Micro positive pressure system in the cab

Abstract

The present invention discloses a micro-positive pressure system in a cab, comprising: a sheet metal shell, an air inlet channel and an exhaust channel, the air inlet channel and the exhaust channel are both connected to the inside and outside of the cab, the air inlet channel and the exhaust channel are both connected to the same full heat exchange core, an air inlet fan is arranged in the air inlet channel; an exhaust fan is arranged in the exhaust channel; the air intake volume of the air inlet fan is greater than the exhaust volume of the exhaust fan, and the air pressure in the cab is kept greater than the air pressure outside the cab by 15-40Pa. The present invention has a simple structure and a reasonable design, solves the sealing problem of the lower cab in the environment of severe dust in mining areas, uses a micro-positive pressure environment to prevent external dust from easily entering the cab, and realizes that the air temperature of the air inlet and the air outlet can adapt to the environment even if there is a large temperature difference between the inside and outside of the cab through the full heat exchange core, reduces the energy consumption of the system's cold and hot circulation device, and ensures the comfort level in the cab.

Description

Technical Field

[0001] The present invention relates to the field of supporting equipment for off-road wide-body dump trucks, and more specifically, to a micro-positive pressure system in a cab. Background Art

[0002] Off-road wide-body dump trucks are often used for transportation in dusty places. During operation, since the cab is not closed, dust can easily enter the cab, which can easily cause short circuits in the cab, affecting driving safety. On the other hand, dust can easily enter the driver's lungs, causing irreparable damage to the driver's health. In order to avoid the above situation, the common treatment method is to seal the cab.

[0003] At present, the domestic solutions for cab sealing of off-road wide-body dump trucks are to reduce the leakage points in the cab by changing the cab sheet metal structure and increasing the amount of sealant, thereby improving the sealing of the cab itself. However, it is impossible to eliminate all the leakage points in the cab.

[0004] When the cab's own sealing technology can no longer be improved after considering factors such as cost and technology, the air environment inside the cab is still not ideal due to the harsh dust environment in actual working conditions. At the same time, when the temperature difference between the inside and outside of the cab is too large, it places a great burden on the cab's temperature control system. Summary of the invention

[0005] An object of the present invention is to solve at least the above problems and to provide at least the advantages which will be described hereinafter.

[0006] Another object of the present invention is to provide a micro-positive pressure system in the cab, which has a simple structure and reasonable design. It solves the sealing problem of the lower cab in the environment of severe dust in mining areas. The micro-positive pressure environment is utilized to prevent external dust from easily entering the cab. Through the full heat exchange core, even if there is a large temperature difference between the inside and outside of the cab, the air temperature of the inlet and outlet can be adapted to the environment, thereby reducing the energy consumption of the system's hot and cold circulation device and ensuring the comfort level in the cab.

[0007] In order to achieve these purposes and other advantages according to the present invention, a micro-positive pressure system in a cab is provided, including a sheet metal shell, an air inlet channel and an exhaust channel, the air inlet channel and the exhaust channel are both connected to the cab and the outside of the cab, the air inlet channel and the exhaust channel are both connected to the same full heat exchange core, an air inlet fan is provided in the air inlet channel; an exhaust fan is provided in the exhaust channel; the air intake volume of the air inlet fan is greater than the exhaust volume of the exhaust fan, so that the air pressure in the cab is kept greater than the air pressure outside the cab by 15 to 40 Pa.

[0008] Preferably, the air inlet fan and the air exhaust fan are connected by controlling an electrically controlled air pressure sensor.

[0009] Preferably, the air inlet of the air inlet channel is covered with an external air inlet grille, the air inlet of the exhaust channel is covered with an internal exhaust grille, the air outlet of the exhaust channel is covered with an external exhaust grille, and the air outlet of the air inlet channel is covered with an internal air inlet grille.

[0010] Preferably, an air inlet filter is provided in the air inlet channel near the external air inlet grille, and an exhaust filter is provided in the exhaust channel between the internal exhaust grille and the total heat exchange core in the exhaust channel.

[0011] Preferably, an air inlet pressure maintaining damper assembly is provided in the air inlet channel close to the air inlet of the air inlet channel.

[0012] Preferably, an exhaust pressure maintaining damper assembly is provided in the exhaust channel near the exhaust channel outlet.

[0013] Preferably, a negative ion generator is provided in the air inlet channel.

[0014] Preferably, a time delay relay is provided between the booster fan connected to the air inlet fan.

[0015] Preferably, the power supply system of the micro-positive pressure system in the cab is connected to a system restart switch.

[0016] Preferably, it also includes a system control circuit, which includes a power supply, an ignition switch, two relays, a time delay relay, an electronically controlled air pressure sensor controller and a system component; wherein the system component includes a negative ion generator, an exhaust motor, an exhaust fan of the exhaust fan, an air intake motor, and a booster fan of the air intake fan;

[0017] The system control circuit is electrically connected through a control harness; specifically, the ignition switch controls the access of the system control circuit power supply through a relay, the negative ion generator, the exhaust motor, the exhaust fan, the air intake motor and the time delay relay are all connected in parallel, and the electronically controlled air pressure sensor controller is connected in series with another relay and then connected to the main switch control of the negative ion generator, the exhaust motor, the exhaust fan, the air intake motor and the time delay relay; the boost fan is directly connected to the power supply, and the time delay relay is connected to the switch control of the boost fan.

[0018] The present invention has at least the following beneficial effects:

[0019] 1. Set the air inlet fan and the air outlet fan so that the air intake of the air inlet fan is greater than the air intake of the air outlet fan. The air pressure in the cab is in a slightly positive pressure state. Since the air pressure in the cab is greater than the outside air pressure, dust from the outside environment cannot easily enter the cab, which solves the sealing problem of the cab in the environment of severe dust in the mining area. At the same time, since the slightly positive pressure system is always in a ventilation state, the driver will not feel suffocated, and fine dust is prevented from entering the cab, causing adverse effects on the circuits in the cab and the health of the driver;

[0020] 2. A full heat exchange core is set in the micro-positive pressure system. When the temperature difference between the inside and outside of the cab is too large, the workload of the cab temperature control device will not be increased due to frequent ventilation, which reduces energy consumption, ensures the comfort of the driver, and extends the service life of the temperature control device; the built-in negative ion generator can further purify the air quality in the cab and improve the air quality in the cab;

[0021] 3. Set a delay relay to control the operation of the booster fan, so that when the indoor and outdoor air pressure difference reaches 40Pa, the circuit is closed, and the booster fan continues to run for 3 seconds before stopping, delaying the shutdown to achieve the pressure maintenance function; set a negative pressure power-off to effectively remind the driver to clean or replace the filter in time, improve the use effect of the device, create a better driving environment for the cab, and ensure the health of the driver.

[0022] Other advantages, objectives and features of the present invention will be embodied in part through the following description, and in part will be understood by those skilled in the art through study and practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 This is a schematic diagram of the structure of a micro-positive pressure system in the cab according to one of the technical solutions of the present invention;

[0024] Figure 2 A schematic diagram of the wind direction of the micro-positive pressure system in the cab according to one of the technical solutions of the present invention;

[0025] Figure 3 This is a schematic diagram of the system control circuit of the micro-positive pressure system in the cab described in one of the technical solutions of the present invention. DETAILED DESCRIPTION

[0026] The present invention is further described in detail below in conjunction with the accompanying drawings so that those skilled in the art can implement the invention with reference to the description.

[0027] It should be understood that terms such as “having”, “including” and “comprising” used herein do not specify the existence or addition of one or more other elements or combinations thereof.

[0028] like Figure 1-3As shown, the present invention provides a micro-positive pressure system in a cab, comprising:

[0029] A sheet metal shell 19 is provided with an air inlet channel and an air exhaust channel in the sheet metal shell 19, the air inlet channel and the air exhaust channel are both connected to the inside and outside of the cab, the air inlet channel and the air exhaust channel are connected in a cross shape through a full heat exchange core 2, the full heat exchange core 2 is used to exchange heat in the air intake and exhaust, so as to achieve the stability of the energy consumption of the temperature control device in the cab; an air inlet fan 4 is provided in the air inlet channel, and the air inlet fan 4 is controlled and connected to an air inlet fan and a boost fan; an exhaust fan 13 is provided in the exhaust channel; the air inlet fan 4 The amount is greater than the exhaust volume of the exhaust fan 13, and the air pressure in the cab is kept greater than the air pressure outside the cab by 15-40Pa, so that the cab is in a state of micro-positive pressure, so that the dust outside the cab of the dump truck during use will not or will not easily enter the cab due to the existence of micro-positive pressure, causing pollution to the environment in the cab. At the same time, when the pressure difference between the inside and outside of the cab is 15-40Pa, the driver's body will not feel uncomfortable, ensuring driving safety; the sheet metal shell 19 is also covered with a layer of sound insulation and sealing cotton, which has the effect of reducing the noise of the micro-positive pressure system;

[0030] By adopting this technical solution, an air inlet fan 4 and an air outlet fan are set so that the air intake of the air inlet fan 4 is greater than the air intake of the air outlet fan, and the air pressure in the cab is in a slightly positive pressure state. Since the air pressure in the cab is greater than the external air pressure, dust from the external environment cannot easily enter the cab, thereby solving the sealing problem of the cab in an environment with severe dust in mining areas. At the same time, since the slightly positive pressure system is always in a ventilation state, the driver will not feel suffocated, and at the same time, fine dust is prevented from entering the cab and causing adverse effects on the circuits in the cab and the health of the driver. A full heat exchange core 2 is set in the slightly positive pressure system. When the temperature difference between the inside and outside of the cab is too large, the workload of the temperature control device in the cab will not be increased due to frequent ventilation, thereby reducing energy consumption, ensuring the comfort of the driver, and extending the service life of the temperature control device.

[0031] In another technical solution, a micro-positive pressure system in a cab comprises: a sheet metal shell 19, an air inlet channel and an air exhaust channel arranged in the sheet metal shell 19, the air inlet channel and the air exhaust channel are both connected to the cab and the outside of the cab, the air inlet channel and the air exhaust channel are connected in a cross shape through a full heat exchange core 2, the full heat exchange core 2 is used to exchange heat in the air between the intake and exhaust air, so as to achieve the stability of the energy consumption of the temperature control device in the cab; an air inlet fan 4 is arranged in the air inlet channel; an exhaust fan 13 is arranged in the exhaust channel; the air intake volume of the air inlet fan 4 is greater than the exhaust volume of the exhaust fan 13, so that the air pressure in the cab is kept greater than the air pressure outside the cab by 15-40Pa ... The dump truck is in a state of micro-positive pressure, so that dust outside the cab of the dump truck will not or will not easily enter the cab during use due to the existence of micro-positive pressure, causing pollution to the environment inside the cab. At the same time, when the pressure difference between the inside and outside of the cab is between 15 and 40 Pa, the driver will not feel uncomfortable, ensuring driving safety. The air intake fan and the exhaust fan are connected through an electrically controlled air pressure sensor; the electrically controlled air pressure sensor has two air pressure monitoring probes, one indoor and one outdoor, which monitor the changes in indoor and outdoor air pressure in real time. When the indoor and outdoor air pressure difference is greater than or equal to 40 Pa, the system is powered off; the cab pressure relief is a natural leak, and the 40 Pa air pressure difference will be reduced to 15 Pa within 5 seconds, and the system is powered on to form a cycle;

[0032] The air inlet of the air inlet channel is covered with an external air inlet grille 9, the air inlet of the exhaust channel is covered with an internal exhaust grille 6, the air outlet of the exhaust channel is covered with an external exhaust grille 14, and the air outlet of the air inlet channel is covered with an internal air inlet grille 3. The external air inlet grille 9 and the internal exhaust grille 6 can prevent dust from clogging the air inlet and exhaust channels, prevent foreign objects from entering the system, and ensure the normal operation of the micro-positive pressure system in the cab; the external exhaust grille 14 and the internal air inlet grille 3 can reduce the noise generated by the operation of the fan or motor in the system, and improve the comfort of using the micro-positive pressure system in the cab.

[0033] In another technical solution, the micro-positive pressure system in the cab comprises: a sheet metal shell 19, an air inlet channel and an air exhaust channel arranged in the sheet metal shell 19, the air inlet channel and the air exhaust channel are both connected to the inside and outside of the cab, the air inlet channel and the air exhaust channel are connected in a cross shape through a full heat exchange core 2, the full heat exchange core 2 is used to heat exchange the heat in the intake and exhaust air to achieve the stability of the energy consumption of the temperature control device in the cab; the air inlet channel is provided with an air inlet fan 4; the exhaust channel is provided with an exhaust fan 13; The air intake volume of the air intake fan 4 is greater than the exhaust volume of the exhaust fan 13, and the air pressure in the cab is kept greater than the air pressure outside the cab by 15-40Pa, so that the cab is in a state of slight positive pressure, so that during the use of the dump truck, dust outside the cab will not or will not easily enter the cab due to the existence of slight positive pressure, causing pollution to the environment in the cab. At the same time, when the pressure difference between the inside and outside of the cab is 15-40Pa, the driver's body will not feel uncomfortable, ensuring driving safety; the air intake fan and the exhaust fan are connected by an electronically controlled air pressure sensor The electronically controlled air pressure sensor has two air pressure monitoring probes, one for indoors and one for outdoors, which monitor the changes in indoor and outdoor air pressure in real time. When the pressure difference between indoor and outdoor is greater than or equal to 40Pa, the system is powered off. The pressure relief in the cab is a natural leakage, and the 40Pa pressure difference will be reduced to 15Pa within 5 seconds. The system is powered on to form a cycle. In addition, the air inlet of the air inlet channel is covered with an external air inlet grille 9, the air inlet of the exhaust channel is covered with an internal exhaust grille 6, and the air outlet of the exhaust channel is covered with an external exhaust grille 14. The air outlet of the channel is covered with an internal air inlet grille 3, an air inlet filter 8 is provided in the air inlet channel near the external air inlet grille 9, and an exhaust filter 7 is provided in the exhaust channel between the internal exhaust grille 6 and the full heat exchange core 2. By arranging the air inlet filter 8 and the exhaust filter 7, the quality of ventilation of the micro-positive pressure system in the cab can be further improved. The air inlet filter 8 can play a filtering and purification role when the air quality outside the cab is poor. The exhaust filter 7 can effectively filter impurities in the exhausted wind to prevent the system from being dirty and blocked.

[0034] In another technical solution, the micro-positive pressure system in the cab includes: a sheet metal shell 19, an air inlet channel and an air exhaust channel arranged in the sheet metal shell 19, the air inlet channel and the air exhaust channel are connected to the inside and outside of the cab, the air inlet channel and the air exhaust channel are connected in a cross shape through a full heat exchange core 2, and the full heat exchange core 2 is used to heat exchange the heat in the intake and exhaust air to achieve the stability of the energy consumption of the temperature control device in the cab; the air inlet channel is provided with an air inlet fan 4; the exhaust channel is provided with an exhaust fan 13; the air intake volume of the air intake fan 4 is greater than the exhaust volume of the exhaust fan 13, and the air pressure in the cab is kept greater than the air pressure outside the cab by 15-40Pa, so that the cab is in a state of slight positive pressure, so that during the use of the dump truck, the dust outside the cab will not or will not easily enter the cab due to the existence of slight positive pressure, causing pollution to the environment in the cab. At the same time, when the pressure difference between the inside and outside of the cab is 15-40Pa, the driver's body will not feel uncomfortable, ensuring the safety of driving; the air intake fan and the exhaust fan The machine is controlled and connected through an electronically controlled air pressure sensor; the electronically controlled air pressure sensor has two air pressure monitoring probes, one probe for indoors and one for outdoors, which monitor the changes in indoor and outdoor air pressure in real time. When the indoor and outdoor air pressure difference is greater than or equal to 40Pa, the system is powered off; the cab pressure relief is a natural leakage, and the 40Pa air pressure difference will be reduced to 15Pa within 5 seconds, and the system is powered on to form a cycle; an air inlet pressure maintaining damper assembly 10 is provided in the air inlet channel near the air inlet of the air inlet channel; an exhaust pressure maintaining damper assembly 15 is provided in the exhaust channel near the air outlet of the exhaust channel, Among them, the air inlet pressure maintaining damper assembly 10 includes: an air inlet motor 11 and an air inlet sealing plate body with a rotating shaft, the air inlet motor 11 drives the rotating shaft to rotate and then adjusts the area of ​​the air inlet sealed by the air inlet sealing plate body, thereby adjusting the air volume; the exhaust air pressure maintaining damper assembly 15 includes: an exhaust motor 12 and an exhaust sealing plate body with a rotating shaft, the exhaust motor 12 drives the rotating shaft to rotate and then adjusts the area of ​​the exhaust outlet closed by the exhaust sealing plate body, thereby adjusting the air outlet; adopting this technical solution, the pressure relief of the cab can be effectively delayed.

[0035] In another technical solution, the micro-positive pressure system in the cab comprises: a sheet metal shell 19, an air inlet channel and an air exhaust channel arranged in the sheet metal shell 19, the air inlet channel and the air exhaust channel are connected to the inside and outside of the cab, the air inlet channel and the air exhaust channel are connected in a cross shape through a full heat exchange core 2, the full heat exchange core 2 is used to heat exchange the heat in the intake and exhaust air to achieve the stability of the energy consumption of the temperature control device in the cab; an air inlet fan 4 is arranged in the air inlet channel; an exhaust fan 13 is arranged in the exhaust channel; the air inlet fan The air intake volume of the exhaust fan 4 is greater than the exhaust volume of the exhaust fan 13, and the air pressure in the cab is kept greater than the air pressure outside the cab by 15-40Pa, so that the cab is in a state of slight positive pressure. When the dump truck is in use, the dust outside the cab will not or will not easily enter the cab due to the existence of slight positive pressure, thereby polluting the environment inside the cab. At the same time, when the pressure difference between the inside and outside of the cab is 15-40Pa, the driver will not feel uncomfortable, thereby ensuring the safety of driving. In addition, the air inlet of the air inlet channel is covered with an external air inlet grille 9, and the exhaust grille 9 is provided on the outside of the air inlet channel. The air inlet of the air channel is covered with an internal exhaust grille 6, the air outlet of the exhaust channel is covered with an external exhaust grille 14, the air outlet of the air inlet channel is covered with an internal air inlet grille 3, an air inlet filter 8 is provided in the air inlet channel near the external air inlet grille 9, an exhaust filter 7 is provided in the exhaust channel between the internal exhaust grille 6 and the full heat exchange core 2 in the exhaust channel, an air inlet pressure maintaining damper assembly 10 is provided in the air inlet channel near the air inlet of the air inlet channel; an exhaust pressure maintaining damper assembly 10 is provided in the exhaust channel near the air outlet of the exhaust channel Component 15, wherein the air inlet pressure maintaining damper assembly 10 comprises: an air inlet motor 11 and an air inlet sealing plate body with a rotating shaft, wherein the air inlet motor 11 drives the rotating shaft to adjust the area of ​​the air inlet sealed by the air inlet sealing plate body, thereby adjusting the air volume; the exhaust air pressure maintaining damper assembly 15 comprises: an exhaust air motor 12 and an exhaust air sealing plate body with a rotating shaft, wherein the exhaust air motor 12 drives the rotating shaft to adjust the area of ​​the exhaust air sealing plate body closing the exhaust air port, thereby adjusting the air volume; a negative ion generator 5 is also arranged in the air inlet duct to perform secondary purification on the incoming air;

[0036] In addition, the micro-positive pressure system in the cab is also provided with a system control circuit, which includes: a power supply, an ignition switch, two relays, a delay relay 17, an electronically controlled air pressure sensor controller 1 and system components;

[0037] Among them, the system components include a negative ion generator 5, an exhaust motor 12, an exhaust fan, an air intake motor 11 and a boost fan;

[0038] The system control circuit is electrically connected through the control harness 16; specifically, the ignition switch controls the access of the circuit power supply through a relay control system, the negative ion generator 5, the exhaust motor 12, the exhaust fan, the air intake motor 11 and the delay relay 17 are all connected in parallel, and the electronically controlled air pressure sensor controller 1 is connected in series with another relay and then connected to the total switch control of the negative ion generator 5, the exhaust motor 12, the exhaust fan, the air intake motor 11 and the delay relay 17; the boost fan is directly connected to the power supply, and the delay relay 17 is connected to the switch control of the boost fan; adopting this technical solution, The system is safer and more efficient during operation. By setting a delay relay 17 to control the operation of the booster fan, when the indoor and outdoor air pressure difference reaches 40Pa, the circuit is closed, and the booster fan continues to run for 3 seconds before stopping, and the shutdown is delayed to realize the pressure maintenance function of the micro-positive pressure system. In addition, compared with the exhaust filter, the air inlet filter is more likely to get dirty and clogged. In this case, the air pressure in the cab may form a negative pressure with the outdoor air pressure, and outdoor dust will more easily enter the cab. When the negative pressure reaches -10Pa, the circuit is disconnected and the micro-positive pressure system stops working to remind the driver to clean or replace the filter, and then press the system restart switch 18 connected to the power supply, and the system will resume normal operation.

[0039] The air inlet fan and the exhaust fan are connected through the control of an electrically controlled air pressure sensor; the electrically controlled air pressure sensor has two air pressure monitoring probes, one probe indoors and one probe outdoors, which monitor the changes in indoor and outdoor air pressure in real time. When the air pressure difference between indoor and outdoor is greater than or equal to 40Pa, the system circuit is automatically closed and the air inlet pressure maintaining damper is closed; the cab pressure relief is a natural leakage, and the 40Pa pressure difference will be relieved to 15Pa within 5 seconds. The system control circuit is restarted, and the air inlet pressure maintaining damper is opened to form a cycle.

[0040] The specific air intake and exhaust paths of the micro-positive pressure system are as follows:

[0041] Air intake path: fresh air outside the cab → external air intake grille 9 → air intake filter 8 → air intake pressure damper assembly 10 → full heat exchange core 2 → negative ion generator 5 → air intake fan 4 → inside the cab

[0042] Exhaust path: turbid air in the cab → internal air intake grille 3 → exhaust filter 7 → full heat exchange core 2 → exhaust pressure damper assembly 15 → exhaust fan 13 → outside of the cab

[0043] The number of devices and processing scales described here are used to simplify the description of the present invention. The application, modification and variation of the micro-positive pressure system in the cab of the present invention are obvious to those skilled in the art.

[0044] Although the embodiments of the present invention have been disclosed as above, they are not limited to the applications listed in the specification and the implementation modes, and they can be fully applied to various fields suitable for the present invention. For those familiar with the art, additional modifications can be easily implemented. Therefore, without departing from the general concept defined by the claims and the scope of equivalents, the present invention is not limited to the specific details and the illustrations shown and described herein.

Claims

1. A micro-positive pressure system in the cab, comprising a sheet metal shell, an air inlet channel and an air exhaust channel, wherein the air inlet channel and the air exhaust channel are both connected to the cab and outside the cab, and characterized in that: The air inlet channel and the air exhaust channel are both connected to the same full heat exchange core, an air inlet fan is provided in the air inlet channel; an air exhaust fan is provided in the air exhaust channel; the air intake volume of the air inlet fan is greater than the air exhaust volume of the exhaust fan, and the air pressure in the cab is kept greater than the air pressure outside the cab by 15-40Pa; It also includes: an air inlet pressure-maintaining damper, an air exhaust pressure-maintaining damper, and a system control circuit, wherein the system control circuit includes a power supply, an ignition switch, two relays, a time delay relay, an electronically controlled air pressure sensor controller, and a system component; wherein the system component includes a negative ion generator, an exhaust motor, an exhaust fan of the exhaust fan, an air inlet motor, and a booster fan of the air inlet fan; The system control circuit is electrically connected via a control harness; specifically, the ignition switch controls the access of the power supply of the system control circuit via a relay, the negative ion generator, the exhaust motor, the exhaust fan, the air intake motor and the time delay relay are all connected in parallel, and the electronically controlled air pressure sensor controller is connected in series with another relay and then connected to the main switch control of the negative ion generator, the exhaust motor, the exhaust fan, the air intake motor and the time delay relay; the boost fan is directly connected to the power supply, and the time delay relay is connected to the switch control of the boost fan; The air inlet fan and the air exhaust fan are controlled and connected via an electrically controlled air pressure sensor; When the pressure difference between indoor and outdoor is greater than or equal to 40Pa, the system is powered off; the boost fan continues to run for 3 seconds before stopping and delaying shutdown; the cab pressure relief is a natural leakage, the 40Pa pressure difference is relieved to 15Pa, the system is powered on, forming a cycle; the power supply of the micro-positive pressure system in the cab is connected to a restart switch, when the negative pressure reaches -10Pa, the circuit is disconnected, and the micro-positive pressure system stops working.

2. The micro-positive pressure system in the cab as claimed in claim 1, characterized in that: The air inlet of the air inlet channel is covered with an external air inlet grille, the air inlet of the exhaust channel is covered with an internal exhaust grille, the air outlet of the exhaust channel is covered with an external exhaust grille, and the air outlet of the air inlet channel is covered with an internal air inlet grille.

3. The micro-positive pressure system in the cab as claimed in claim 2, characterized in that: An air inlet filter is provided in the air inlet channel near the external air inlet grille, and an exhaust filter is provided in the exhaust channel between the internal exhaust grille and the total heat exchange core in the exhaust channel.

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