Control methods for fresh air systems and fresh air systems

Abstract

This invention relates to a control method for a fresh air system and a fresh air system itself. When the fresh air system is in operation, the control method includes: acquiring the outlet air temperature T1, the indoor unit coil temperature T2, and the fresh air temperature T3 of the fresh air system; comparing the outlet air temperature T1 with a target set temperature; determining the initial operating wind speed of the fresh air fan based on the comparison result of the outlet air temperature T1 and the target set temperature; comparing the difference between the indoor unit coil temperature T2 and the fresh air temperature T3 with a preset temperature threshold; and determining the final operating wind speed of the fresh air fan based on the comparison result of the difference and the preset temperature threshold. By employing this control method, the fresh air system of this invention can avoid significant fluctuations in the outlet air temperature, prevent sudden changes in outlet air temperature, and improve the user experience.

Description

Technical Field

[0001] This invention relates to the field of air conditioning technology, and more specifically to a control method and a fresh air system for a fresh air system. Background Technology

[0002] A ventilation system is an independent air handling system consisting of a supply air system and an exhaust air system. A typical ventilation system comprises a fresh air fan, filters, a heat exchanger, an exhaust fan, and ductwork fittings. Fresh air from the outside environment is drawn into the ventilation duct by the fresh air fan, heated or cooled by the heat exchanger, and then filtered for dust removal and sterilization before being delivered indoors. Stale indoor air is exhausted directly to the outside through the exhaust duct by the exhaust fan. Ventilation systems effectively meet the indoor air exchange needs and prevent "air conditioning sickness," thus their application is becoming increasingly widespread.

[0003] In low-temperature conditions, the external ambient temperature is low. To ensure that the outlet air temperature is maintained within the target set temperature range, the fresh air system requires frequent adjustment of the fresh air fan speed. Specifically, when the outlet air temperature is high, the fresh air fan can operate at a higher speed. As cooler fresh air is continuously delivered into the room, the outlet air temperature will drop rapidly. Therefore, the fresh air fan speed needs to be reduced until the outlet air temperature rises again, at which point the speed is increased again. Frequent adjustments to the fresh air fan speed not only affect the airflow but also cause fluctuations in the outlet air temperature, significantly impacting the user experience.

[0004] Therefore, a new technical solution is needed in this field to solve the above problems. Summary of the Invention

[0005] To address or improve to some extent the technical problem of uneven outlet air temperature in existing fresh air systems under low-temperature conditions, this invention provides a control method for a fresh air system. When the fresh air system is in operation, the control method includes: acquiring the outlet air temperature T1, the indoor unit coil temperature T2, and the fresh air temperature T3 of the fresh air system; comparing the outlet air temperature T1 with a target set temperature; determining the initial operating wind speed of the fresh air fan based on the comparison result of the outlet air temperature T1 and the target set temperature; comparing a first difference between the indoor unit coil temperature T2 and the fresh air temperature T3 with a preset temperature threshold; and determining the final operating wind speed of the fresh air fan based on the comparison result of the first difference and the preset temperature threshold.

[0006] In the control method for a fresh air system of the present invention, the outlet air temperature T1, the indoor unit coil temperature T2, and the fresh air temperature T3 of the fresh air system are first obtained. Next, the outlet air temperature T1 is compared with a target set temperature. Then, based on the comparison result between the outlet air temperature T1 and the target set temperature, the initial operating wind speed of the fresh air fan is determined. After the initial operating wind speed of the fresh air fan is determined, the first difference between the indoor unit coil temperature T2 and the fresh air temperature T3 is compared with a preset temperature threshold, and the final operating wind speed of the fresh air fan is determined based on the comparison result. Through the above settings, the control method for a fresh air system of the present invention first determines the initial operating wind speed of the fresh air fan based on the comparison between the outlet air temperature T1 and the target set temperature, and then determines the final operating wind speed of the fresh air fan based on the difference between the indoor unit coil temperature T2 and the fresh air temperature T3. This allows the wind speed of the fresh air fan to better meet actual needs, avoids frequent wind speed adjustments, prevents sudden fluctuations in outlet air temperature, and improves the user experience.

[0007] In the preferred technical solution for the above-mentioned fresh air system, the step of determining the initial operating wind speed of the fresh air fan based on the comparison result of the outlet air temperature T1 and the target set temperature includes: when the outlet air temperature T1 is greater than or equal to the target set temperature, the initial operating wind speed is determined to be a first wind speed; when the outlet air temperature T1 is less than the target set temperature and greater than or equal to the difference between the target set temperature and the preset temperature, the initial operating wind speed is determined to be a second wind speed; when the outlet air temperature T1 is less than the difference between the target set temperature and the preset temperature, the initial operating wind speed is determined to be a third wind speed, wherein the second wind speed is less than the first wind speed and greater than the third wind speed. Through the above settings, the initial operating wind speed can be flexibly adjusted according to the actual outlet air temperature T1.

[0008] In the preferred technical solution for the above-mentioned fresh air system, the step of determining the final operating wind speed of the fresh air fan based on the comparison result of the first difference and the preset temperature threshold includes: when the first difference is greater than or equal to the preset temperature threshold, the determined preliminary operating wind speed is taken as the final operating wind speed; when the first difference is less than the preset temperature threshold, an operating wind speed lower than the determined preliminary operating wind speed is taken as the final operating wind speed. When the first difference between the indoor unit coil temperature T2 and the fresh air temperature T3 is greater than or equal to the preset temperature threshold, it indicates that the indoor unit coil temperature T2 is high at this time, so the determined preliminary operating wind speed is taken as the final operating wind speed to ensure the heating effect; when the first difference between the indoor unit coil temperature T2 and the fresh air temperature T3 is less than the preset temperature threshold, it indicates that the indoor unit coil temperature T2 is low at this time, so an operating wind speed lower than the determined preliminary operating wind speed is taken as the final operating wind speed to appropriately reduce the wind speed and avoid large fluctuations in the outlet air temperature.

[0009] In the preferred technical solution for the above-mentioned fresh air system, when the first difference is less than the preset temperature threshold, the initial operating wind speed is obtained; if the initial operating wind speed is the first wind speed, the final operating wind speed is determined to be the second wind speed; if the initial operating wind speed is the second wind speed, the final operating wind speed is determined to be the third wind speed; if the initial operating wind speed is the third wind speed, the final operating wind speed is determined to be the fourth wind speed, wherein the fourth wind speed is less than the third wind speed. Through the above settings, the control logic can be simplified, facilitating control.

[0010] In the preferred technical solution for the above-mentioned fresh air system, the control method further includes: when the first difference is greater than or equal to the preset temperature threshold, controlling the compressor of the fresh air system to operate at the current operating frequency; when the first difference is less than the preset temperature threshold, controlling the compressor to increase the operating frequency. When the first difference between the indoor unit coil temperature T2 and the fresh air temperature T3 is greater than or equal to the preset temperature threshold, it indicates that the indoor unit coil temperature T2 is high at this time, so the compressor of the fresh air system is controlled to operate at the current operating frequency to ensure stable system operation; when the first difference between the indoor unit coil temperature T2 and the fresh air temperature T3 is less than the preset temperature threshold, it indicates that the indoor unit coil temperature T2 is low at this time, so the compressor is controlled to increase the operating frequency, thereby appropriately increasing the indoor unit coil temperature T2 and avoiding significant fluctuations in the outlet air temperature.

[0011] In the preferred technical solution for the above-mentioned fresh air system, when the fresh air system receives a start-up signal, the control method includes: controlling the compressor of the fresh air system to operate at an initial operating frequency and keeping the fresh air fan off; acquiring the outlet air temperature T1, the indoor unit coil temperature T2, and the fresh air temperature T3; comparing a first difference between the indoor unit coil temperature T2 and the fresh air temperature T3 with a first preset difference, and comparing a second difference between the indoor unit coil temperature T2 and the outlet air temperature T1 with a second preset difference; when the first difference is greater than or equal to the first preset difference, and the second difference is greater than or equal to the second preset difference, controlling the fresh air fan to start at a preset start-up speed, wherein the second preset difference is less than the first preset difference. Through the above settings, the fresh air fan is only controlled to start when the indoor unit coil temperature is at a relatively high level, thus ensuring the stability of the outlet air temperature.

[0012] In the preferred technical solution for the above-described fresh air system, the first preset difference is equal to the preset temperature threshold. This setting simplifies the control logic and facilitates control.

[0013] In the preferred technical solution for the above-mentioned fresh air system, the preset temperature difference ranges from 8℃ to 12℃. This setting ensures that the preset temperature difference has a suitable range.

[0014] In the preferred technical solution for the above-described fresh air system, the preset temperature threshold is equal to the target set temperature. This setting simplifies the control logic and facilitates control.

[0015] To address or improve to some extent the technical problem of uneven outlet air temperature in existing fresh air systems under low-temperature conditions, this invention provides a fresh air system. The control method for fresh air systems described in any of the preceding claims is executed within the fresh air system. By employing the control method described in any of the preceding claims, the fresh air system of this invention can avoid significant fluctuations in outlet air temperature, prevent sudden changes in outlet air temperature, and improve the user experience. Attached Figure Description

[0016] The preferred embodiments of the present invention are described below with reference to the accompanying drawings, in which:

[0017] Figure 1 This is a schematic diagram of the structure of an embodiment of the fresh air system of the present invention;

[0018] Figure 2 This is a flowchart illustrating the control method of the present invention for a fresh air system;

[0019] Figure 3 This is a flowchart illustrating the first embodiment of the control method for a fresh air system according to the present invention;

[0020] Figure 4 This is a flowchart illustrating the second embodiment of the control method for a fresh air system according to the present invention.

[0021] List of reference numerals in the attached diagram:

[0022] 100. Fresh air system; 10. Fresh air duct; 11. Fresh air inlet; 12. Fresh air temperature sensor; 20. Fresh air fan; 30. Heat exchanger; 31. Coil temperature sensor; 40. Air outlet duct; 41. Air outlet; 42. Air outlet temperature sensor; 43. Filter; 50. Exhaust duct; 51. Exhaust outlet; 60. Exhaust fan. Detailed Implementation

[0023] Preferred embodiments of the present invention will now be described with reference to the accompanying drawings. Those skilled in the art should understand that these embodiments are merely illustrative of the technical principles of the present invention and are not intended to limit the scope of protection of the present invention.

[0024] It should be noted that in the description of this invention, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance. The terms "installation," "setting," and "connection" should be interpreted broadly; for example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a direct connection, an indirect connection through an intermediate medium, or a connection within two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0025] To address or improve to some extent the technical problem of uneven outlet air temperature in existing fresh air systems under low-temperature conditions, this invention provides a control method for a fresh air system 100. When the fresh air system 100 is in operation, the control method includes: acquiring the outlet air temperature T1, indoor unit coil temperature T2, and fresh air temperature T3 of the fresh air system 100 (step S1); comparing the outlet air temperature T1 with a target set temperature (step S2); determining the initial operating wind speed of the fresh air fan based on the comparison result of the outlet air temperature T1 and the target set temperature (step S3); comparing a first difference between the indoor unit coil temperature T2 and the fresh air temperature T3 with a preset temperature threshold (step S4); and determining the final operating wind speed of the fresh air fan based on the comparison result of the first difference and the preset temperature threshold (step S5).

[0026] Figure 1 This is a structural schematic diagram of an embodiment of the fresh air system of the present invention. (See diagram below.) Figure 1 As shown, in one or more embodiments, the fresh air system 100 of the present invention includes components such as a fresh air duct 10, a fresh air fan 20, a heat exchanger 30, an outlet air duct 40, an exhaust air duct 50, and an exhaust fan 60. The fresh air duct 10 can be made of PVC, PE, EPP, or a suitable metal material. The fresh air duct 10 has a fresh air inlet 11 to allow fresh air from the external environment to enter the fresh air duct 10. In one or more embodiments, a louver (not shown) is provided at the fresh air inlet 11 to adjust the airflow and speed, improve air uniformity, and achieve energy saving and noise reduction. In one or more embodiments, a damper (not shown) is also provided in the fresh air duct 10 to adjust the opening and closing of the fresh air duct 10. The damper can be, but is not limited to, a butterfly valve, a ball valve, etc. In one or more embodiments, a fresh air temperature sensor 12 is also provided on the fresh air duct 10 to detect the temperature of the fresh air. The fresh air temperature sensor 12 can be, but is not limited to, a thermistor sensor, a thermocouple sensor, etc. The number and placement of the fresh air temperature sensors 12 can also be adjusted according to actual needs.

[0027] See also Figure 1A fresh air fan 20 is arranged within the fresh air duct 10 to draw fresh air from the outside environment into the duct 10 by controlling its rotation. The speed of the fresh air fan 20 is adjustable, allowing for easy adjustment of the airflow volume and velocity. The fresh air fan 20 can be a cross-flow fan, axial flow fan, or centrifugal fan. The number of fresh air fans 20 can also be set in multiples according to actual needs, such as two or three.

[0028] See also Figure 1 In one or more embodiments, the heat exchanger 30 is arranged within the fresh air duct 10 and upstream of the fresh air fan 20. Alternatively, the heat exchanger 30 may also be arranged downstream of the fresh air fan 20. In one or more embodiments, the heat exchanger 30, together with components such as the compressor, throttling device, and evaporator (not shown), forms a refrigeration loop through which a refrigerant (e.g., R34A) circulates. The heat exchanger 30 may be a plate heat exchanger, a finned coil heat exchanger, or other suitable heat exchanger. In one or more embodiments, a coil temperature sensor 31 is provided on the heat exchanger 30 to detect the temperature of the heat exchanger 30. The coil temperature sensor 31 may be, but is not limited to, a thermistor sensor, a thermocouple sensor, etc. The number and arrangement of the coil temperature sensors 31 can also be adjusted according to actual needs.

[0029] See also Figure 1 The exhaust duct 40 is connected to the fresh air duct 10 to form a channel that allows airflow. The exhaust duct 40 can be made of PVC, PE, EPP, or a suitable metal. The exhaust duct 40 has an air outlet 41, which is connected to the space to be regulated (e.g., living room, kitchen, bedroom, etc.). In one or more embodiments, a louver (not shown) is provided at the air outlet 41 to adjust the air volume and speed, improve air uniformity, and reduce energy consumption and noise. In one or more embodiments, an exhaust temperature sensor 42 is also provided on the exhaust duct 40 to detect the temperature of the exhaust air. The exhaust temperature sensor 42 can be, but is not limited to, a thermistor sensor, a thermocouple sensor, etc. The number and arrangement of the exhaust temperature sensors 42 can also be adjusted according to actual needs. In one or more embodiments, a filter element 43 is also provided in the exhaust duct 40 to filter the airflow passing through it and prevent dust, bacteria, viruses, etc. from entering the space to be regulated. The material of filter element 43 can be, but is not limited to, glass fiber, activated carbon, modified fiber, etc. The installation of filter element 43 can improve air cleanliness and enhance air quality. The number and arrangement of filter elements 43 can be adjusted according to actual needs.

[0030] See also Figure 1The exhaust duct 50 is separated from the fresh air duct 10. The exhaust duct 50 can be made of PVC, PE, EPP, or a suitable metal. One end of the exhaust duct 50 is provided with an exhaust port 51, which is connected to the space to be regulated. The other end of the exhaust duct 50 is connected to the external environment, so that the stale air in the space to be regulated can be directly discharged through the exhaust duct 50. In one or more embodiments, a damper (not shown in the figure) is also provided in the exhaust duct 50 to regulate the opening and closing of the exhaust duct 50. The damper can be, but is not limited to, a butterfly valve, a ball valve, etc. An exhaust fan 60 is arranged in the exhaust duct 50 so that the stale air in the space to be regulated can be quickly discharged by controlling the rotation of the exhaust fan 60. The rotation speed of the exhaust fan 60 is adjustable, so that the exhaust volume and exhaust speed can be easily adjusted by controlling the rotation speed of the exhaust fan 60. The exhaust fan 60 can be a cross-flow fan, an axial flow fan, or a centrifugal fan. The number of exhaust fans 60 can also be set in multiples according to actual needs, such as 2 or 3.

[0031] Below, in conjunction with Figures 2-4 This document details embodiments of the control method for a fresh air system 100 according to the present invention. It should be noted that the control method for a fresh air system 100 of the present invention can be implemented in any of the fresh air systems 100 described in the above embodiments, and can also be used in other suitable fresh air systems.

[0032] Figure 2 This is a flowchart illustrating the control method of the present invention for a fresh air system. Figure 2As shown, in one or more embodiments, when the fresh air system 100 is in operation (e.g., heating), the control method of the present invention for the fresh air system 100 first executes step S1, that is, to obtain the outlet air temperature T1, indoor unit coil temperature T2, and fresh air temperature T3 of the fresh air system 100. The outlet air temperature T1 can be measured by an outlet air temperature sensor 42 arranged near the air outlet 41. Correspondingly, the indoor unit coil temperature T2 can be measured by a coil temperature sensor 31 arranged on the heat exchanger 30, and the fresh air temperature T3 can be measured by a fresh air temperature sensor 12 arranged near the fresh air inlet 11. Next, step S2 is executed, comparing the outlet air temperature T1 with the target set temperature. The user can adjust the target set temperature through a remote control, control panel, smartphone, or other control terminal. Then, step S3 is executed, determining the initial operating wind speed of the fresh air fan 20 of the fresh air system 100 based on the comparison result of the outlet air temperature T1 and the target set temperature. Once the initial operating airflow speed of the fresh air fan 20 is determined, it does not operate directly at that speed. Instead, it continues to determine the final operating airflow speed based on the difference between the indoor unit coil temperature T2 and the fresh air temperature T3. Specifically, the control method executes step S4, which compares the first difference between the indoor unit coil temperature T2 and the fresh air temperature T3 with a preset temperature threshold. Then, based on the comparison result between the first difference and the preset temperature threshold, the final operating airflow speed of the fresh air fan 20 is determined. Through the above settings, the operating airflow speed of the fresh air fan 20 can better meet actual needs, avoiding frequent adjustments to the airflow speed and preventing sudden fluctuations in the outlet air temperature, thereby improving the user experience.

[0033] Figure 3 This is a flowchart illustrating the first embodiment of the control method for a fresh air system according to the present invention. Figure 3As shown, in one or more embodiments, when the fresh air system 100 is in operation (e.g., heating), the control method for the fresh air system 100 of the present invention first executes step S10, that is, to obtain the outlet air temperature T1, indoor unit coil temperature T2, and fresh air temperature T3 of the fresh air system 100. Next, the control method executes step S21, that is, to determine whether the outlet air temperature T1 is greater than or equal to the target set temperature. When the determination result is yes, it indicates that the outlet air temperature T1 is relatively high, and the fresh air fan 20 can operate at a higher wind speed to ensure heating efficiency; therefore, the initial operating wind speed is determined as the first wind speed (i.e., step S31). The specific value of the first wind speed can be adjusted according to actual needs, for example, 1800 r / min. When the determination result is no, the control method continues to execute step S22, that is, to determine whether the outlet air temperature T1 is less than the difference between the target set temperature and the preset temperature difference. In one or more embodiments, the preset temperature difference ranges from 8℃ to 12℃. Alternatively, the preset temperature difference can also be set to other suitable values. If the judgment result is negative, it means that the current air outlet temperature T1 is between (target set temperature - preset temperature difference) and the target set temperature, and the initial operating wind speed is determined to be the second wind speed (i.e., step S32). The second wind speed is less than the first wind speed. The specific value of the second wind speed can also be adjusted according to actual needs, for example, 1500 r / min. If the judgment result is positive, it means that the current air outlet temperature T1 is relatively low, and the initial operating wind speed is determined to be the third wind speed (i.e., step S33). The third wind speed is less than the second wind speed. The specific value of the third wind speed can also be adjusted according to actual needs, for example, 1200 r / min.

[0034] In one or more embodiments, after the initial operating wind speed is determined, the control method further determines whether the first difference between the indoor unit coil temperature T2 and the fresh air temperature T3 is greater than or equal to a preset temperature threshold, thereby determining the final operating wind speed of the fresh air fan 20. When the first difference is greater than or equal to the preset temperature threshold, it indicates that the indoor unit coil temperature T2 is also relatively high, and the determined initial operating wind speed can be used as the final operating wind speed. When the first difference is less than the preset temperature threshold, it indicates that the indoor unit coil temperature T2 is relatively low. If the fresh air fan 20 continues to operate at a high wind speed, the outlet air temperature T1 will drop rapidly in a short period of time, causing the outlet air temperature to fluctuate. Therefore, the final operating wind speed is set to a lower operating wind speed than the determined initial operating wind speed, thereby appropriately reducing the wind speed of the fresh air fan 20 and ensuring that the outlet air temperature does not fluctuate drastically.

[0035] In one or more embodiments, the control method of the present invention further includes the following steps: when the first difference between the indoor unit coil temperature T2 and the fresh air temperature T3 is less than a preset temperature threshold (e.g., when the judgment result is negative when executing steps S41, S42, and S43), the compressor of the fresh air system 100 is controlled to increase its operating frequency to appropriately increase the indoor unit coil temperature T2. The specific value of the increased operating frequency of the compressor can be adjusted according to actual needs, such as 20Hz, 30Hz, 40Hz, etc. When the first difference between the indoor unit coil temperature T2 and the fresh air temperature T3 is greater than or equal to the preset temperature threshold (e.g., when the judgment result is positive when executing steps S41, S42, and S43), the compressor of the fresh air system 100 is controlled to operate at the current operating frequency to ensure stable system operation.

[0036] See also Figure 3 In one or more embodiments, after step S31 is completed, the control method executes step S41, that is, determining whether (indoor unit coil temperature T2 - indoor unit coil temperature T2) is greater than or equal to a preset temperature threshold. In one or more embodiments, the preset temperature threshold is equal to the target set temperature to simplify the control logic and facilitate control. Alternatively, the preset temperature threshold can also be set to other suitable values ​​according to actual needs. When the determination result is yes, it means that the indoor unit coil temperature T2 is high at this time, so the first fan speed is used as the final operating fan speed (i.e., step S51). When the determination result is no, it means that the indoor unit coil temperature T2 is low at this time, so the second fan speed is used as the final operating fan speed (i.e., step S52) to appropriately reduce the fan speed.

[0037] See also Figure 3 After step S32 is completed, the control method executes step S42, which determines whether (indoor unit coil temperature T2 - indoor unit coil temperature T2) is greater than or equal to a preset temperature threshold. If the determination result is yes, it means that the indoor unit coil temperature T2 is high at this time, so the second fan speed is used as the final operating fan speed (i.e., step S53). If the determination result is no, it means that the indoor unit coil temperature T2 is low at this time, so the third fan speed is used as the final operating fan speed (i.e., step S54) to appropriately reduce the fan speed.

[0038] See also Figure 3After step S33 is completed, the control method executes step S43, which determines whether (indoor unit coil temperature T2 - indoor unit coil temperature T2) is greater than or equal to a preset temperature threshold. If the determination result is yes, it means that the indoor unit coil temperature T2 is high at this time, so the third fan speed is used as the final operating fan speed (i.e., step S53). If the determination result is no, it means that the indoor unit coil temperature T2 is low at this time, so the fourth fan speed, which is lower than the third fan speed, is used as the final operating fan speed (i.e., step S54) to appropriately reduce the fan speed. The specific value of the fourth fan speed can also be adjusted according to actual needs, for example, 1000 r / min.

[0039] Figure 4 This is a flowchart illustrating a second embodiment of the control method for a fresh air system according to the present invention. Figure 4 As shown, in one or more embodiments, when the fresh air system 100 receives a start-up signal, the control method first executes step S60, that is, controls the compressor of the fresh air system 100 to run at the initial operating frequency and keeps the fresh air fan 20 off. The specific value of the initial operating frequency can be adjusted according to actual needs. Next, the control method executes step S61, that is, obtains the outlet air temperature T1, the indoor unit coil temperature T2, and the fresh air temperature T3. Then, the control method executes step S62, determining whether the first difference between the indoor unit coil temperature T2 and the fresh air temperature T3 is greater than or equal to a first preset difference. The specific value of the first preset difference can be adjusted according to actual needs, such as 18℃, 20℃, etc. If the determination result is negative, then step S61 is continued, that is, the outlet air temperature T1, the indoor unit coil temperature T2, and the fresh air temperature T3 are repeatedly obtained. If the determination result is positive, then step S63 is executed, that is, the second difference between the indoor unit coil temperature T2 and the outlet air temperature T2 is further determined to be greater than or equal to a second preset difference. The second preset difference is less than the first preset difference. The specific value of the second preset difference can be adjusted according to actual needs, such as 8℃, 10℃, etc. If the judgment result is negative, then continue to execute step S61, that is, repeatedly obtain the outlet air temperature T1, indoor unit coil temperature T2, and fresh air temperature T3. If the judgment result is positive, then execute step S64, that is, control the fresh air fan 20 to start at the preset start-up fan speed. The specific value of the preset start-up fan speed can be adjusted according to actual needs, such as 1200r / min.

[0040] It should be noted that the parts not mentioned in the second embodiment can be configured the same as in the first embodiment, and will not be repeated here.

[0041] The technical solution of the present invention has been described above with reference to the preferred embodiments shown in the accompanying drawings. However, it will be readily understood by those skilled in the art that the scope of protection of the present invention is obviously not limited to these specific embodiments. Without departing from the principles of the present invention, those skilled in the art can make equivalent changes or substitutions to the relevant technical features, and the technical solutions after such changes or substitutions will all fall within the scope of protection of the present invention.

Claims

1. A control method for a fresh air system, characterized in that, When the fresh air system is in operation, the control method includes: Obtain the outlet air temperature T1, indoor unit coil temperature T2, and fresh air temperature T3 of the fresh air system; Compare the outlet air temperature T1 with the target set temperature; Based on the comparison between the outlet air temperature T1 and the target set temperature, the initial operating wind speed of the fresh air fan of the fresh air system is determined. The first difference between the indoor unit coil temperature T2 and the fresh air temperature T3 is compared with a preset temperature threshold. Based on the comparison between the first difference and the preset temperature threshold, the final operating wind speed of the fresh air fan is determined.

2. The control method for a fresh air system according to claim 1, characterized in that, The steps for determining the initial operating wind speed of the fresh air fan based on the comparison between the outlet air temperature T1 and the target set temperature include: When the outlet air temperature T1 is greater than or equal to the target set temperature, the initial operating wind speed is determined to be the first wind speed; When the outlet air temperature T1 is less than the target set temperature and greater than or equal to the difference between the target set temperature and the preset temperature, the initial operating wind speed is determined to be the second wind speed. When the outlet air temperature T1 is less than the difference between the target set temperature and the preset temperature, the initial operating wind speed is determined to be the third wind speed. Wherein, the second wind speed is less than the first wind speed but greater than the third wind speed.

3. The control method for a fresh air system according to claim 2, characterized in that, The step of determining the final operating wind speed of the fresh air fan based on the comparison result of the first difference and the preset temperature threshold includes: When the first difference is greater than or equal to the preset temperature threshold, the determined initial operating wind speed is taken as the final operating wind speed. When the first difference is less than the preset temperature threshold, the final operating wind speed is the operating wind speed that is smaller than the determined initial operating wind speed.

4. The control method for a fresh air system according to claim 3, characterized in that, When the first difference is less than the preset temperature threshold, the initial operating wind speed is obtained; If the initial operating wind speed is the first wind speed, then the final operating wind speed is determined to be the second wind speed; If the initial operating wind speed is the second wind speed, then the final operating wind speed is determined to be the third wind speed; If the initial operating wind speed is the third wind speed, then the final operating wind speed is determined to be the fourth wind speed. The fourth wind speed is less than the third wind speed.

5. The control method for a fresh air system according to claim 3, characterized in that, The control method further includes: When the first difference is greater than or equal to the preset temperature threshold, the compressor of the fresh air system is controlled to run at the current operating frequency. When the first difference is less than the preset temperature threshold, the compressor is controlled to increase the operating frequency.

6. The control method for a fresh air system according to any one of claims 1-5, characterized in that, When the fresh air system receives a start-up signal, the control method includes: Control the compressor of the fresh air system to operate at the initial operating frequency, and keep the fresh air fan off; Obtain the outlet air temperature T1, the indoor unit coil temperature T2, and the fresh air temperature T3; The first difference between the indoor unit coil temperature T2 and the fresh air temperature T3 is compared with a first preset difference, and the second difference between the indoor unit coil temperature T2 and the air outlet temperature T1 is compared with a second preset difference. When the first difference is greater than or equal to the first preset difference, and the second difference is greater than or equal to the second preset difference, the fresh air fan is controlled to start at a preset start-up speed. Wherein, the second preset difference is less than the first preset difference.

7. The control method for a fresh air system according to claim 6, characterized in that, The first preset difference is equal to the preset temperature threshold.

8. The control method for a fresh air system according to claim 2, characterized in that, The preset temperature difference ranges from 8℃ to 12℃.

9. The control method for a fresh air system according to claim 1, characterized in that, The preset temperature threshold is equal to the target set temperature.

10. A fresh air system, characterized in that, The control method for a fresh air system according to any one of claims 1-9 is performed in the fresh air system.

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