air conditioner indoor unit

Abstract

This utility model provides an indoor air conditioning unit, belonging to the field of air conditioning technology. The indoor air conditioning unit includes: a casing; a fresh air fan disposed within the casing and comprising: a volute, the volute including a volute tongue, the volute defining a connected impeller cavity and an air outlet duct located on both sides of the volute tongue, the impeller cavity having an outlet diffuser section near the air outlet duct; a centrifugal impeller disposed within the impeller cavity, the rotation of the centrifugal impeller driving outdoor fresh air into the impeller cavity and out through the air outlet duct; a guide vane disposed at the outlet diffuser section, forming a guide channel between the guide vane and the outer edge of the centrifugal impeller, the guide channel exhibiting a tendency to first contract and then expand along the airflow direction; the guide vane's central arc is a multi-segment curved shape, including a first curved segment near the volute tongue, the center of curvature of the first curved segment located on the side of the guide vane away from the centrifugal impeller. Through the above-mentioned guide vane, the backflow in the impeller channel of the outlet diffuser section and the static pressure distribution on the surface of the volute tongue can be improved simultaneously, achieving noise reduction.

Description

Technical Field

[0001] This utility model belongs to the field of air conditioning technology, and in particular relates to an indoor unit of an air conditioner. Background Technology

[0002] As people's requirements for indoor air quality increase, air conditioning indoor units with fresh air function are gradually becoming the mainstream in the market.

[0003] A typical indoor unit of a fresh air conditioning system includes a casing, heat exchange components, and a fresh air module housed within the casing. The fresh air module, comprising a fresh air fan, is a key aerodynamic component responsible for drawing in and pressurizing outdoor fresh air before delivering it indoors. Its performance directly impacts the overall unit's fresh air volume, static pressure, and noise level. In high static pressure applications (such as fresh air modules with a total pressure greater than 250 Pa), the fresh air fan must overcome significant system resistance, thus placing higher demands on the aerodynamic design and flow field control of the fan's casing.

[0004] In existing technologies, some fresh air fans employ flow-guiding structure designs to improve the flow state inside the volute, such as setting flow guide vanes or irregular structures at the volute outlet or volute tongue area to guide airflow and reduce flow losses. Common flow-guiding structures include inclined volute tongues, stepped volute tongues, or local flow guides in the volute profile, designed to mitigate airflow impact and improve outlet flow uniformity.

[0005] However, existing flow guiding structures have significant drawbacks in practical applications: on the one hand, the position and shape of the flow guide vanes do not match the volute profile well, making it difficult to effectively suppress backflow in the outlet diffuser region under high static pressure conditions; on the other hand, traditional flow guiding structure designs often sacrifice the fan's work capacity, leading to a decrease in airflow or efficiency. Furthermore, while irregularly shaped volute tongue structures can alleviate the pressure gradient on the volute tongue surface, they are complex to manufacture, costly, and in high static pressure fans, it is difficult to achieve an ideal misalignment between the airflow direction and the volute tongue position, limiting their practical application effectiveness. Utility Model Content

[0006] This utility model aims to at least partially solve one of the technical problems in related technologies. Therefore, This utility model provides an indoor unit for an air conditioner, which includes: A housing having an internally defined receiving space, the housing including a fresh air outlet; A fresh air fan is disposed in the accommodating space, the fresh air fan comprising: The volute has a volute inlet and a volute outlet, the volute outlet is connected to the fresh air outlet, the volute includes a volute tongue, and the volute defines a connected impeller cavity and an air outlet duct located on both sides of the volute tongue. The impeller cavity has an outlet diffuser section close to the air outlet duct. A centrifugal impeller is disposed in the impeller cavity. The rotation of the centrifugal impeller drives outdoor fresh air to enter the impeller cavity through the volute inlet, and then blows it into the room through the air outlet duct, the volute outlet, and the fresh air outlet in sequence. A guide vane is disposed at the outlet diffuser section, and a guide channel is formed between the guide vane and the outer edge of the centrifugal impeller. The guide channel tends to contract first and then expand along the airflow direction. The guide vane has a multi-segment curved shape, including a first curved segment near the volute tongue, and the center of curvature of the first curved segment is located on the side of the guide vane away from the centrifugal impeller.

[0007] The above technical solution has the following advantages or beneficial effects: the contraction section of the guide channel can accelerate and depressurize the fresh airflow, effectively reducing the reverse pressure gradient in the outlet diffuser section area and effectively suppressing the backflow phenomenon; the expansion section of the guide channel decelerates and pressurizes the fresh airflow, smoothly restoring static pressure, ensuring the work capacity of the fresh air fan, and making the airflow towards the volute tongue more uniform and stable. The curvature center of the first curve section is located on the side of the guide vane away from the centrifugal impeller, causing the rear half of the guide vane to "rise," which guides the outdoor fresh air from a position away from the volute tongue into the outlet air duct. This can improve the uniformity of static pressure distribution on the surface of the volute tongue, reduce the impact of the fresh airflow on the volute tongue, reduce BPF noise, and achieve noise reduction.

[0008] According to an embodiment of this disclosure, on a cross section perpendicular to the axial direction of the centrifugal impeller, the included angle β formed by connecting the upstream end of the guide vane and the center of the volute tongue with the rotation center of the centrifugal impeller as the vertex satisfies: β≥35°, β≤40°.

[0009] The above technical solution has the following advantages or beneficial effects: If β < 35°, the upstream end of the guide vane is too close to the volute tongue, resulting in insufficient coverage of the guide vane, inability to effectively suppress backflow, and poor noise reduction effect. If β > 40°, the upstream end of the guide vane is too far from the volute tongue, prematurely constraining and guiding the airflow, affecting the working capacity of the fresh air fan, and causing significant air volume loss. By setting the included angle β within any range of 35°~40°, the position of the upstream end of the guide vane relative to the volute tongue is optimized, ensuring that the guide vane covers the impeller flow channel area with severe backflow, effectively suppressing backflow while controlling the impact angle of the airflow on the volute tongue, reducing noise caused by periodic impacts.

[0010] According to an embodiment of this disclosure, the radial distance L2 between the downstream end of the guide vane and the outer edge of the centrifugal impeller satisfies: L2≥0.2R, L2≤0.25R, where R is the radius of the centrifugal impeller.

[0011] The above technical solution has the following advantages or beneficial effects: If the radial distance L2 > 0.25R, the downstream end of the guide vane is far from the centrifugal impeller, which cannot effectively guide the airflow, resulting in poor backflow suppression and poor protection of the volute tongue. If the radial distance L2 < 0.2R, the downstream end of the guide vane is close to the centrifugal impeller, which in turn makes the overall guide vane close to the centrifugal impeller, easily generating rotational noise, increasing flow resistance, and leading to a decrease in airflow and efficiency. By setting the radial distance L2 within the range of 0.2R to 0.25R, ensuring that the gap between the downstream end of the guide vane and the outer edge of the centrifugal impeller is appropriate, it can effectively guide the airflow while avoiding rotational noise or flow loss.

[0012] According to an embodiment of this disclosure, the radial distance L1 between the upstream end of the guide vane and the outer edge of the centrifugal impeller satisfies: L1≥0.2R, L1≤0.25R, where R is the radius of the centrifugal impeller.

[0013] The above technical solution has the following advantages or beneficial effects: If the radial distance L1 > 0.25R, the upstream end of the guide vane is too far from the centrifugal impeller, making it unable to effectively guide the airflow and resulting in poor backflow suppression. If the radial distance L1 < 0.2R, the upstream end of the guide vane is too close to the centrifugal impeller, which not only increases the airflow impact loss at the inlet of the guide channel but also leads to rotational noise. By setting the radial distance L1 within the range of 0.2R to 0.25R, ensuring an appropriate gap between the upstream end of the guide vane and the outer edge of the centrifugal impeller, effective airflow guidance can be achieved while avoiding rotational noise or flow loss.

[0014] According to an embodiment of this disclosure, in a cross section perpendicular to the axial direction of the centrifugal impeller, the line connecting the leading edge point A of the guide vane away from the outline of the centrifugal impeller to the rotation center of the centrifugal impeller intersects the outer edge of the centrifugal impeller at point B, and the angle γ formed by the tangent at point A and the tangent at point B satisfies: γ≥-5°, γ≤5°.

[0015] The above technical solution has the following advantages or beneficial effects: If γ < -5° or γ > 5°, the airflow will not match the upstream end of the guide vane, resulting in impact, vortexes, and separation, increasing aerodynamic losses and noise. By setting γ within the range of -5° to 5°, the upstream end of the guide vane is made to be basically parallel to the airflow direction, allowing the airflow to pass smoothly through the guide vane, reducing flow separation and energy loss, and improving guiding efficiency.

[0016] According to an embodiment of this disclosure, on a cross section perpendicular to the axial direction of the centrifugal impeller, with the rotation center of the centrifugal impeller as the vertex, the included angle θ formed by connecting the upstream end and the downstream end of the guide vane satisfies: θ≥20°, θ≤30°.

[0017] The above technical solution has the following advantages or beneficial effects: The included angle θ is determined based on the circumferential range of the recirculation zone within the centrifugal impeller. If θ > 30°, the length between the upstream and downstream ends of the guide vane becomes too long, significantly suppressing the working capacity of the volute and resulting in a large airflow loss. If θ < 20°, the suppression effect on recirculation is not significant, and noise reduction is poor. By setting the included angle θ within any range of 20° to 30°, the guide vane effectively reduces the recirculation flow for the impeller channels with higher recirculation velocities.

[0018] According to an embodiment of this disclosure, the middle arc line further includes a second curve segment connected to the first curve segment. The second curve segment is farther away from the volute tongue relative to the first curve segment, and its radius r2 satisfies: r2≥0.62R, r2≤0.64R; the bending directions of the first curve segment and the second curve segment are opposite, and R is the radius of the centrifugal impeller.

[0019] The above technical solution has the following advantages or beneficial effects: If r2 > 0.64R, the curvature of the second curve segment is too small, resulting in insufficient acceleration effect of the contraction section of the guide channel and reduced backflow suppression capability. If r2 < 0.62R, the curvature of the second curve segment is too large, causing the airflow to accelerate too quickly, easily generating separation and vortices. By setting the radius r2 of the second curve segment within a reasonable range of 0.62R to 0.64R, its curvature profile is optimized. This design ensures that after the airflow accelerates smoothly in the first half of the guide vane, it can achieve a smooth turn and transition here, effectively reducing flow separation and energy loss, thereby providing stable and uniform intake conditions for the subsequent expansion section of the flow channel, ultimately improving the overall guide efficiency.

[0020] According to an embodiment of this disclosure, the radius r1 of the first curve segment satisfies: r1≥0.53R, r1≤0.55R.

[0021] The above technical solution has the following advantages or beneficial effects: If r1 > 0.55R, the curvature of the first curve segment is too small, resulting in insufficient upward tilting effect of the latter half of the guide vane, failing to effectively guide the airflow away from the volute tongue, and potentially exacerbating the impact of the volute tongue. If r1 < 0.53R, the curvature of the first curve segment is too large, causing drastic changes in airflow direction, making separation easy and increasing noise and losses. By optimizing the radius of curvature of the second curve segment to be within the range of 0.53R to 0.55R, smooth airflow turning and effective guidance are achieved. This design significantly reduces flow separation on the one hand, and actively mitigates the direct impact of airflow on the volute tongue on the other hand, thanks to the upward tilting shape at the end. The coordinated work of the first and second curve segments enables the entire guide channel to achieve a smooth transition of "contraction followed by expansion," significantly improving flow field stability and aerodynamic performance.

[0022] According to embodiments of this disclosure, the thickness of the guide plate satisfies: t≥1.5mm, t≤3mm.

[0023] The above technical solution has the following advantages or beneficial effects: If t < 1.5mm, the rigidity of the guide vane is insufficient, making it prone to vibration or damage, affecting long-term reliability. If t > 3mm, the noise reduction effect is not significant, and it increases unnecessary flow resistance and material costs, increasing the weight of the volute. By setting the thickness t within a reasonable range of 1.5mm to 3mm, the structural strength and rigidity of the guide vane are effectively guaranteed, vibration or deformation is avoided, and flow resistance and weight are minimized.

[0024] According to an embodiment of this disclosure, the guide vanes are connected to two opposite sidewalls of the volute at both ends of the centrifugal impeller in the axial direction.

[0025] The above technical solution has the following advantages or beneficial effects: by connecting the two ends of the guide plate to the two side walls of the volute, it not only ensures that the guide plate is firmly fixed and prevents vibration and noise, but also makes the guide plate guide the flow uniformly throughout the thickness of the entire guide channel, avoiding end leakage or uneven flow. Attached Figure Description

[0026] Figure 1 This is a schematic diagram of the appearance of the fresh air module according to one embodiment of the present disclosure; Figure 2 This is a schematic diagram of the appearance of the fresh air module from another perspective according to one embodiment of the present disclosure; Figure 3 This is a partial explosion diagram of the fresh air module according to one embodiment of this disclosure; Figure 4 This is an exploded view of the fresh air module according to one embodiment of the present disclosure; Figure 5 This is a structural schematic diagram of a fresh air fan according to one embodiment of the present disclosure; Figure 6 This is a structural schematic diagram of the fresh air module from another perspective according to one embodiment of the present disclosure; Figure 7 This is a cross-sectional view of the volute according to an embodiment of the present disclosure; Figures 8-10 This is a schematic diagram of the internal structure of the volute according to an embodiment of the present disclosure; Figure 11 This is a partial structural diagram of the interior of the volute according to an embodiment of the present disclosure; Figure 12 This is a comparison diagram of the velocity vector inside the fresh air fan before and after the improvement; Figure 13 This is a comparison cloud map of the static pressure on the surface of the volute of the fresh air fan before and after the improvement.

[0027] In the above figures: Fresh air module 10; Fresh air fan 1; Volute 11; Volute tongue 111; Centrifugal impeller 12; Volute inlet 13; Volute outlet 14; Impeller cavity 15; Outlet diffuser section 151; Outlet air duct 16; Inlet hood 2; Inlet cavity 21; Inlet pipe 3; Fresh air inlet 31; Guide vane 4; Mid-arc line 41; First curve section 411; Second curve section 412; Guide channel 5; Through section 6. Detailed Implementation

[0028] The present invention will now be described in detail through exemplary embodiments. However, it should be understood that, without further description, elements, structures, and features in one embodiment may be advantageously incorporated into other embodiments.

[0029] In this utility model, the reference to "embodiment" means that a specific feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places in the specification does not necessarily refer to the same embodiment, nor is it a mutually exclusive, independent, or alternative embodiment. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described in this application may be combined with other embodiments without conflict.

[0030] In the description of this utility model, it should be understood that the terms "center", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this utility model.

[0031] The terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature.

[0032] In the description of this utility model, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "joining" 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 or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this utility model based on the specific circumstances.

[0033] An air conditioner's indoor unit is part of the air conditioner. It is installed indoors and used for heat exchange with the indoor environment. Additionally, an air conditioner includes an outdoor unit, which is typically located outdoors and used to transfer heat from the indoor environment to the outside.

[0034] The air conditioner indoor unit provided in this embodiment is a wall-mounted air conditioner indoor unit, which can have various implementation forms.

[0035] An indoor air conditioner unit may include a casing. The casing is installed on the indoor wall and forms the overall appearance of the indoor air conditioner unit. The casing is rectangular in shape, with its left and right ends being the two ends along its length.

[0036] The interior of the casing has a storage space. This space is used to house and secure the various components inside the air conditioner indoor unit, preventing collisions between external objects and these components, thereby improving the reliability of the air conditioner indoor unit during transportation or installation.

[0037] The housing may include an air conditioning inlet. The air conditioning inlet is connected to the housing space and serves as the inlet for external air to flow into the housing, allowing indoor air to enter the housing space through the air conditioning inlet.

[0038] The housing may include an air conditioning vent. The air conditioning vent is connected to the housing space and serves as an outlet for airflow within the housing, allowing airflow within the housing space to exit through the air conditioning vent.

[0039] In some embodiments of this application, the air conditioning inlet is located at the top of the housing. The air conditioning outlet may be located at the bottom front side of the housing.

[0040] The air conditioner vent is elongated and can extend along the length of the unit casing, improving the aesthetics of the indoor unit. In this embodiment, when the indoor unit is operating, air enters from the top and exits towards the bottom front, facilitating installation.

[0041] It should be noted that the directions described in the text are based on the direction the user faces when facing the indoor unit of the air conditioner. Specifically, the side of the indoor unit facing the user when in use is defined as the front side, and the opposite side is defined as the rear side. The left and right sides are distinguished by the direction the user faces when facing the indoor unit.

[0042] An indoor unit of an air conditioner may include an indoor heat exchanger. The indoor heat exchanger extends along the length of the unit casing and is located inside the casing to exchange heat with the airflow inside the casing.

[0043] An indoor unit of an air conditioner may include an indoor fan. The indoor fan is located within a housing space and is used to drive indoor air from outside the unit casing through the air conditioner inlet into the housing space inside the unit casing. The indoor fan drives the airflow within the housing space to flow from the air conditioner inlet toward the air conditioner outlet.

[0044] An air conditioner may include an outdoor heat exchanger and a compressor, which are installed in the outdoor unit of the air conditioner.

[0045] Air conditioners may include a throttling device. The throttling device is used to limit airflow. The throttling device can be provided in either the indoor or outdoor unit of the air conditioner.

[0046] Air conditioners execute a refrigeration cycle using a compressor, condenser, throttling device, and evaporator. The refrigeration cycle involves a series of processes including compression, condensation, expansion, and evaporation, supplying refrigerant to the conditioned and heat-exchanged air.

[0047] The compressor compresses the refrigerant gas at low temperature and low pressure and discharges it at high temperature and high pressure. The discharged refrigerant gas flows into the condenser.

[0048] The condenser condenses the compressed refrigerant into a liquid phase, and the heat is released into the surrounding environment through the condensation process.

[0049] The throttling device causes the high-temperature, high-pressure liquid refrigerant condensed in the condenser to expand into a low-pressure liquid refrigerant.

[0050] The evaporator evaporates the refrigerant that expands in the throttling device and returns the refrigerant gas, now at a low temperature and low pressure, to the compressor. The evaporator achieves its cooling effect by utilizing the latent heat of refrigerant evaporation to exchange heat with the material being cooled. Throughout the cycle, the air conditioner regulates the temperature of the indoor space.

[0051] In the indoor heat exchanger and the outdoor heat exchanger, one is a condenser and the other is an evaporator. When the indoor heat exchanger is used as a condenser, the air conditioner is used as a heater in heating mode. When the indoor heat exchanger is used as an evaporator, the air conditioner is used as a cooler in cooling mode.

[0052] To improve indoor air quality, in some embodiments of this application, the indoor unit of the air conditioner may include a fresh air module 10, which is disposed in the casing and used to introduce outdoor fresh air into the room. The fresh air module 10 and the indoor heat exchanger are spaced apart along the length of the casing.

[0053] Specifically, the casing may include a fresh air outlet, and the fresh air module 10 connects the outdoor environment to the fresh air outlet. The fresh air outlet provides a fresh air outlet path; outdoor fresh air, after being processed by the fresh air module 10, is smoothly discharged into the room through the fresh air outlet, realizing fresh air circulation. The fresh air outlet can be located at the bottom front of the indoor unit of the air conditioner, or on one side of the air conditioner's air outlet.

[0054] refer to Figure 1 The fresh air module 10 may include a fresh air fan 1, which is located in the housing space and is used to actively introduce outdoor fresh air. The fresh air fan 1 drives the airflow of fresh air to ensure the efficient operation of the fresh air module 10. The fresh air fan 1 is a centrifugal fan.

[0055] refer to Figure 4 and Figure 5 The fresh air fan 1 may include a volute 11, which has a volute inlet 13 and a volute outlet 14. The volute 11 provides an airflow channel, allowing airflow to flow from the volute inlet 13 to the volute outlet 14.

[0056] In this embodiment, the volute inlet 13 serves as the inlet for external air to flow into the volute 11, allowing fresh outdoor air to enter the volute. The volute outlet 14 serves as the outlet for fresh outdoor air to flow out of the volute 11, allowing airflow within the volute to exit through the outlet 14. The volute outlet 14 is connected to the casing and communicates with the fresh air outlet, allowing the fresh outdoor air exiting the volute outlet 14 to flow into the indoor environment through the fresh air outlet.

[0057] refer to Figure 1 , Figure 3 The fresh air module 10 may include an air inlet shroud 2, which is connected to a volute 11, and the air inlet shroud 2 and the volute 11 together define an air inlet cavity 21. The air inlet cavity 21 is connected to the impeller cavity 15 through a volute inlet 13. The air inlet cavity 21 serves as a transition area for fresh airflow from the outside to the centrifugal impeller 12. Proper design of the air inlet cavity 21 can improve the performance of the centrifugal fan.

[0058] refer to Figures 2-4 The fresh air module 10 may include an air inlet duct 3, one end of which is connected to an air inlet cover, and the other end of which forms a fresh air inlet that communicates with the air inlet cavity. The fresh air inlet 31 serves as the inlet for external air to flow into the fresh air module 10, allowing outdoor fresh air to enter the air inlet cavity 21 through the fresh air inlet 31.

[0059] refer to Figure 3For example, in this embodiment, the air inlet shroud 2 and the volute 11 are connected to define an air inlet cavity 21 and a through portion 6 communicating with the air inlet cavity 24. The air inlet pipe 3 is installed at the through portion 6 and is connected to the air inlet shroud 2 and the volute 11 so that the fresh air inlet 31 communicates with the air inlet cavity 21 through the air inlet pipe 3.

[0060] In some embodiments, the fresh air inlet 31 can be connected to the outdoor environment through a fresh air corrugated duct. Under the rotation of the centrifugal impeller 12, outdoor fresh air enters the air intake chamber 21 through the fresh air inlet 31, and then enters the impeller chamber 15 through the volute inlet 13. After entering the impeller chamber 15, the outdoor fresh air is accelerated by the centrifugal impeller 12, becoming high-pressure outdoor fresh air, and is then discharged through the volute outlet 14, finally flowing into the room through the fresh air outlet.

[0061] In fresh air module 10, refer to Figure 1 , Figure 4 A filter assembly 5 is installed inside the air inlet cavity 21 near the volute inlet 13. The filter assembly 5 includes a filter 51, which is used to filter outdoor fresh air to ensure the air quality delivered into the room. The filter 51 is installed in the air inlet cavity 21 via a filter bracket 52.

[0062] refer to Figure 7 The volute 11 contains a fan chamber 15 and an air outlet duct 16 located on both sides of the volute tongue 111. The fan chamber 15 and the air outlet duct 16 are connected. The fan chamber 15 has an outlet diffuser section 151 near the air outlet duct 16, and the volute outlet 14 is formed at the end of the air outlet duct 16 away from the volute tongue 111.

[0063] Continue to refer to Figure 7 The fresh air fan 1 may include a centrifugal impeller 12, which is disposed within the impeller cavity 15. The volute inlet is located at one end of the centrifugal impeller 12 along its axial direction. The centrifugal impeller 12 is the core component of the fresh air fan 1; its rotation generates centrifugal force to drive airflow, producing wind pressure and air volume. The rotation of the centrifugal impeller 12 drives outdoor fresh air into the impeller cavity 15 through the volute inlet, and then sequentially blows it into the room through the air outlet duct 16, the volute outlet 14, and the fresh air outlet.

[0064] Specifically, in this embodiment, the volute resembles a snail shell. The volute may include a body portion, within which a fan cavity 15 is defined. The volute inlet is located on the body portion. The volute may also include an outlet portion, within which an air outlet duct 16 is defined, and the volute outlet is located on the outlet portion.

[0065] A volute tongue 111 is formed at the connection between the main body and the outlet. The volute tongue 111 has a tongue-shaped structure that prevents air from circulating inside the volute. Outdoor air that enters the impeller cavity 15 through the volute inlet flows through the annular flow channel between the main body and the centrifugal impeller 12 and is discharged through the air outlet duct 16 in the outlet.

[0066] In some embodiments of this application, the volute 11 can be formed by fastening together a first volute and a second volute, which is prior art and will not be described in detail here.

[0067] The rapid increase in the flow area of ​​the outlet diffuser section 151 leads to a larger back pressure in this area, which easily causes backflow in the impeller flow channel near this region. This phenomenon is particularly prominent in high static pressure fresh air fans (total pressure greater than 250 Pa). This is because high static pressure fresh air fans need to have a stronger working capacity to overcome the greater system resistance, and their volute working section has a larger flow area, resulting in a more severe backflow phenomenon in the impeller flow channel near the outlet diffuser section 151, affecting the aerodynamic noise of the fresh air fan. In addition, the volute tongue 111 is subjected to periodic airflow impacts, which will form flow stagnation points on its surface. The high pressure at the stagnation point and the low pressure area at the inlet of the volute tongue 111 form a large pressure gradient on the surface of the volute tongue 111, resulting in unstable flow and easily causing BPF abnormal noise, which is also an important reason affecting the aerodynamic noise of high static pressure fresh air fans.

[0068] It should be noted that the impeller flow channel is the flow channel formed between adjacent blades of the centrifugal impeller 12.

[0069] In related technologies, the conventional solution to the backflow phenomenon in the flow channel caused by a sudden increase in the flow area of ​​the volute is to adjust the volute profile and the blade profile. However, this is technically difficult and the effect is not good. Moreover, the reduced outlet expansion will reduce the working capacity of the fresh air fan and affect the air volume.

[0070] To address the issue of a large pressure gradient on the surface of the volute tongue 111 caused by airflow impact, conventional methods include adjusting the volute tongue position or using a non-standard volute tongue structure. However, due to the inherent characteristics of high static pressure fresh air fans, it is difficult to align the position of the volute tongue 111 with the outlet airflow direction. While non-standard volute tongue structures reduce the surface pressure gradient to some extent, they increase the design and manufacturing difficulty of the volute casing, affecting production efficiency. Furthermore, related technologies also include flow guides installed in the outlet diffuser section 151; however, the shape and dimensional parameters of these flow guides are often improperly designed, failing to effectively suppress backflow and inhibiting the fresh air fan's work capacity, resulting in significant airflow loss.

[0071] To address the aforementioned technical issues, in some embodiments of this application, the fresh air module may include a guide vane 4, which is disposed at the outlet diffuser section 151 to guide outdoor fresh air from a position away from the volute tongue 111 into the outlet air duct 16.

[0072] Specifically, the guide vane 4 can divert and guide the outdoor fresh air that is about to be discharged into the air outlet duct 16 within the outlet diffuser section 151, so that most of the fresh air flow can enter the air outlet duct 16 from a position away from the volute tongue 111, reducing the amount of air diverted at the volute tongue 111, and reducing the airflow impact that the volute tongue 111 may be subjected to, thereby effectively reducing the aerodynamic noise of the fresh air fan.

[0073] refer to Figure 8 A flow channel 5 is formed between the guide vane 4 and the outer edge of the centrifugal impeller 12. The flow channel 5 first contracts and then expands along the airflow direction. In this embodiment, the distance between the middle arc line 41 of the guide vane 4 and the outer edge of the centrifugal impeller 12 first decreases and then increases along the airflow direction.

[0074] In this embodiment, reference Figure 7 The guide vane 4 can divert and guide the fresh air destined for the outlet duct 16 within the outlet diffuser section 151, allowing most of the fresh air to flow in the area of ​​the guide vane 4 away from the centrifugal impeller 12 and sequentially enter the outlet duct 16 from a position away from the volute tongue 111, thus meeting the need for large-volume air supply. Figure 7 The arrows shown indicate the direction of airflow.

[0075] The guide vane 4 allows a small portion of the airflow to flow within the guide channel 5 and sequentially reach the location of the volute tongue 111. Under the guiding effect of the volute tongue 111, most of the air is diverted to the outlet duct 16, while a smaller amount of air enters the area between the centrifugal impeller 12 and the volute tongue 111. This reduces the amount of airflow reaching the volute tongue 111 and being diverted there, as well as the potential impact on the volute tongue 111, thereby reducing duct noise.

[0076] In this embodiment, the contraction section of the guide channel 5 can accelerate and depressurize the fresh airflow, effectively reducing the reverse pressure gradient in the outlet diffuser section 151 region, thereby weakening the airflow return velocity and reducing the return flow rate. This effectively suppresses the airflow return phenomenon and improves the flow stability within the impeller channel. The accelerated and depressurized fresh airflow is decelerated and pressurized through the expansion section of the guide channel 5, smoothly restoring the static pressure, ensuring the work capacity of the fresh air fan, and making the airflow towards the volute tongue 111 more uniform and stable.

[0077] refer to Figure 11The middle arc 41 of the guide vane 4 has a multi-segment curved shape. The middle arc 41 of the guide vane 4 includes a first curved segment 411 near the volute tongue 111. The curvature center of the first curved segment 411 is located on the side of the guide vane 4 away from the centrifugal impeller 12.

[0078] It should be noted that the central arc line 41 of the guide vane 4 is characterized as the geometric center line connecting the two opposing surfaces of the guide vane.

[0079] In this embodiment, the curvature center of the first curve segment 411 is located on the side of the guide vane 4 away from the centrifugal impeller 12, causing the rear half of the guide vane 4 near the volute tongue 111 to "rise". This can effectively guide a small portion of the airflow entering the guide channel 5 to flow away from the volute tongue 111, reducing the impact intensity of the airflow on the volute tongue 111, reducing the pressure fluctuation on the surface of the volute tongue 111, effectively improving the static pressure uniformity on the surface of the volute tongue 111, reducing flow separation and pressure pulsation caused by large pressure gradients, thereby effectively suppressing BPF noise and achieving noise reduction.

[0080] In some embodiments of this application, reference is made to Figure 8 On a cross section perpendicular to the axial direction of the centrifugal impeller 12, with the rotation center O of the centrifugal impeller 12 as the vertex, the included angle β formed by connecting the upstream end of the guide vane 4 and the center of the volute tongue 111 satisfies: β≥35°, β≤40°. This range of included angle β optimizes the position of the upstream end of the guide vane 4 relative to the volute tongue 111, ensuring that the guide vane 4 covers the impeller flow channel area with severe backflow, effectively suppressing backflow while controlling the impact angle of the airflow on the volute tongue 111, and reducing the noise caused by periodic impact.

[0081] If β < 35°, the upstream end of the guide vane 4 is too close to the volute tongue 111, resulting in insufficient coverage of the guide vane 4, which cannot effectively suppress backflow and has poor noise reduction effect.

[0082] If β>40°, the upstream end of the guide vane 4 is too far from the volute tongue 111, which prematurely constrains and guides the airflow, causing unnecessary flow resistance in the front section, affecting the working capacity of the fresh air fan, and resulting in a large loss of air volume.

[0083] By setting the included angle β within a reasonable range of 35° to 40°, the circumferential installation position of the guide vane 4 relative to the volute tongue 111 is defined, ensuring that the guide vane 4 is in its most effective position, while simultaneously solving the two core problems of outlet backflow and volute tongue 111 impact.

[0084] In some embodiments of this application, reference continues to be made to Figure 8On a cross section perpendicular to the axial direction of the centrifugal impeller 12, with the rotation center O of the centrifugal impeller 12 as the vertex, the included angle θ formed by connecting the upstream end and the downstream end of the guide vane 4 respectively satisfies: θ≥20°, θ≤30°.

[0085] The included angle θ is determined based on the circumferential range of the recirculation zone within the centrifugal impeller 12. By setting the included angle θ within any range of 20° to 30°, it is ensured that the guide vane 4 has sufficient length to effectively guide and reshape the flow field, so that the coverage of the guide vane 4 is precisely aligned with the impeller channels with larger recirculation velocities, effectively suppressing recirculation, optimizing noise reduction, and avoiding performance degradation due to insufficient or excessive coverage.

[0086] If θ > 30°, the length between the upstream and downstream ends of the guide vane 4 will be too long, meaning the overall length of the guide vane 4 will be too long in the cross-section perpendicular to the axial direction of the centrifugal impeller 12. This will excessively increase the contact area with the airflow and frictional resistance, increasing flow losses and reducing the efficiency of the centrifugal fan. Simultaneously, the excessively long guide vane 4 will extend into areas where the flow field has stabilized, creating harmful resistance and significantly suppressing the work capacity of the volute, resulting in a substantial airflow loss.

[0087] If θ < 20°, then on the cross section perpendicular to the axial direction of the centrifugal impeller 12, the overall length of the guide vane 4 is too short, the coverage area of ​​the guide vane 4 is too small, the effect of suppressing backflow is not obvious, and the noise reduction is poor. At the same time, its flow pattern shaping effect of "contraction followed by expansion" and "upward movement at the end" will also be weakened.

[0088] It should be noted that in this paper, on the cross section perpendicular to the axial direction of the centrifugal impeller 12, the leading edge point A of the guide vane 4 away from the outline of the centrifugal impeller 12 is the upstream end point of the guide vane 4, and the trailing edge point of the guide vane 4 away from the outline of the centrifugal impeller 12 is the downstream end point of the guide vane 4.

[0089] In some embodiments of this application, reference is made to Figure 9 The radial distance L2 between the downstream end of the guide vane 4 and the outer edge of the centrifugal impeller 12 satisfies: L2≥0.2R, L2≤0.25R, to ensure that the gap between the downstream end of the guide vane 4 and the outer edge of the centrifugal impeller 12 is appropriate, which can effectively guide the flow and avoid causing rotational noise or flow loss. Wherein, R is the radius of the centrifugal impeller 12.

[0090] It should be noted that the radial distance L2 is the distance from the downstream end of the guide vane 4 to the outer contour circle of the centrifugal impeller 12 in the direction pointing towards the rotation center O of the centrifugal impeller 12.

[0091] If the radial distance L2>0.25R, the downstream end of the guide vane 4 will be far from the centrifugal impeller, and the guiding and "uplifting" effect of the end of the guide vane 4 will be weakened, making it unable to effectively guide the airflow, resulting in poor backflow suppression and a worse protection effect on the volute tongue 111.

[0092] If the radial distance L2 < 0.2R, the downstream end of the guide vane 4 is closer to the centrifugal impeller, which in turn makes the guide vane 4 as a whole closer to the centrifugal impeller 12. This not only increases the flow resistance, leading to a decrease in air volume and efficiency, but also easily generates rotational noise.

[0093] In some embodiments of this application, the radial distance L1 between the upstream end of the guide vane 4 and the outer edge of the centrifugal impeller 12 satisfies: L1≥0.2R, L1≤0.25R, to ensure that the gap between the upstream end of the guide vane 4 and the outer edge of the centrifugal impeller 12 is appropriate, which can effectively guide the flow and avoid causing rotational noise or flow loss.

[0094] It should be noted that the radial distance L1 is the distance from the upstream end of the guide vane 4, pointing in the direction of the rotation center O of the centrifugal impeller 12, to the outer contour circle of the centrifugal impeller 12.

[0095] If the radial distance L1>0.25R, the upstream end of the guide vane 4 will be far from the centrifugal impeller, which will weaken the "capture" and guidance effect of the guide vane 4 on the airflow, making it unable to effectively guide the airflow and resulting in poor backflow suppression effect.

[0096] If the radial distance L1 < 0.2R, the upstream end of the guide vane 4 is closer to the centrifugal impeller, which will not only increase the airflow impact loss at the inlet of the guide channel 5, but also cause rotational noise.

[0097] In some embodiments of this application, reference is made to Figure 10 On a cross section perpendicular to the axial direction of the centrifugal impeller 12, the line OA connecting the leading edge point A of the guide vane 4 away from the outline of the centrifugal impeller 12 to the rotation center O intersects the outer edge of the centrifugal impeller 12 at point B. The angle γ formed by the tangent P at point A and the tangent N at point B satisfies: γ≥-5°, γ≤5°. This ensures that the fresh airflow does not have a significant angle of attack when it comes into contact with the guide vane 4, achieving seamless connection and smooth transition of the fresh airflow. This fundamentally avoids eddies and turbulence caused by impacting the leading edge of the guide vane 4, greatly reducing the impact loss of the fresh airflow.

[0098] If γ < -5° or γ > 5°, the airflow will not match the upstream end of the guide vane 4, resulting in impact, vortex, and separation, increasing aerodynamic losses and noise. Therefore, by setting γ in the range of -5° to 5°, the upstream end of the guide vane 4 is made to be basically parallel to the airflow direction, allowing the airflow to pass smoothly through the guide vane 4, reducing flow separation and energy loss, and improving the flow diversion and guiding efficiency.

[0099] In some embodiments of this application, the middle arc 41 of the guide vane 4 may include a second curved segment 412, which is connected to the first curved segment 411, and the second curved segment 412 is farther away from the volute tongue 111 relative to the first curved segment 411. (See reference) Figure 11 The first curved segment 411 and the second curved segment 412 have opposite bending directions. The first curved segment 411 and the second curved segment 412 work together to enable the entire guide channel 5 to achieve a smooth transition of "contraction followed by expansion", which significantly improves the flow field stability and aerodynamic performance.

[0100] In some embodiments of this application, reference continues to be made to Figure 11 The radius r1 of the first curve segment 411 satisfies: r1≥0.53R, r1≤0.55R. This setting significantly reduces flow separation on the one hand, and actively reduces the direct impact of airflow on the volute tongue 111 by virtue of the "upturned" shape at the end, thus achieving the purpose of noise reduction.

[0101] If r1>0.55R, the curvature of the first curve segment 411 is too small, resulting in insufficient upward tilting effect of the latter half of the guide vane 4. This makes it impossible to effectively guide the airflow away from the volute tongue 111, and a large amount of airflow still flows towards the volute tongue 111 at a low angle, thereby weakening the effect of improving the static pressure uniformity of the volute tongue 111 surface and reducing impact noise.

[0102] If r1 < 0.53R, the curvature of the first curve segment 411 is too large, and the airflow direction changes drastically when the airflow passes through it, which can easily cause severe flow separation. This will not only increase additional noise and energy loss, but also cause the guide vane 4 to lose effective control over the airflow direction, making it impossible to achieve the predetermined upward guiding target.

[0103] In this embodiment, by optimizing the radius of curvature of the first curve segment 411 to be within the range of 0.53R to 0.55R, the smooth turning and effective guidance of the airflow are achieved, which effectively improves the backflow of the impeller channel and the static pressure distribution on the surface of the volute tongue 111, thus achieving the goal of low noise and high efficiency of the high static pressure fan.

[0104] In some embodiments of this application, the radius r2 of the second curve segment 412 satisfies: r2≥0.62R, r2≤0.64R, to ensure that the airflow can smoothly turn and transition after the airflow is smoothly accelerated in the first half of the guide vane 4, effectively reducing flow separation and energy loss, thereby providing stable and uniform air intake conditions for the expansion section of the subsequent flow channel, and ultimately improving the overall flow guiding efficiency.

[0105] If r2>0.64R, the curvature of the second curve segment 412 is too small, which will weaken the "capture" and guiding ability of the front section of the guide vane 4, thus making the speed-up and pressure-reduction effect of the guide channel 5 insufficient and the backflow suppression ability reduced.

[0106] If r2 < 0.62R, the curvature of the second curve segment 412 is too large, the airflow accelerates too quickly, and separation and eddies are easily generated. This may disrupt the stability of the flow field, increase flow losses, and cause the entire subsequent guiding process to proceed on a chaotic basis, greatly reducing the guiding efficiency.

[0107] In this embodiment, by optimizing the radius r2 of the second curve segment 412 to between 0.62R and 0.64R, and simultaneously optimizing the radius r1 of the first curve segment 411 to between 0.53R and 0.55R, the curvature profile of the guide vane 4 is smoothly transitioned. This design ensures that the airflow direction changes gently as it flows through the guide vane 4, avoiding flow separation and effectively covering the impeller area where backflow occurs, thereby achieving a better noise reduction effect.

[0108] In some embodiments of this application, reference continues to be made to Figure 11 The thickness of the guide vane 4 satisfies: t≥1.5mm, t≤3mm. The guide vane 4 can be configured as either of uniform or non-uniform thickness.

[0109] If t < 1.5 mm, the rigidity of the guide vane 4 is insufficient. Under the pulsating pressure of high-speed airflow, the guide vane 4 is prone to vibration or damage, affecting long-term reliability.

[0110] If t > 3mm, the noise reduction effect is not obvious, and it will unnecessarily reduce the effective flow channel area, increase flow resistance and material cost, and increase the weight of the volute.

[0111] In this embodiment, by setting the thickness t within a reasonable range of 1.5mm to 3mm, the structural strength and rigidity of the guide vane 4 are effectively guaranteed, vibration or deformation is avoided, and flow resistance and weight are minimized.

[0112] In some embodiments of this application, the guide vanes 4 are connected to the two opposite sidewalls of the volute at both ends in the axial direction of the centrifugal impeller 12.

[0113] In this embodiment, by connecting the two ends of the guide plate 4 to the two side walls of the volute, not only is it ensured that the guide plate 4 is firmly fixed to prevent vibration and noise, but it also ensures that the guide plate 4 guides the flow uniformly throughout the thickness of the entire guide channel 5, avoiding end leakage or uneven flow.

[0114] To verify the technical effect of this utility model, a computational fluid dynamics (CFD) simulation was conducted to compare the fresh air fan before optimization (reference) with the optimized fresh air fan using the guide vanes of this application. The results are as follows: Figures 12 to 13 As shown.

[0115] Figure 12 The image shows a comparison of the velocity vectors inside the fresh air fan before and after the improvement. Figure 12 In the reference centrifugal fan shown in Figure 'a', a large-area, high-velocity recirculation zone exists within the impeller flow channel near the diffuser section at the volute outlet. After the airflow exits the impeller, under the influence of a strong adverse pressure gradient, part of the high-speed airflow flows back to the impeller, forming a distinct vortex structure. In contrast, as shown in Figure 'a', Figure 12 As shown in b, after adding the guide vane, the backflow phenomenon in this area (dashed line area) basically disappears. The first contraction channel formed by the guide vane effectively weakens the reverse pressure gradient, which is beneficial to improving the flow stability and aerodynamic noise inside the fan.

[0116] Figure 13 To optimize the static pressure comparison cloud map of the volute surface of the front and rear fresh air fans. For example... Figure 13 As shown in Figure a, the volute surface of the reference fresh air fan (before optimization) exhibits a significant static pressure gradient. A very small area of ​​high static pressure (pressure peak) forms at the leading edge of the volute (impact point), rapidly transitioning to a large area of ​​low pressure (blue) around it. This large pressure difference indicates intense flow separation and impact at this point, directly causing the abnormal BPF (blade pass frequency) noise. In contrast, in... Figure 13 As shown in Figure b, in the optimized fresh air fan 1 of this application, the static pressure distribution on the surface of the volute tongue becomes very uniform. The original high-pressure peak is significantly reduced, the low-pressure area is shrunk, and the overall color transition is smooth, indicating a significant reduction in the static pressure gradient. The uniform static pressure distribution means that the periodic impact intensity of the airflow on the volute tongue is weakened, the flow is more stable, and the generation of BPF abnormal noise is fundamentally suppressed, achieving the noise reduction purpose. CFD simulation results show that, under the premise of maintaining a comparable air volume, the optimized fresh air fan 1 designed in this utility model improves the fan efficiency by 1%, while effectively suppressing backflow and reducing noise.

[0117] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application.

[0118] For ease of explanation, the above description has been provided in conjunction with specific embodiments. However, the above exemplary discussion is not intended to be exhaustive or to limit the embodiments to the specific forms disclosed above. Various modifications and variations can be obtained based on the above teachings. The selection and description of the above embodiments are for the purpose of better explaining the principles and practical applications, thereby enabling those skilled in the art to better utilize the described embodiments and various different variations of embodiments suitable for specific use considerations.

Claims

1. An air conditioner indoor unit characterized by comprising: include: A housing having an internally defined receiving space, the housing including a fresh air outlet; A fresh air fan is disposed in the accommodating space, the fresh air fan comprising: The volute has a volute inlet and a volute outlet, the volute outlet is connected to the fresh air outlet, the volute includes a volute tongue, and the volute defines a connected impeller cavity and an air outlet duct located on both sides of the volute tongue. The impeller cavity has an outlet diffuser section close to the air outlet duct. A centrifugal impeller is disposed in the impeller cavity. The rotation of the centrifugal impeller drives outdoor fresh air to enter the impeller cavity through the volute inlet, and then blows it into the room through the air outlet duct, the volute outlet, and the fresh air outlet in sequence. A guide vane is disposed at the outlet diffuser section, and a guide channel is formed between the guide vane and the outer edge of the centrifugal impeller. The guide channel tends to first contract and then expand along the airflow direction. The guide vane has a multi-segment curved shape, including a first curved segment near the volute tongue, and the center of curvature of the first curved segment is located on the side of the guide vane away from the centrifugal impeller. 2.The indoor unit of the air conditioner according to claim 1, characterized by, On a cross section perpendicular to the axial direction of the centrifugal impeller, with the center of rotation of the centrifugal impeller as the vertex, the included angle β formed by connecting the upstream end of the guide vane and the center of the volute tongue satisfies: β≥35°, β≤40°. 3.The indoor unit of the air conditioner according to claim 2, characterized by, The radial distance L2 between the downstream end of the guide vane and the outer edge of the centrifugal impeller satisfies: L2≥0.2R, L2≤0.25R, where R is the radius of the centrifugal impeller. 4.The indoor unit of the air conditioner according to claim 3, characterized by, The radial distance L1 between the upstream end of the guide vane and the outer edge of the centrifugal impeller satisfies: L1≥0.2R, L1≤0.25R. 5.The indoor unit of the air conditioner according to claim 1, characterized by, On a cross section perpendicular to the axial direction of the centrifugal impeller, the line connecting the leading edge point A of the guide vane away from the outline of the centrifugal impeller to the center of rotation of the centrifugal impeller intersects the outer edge of the centrifugal impeller at point B. The angle γ formed by the tangent at point A and the tangent at point B satisfies: γ≥-5°, γ≤5°.

6. The air conditioning indoor unit according to any one of claims 1 to 5, characterized by On a cross section perpendicular to the axial direction of the centrifugal impeller, with the rotation center of the centrifugal impeller as the vertex, the included angle θ formed by connecting the upstream end and the downstream end of the guide vane satisfies: θ≥20°, θ≤30°. 7.The indoor unit of the air conditioner according to claim 1, characterized by, The middle arc also includes a second curve segment connected to the first curve segment. The second curve segment is farther away from the volute tongue relative to the first curve segment, and its radius r2 satisfies: r2≥0.62R, r2≤0.64R. The first curve segment and the second curve segment have opposite bending directions, and R is the radius of the centrifugal impeller. 8.The indoor unit of the air conditioner according to claim 7, characterized by, The radius r1 of the first curve segment satisfies: r1≥0.53R, r1≤0.55R. 9.The indoor unit of the air conditioner according to claim 1, characterized by, The thickness of the guide vane satisfies: t≥1.5mm, t≤3mm. 10.The indoor unit of the air conditioner according to claim 1, characterized by, The guide vanes are connected to the two opposite sidewalls of the volute at both ends in the axial direction of the centrifugal impeller.

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