Cargo cabin fan control system and control method

Abstract

The invention relates to the technical field of ship ventilation, in particular to a cargo compartment fan control system and a control method, which are used for judging the types of containers in a cargo compartment by arranging a cargo loading computer. The control box can control the first frequency conversion draught fan of the corresponding cargo hold to work in different states according to different container types, and therefore the complex storage environment requirement is met. And meanwhile, the purposes of accurate temperature control, energy conservation and emission reduction are achieved by utilizing the frequency conversion characteristic of the first frequency conversion fan.

Description

Technical Field

[0001] The present invention relates to the technical field of ship ventilation, and in particular to a cargo hold fan control system and a control method. Background Art

[0002] Large container ships are usually equipped with multiple cargo holds and hundreds of fans to ventilate each cargo hold. In the prior art, fixed-speed fans or two-speed fans are usually used to control the start and stop of the fans by sensing the temperature inside the cargo hold, so as to achieve the purpose of ventilating each cargo hold area. However, since the types of containers in each cargo hold may be different, including dangerous goods containers and refrigerated containers, the storage environment requirements in the cargo hold are also different. Relying solely on temperature monitoring to control the start and stop of fixed-speed fans or two-speed fans can no longer meet the complex storage environment requirements. Summary of the invention

[0003] In view of the shortcomings of the prior art mentioned above, an object of the present invention is to provide a cargo hold fan control system and control method, which are used to solve the problem that the prior art only relies on temperature monitoring to control the start and stop of a fixed-speed fan or a two-speed fan, which can no longer meet the requirements of a complex storage environment.

[0004] To achieve the above-mentioned purpose and other related purposes, the present invention provides a cargo hold fan control system, the control system includes a control box, a frequency converter, a first frequency converter fan, a temperature sensor and a cargo loading computer, each cargo hold is provided with the first frequency converter fan and the temperature sensor, the first frequency converter fan is used for ventilation of the cargo hold, the temperature sensor is used for monitoring the temperature in the cargo hold, each of the first frequency converter fans is electrically connected to a frequency converter, the frequency converter is used for controlling the rotation speed of the first frequency converter fan, the frequency converter, the temperature sensor and the cargo loading computer are all electrically connected to the control box, the cargo loading computer is used for acquiring data of containers in the cargo hold and transmitting it to the control box.

[0005] Optionally, the control system also includes a fire alarm system and a monitoring alarm system, both of which are electrically connected to the control box. The fire alarm system is used to monitor whether a fire occurs in the cargo hold, and the monitoring alarm system is used to obtain data from the control box and determine whether to issue an alarm based on the data.

[0006] Optionally, the control system also includes a CO2 sensor and a second variable frequency fan. The CO2 sensor and the second variable frequency fan are provided in each cargo hold. The CO2 sensor is used to monitor the concentration of CO2 in the cargo hold. The second variable frequency fan is used to accelerate the discharge of CO2 in the cargo hold. Each of the second variable frequency fans is electrically connected to a corresponding frequency converter, and the frequency converter can control the rotation speed of the second variable frequency fan. The CO2 sensor is electrically connected to the control box.

[0007] Optionally, the control box includes a main control box and multiple sub-control boxes, and the multiple sub-control boxes are electrically connected to the main control box. The main control box is used to send instructions to the sub-control boxes and receive information from the sub-control boxes. Each of the sub-control boxes is electrically connected to the frequency converter, the temperature sensor and the CO2 sensor. The sub-control boxes are used to collect signals from the frequency converter, the temperature sensor and the CO2 sensor and receive instructions from the main control box. The cargo loading computer, the fire alarm system and the monitoring alarm system are all electrically connected to the main control box.

[0008] Optionally, each of the sub-control boxes is electrically connected to a plurality of the frequency converters, and the plurality of frequency converters are installed in the corresponding sub-control box.

[0009] Optionally, the sub-control box includes a box body, and a control panel is arranged on the side wall of the box body, the control panel includes a control knob and a plurality of operation indicator lights, the control knob is used to control the on and off of the power supply of the sub-control box, and the plurality of operation indicator lights are respectively used to indicate the operating status of each of the inverters in the sub-control box.

[0010] Optionally, a vent is provided on the top of the box body, the vent is arranged in a grid shape, a waterproof cover is provided above the vent, and a plurality of cable stuffing boxes are provided at the bottom of the box body.

[0011] Optionally, the first variable frequency fan, the second variable frequency fan and the temperature sensor are all arranged on the top layer of the cargo hold, and the CO2 sensor is arranged on the bottom layer of the cargo hold.

[0012] Optionally, the main control box is connected to the sub-control box via a CAT6A network cable, and the cargo loading computer, the fire alarm system and the monitoring alarm system are all connected to the main control box via an RS485 cable.

[0013] The present invention also provides a cargo hold fan control method, based on any of the above cargo hold fan control systems, the control method comprises:

[0014] Determine whether there are dangerous goods containers in the cargo hold;

[0015] If yes, control the first variable frequency fan in the corresponding cargo hold to run at full speed and maintain it until the end of the shipping; if no, determine whether there is a refrigerated container in the cargo hold;

[0016] If yes, control the first variable frequency fan in the corresponding cargo hold to operate at a first set speed; if no, control the first variable frequency fan in the corresponding cargo hold to operate normally at a second set speed; wherein the first set speed is greater than the second set speed;

[0017] Determine whether the temperature in the cargo hold where no dangerous goods container exists is within the set temperature range;

[0018] If the temperature is higher than the set temperature range, the first variable frequency fan in the corresponding cargo hold is controlled to gradually accelerate; if the temperature is lower than the set temperature range, the first variable frequency fan in the corresponding cargo hold is controlled to gradually decelerate;

[0019] Determine whether the concentration of CO2 in the cargo hold is within the set concentration range;

[0020] If not, control the second variable frequency fan in the corresponding cargo hold to gradually slow down until it stops;

[0021] Determine whether there is a fire in the cargo hold;

[0022] If yes, control the first variable frequency fan and the second variable frequency fan in the corresponding cargo hold to stop running;

[0023] In a cargo hold fan control system and control method of the present invention, a cargo loading computer is provided to judge the type of container in the cargo hold. The control box can control the first variable frequency fan of the corresponding cargo hold to work in different states according to different types of containers, thereby meeting complex storage environment requirements. At the same time, the variable frequency characteristics of the first variable frequency fan are utilized to achieve the purpose of precise temperature control, energy saving and emission reduction. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is a principle block diagram of a cargo hold fan control system according to an embodiment of the present invention.

[0025] Figure 2 is a schematic diagram of the location distribution of the temperature sensor and the CO2 sensor in the cargo hold in one embodiment of the present invention;

[0026] Figure 3 is a schematic structural diagram of a sub-control box in one embodiment of the present invention;

[0027] Figure 4 It is a flow chart of a cargo hold fan control method according to an embodiment of the present invention. DETAILED DESCRIPTION

[0028] Refer to the following Figures 1 to 4To describe a cargo hold fan control system and control method of the present invention. In the description of this embodiment, it should be understood that the terms "first" and "second" are used for descriptive purposes only, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features, that is, include one or more of the features. In the description of the present invention, the meaning of "multiple" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined. When a feature "includes or contains" one or some of the features it covers, unless otherwise specifically described, this indicates that other features are not excluded and may further include other features.

[0029] Unless otherwise clearly defined and limited, the terms "set", "install", "connect", "connect", "fix", "couple" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral one; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements, unless otherwise clearly defined. A person skilled in the art should be able to understand the specific meanings of the above terms in the present invention according to the specific circumstances.

[0030] In addition, in the description of this embodiment, the first feature being "above" or "below" the second feature may include the first and second features being in direct contact, or may include the first and second features not being in direct contact but being in contact through another feature between them. That is, in the description of this embodiment, the first feature being "above", "above", and "above" the second feature includes the first feature being directly above and obliquely above the second feature, or simply indicates that the first feature is higher in level than the second feature. The first feature being "below", "below", or "below" the second feature may mean that the first feature is directly below or obliquely below the second feature, or simply indicates that the first feature is lower in level than the second feature.

[0031] In the description of the present embodiment, the description with reference to the terms "one embodiment", "some embodiments", "illustrative embodiments", "examples", "specific examples", or "some examples" means that the specific features, structures, materials, or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described may be combined in any one or more embodiments or examples in a suitable manner.

[0032] like Figure 1-Figure 3As shown, an embodiment of the present invention provides a cargo hold fan control system, including a control box, a frequency converter 3, a first frequency converter fan 41, a temperature sensor 5 and a cargo loading computer 8. A first frequency converter fan 41 and a temperature sensor 5 are provided in each cargo hold 10. The first frequency converter fan 41 is used for ventilation of the cargo hold 10, and the temperature sensor 5 is used for monitoring the temperature in the cargo hold 10. Each first frequency converter fan 41 is electrically connected to a frequency converter 3, and the frequency converter 3 is used to control the rotation speed of the first frequency converter fan 41. The frequency converter 3, the temperature sensor 5 and the cargo loading computer 8 are all electrically connected to the control box. The cargo loading computer 8 is used to obtain the data of the container in the cargo hold 10 and transmit it to the control box.

[0033] The cargo loading computer 8 determines the type of container in the cargo hold 10 to obtain information about the cargo hold 10 loaded with dangerous goods containers and refrigerated containers, and transmits the information to the control box. For the cargo hold 10 loaded with dangerous goods containers, in order to ensure the safety of the air quality in the corresponding cargo hold 10, the control box controls the first variable frequency fan 41 to run at full speed through the inverter 3 of the corresponding cargo hold 10, and keeps it running until the end of this shipping.

[0034] For a cargo hold 10 loaded with a refrigerated container, the control box controls the first variable frequency fan 41 to start at the first set speed through the inverter 3 of the corresponding cargo hold 10. For a cargo hold 10 loaded with neither a dangerous goods container nor a refrigerated container, the control box controls the first variable frequency fan 41 to start at the second set speed through the inverter 3 of the corresponding cargo hold 10. Since the ambient temperature required by the cargo hold 10 loaded with a refrigerated container is lower, the first set speed is set to be greater than the second set speed.

[0035] When the temperature sensor 5 detects that the temperature of the cargo hold 10 without any dangerous goods container is lower than the set temperature, the temperature sensor 5 transmits a signal to the control box, and the control box controls the first variable frequency fan 41 to gradually slow down until it stops through the inverter 3 corresponding to the cargo hold 10. When the temperature sensor 5 detects that the temperature of the cargo hold 10 without any dangerous goods container is higher than the set temperature, the temperature sensor 5 transmits a signal to the control box, and the control box controls the first variable frequency fan 41 to accelerate step by step through the inverter 3 corresponding to the cargo hold 10, and the cycle repeats.

[0036] By setting the cargo loading computer 8, the type of container in the cargo hold 10 is judged. The control box can control the first variable frequency fan 41 of the corresponding cargo hold 10 to work in different states according to different container types, thereby meeting complex storage environment requirements. At the same time, the variable frequency characteristics of the first variable frequency fan 41 are used to achieve the purpose of precise temperature control, energy saving and emission reduction.

[0037] Optionally, the first variable frequency fan 41 is set to ten gears, and the rotation speed of the first variable frequency fan 41 is from low to high according to the gear size. For the cargo hold 10 loaded with dangerous goods containers, the first variable frequency fan 41 runs at ten gears. For the cargo hold 10 loaded with refrigerated containers, the first variable frequency fan 41 is started at five gears, and for the cargo hold 10 not loaded with refrigerated containers, the first variable frequency fan 41 is started at one gear. Optionally, the first variable frequency fan 41 realizes ventilation by delivering air into the cargo hold 10.

[0038] Furthermore, the control system also includes a CO2 sensor 6 and a second variable frequency fan 42. A CO2 sensor 6 and a second variable frequency fan 42 are provided in each cargo hold 10. The CO2 sensor 6 is used to monitor the concentration of CO2 in the cargo hold 10, and the second variable frequency fan 42 is used to accelerate the discharge of CO2 in the cargo hold 10. Each second variable frequency fan 42 is electrically connected to a frequency converter 3, and the frequency converter 3 can control the rotation speed of the second variable frequency fan 42. The CO2 sensor 6 is electrically connected to the control box.

[0039] Initially, the second variable frequency fan 42 does not work. When the CO2 sensor 6 detects that the CO2 concentration in the cargo hold 10 exceeds the set value, the CO2 sensor 6 will feed back a signal to the control box, and the control box will control the second variable frequency fan 42 to start through the inverter 3 corresponding to the cargo hold 10, thereby accelerating the discharge of CO2 in the cargo hold 10 through the second variable frequency fan 42. When the CO2 sensor 6 detects that the CO2 concentration in the cargo hold 10 is lower than the set value, the CO2 sensor 6 will also feed back a signal to the control box, and the control box will control the second variable frequency fan 42 to decelerate step by step until it stops through the inverter 3 corresponding to the cargo hold 10, and this cycle repeats. Regardless of the type of container in the cargo hold, CO2 concentration monitoring is required.

[0040] Optionally, the second variable frequency fan 42 is also set to ten gears. When the CO2 sensor 6 detects that the CO2 concentration in the cargo hold 10 exceeds the set value, the second variable frequency fan 42 operates at ten gears. The second variable frequency fan 42 is a reversible variable frequency fan, which can both deliver air to the cargo hold 10 and discharge the gas in the cargo hold 10. Compared with the first variable frequency fan 41, the ventilation efficiency is higher.

[0041] Further, the first variable frequency fan 41, the second variable frequency fan 42, the temperature sensor 5 and the CO2 sensor 6 are all provided in plurality to make the ventilation efficiency higher. The number of the first variable frequency fan 41 and the second variable frequency fan 42 in each cargo hold 10 is determined according to the total number of containers that can be loaded in the cargo hold 10. Optionally, one first variable frequency fan 41 is provided for every two containers, and one second variable frequency fan 42 is provided for every three containers. The number of the temperature sensor 5 in each cargo hold 10 is determined according to the number of containers loaded in each layer of the cargo hold 10. Optionally, one temperature sensor 5 is provided for every two containers.

[0042] Optionally, the control box acquires data from the temperature sensor 5 and the CO2 sensor 6 every 10 minutes.

[0043] Furthermore, the control system also includes a fire alarm system 7 and a monitoring alarm system 9. Both the fire alarm system 7 and the monitoring alarm system 9 are electrically connected to the control box. The fire alarm system 7 is used to monitor whether a fire occurs in the cargo hold 10. The monitoring alarm system 9 is used to obtain data from the control box and determine whether to alarm based on the data.

[0044] When the fire alarm system 7 detects a fire in a cargo hold 10, the fire alarm system 7 feeds back a signal to the control box, and the control box controls the first variable frequency fan 41 of the corresponding cargo hold 10 to stop, so as to prevent the wind from helping the fire and causing greater safety hazards. At this time, at the same time, the monitoring alarm system 9 obtains information about the fire and will sound an alarm. In addition, when the monitoring alarm system 9 obtains that the temperature in the cargo hold 10 is lower than or higher than the set temperature and the CO2 concentration exceeds the set value, it will also sound an alarm. Regardless of the type of container in the cargo hold, fire monitoring is required.

[0045] Furthermore, the control box includes a main control box 1 and a plurality of sub-control boxes 2. The plurality of sub-control boxes 2 are all electrically connected to the main control box 1, and the main control box 1 is used to send instructions to the sub-control box 2 and receive information from the sub-control box 2. Each sub-control box 2 is electrically connected to a frequency converter 3, a temperature sensor 5 and a CO2 sensor 6, and the sub-control box 2 is used to collect signals from the frequency converter 3, the temperature sensor 5 and the CO2 sensor 6 and receive instructions from the main control box 1. The cargo loading computer 8, the fire alarm system 7 and the monitoring alarm system 9 are all electrically connected to the main control box 1. By setting up a plurality of sub-control boxes 2, electrically connecting the frequency converter 3, the temperature sensor 5 and the CO2 sensor 6 to the sub-control box 2, and then electrically connecting the sub-control box 2 to the main control box 1, the difficulty and quantity of cable layout can be reduced.

[0046] Furthermore, the main control box 1 is arranged in the ship's office to facilitate crew monitoring. The sub-control boxes 2 are arranged in the passages on both sides of the cargo hold 10 and are wall-mounted. Each sub-control box 2 is electrically connected to a plurality of frequency converters 3, and the plurality of frequency converters 3 are installed in the corresponding sub-control box 2. Optionally, five frequency converters 3 are arranged in each sub-control box 2. Arranging a plurality of frequency converters 3 in the sub-control box 2 reduces the difficulty of arranging the frequency converters 3 and the number of cables. In addition, arranging the sub-control box 2 in the passages on both sides of the cargo hold 10 facilitates the connection between the frequency converter 3 and the first variable frequency fan 41 and the second variable frequency fan 42, and the connection between the sub-control box 2 and the temperature sensor 5 and the CO2 sensor 6 in the cargo hold 10.

[0047] Furthermore, the sub-control box 2 includes a box body 21, and a control panel 22 is arranged on the side wall of the box body 21. The control panel 22 includes a control knob 23 and a plurality of operation indicator lights 24, the control knob 23 is used to control the on and off of the power supply of the sub-control box 2, and the plurality of operation indicator lights 24 are respectively used to indicate the operating status of each inverter 3 in the sub-control box 2. A vent 25 is arranged on the top of the box body 21 for heat dissipation of the internal inverter 3. The vent 25 is arranged in a grid shape, which can be used for dust prevention. A waterproof cover 26 is provided on the upper cover of the vent 25 to prevent external water from entering the box body 21 and damaging the internal components. A plurality of cable stuffing boxes 27 are arranged at the bottom of the box body 21 to facilitate the arrangement of cables.

[0048] Furthermore, since the temperature of the top layer of the cargo hold 10 is higher than that of the bottom layer, the first variable frequency fan 41, the second variable frequency fan 42 and the temperature sensor 5 are all arranged on the top layer of the cargo hold 10, so as to facilitate heat dissipation and temperature detection. Since CO2 gas is heavier than air, the CO2 sensor 6 is arranged on the bottom layer of the cargo hold 10.

[0049] Furthermore, the main control box 1 is connected to the sub-control box 2 via a CAT6A network cable. The cargo loading computer 8, the fire alarm system 7 and the monitoring alarm system 9 are all connected to the main control box 1 via RS485 cables.

[0050] Optionally, both the main control box 1 and the sub-control box 2 use a PLC controller 28 .

[0051] refer to Figure 4 The present invention further provides a cargo hold fan control method. Based on the cargo hold fan control system in any of the above embodiments, the control method comprises:

[0052] Step S1, determining whether there is a dangerous goods container in the cargo hold;

[0053] Step S2: If yes, control the first variable frequency fan in the corresponding cargo hold to run at full speed and maintain it until the end of the shipping;

[0054] Step S3, if not, determine whether there is a refrigerated container in the cargo hold;

[0055] Step S4: If yes, control the first variable frequency fan in the corresponding cargo hold to run at a first set speed;

[0056] Step S5: if not, control the first variable frequency fan in the corresponding cargo hold to operate normally at a second set speed;

[0057] Wherein, the first set speed is greater than the second set speed;

[0058] Step S6, determining whether the temperature in the cargo hold where no dangerous goods container exists is within a set temperature range;

[0059] Step S7, if the temperature is higher than the set temperature range, control the first variable frequency fan in the corresponding cargo hold to gradually accelerate;

[0060] Step S8, if the temperature is lower than the set temperature range, control the first variable frequency fan in the corresponding cargo hold to gradually slow down;

[0061] Step S9, determining whether the concentration of CO2 in the cargo hold is higher than a set concentration;

[0062] Step S10: If yes, control the second variable frequency fan in the corresponding cargo hold to run at full speed;

[0063] Step S11, if not, control the second variable frequency fan in the corresponding cargo hold to gradually slow down until it stops;

[0064] Step S12, determining whether a fire occurs in the cargo hold;

[0065] Step S13: If yes, control the first variable frequency fan and the second variable frequency fan in the corresponding cargo hold to stop running;

[0066] If not, the first variable frequency fan and the second variable frequency fan in the cargo hold are controlled to maintain the original state, that is, the first variable frequency fan operates according to steps S1-S8, and the second variable frequency fan operates according to steps S9-S11.

[0067] Furthermore, the first variable frequency fan and the second variable frequency fan are both set to ten gears, and the speed of the first variable frequency fan is from low to high according to the gear size. For a cargo hold loaded with dangerous goods containers, the first variable frequency fan runs at ten gears. For a cargo hold loaded with refrigerated containers, the first variable frequency fan starts at five gears. For a cargo hold not loaded with refrigerated containers, the first variable frequency fan starts at one gear. For a cargo hold where the CO2 concentration exceeds the set value, the second variable frequency fan runs at ten gears.

[0068] By judging the type of container in the cargo hold, whether a fire has occurred, and the concentration of CO2, the control box will control the first variable frequency fan and the second variable frequency fan of the corresponding cargo hold to work in different states, thereby meeting the complex storage environment requirements. At the same time, the variable frequency characteristics of the first variable frequency fan and the second variable frequency fan are used to achieve the purpose of precise temperature control, energy saving and emission reduction.

[0069] The above embodiments are merely illustrative of the principles and effects of the present invention, and are not intended to limit the present invention. Anyone familiar with the art may modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by a person of ordinary skill in the art without departing from the spirit and technical concept disclosed by the present invention shall still be covered by the claims of the present invention.

Claims

1. A cargo hold fan control system, characterized in that: The control system includes a control box, a frequency converter, a first variable frequency fan, a temperature sensor and a cargo loading computer. The first variable frequency fan and the temperature sensor are provided in each cargo hold. The first variable frequency fan is used for ventilation of the cargo hold. The temperature sensor is used for monitoring the temperature in the cargo hold. Each of the first variable frequency fans is electrically connected to a corresponding frequency converter. The frequency converter is used to control the rotation speed of the first variable frequency fan. The frequency converter, the temperature sensor and the cargo loading computer are all electrically connected to the control box. The cargo loading computer is used to obtain data of containers in the cargo hold and transmit it to the control box.

2. The cargo hold fan control system according to claim 1, characterized in that: The control system also includes a fire alarm system and a monitoring alarm system. Both the fire alarm system and the monitoring alarm system are electrically connected to the control box. The fire alarm system is used to monitor whether a fire occurs in the cargo hold. The monitoring alarm system is used to obtain data from the control box and determine whether to issue an alarm based on the data.

3. The cargo hold fan control system according to claim 2, characterized in that: The control system also includes a CO2 sensor and a second variable frequency fan. The CO2 sensor and the second variable frequency fan are provided in each cargo hold. The CO2 sensor is used to monitor the concentration of CO2 in the cargo hold. The second variable frequency fan is used to accelerate the discharge of CO2 in the cargo hold. Each of the second variable frequency fans is electrically connected to a corresponding frequency converter. The frequency converter can control the rotation speed of the second variable frequency fan. The CO2 sensor is electrically connected to the control box.

4. The cargo hold fan control system according to claim 3, characterized in that: The control box includes a main control box and multiple sub-control boxes, and the multiple sub-control boxes are electrically connected to the main control box. The main control box is used to send instructions to the sub-control boxes and receive information from the sub-control boxes. Each of the sub-control boxes is electrically connected to the frequency converter, the temperature sensor and the CO2 sensor. The sub-control boxes are used to collect signals from the frequency converter, the temperature sensor and the CO2 sensor and receive instructions from the main control box. The cargo loading computer, the fire alarm system and the monitoring alarm system are all electrically connected to the main control box.

5. The cargo hold fan control system according to claim 4, characterized in that: Each of the sub-control boxes is electrically connected to a plurality of the frequency converters, and the plurality of frequency converters are installed in the corresponding sub-control box.

6. The cargo hold fan control system according to claim 5, characterized in that: The sub-control box includes a box body, and a control panel is arranged on the side wall of the box body. The control panel includes a control knob and a plurality of operation indicator lights. The control knob is used to control the on and off of the power supply of the sub-control box, and the plurality of operation indicator lights are respectively used to indicate the operating status of each of the inverters in the sub-control box.

7. The cargo hold fan control system according to claim 6, characterized in that: The top of the box body is provided with a vent, the vent is arranged in a grid shape, the upper cover of the vent is provided with a waterproof cover, and the bottom of the box body is provided with a plurality of cable stuffing boxes.

8. The cargo hold fan control system according to claim 3, characterized in that: The first variable frequency fan, the second variable frequency fan and the temperature sensor are all arranged on the top layer of the cargo hold, and the CO2 sensor is arranged on the bottom layer of the cargo hold.

9. The cargo hold fan control system according to claim 4, characterized in that: The main control box is connected to the sub-control box via a CAT6A network cable, and the cargo loading computer, the fire alarm system and the monitoring alarm system are all connected to the main control box via RS485 cables.

10. A cargo hold fan control method, characterized in that: Based on the cargo hold fan control system according to any one of claims 1 to 9, the control method comprises: Determine whether there are dangerous goods containers in the cargo hold; If yes, control the first variable frequency fan in the corresponding cargo hold to run at full speed and maintain it until the end of the shipping; if no, determine whether there is a refrigerated container in the cargo hold; If yes, control the first variable frequency fan in the corresponding cargo hold to operate at a first set speed; if no, control the first variable frequency fan in the corresponding cargo hold to operate normally at a second set speed; wherein the first set speed is greater than the second set speed; Determine whether the temperature in the cargo hold where no dangerous goods container exists is within the set temperature range; If the temperature is higher than the set temperature range, the first variable frequency fan in the corresponding cargo hold is controlled to gradually accelerate; if the temperature is lower than the set temperature range, the first variable frequency fan in the corresponding cargo hold is controlled to gradually decelerate; Determine whether the concentration of CO2 in the cargo hold is within the set concentration range; If not, control the second variable frequency fan in the corresponding cargo hold to gradually slow down until it stops; Determine whether there is a fire in the cargo hold; If so, the first variable frequency fan and the second variable frequency fan in the corresponding cargo hold are controlled to stop running.

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