pressure protection of a flameproof motor. Background Art

[0002] Article 163 of the "Safety Regulations for Coal Mines" (2022 edition) stipulates that tunneling must be ventilated with the full air pressure of the mine or with local ventilators. When local ventilators are used for ventilation in coal tunnels, semi-coal-rock tunnels, and rock tunnels with gas gushing, the pressure-in type should be used, and the extraction type shall not be used (compressed air and hydraulic ejectors are not subject to this limitation); if a mixed type is used, safety measures must be formulated. When local ventilators are used for ventilation in gas eruption areas and protruding coal seams, the pressure-in type must be used. According to the requirements of the above clauses, local extraction ventilators that use flameproof motors as power sources are not allowed to be used in coal tunnels, semi-coal-rock tunnels, and rock tunnels with gas gushing; at the same time, any type of local extraction ventilators are not allowed to be used in gas eruption areas and protruding coal seams. The reason for making the above clauses is that there is a risk of gas gushing / gushing in coal lanes, semi-coal-rock lanes, rock lanes with gas gushing, gas gushing areas, gas gushing areas and protruding coal seams. When the gas explosion concentration is reached in the lane, an explosive gas environment will be formed. At present, all motor-driven exhaust fans used in coal mines have matching flameproof motors with an explosion-proof type of Ex dbⅠMb and an equipment protection level (EPL) of Mb. They are only protected by flameproof enclosures. When there is gas gushing / gushing in the exhaust fan application scenario to form an explosive gas environment, the matching flameproof motor will be surrounded by explosive gas and enter the motor through the flameproof gap. At this time, if sparks or other ignition sources are generated inside the motor, the gas inside the motor will explode, resulting in a certain probability of the motor casing failing to explode, igniting the explosive environment and ultimately causing a large-scale gas explosion accident in the underground lanes. Therefore, according to the provisions of the Mb protection level, when the motor is in an explosive gas environment, it must be shut down. Therefore, this type of exhaust fan cannot achieve the function of 24-hour uninterrupted operation to continuously supply air to the working face. Therefore, the "Coal Mine Safety Regulations" restricts the use of motor-driven exhaust fans in places where explosive gases exist.

[0003] At present, the explosion-proof pressure-type ventilators used in large quantities to supply air to the working face will cause serious dust and air pollution at the air-using locations, and cause large-scale pollution to the tunnels flowing through, seriously affecting the occupational health of the workers. If local exhaust fans can be used in the underground tunnels of coal mines, the dust pollution level at the air-using locations can be significantly reduced, and the dirty air at the locations can be extracted and transported to the dedicated return air tunnel through the wind pipe, avoiding the large-scale pollution caused by the dirty air flowing through the rest of the tunnel, which is conducive to maintaining the non-explosiveness of the tunnel air and creating good labor hygiene conditions. However, for equipment used in explosive gas environments, absolute safety is required in principle. Therefore, equipment operating in explosive environments generally needs to have two independent layers of protection, and the equipment protection level (EPL) reaches the Ma level (when one of them fails, there are still additional measures to ensure its reliable safety performance). However, my country's coal mines do not yet have exhaust fans driven by flameproof motors with this protection level.

[0004] In view of the advantages of using local exhaust fans and the existing safety issues, it is of great significance to develop a Ma protection level explosion-proof exhaust fan with positive pressure protection inside the explosion-proof motor. Summary of the invention

[0005] In view of this, the purpose of the present invention is to provide a Ma protection level explosion-proof exhaust fan with positive pressure protection inside an explosion-proof motor to solve the safety problems existing in the existing explosion-proof exhaust fans, and then to solve the occupational health problems such as severe dust, air pollution, and tunnel pollution caused by the current explosion-proof pressure-in fans supplying air to the working surface through the explosion-proof exhaust fan.

[0006] In order to achieve the above object, the present invention provides the following technical solutions:

[0007] A Ma protection level explosion-proof exhaust fan with positive pressure protection inside a flameproof motor comprises a fan flow channel, a flameproof motor arranged in the fan flow channel, an impeller drivingly connected to the flameproof motor, and a junction box for controlling the flameproof motor, and also comprises a pressurized sealed cavity connecting the inner cavity of the flameproof motor and the inner cavity of the junction box, and the pressure of the pressurized sealed cavity is greater than the pressure in the fan flow channel, so that explosive gas flowing through the fan flow channel cannot enter the pressurized sealed cavity.

[0008] Furthermore, the pressurized sealed cavity includes an inner cavity of the flameproof motor, an inner cavity of the junction box, and an inner cavity of a motor outlet pipe for connecting the flameproof motor and the junction box;

[0009] An air intake one-way solenoid valve is connected to the flameproof motor, and an exhaust one-way solenoid valve is provided on the junction box to discharge the explosive gas inside the pressurized sealed cavity before the flameproof motor is started and form positive pressure protection in the pressurized sealed cavity.

[0010] Furthermore, the flameproof motor comprises a motor winding and a motor housing for accommodating the motor winding, the motor housing comprises a motor housing body and a front cover plate and a rear cover plate sealed at both ends of the motor housing body, and the motor rotating shaft seal of the flameproof motor passes through the front cover plate and is connected to the impeller;

[0011] A motor outlet pipe for leading out cables is provided on the motor housing body, and one end of the motor outlet pipe away from the motor housing body is sealed and abutted against the outside of the junction box and connected to the inner cavity of the junction box to form a pressurized sealed cavity including the inner cavity of the flameproof motor, the inner cavity of the junction box and the inner cavity of the motor outlet pipe.

[0012] Furthermore, a front end static seal and a rear end static seal are respectively provided between the front end cover plate and the rear end cover plate and the motor housing body, a motor rotating shaft dynamic seal is provided between the motor rotating shaft and the front end cover plate, and a wire outlet pipe static seal is provided between the motor wire outlet pipe and the motor housing body, so that the inner cavity of the motor housing forms a sealed cavity.

[0013] Furthermore, the junction box comprises a junction box housing and a junction box cover plate buckled on the junction box housing, and a junction terminal is provided at the bottom of the junction box housing;

[0014] The wiring terminal penetrates through the junction box shell and is gap-connected, the motor outlet pipe is abutted against the bottom of the junction box shell, and is gap-connected with the junction box shell through the wiring terminal to communicate with the inner cavity of the junction box.

[0015] Furthermore, a junction box cover plate static seal is provided between the junction box shell and the junction box cover plate, and a junction box static seal is provided between the junction box shell and the motor outlet pipe to ensure the sealing of the junction box and the motor outlet pipe.

[0016] Furthermore, a flameproof air inlet connector is provided on the motor housing body, and the air inlet one-way solenoid valve is connected to the flameproof air inlet connector via an air inlet pipeline so as to be connected to the flameproof motor.

[0017] Furthermore, the air intake one-way solenoid valve is connected to a non-explosive gas source to feed non-explosive gas into the pressurized sealed cavity.

[0018] Furthermore, a first pressure sensor is connected to the non-explosive gas source to monitor the maximum pressure applied by the non-explosive gas source to the pressurized sealed chamber, and a second pressure sensor and a methane concentration sensor are arranged on the junction box to detect the pressure and methane concentration of the pressurized sealed chamber.

[0019] Furthermore, it also includes a master control device, in which the first pressure sensor, the second pressure sensor, the methane concentration sensor, the intake one-way solenoid valve, the exhaust one-way solenoid valve and the junction box are all connected to the master control device through signal cables, and the monitoring data of each sensor is collected in real time, combined with the internal control program of the master control device to control the junction box and each solenoid valve.

[0020] The beneficial effects of the present invention are:

[0021] The Ma protection level explosion-proof exhaust ventilator with internal positive pressure protection of the explosion-proof motor provided by the present invention is based on the common explosion-proof exhaust ventilator. The inner cavity of the explosion-proof motor is sealed and connected with the inner cavity of the junction box to form a pressurized sealed cavity, thereby preventing external explosive gas from entering the inner cavity of the explosion-proof motor and the junction box, so as to improve the protection level of the common explosion-proof exhaust ventilator to the Ma protection level.

[0022] Before operation, the original dirty air in the pressurized sealed chamber is replaced with fresh air through a non-explosive gas source in conjunction with an intake one-way solenoid valve and an exhaust one-way solenoid valve, thereby preventing the motor from being in an explosive gas environment before starting. During operation, the first pressure sensor, the second pressure sensor, and the methane concentration sensor monitor that the internal pressure of the pressurized sealed chamber is always higher than the maximum internal pressure of the fan, forming an internal positive pressure environment, and explosive gas cannot enter the flameproof motor and the junction box, thereby ensuring the safe and continuous operation environment of the motor. The master control equipment, electromagnetic control valve, and sensor are used for automatic control, and the control action is accurate, timely, and highly reliable, which greatly reduces the degree of manual participation, that is, it ensures the stability of the operation and reduces the labor intensity of the operator, so that the exhaust fan can be used in places with explosive gases, greatly reducing the pollution of the tunnel, creating a safe and healthy working environment, and clearing the technical obstacles for its use in coal tunnels, semi-coal-rock tunnels, rock tunnels with gas gushing, gas gushing areas, and protruding coal seams, and it can operate 24 hours uninterruptedly to continuously supply air to the working face.

[0023] Secondly, by using explosion-proof exhaust fans in underground coal mine tunnels, the polluted air in local air-using locations can be extracted and transported to a dedicated return air tunnel through wind ducts, avoiding large-scale pollution caused by polluted air flowing through other locations in the tunnel, which is beneficial to maintaining the non-explosiveness of the tunnel air and creating good working and hygiene conditions.

[0024] Other advantages, objectives and features of the present invention will be described in the following description to some extent, and to some extent, will be obvious to those skilled in the art based on the following examination and study, or can be taught from the practice of the present invention. The objectives and other advantages of the present invention can be realized and obtained through the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to make the purpose, technical solutions and advantages of the present invention more clear, the present invention will be described in detail below in conjunction with the accompanying drawings, wherein:

[0026] Figure 1 It is a structural schematic diagram of a Ma protection level explosion-proof exhaust ventilator with internal positive pressure protection of a flameproof motor in Example 1;

[0027] Figure 2 It is a partial structural schematic diagram of the junction box in Example 1;

[0028] Figure 3 It is a structural schematic diagram of a Ma protection level explosion-proof exhaust ventilator with internal positive pressure protection of a flameproof motor in Example 2;

[0029] Figure 4 This is a schematic diagram of the use process of a Ma protection level explosion-proof exhaust ventilator with positive pressure protection inside a flameproof motor in Example 1.

[0030] Figure numerals: static seal 1 at the front end of the motor housing, dynamic seal 2 at the motor rotating shaft, motor housing 3, motor housing body 31, front cover plate 32, rear cover plate 33, static seal 4 at the rear end of the motor housing, static seal 5 at the air inlet joint, explosion-proof air inlet joint 6, air inlet pipeline 7, air inlet one-way solenoid valve 8, motor outlet pipe 9, static seal 10 at the outlet pipe, static seal 11 at the junction box 12, junction box housing 121, junction box cover plate 122, exhaust one-way solenoid valve 13, static seal at the junction box cover plate 14, terminal 15, master control device 16, non-explosive gas source 17, first pressure sensor 18, second pressure sensor 19, methane concentration sensor 20. DETAILED DESCRIPTION

[0031] The following describes the embodiments of the present invention by specific examples, and those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that the illustrations provided in the following embodiments only illustrate the basic concept of the present invention in a schematic manner, and the following embodiments and features in the embodiments can be combined with each other without conflict.

[0032] Among them, the drawings are only used for illustrative explanations, and they only represent schematic diagrams rather than actual pictures, and should not be understood as limitations on the present invention. In order to better illustrate the embodiments of the present invention, some parts of the drawings may be omitted, enlarged or reduced, and do not represent the size of actual products. For those skilled in the art, it is understandable that some well-known structures and their descriptions in the drawings may be omitted.

[0033] The same or similar numbers in the drawings of the embodiments of the present invention correspond to the same or similar parts; in the description of the present invention, it should be understood that if the terms "upper", "lower", "left", "right", "front", "rear", etc. indicate the orientation or position relationship, they are based on the orientation or position relationship shown in the drawings, which is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operate in a specific orientation. Therefore, the terms describing the position relationship in the drawings are only used for illustrative purposes and cannot be understood as limiting the present invention. For ordinary technicians in this field, the specific meanings of the above terms can be understood according to specific circumstances.

[0034] See also Figure 1-2 , is a Ma protection level explosion-proof exhaust fan with positive pressure protection inside the explosion-proof motor. On the basis of the ordinary explosion-proof exhaust fan, safety facilities are added to the explosion-proof motor and the junction box. The safety facilities include a pressurized sealed chamber, a sensor, and a master control device 16. The ordinary explosion-proof exhaust fan includes a fan flow channel formed by a fan housing, a flameproof motor arranged in the fan housing, an impeller connected to the motor rotating shaft of the flameproof motor, and a junction box 12 for controlling the flameproof motor. The junction box is usually used as a fan power switch controller.

[0035] The flameproof motor comprises a motor winding and a motor housing 3 for accommodating the motor winding, the motor housing 3 comprises a motor housing body 31 for accommodating the motor winding and a front cover plate 32 and a rear cover plate 33 installed at both ends of the motor housing body, the motor rotating shaft of the flameproof motor passes through the front cover plate 32 and is connected to the impeller, and a motor outlet pipe 5 for leading out cables is provided on the motor housing body 31;

[0036] One end of the motor outlet pipe 5 away from the motor housing body 31 is in sealing contact with the outer side of the junction box 12 and communicates with the inner cavity of the junction box 12 .

[0037] Specifically, a front end static seal 1 and a rear end static seal 4 are respectively provided between the front end cover plate 32 and the rear end cover plate 33 and the motor housing body 31, a motor rotating shaft dynamic seal 2 is provided between the motor rotating shaft and the front end cover plate, and a wire outlet pipe static seal 6 is provided between the motor wire outlet pipe 5 and the motor housing body, so that the inner cavity of the motor housing 3 forms a sealed cavity.

[0038] The junction box 12 includes a junction box housing 121 and a junction box cover 122 buckled on the junction box housing 121. A junction terminal 13 for connecting an external cable and a cable in the motor outlet pipe 5 is provided at the bottom of the junction box housing 121.

[0039] The wiring terminal 15 passes through the junction box housing 121 and is inserted into the motor outlet pipe 9, and the bottom of the junction box housing 121 is in contact with the motor outlet pipe 9 to seal the opening of the motor outlet pipe 9, and there is a gap connection between the wiring terminal 15 and the junction box housing 121, so that the inner cavity of the motor outlet pipe 9 is connected to the inner cavity of the junction box, and then the inner cavity of the motor housing 3, the inner cavity of the motor outlet pipe 5 and the inner cavity of the junction box 12 are connected to each other to form a pressurized sealed cavity.

[0040] Preferably, a junction box cover plate static seal 14 is provided between the junction box housing 121 and the junction box cover plate 122, and a junction box static seal 11 is provided between the junction box housing and the motor outlet pipe to ensure the sealing of the junction box.

[0041] Specifically, a trumpet mouth (not shown) for entering and exiting external cables is provided on the side of the junction box housing 121, and a cable static seal is provided on the trumpet mouth to ensure that external gas is prevented from entering the sealed cavity of the junction box when the cable is connected; the motor outlet pipe 9 has a cable connecting the terminal 15 and the motor winding. The static seal and dynamic seal mentioned in this embodiment are generally sealed rings or other structures that can achieve corresponding functions.

[0042] The pressurized sealed cavity includes the inner cavity of the motor housing 3 (i.e., the inner cavity of the flameproof motor), the inner cavity of the motor outlet pipe 5, and the inner cavity of the junction box 12, and an air intake one-way solenoid valve 8 is connected to the motor housing body 31, and an exhaust one-way solenoid valve 13 is provided on the junction box 12 to discharge the explosive gas inside the pressurized sealed cavity before the flameproof motor is started, and form positive pressure protection in the pressurized sealed cavity.

[0043] Furthermore, a flameproof air inlet connector 6 is provided on the motor housing body 31 , and the air inlet one-way solenoid valve 8 is connected to the flameproof air inlet connector 6 via an air inlet pipeline 7 so as to be connected to the motor housing body 31 .

[0044] Furthermore, the air inlet one-way solenoid valve 8 is connected to a non-explosive gas source 17 to feed non-explosive gas into the pressurized sealed cavity.

[0045] Preferably, the sensor includes a second pressure sensor 19 and a methane concentration sensor 20 arranged on the junction box 12 to detect the pressure and methane concentration of the pressurized sealed chamber; and a first pressure sensor 18 arranged on the non-explosive gas source 17 to monitor the maximum pressure that can be applied to the pressurized sealed chamber.

[0046] Furthermore, the second pressure sensor 19 and the methane concentration sensor 20 are arranged on the upper part of the junction box 12 .

[0047] The master control device 16 is respectively connected to the first pressure sensor 18, the second pressure sensor 19, the methane concentration sensor 20, the intake one-way solenoid valve 8, the exhaust one-way solenoid valve 13 and the junction box 12 to achieve automatic control.

[0048] Preferably, the master control device 16 is placed in a non-explosive airflow tunnel underground, and is also electrically connected to the fan power switch controller (junction box) through a signal cable. By real-time collection of monitoring data from the first pressure sensor 18, the second pressure sensor 19 and the methane concentration sensor 20, control of the fan power switch controller, the air intake one-way solenoid valve 8 and the exhaust one-way solenoid valve 13 is achieved according to the internal control program of the master control device 16.

[0049] In this embodiment, the non-explosive gas source 17 is used to inject the compressed air or other non-explosive gas sources in the underground compressed air duct of the coal mine into the pressurized sealed cavity, so that the pressurized sealed cavity composed of the flameproof motor, the threading tube and the inner cavity of the junction box is always in a positive pressure environment, and the pressure in the pressurized sealed cavity is greater than the maximum pressure of the air outlet end of the fan impeller, so that the dirty air sucked by the fan impeller cannot enter the pressurized sealed cavity, ensuring that the flameproof motor always operates in a non-explosive gas environment. In this process, automatic control is performed through the master control equipment, electromagnetic control valve, sensor, etc., and the start and stop of the flameproof motor is controlled according to the operating environment parameters of the flameproof motor.

[0050] See also Figure 4 The steps for using the Ma protection level explosion-proof exhaust fan with positive pressure protection inside the above-mentioned explosion-proof motor are as follows:

[0051] S1: After completing the motor wiring in the junction box 12, close the junction box cover 122, remotely start the master control device 16, the master control device 16 controls the air intake one-way solenoid valve 8 and the exhaust one-way solenoid valve 13 to open, and the pressurized sealed chamber begins to be filled with non-explosive gas to replace the original air; when the predetermined ventilation time is reached and the methane concentration sensor 20 detects that the methane concentration in the pressurized sealed chamber is zero, close the exhaust one-way solenoid valve 13, continue to inflate the pressurized sealed chamber, and when the pressure in the pressurized sealed chamber reaches the set value P 21 (adaptable settings can be made according to actual needs) when the air intake one-way solenoid valve 8 is closed, the master control device 16 controls the fan power switch controller to start the fan flameproof motor;

[0052] S2: During the operation of the fan, the first pressure sensor 18, the second pressure sensor 19 and the methane concentration sensor 20 continuously monitor the parameters of the non-explosive gas source 17 and the internal pressure of the pressurized sealed chamber. When the pressure inside the pressurized sealed chamber is less than the set pressure P 22(It can be set adaptively according to actual needs) when the air inlet one-way solenoid valve 8 is opened to inflate the pressurized sealed cavity. When the pressure in the pressurized sealed cavity reaches the set value P 21 When the air inlet one-way solenoid valve 8 is closed, the fan continues to operate normally; when the methane concentration sensor 20 detects that there is methane in the pressurized sealed chamber or the pressure of the non-explosive gas source 17 is less than the set value P0 (which can be adaptively set according to actual needs), it will immediately feedback to the master control device 16, and then control the fan to stop and remind to check the gas source. It can only be restarted after the ventilation is qualified again and the pressure of the non-explosive gas source 17 is greater than P0 (which can be adaptively set according to actual needs);

[0053] S3: When the fan needs to be shut down for maintenance, the master control device 16 first controls the explosion-proof motor to be powered off, and then controls the air intake one-way solenoid valve 8 to be powered off, and then opens the exhaust one-way solenoid valve 13 to exhaust. When the pressure in the pressurized sealed chamber is consistent with the ambient pressure, the exhaust one-way solenoid valve 8 is closed, the master control device 16 is powered off, and the fan stops working before subsequent operations such as opening the cover for maintenance can be carried out.

[0054] Example 2

[0055] See also Figure 3 The difference between this embodiment and embodiment 1 is that the motor housing 3 includes a motor housing body 31 for accommodating the motor winding and a rear end cover plate 33 installed at the open end of the motor housing body 31, and the motor rotating shaft passes through the motor housing body 31 toward the end away from the rear end cover plate 33 to connect to the impeller.

[0056] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solution of the present invention can be modified or replaced by equivalents without departing from the purpose and scope of the technical solution, which should be included in the scope of the claims of the present invention.

Claims

1. A Ma protection level explosion-proof exhaust fan with internal positive pressure protection of a flameproof motor, comprising a fan flow channel, a flameproof motor arranged in the fan flow channel, an impeller drivingly connected to the flameproof motor, and a junction box for controlling the flameproof motor, characterized in that: It also includes a pressurized sealed cavity connecting the inner cavity of the flameproof motor and the inner cavity of the junction box, and the pressure of the pressurized sealed cavity is greater than the pressure in the fan flow channel, so that the explosive gas flowing through the fan flow channel cannot enter the pressurized sealed cavity.

2. The explosion-proof exhaust ventilator with Ma protection level and internal positive pressure protection for flameproof motor according to claim 1 is characterized in that: The pressurized sealed cavity includes an inner cavity of the flameproof motor, an inner cavity of the junction box, and an inner cavity of a motor outlet pipe for connecting the flameproof motor and the junction box; An air intake one-way solenoid valve is connected to the flameproof motor, and an exhaust one-way solenoid valve is provided on the junction box to discharge the explosive gas inside the pressurized sealed cavity before the flameproof motor is started and form positive pressure protection in the pressurized sealed cavity.

3. The explosion-proof exhaust ventilator with Ma protection level and internal positive pressure protection for flameproof motor according to claim 2 is characterized in that: The flameproof motor comprises a motor winding and a motor housing for accommodating the motor winding, the motor housing comprises a motor housing body and a front cover plate and a rear cover plate sealed at both ends of the motor housing body, and the motor rotating shaft seal of the flameproof motor passes through the front cover plate and is connected to the impeller; A motor outlet pipe for leading out cables is provided on the motor housing body, and one end of the motor outlet pipe away from the motor housing body is sealed and abutted against the outside of the junction box and connected to the inner cavity of the junction box to form a pressurized sealed cavity including the inner cavity of the flameproof motor, the inner cavity of the junction box and the inner cavity of the motor outlet pipe.

4. The explosion-proof exhaust ventilator with Ma protection level and internal positive pressure protection for flameproof motor according to claim 3 is characterized in that: A front end static seal and a rear end static seal are respectively provided between the front end cover plate, the rear end cover plate and the motor housing body, a motor rotating shaft dynamic seal is provided between the motor rotating shaft and the front end cover plate, and a wire outlet pipe static seal is provided between the motor wire outlet pipe and the motor housing body, so that the inner cavity of the motor housing forms a sealed cavity.

5. The explosion-proof exhaust ventilator with Ma protection level and internal positive pressure protection for flameproof motor according to claim 4 is characterized in that: The junction box comprises a junction box shell and a junction box cover plate buckled on the junction box shell, and a junction terminal is arranged at the bottom of the junction box shell; The wiring terminal penetrates through the junction box shell and is gap-connected, the motor outlet pipe is abutted against the bottom of the junction box shell, and is gap-connected with the junction box shell through the wiring terminal to communicate with the inner cavity of the junction box.

6. The explosion-proof exhaust ventilator with Ma protection level and internal positive pressure protection for flameproof motor according to claim 5 is characterized in that: A junction box cover plate static seal is provided between the junction box shell and the junction box cover plate, and a junction box static seal is provided between the junction box shell and the motor outlet pipe to ensure the sealing of the junction box and the motor outlet pipe.

7. The explosion-proof exhaust ventilator with Ma protection level and internal positive pressure protection for flameproof motor according to claim 6, characterized in that: A flameproof air inlet connector is provided on the motor housing body, and the air inlet one-way solenoid valve is connected to the flameproof air inlet connector through an air inlet pipeline so as to be connected to the flameproof motor.

8. The explosion-proof exhaust ventilator with Ma protection level and internal positive pressure protection for flameproof motor according to claim 7, characterized in that: The air intake one-way solenoid valve is connected to a non-explosive gas source to feed non-explosive gas into the pressurized sealed cavity.

9. The explosion-proof exhaust ventilator with Ma protection level and internal positive pressure protection for flameproof motor according to claim 8, characterized in that: A first pressure sensor is connected to the non-explosive gas source to monitor the maximum pressure applied by the non-explosive gas source to the pressurized sealed chamber. A second pressure sensor and a methane concentration sensor are arranged on the junction box to detect the pressure and methane concentration of the pressurized sealed chamber.

10. The explosion-proof exhaust ventilator with Ma protection level and internal positive pressure protection for flameproof motor according to claim 9, characterized in that: It also includes a master control device, in which the first pressure sensor, the second pressure sensor, the methane concentration sensor, the intake one-way solenoid valve, the exhaust one-way solenoid valve and the junction box are all connected to the master control device through signal cables, and the monitoring data of each sensor is collected in real time, combined with the internal control program of the master control device to control the junction box and each solenoid valve.

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