Control method for fresh air system and fresh air system

Abstract

The invention relates to a control method for a fresh air system and the fresh air system. When the fresh air system is in a running state, the control method comprises the steps that the air outlet temperature T1, the indoor unit coil pipe temperature T2 and the fresh air temperature T3 of the fresh air system are obtained; the air outlet temperature T1 is compared with a target set temperature; based on the comparison result of the air outlet temperature T1 and the target set temperature, the initial operation air speed of a fresh air fan of the fresh air system is determined; the difference value between the indoor unit coil pipe temperature T2 and the fresh air temperature T3 is compared with a preset temperature threshold value; and based on the comparison result of the difference value and the preset temperature threshold value, the final operation air speed of the fresh air fan is determined. By the adoption of the control method, the fresh air system can avoid obvious fluctuation of the air outlet temperature, the air outlet temperature is prevented from being suddenly high and suddenly low, and the use experience of a user is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of air conditioning, and in particular to a control method for a fresh air system and a fresh air system. Background Art

[0002] The fresh air system (i.e. Ventilation System) is an independent air treatment system consisting of an air supply system and an exhaust system. The fresh air system is generally composed of fresh air fans, filters, heat exchangers, exhaust fans, and pipe fittings. Fresh air from the outside environment is sucked into the fresh air duct through the fresh air fan, heated or cooled after passing through the heat exchanger, and then transported to the room after dust removal and sterilization through the filter. The turbid air in the room is directly discharged to the outside through the exhaust duct under the action of the exhaust fan. The fresh air system can meet the needs of indoor fresh air ventilation and effectively prevent "air conditioning disease", so it is more and more widely used.

[0003] Under low temperature conditions, the temperature of the external environment is low. In order to ensure that the outlet air temperature is roughly maintained within the target set temperature range, the fresh air system needs to frequently control the speed of the fresh air fan when in use. Specifically, when the outlet air temperature is high, the fresh air fan can run at a higher speed. As the lower temperature fresh air is continuously delivered into the room, the outlet air temperature will drop rapidly. Therefore, it is necessary to lower the speed of the fresh air fan until the outlet air temperature rises again and then increase the speed. Frequent adjustment of the speed of the fresh air fan will not only affect the outlet air volume, but also the outlet air temperature will fluctuate, greatly affecting the user experience.

[0004] Therefore, this field needs a new technical solution to solve the above problems. Summary of the invention

[0005] In order to solve or improve to a certain extent the technical problem of uneven air outlet temperature of the fresh air system under low temperature conditions in the prior art, the present invention provides a control method for the fresh air system. When the fresh air system is in operation, the control method includes: obtaining the air outlet temperature T1, the indoor unit coil temperature T2 and the fresh air temperature T3 of the fresh air system; comparing the air outlet temperature T1 with the target setting temperature; determining the initial operating wind speed of the fresh air fan of the fresh air system based on the comparison result of the air outlet temperature T1 and the target setting temperature; comparing the first difference between the indoor unit coil temperature T2 and the fresh air temperature T3 with a preset temperature threshold; determining the final operating wind speed of the fresh air fan based on the comparison result of the first difference with 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. Then, the outlet air temperature T1 is compared with the target setting temperature. Then, the initial operating wind speed of the fresh air fan is determined based on the comparison result between the outlet air temperature T1 and the target setting temperature. When 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 the 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 preliminarily determines the initial operating wind speed of the fresh air fan according to the comparison between the outlet air temperature T1 and the target setting temperature, and then determines the final operating wind speed of the fresh air fan according to the difference between the indoor unit coil temperature T2 and the fresh air temperature T3, which can make the wind speed of the fresh air fan more in line with actual needs, avoid frequent adjustment of the wind speed, prevent the outlet air temperature from fluctuating, and improve the user experience.

[0007] In the above preferred technical solution for the 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 setting temperature includes: when the outlet air temperature T1 is greater than or equal to the target setting temperature, determining the initial operating wind speed to be the first wind speed; when the outlet air temperature T1 is less than the target setting temperature and greater than or equal to the difference between the target setting temperature and the preset temperature difference, determining the initial operating wind speed to be the second wind speed; when the outlet air temperature T1 is less than the difference between the target setting temperature and the preset temperature difference, determining the initial operating wind speed to be the 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 above preferred technical solution for the 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 comprises: when the first difference is greater than or equal to the preset temperature threshold, the determined preliminary operating wind speed is used as the final operating wind speed; when the first difference is less than the preset temperature threshold, the operating wind speed smaller than the determined preliminary operating wind speed is used 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 means that the indoor unit coil temperature T2 is relatively high at this time, and the determined preliminary operating wind speed is used 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 means that the indoor unit coil temperature T2 is relatively low at this time, and the operating wind speed smaller than the determined preliminary operating wind speed is used as the final operating wind speed to appropriately reduce the wind speed and avoid large fluctuations in the outlet air temperature.

[0009] In the above preferred technical solution for the fresh air system, when the first difference is less than the preset temperature threshold, the preliminary operating wind speed is obtained; if the preliminary operating wind speed is the first wind speed, the final operating wind speed is determined to be the second wind speed; if the preliminary operating wind speed is the second wind speed, the final operating wind speed is determined to be the third wind speed; if the preliminary 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 and the control is convenient.

[0010] In the above preferred technical solution for the 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 means that the indoor unit coil temperature T2 is relatively high at this time, and then the compressor of the fresh air system is controlled to operate at the current operating frequency to ensure stable operation of the system; 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 means that the indoor unit coil temperature T2 is relatively low at this time, and then the compressor is controlled to increase the operating frequency, thereby appropriately increasing the indoor unit coil temperature T2 to avoid significant fluctuations in the outlet air temperature.

[0011] In the above preferred technical solution for the 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 stopped; obtaining the outlet air temperature T1, the indoor unit coil temperature T2 and the fresh air temperature T3; comparing the first difference between the indoor unit coil temperature T2 and the fresh air temperature T3 with a first preset difference, and comparing the 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 wind speed, wherein the second preset difference is less than the first preset difference. Through the above settings, the fresh air fan is controlled to start only when the indoor unit coil temperature is at a higher level to ensure the stability of the outlet air temperature.

[0012] In the above preferred technical solution for the fresh air system, the first preset difference is equal to the preset temperature threshold. Through the above setting, the control logic can be simplified and the control is convenient.

[0013] In the above preferred technical solution for the fresh air system, the range of the preset temperature difference is 8° C.-12° C. Through the above setting, the preset temperature difference can have a moderate range.

[0014] In the above preferred technical solution for the fresh air system, the preset temperature threshold is equal to the target set temperature. Through the above setting, the control logic can be simplified and the control is convenient.

[0015] In order to solve or improve to a certain extent the technical problem of uneven air outlet temperature of a fresh air system in the prior art under low temperature conditions, the present invention provides a fresh air system. The control method for a fresh air system according to any one of the above items is executed in the fresh air system. By adopting the control method for a fresh air system according to any one of the above items, the fresh air system of the present invention can avoid obvious fluctuations in the air outlet temperature, prevent the air outlet temperature from fluctuating, and improve the user experience. BRIEF DESCRIPTION OF THE DRAWINGS

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

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

[0018] Figure 2 It is a flow chart of a control method for a fresh air system according to the present invention;

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

[0020] Figure 4 It is a flow chart of a second embodiment of a control method for a fresh air system according to the present invention.

[0021] List of reference numerals:

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

[0023] The preferred embodiments of the present invention are described below with reference to the accompanying drawings. It should be understood by those skilled in the art that these embodiments are only used to explain the technical principles of the present invention and are not intended to limit the protection scope of the present invention.

[0024] It should be noted that in the description of the present invention, the terms "first" and "second" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance. The terms "installation", "setting" and "connection" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a direct connection, an indirect connection through an intermediate medium, or the internal connection of two elements. For those skilled in the art, the specific meanings of the above terms in the present invention can be understood according to the specific circumstances.

[0025] In order to solve or improve to a certain extent the technical problem of uneven air outlet temperature of the fresh air system under low temperature conditions in the prior art, the present invention provides a control method for a fresh air system 100. When the fresh air system 100 is in operation, the control method of the present invention includes: obtaining the air outlet temperature T1, the indoor unit coil temperature T2 and the fresh air temperature T3 of the fresh air system 100 (step S1); comparing the air outlet temperature T1 with the target setting temperature (step S2); determining the initial operating wind speed of the fresh air fan of the fresh air system based on the comparison result of the air outlet temperature T1 and the target setting temperature (step S3); comparing the first difference between the indoor unit coil temperature T2 and the fresh air temperature T3 with a preset temperature threshold (step S4); determining the final operating wind speed of the fresh air fan based on the comparison result of the first difference with the preset temperature threshold (step S5).

[0026] Figure 1 Schematic diagram of the structure of an embodiment of the fresh air system of the present invention. 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 air outlet duct 40, an exhaust duct 50 and an exhaust fan 60. Among them, 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 outlet 11 to allow fresh air from the external environment to enter the fresh air duct 10 through the fresh air outlet 11. In one or more embodiments, a swing blade (not shown in the figure) is provided at the fresh air outlet 11 to adjust the air volume and wind speed, improve air uniformity and save energy and reduce noise. In one or more embodiments, a damper (not shown in the figure) 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 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 not limited to a thermistor sensor, an electric thermocouple sensor, etc. The number and arrangement positions of the fresh air temperature sensors 12 can also be adjusted according to actual needs.

[0027] Continue to see Figure 1The fresh air fan 20 is arranged in the fresh air duct 10 so that the fresh air from the external environment is delivered into the fresh air duct 10 by controlling the rotation of the fresh air fan 20. The rotation speed of the fresh air fan 20 is adjustable, so that the air volume and the air speed can be conveniently adjusted by controlling the rotation speed of the fresh air fan 20. The fresh air fan 20 can be a cross-flow fan, an axial flow fan or a centrifugal fan. The number of the fresh air fan 20 can also be set according to actual needs, such as 2, 3, etc.

[0028] Continue to see Figure 1 In one or more embodiments, the heat exchanger 30 is arranged in the fresh air duct 10 and is located upstream of the fresh air fan 20. Alternatively, the heat exchanger 30 can also be arranged downstream of the fresh air fan 20. In one or more embodiments, the heat exchanger 30 and the compressor, throttling device, evaporator (not shown in the figure) and other components form a refrigeration circuit that allows the refrigerant (such as R34A, etc.) to circulate therein through the refrigerant pipeline. The heat exchanger 30 can be a plate heat exchanger, a fin 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 can be but is not limited to a thermistor sensor, an electric thermocouple sensor, etc. The number and arrangement position of the coil temperature sensor 31 can also be adjusted according to actual needs.

[0029] Continue to see Figure 1 , the air outlet duct 40 is connected to the fresh air duct 10 to form a channel allowing air flow to flow therein. The air outlet duct 40 can be made of PVC, PE, EPP or a suitable metal material. The air outlet duct 40 has an air outlet 41, which is connected to the space to be regulated (such as a living room, kitchen, bedroom, etc.). In one or more embodiments, a swing blade (not shown in the figure) is provided at the air outlet 41 to adjust the air volume and wind speed, improve air uniformity and energy saving and noise reduction. In one or more embodiments, an air outlet temperature sensor 42 is also provided on the air outlet duct 40 to detect the temperature of the outlet air. The air outlet temperature sensor 42 can be but is not limited to a thermistor sensor, a thermocouple sensor, etc. The number and arrangement position of the air outlet temperature sensor 42 can also be adjusted according to actual needs. In one or more embodiments, a filter 43 is also provided in the air outlet duct 40 to filter the air flow flowing therethrough to prevent dust, bacteria, viruses, etc. from entering the space to be regulated. The material of the filter element 43 may be, but is not limited to, glass fiber, activated carbon, modified fiber, etc. The arrangement of the filter element 43 can improve air cleanliness and enhance air quality. The number and arrangement position of the filter element 43 can be adjusted according to actual needs.

[0030] Continue to see Figure 1, the 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 material. An exhaust port 51 is provided at one end of the exhaust duct 50, and the exhaust port 51 is connected to the space to be regulated. The other end of the exhaust duct 50 is connected to the external environment so as to allow the turbid air in the space to be regulated to 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 adjust the opening and closing of the exhaust duct 50. The damper can be but not limited to a butterfly valve, a ball valve, etc. The exhaust fan 60 is arranged in the exhaust duct 50 so as to quickly discharge the turbid air in the space to be regulated 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 wind speed can be conveniently 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 the exhaust fans 60 can also be multiple according to actual needs, such as 2, 3, etc.

[0031] Next, combine Figure 2-Figure 4 The embodiment of the control method for the fresh air system 100 of the present invention is described in detail. It should be noted that the control method for the fresh air system 100 of the present invention can be executed in the fresh air system 100 described in any of the above embodiments, and can also be used in other suitable fresh air systems.

[0032] Figure 2 FIG. 1 is a flow chart of a control method for a fresh air system according to the present invention. Figure 2As 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 S1, i.e., obtaining the outlet air temperature T1, the indoor unit coil temperature T2, and the fresh air temperature T3 of the fresh air system 100. The outlet air temperature T1 can be measured by the outlet air temperature sensor 42 arranged near the air outlet 41. Correspondingly, the indoor unit coil temperature T2 can be measured by the coil temperature sensor 31 arranged on the heat exchanger 30, and the fresh air temperature T3 can be measured by the fresh air temperature sensor 12 arranged near the fresh air outlet 11. Then, step S2 is executed to compare the outlet air temperature T1 with the target set temperature. The user can adjust the target set temperature through a control terminal such as a remote control, a control panel, or a smart phone. Then, step S3 is executed to determine 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. After the initial operating wind speed of the fresh air fan 20 is determined, the fresh air fan 20 does not directly operate at the initial operating wind speed, but continues to determine the final operating wind speed according to the difference between the indoor unit coil temperature T2 and the fresh air temperature T3. Specifically, the control method executes step S4, that is, comparing the first difference between the indoor unit coil temperature T2 and the fresh air temperature T3 with the preset temperature threshold. Then, based on the comparison result of the first difference with the preset temperature threshold, the final operating wind speed of the fresh air fan 20 is determined. Through the above settings, the operating wind speed of the fresh air fan 20 can be made to better meet actual needs, avoid frequent adjustments to the wind speed, and prevent the outlet air temperature from fluctuating, thereby improving the user experience.

[0033] Figure 3 1 is a flow chart of a first embodiment of a 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, i.e., obtaining the outlet air temperature T1, the indoor coil temperature T2, and the fresh air temperature T3 of the fresh air system 100. Next, the control method executes step S21, i.e., determining whether the outlet air temperature T1 is greater than or equal to the target set temperature. When the judgment result is yes, it means that the outlet air temperature T1 is high at this time, and the fresh air fan 20 can operate at a higher wind speed to ensure the heating efficiency, then the initial operating wind speed is determined to be the first wind speed (i.e., step S31). The specific value of the first wind speed can be adjusted according to actual needs, such as 1800r / min (revolutions per minute). When the judgment result is no, the control method continues to execute step S22, i.e., determining 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°C to 12°C. Alternatively, the preset temperature difference can also be set to other suitable values. When the judgment result is no, it means that the air outlet temperature T1 is between (target setting temperature - preset temperature difference) and the target setting 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, such as 1500r / min. When the judgment result is yes, it means that the air outlet temperature T1 is relatively small at this time, 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, such as 1200r / min.

[0034] In one or more embodiments, after the preliminary operating wind speed is determined, the control method continues to determine whether 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, 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 means that the indoor unit coil temperature T2 is also relatively high at this time, and the determined preliminary operating wind speed can be used as the final operating wind speed. When the first difference is less than the preset temperature threshold, it means that the indoor unit coil temperature T2 is relatively low at this time. If the fresh air fan 20 still operates at a relatively high wind speed, the outlet air temperature T1 will drop rapidly in a short time, resulting in the outlet air temperature fluctuating. Therefore, the operating wind speed that is smaller than the determined preliminary operating wind speed is used as the final operating wind speed, thereby appropriately reducing the wind speed of the fresh air fan 20 to ensure that the outlet air temperature does not fluctuate violently.

[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 (for example, when the judgment result is no when executing steps S41, S42 and S43), the compressor of the fresh air system 100 is controlled to increase the operating frequency to appropriately increase the indoor unit coil temperature T2. The specific value of the operating frequency increased by 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 (for example, when the judgment result is yes 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 smooth operation of the system.

[0036] Continue to see Figure 3 In one or more embodiments, after step S31 is completed, the control method executes step S41, i.e., determines whether (indoor unit coil temperature T2-indoor unit coil temperature T2) is greater than or equal to the preset temperature threshold. In one or more embodiments, the preset temperature threshold is equal to the target setting 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 judgment result is yes, it means that the indoor unit coil temperature T2 is relatively high at this time, and the first wind speed is used as the final operating wind speed (i.e., step S51). When the judgment result is no, it means that the indoor unit coil temperature T2 is relatively low at this time, and the second wind speed is used as the final operating wind speed (i.e., step S52) to appropriately reduce the wind speed.

[0037] Continue to see Figure 3 After step S32 is completed, the control method executes step S42, i.e., judging whether (indoor unit coil temperature T2-indoor unit coil temperature T2) is greater than or equal to the preset temperature threshold. When the judgment result is yes, it means that the indoor unit coil temperature T2 is relatively high at this time, and the second wind speed is used as the final operating wind speed (i.e., step S53). When the judgment result is no, it means that the indoor unit coil temperature T2 is relatively low at this time, and the third wind speed is used as the final operating wind speed (i.e., step S54) to appropriately reduce the wind speed.

[0038] Continue to see Figure 3, after step S33 is completed, the control method executes step S43, i.e., judging whether (indoor unit coil temperature T2-indoor unit coil temperature T2) is greater than or equal to the preset temperature threshold. When the judgment result is yes, it means that the indoor unit coil temperature T2 is relatively high at this time, and the third wind speed is used as the final operating wind speed (i.e., step S53). When the judgment result is no, it means that the indoor unit coil temperature T2 is relatively low at this time, and the fourth wind speed which is smaller than the third wind speed is used as the final operating wind speed (i.e., step S54) to appropriately reduce the wind speed. The specific value of the fourth wind speed can also be adjusted according to actual needs, for example, 1000r / min.

[0039] Figure 4 2 is a flow chart of 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 the start-up signal, the control method first executes step S60, that is, controls the compressor of the fresh air system 100 to operate at the initial operating frequency, and keeps the fresh air fan 20 stopped. 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 to determine whether the first difference between the indoor unit coil temperature T2 and the fresh air temperature T3 is greater than or equal to the first preset difference. The specific value of the first preset difference can be adjusted according to actual needs, such as 18°C, 20°C, etc. If the judgment result is no, then continue to execute step S61, that is, repeatedly obtain the outlet air temperature T1, the indoor unit coil temperature T2 and the fresh air temperature T3. If the judgment result is yes, then execute step S63, that is, continue to determine whether the second difference between the indoor unit coil temperature T2 and the outlet air temperature T2 is greater than or equal to the second preset difference. Among them, 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°C, 10°C, etc. If the judgment result is no, continue to execute step S61, that is, repeatedly obtain the outlet air temperature T1, the indoor unit coil temperature T2 and the fresh air temperature T3. If the judgment result is yes, execute step S64, that is, control the fresh air fan 20 to start at the preset startup wind speed. The specific value of the preset startup wind 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 may be configured the same as those in the first embodiment and will not be described in detail here.

[0041] So far, the technical solutions of the present invention have been described in conjunction with the preferred embodiments shown in the accompanying drawings. However, it is easy for those skilled in the art to understand that the protection scope of the present invention is obviously not limited to these specific embodiments. Without departing from the principle 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 these changes or substitutions will fall within the protection scope 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, the indoor unit coil temperature T2 and the fresh air temperature T3 of the fresh air system; Comparing the air outlet temperature T1 with the target set temperature; Based on the comparison result of the outlet air temperature T1 and the target set temperature, determining the initial operating wind speed of the fresh air fan of the fresh air system; Compare a first difference between the indoor unit coil temperature T2 and the fresh air temperature T3 with a preset temperature threshold; Based on the comparison result of 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 step of determining the initial operating wind speed of the fresh air fan based on the comparison result between the outlet air temperature T1 and the target set temperature includes: When the air outlet temperature T1 is greater than or equal to the target set temperature, determining the initial operating wind speed to be the first wind speed; When the air outlet temperature T1 is lower than the target setting temperature and is greater than or equal to the difference between the target setting temperature and the preset temperature difference, determining the preliminary operation wind speed to be the second wind speed; When the outlet air temperature T1 is less than the difference between the target setting temperature and the preset temperature difference, the preliminary operation wind speed is determined to be the third wind speed. The second wind speed is less than the first wind speed and 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 comprises: When the first difference is greater than or equal to the preset temperature threshold, the determined preliminary operating wind speed is used as the final operating wind speed; When the first difference is less than the preset temperature threshold, an operating wind speed that is smaller than the determined preliminary operating wind speed is used as the final 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, obtaining the preliminary operating wind speed; If the preliminary operating wind speed is the first wind speed, determining the final operating wind speed to be the second wind speed; If the preliminary operating wind speed is the second wind speed, determining the final operating wind speed to be the third wind speed; If the preliminary operating wind speed is the third wind speed, determining the final operating wind speed to be the fourth wind speed, Wherein, 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 comprises: 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, 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 to 5, characterized in that: When the fresh air system receives a power-on 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 stopped; Obtain the outlet air temperature T1, the indoor unit coil temperature T2 and the fresh air temperature T3; Compare a first difference between the indoor unit coil temperature T2 and the fresh air temperature T3 with a first preset difference, and compare 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, the fresh air fan is controlled to start at a preset start-up wind speed, The second preset difference is smaller 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°C to 12°C.

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 setting temperature.

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

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