A total heat exchanger

Abstract

The utility model belongs to ventilation equipment technical field, concretely relates to a total heat exchanger, including casing, heat exchange core body and fan. The casing is equipped with fresh air channel and exhaust channel, and the heat exchange core body realizes the heat exchange of indoor exhaust and outdoor fresh air, and the fan drives air flow, and its impeller contains wheel disc and multiple arc vanes. The vanes are arranged along the circumference of the wheel disc, and the ratio of the inner diameter to the outer diameter of the vane is 0.78-0.82; one end of the vane close to the center of the wheel disc is the leading edge, and the other end close to the peripheral wall is the trailing edge; at least two wave units are arranged on the suction surface of the vane from front to back. When the airflow passes through the vane, the wave unit disturbs the near-surface airflow, making it exchange kinetic energy with the outer high-speed airflow; the flow channel contraction and expansion convert dynamic pressure into static pressure. This design balances airflow blockage and working area, reduces the speed difference between airflow layers, avoids airflow separation and large cyclones, improves the static pressure resistance and reduces noise by more than 2dBA.

Description

Technical Field

[0001] This application relates to the field of ventilation equipment technology, and more particularly to a total heat exchanger. Background Technology

[0002] A total heat exchanger is an energy-saving ventilation device that simultaneously replaces indoor and outdoor air and recovers and utilizes the sensible and latent heat carried by the air. It is widely used in various buildings such as residences, office buildings, and shopping malls. By recovering exhaust air energy, it reduces the energy consumption of the air conditioning system while ensuring indoor air freshness. Its main structure includes an outer shell, a heat exchange core, a fresh air duct, an exhaust air duct, a fan, and filter components. The heat exchange core is the core component, where energy exchange between fresh and exhaust air occurs. The fan drives the fresh and exhaust air to flow in their respective ducts, and the filter components purify the incoming fresh air.

[0003] The fan is the core power component of a total heat exchanger. Its main function is to drive airflow through the fresh air and exhaust air ducts inside the equipment, achieving forced air exchange between indoors and outdoors. Its performance directly affects the ventilation efficiency, airflow stability, and energy consumption level of the total heat exchanger. Since total heat exchangers are mostly installed indoors or near living areas, there are specific requirements for the fan: firstly, stable airflow; secondly, low noise to avoid noise pollution to the indoor environment; and thirdly, high static pressure resistance.

[0004] The fan blade is one of the core components of a multi-blade centrifugal fan. The traditional ratio of the inner diameter to the outer diameter of existing fan blades ranges from 0.74 to 0.86. A smaller ratio results in a larger working area, but also a longer flow path, higher frictional resistance, and severe airflow obstruction, making it suitable for high static pressure designs. Conversely, a larger ratio results in a shorter flow path and less airflow obstruction, but a smaller working area, making it suitable for low static pressure designs. To balance the conflict between airflow obstruction and working area, traditional designs often employ a single circular arc blade profile (with a single-segment circular arc in the middle) and increase the number of blades to improve static pressure resistance. However, existing fan blade designs still have significant limitations and struggle to meet the performance requirements of total heat exchangers. On the one hand, the simple design of a single circular arc blade cannot adapt to complex flow fields, leading to airflow separation on the blade surface. Especially under high static pressure conditions, the interaction between the separated airflow and the blade generates abnormal noises such as BPF (blade pass frequency) sound and low-frequency sound, directly exacerbating the noise problem. Even if the airflow inlet state and flow channel organization are improved by increasing the airflow turning angle and using a large chord length blade, the increased airflow turning angle will further aggravate airflow separation, negatively impacting aerodynamic noise. Even with adjustments to the overall structure, it is still difficult to avoid the problem of significant BPF sound, and in extreme cases, surge may occur, affecting operational stability. On the other hand, while increasing the number of blades can improve static pressure resistance, it increases material costs and exacerbates airflow interference between blades, leading to increased airflow loss and amplified noise, creating a dual problem of "increased cost and deteriorated performance". Utility Model Content

[0005] This application provides a total heat exchanger, the purpose of which is to solve the contradiction between airflow obstruction and difficulty in balancing the working area of ​​existing fan blades by controlling the inner diameter ratio range of multi-blade centrifugal fan blades to 0.78~0.82 and adopting a multi-peak and trough design of the fan blades, thereby achieving the effect of high static pressure and low noise.

[0006] To achieve the above objectives, this application adopts the following technical solution: In a first aspect, a total heat exchanger is provided, comprising: The casing contains a fresh air duct and an exhaust air duct. A heat exchange core is disposed within the housing; it is used to achieve heat exchange between indoor exhaust air and outdoor fresh air. A fan, disposed within the housing, is used to drive airflow in the fresh air duct or the exhaust air duct; wherein the fan includes an impeller; The impeller includes: Roulette; Multiple fan blades are spaced apart along the circumference of the wheel. The fan blades are arc-shaped, and the ratio of the inner diameter to the outer diameter of the fan blade is 0.78 to 0.82. The end of the fan blade near the center of the wheel is the leading edge, and the end near the peripheral wall of the wheel is the trailing edge. From the leading edge to the trailing edge, at least two wave units are provided on the suction surface of the fan blade. When the airflow passes through the fan blades, the airflow close to the surface of the fan blades is disturbed by the wave unit, and then exchanges kinetic energy with the outer high-speed airflow away from the surface of the fan blades; at the same time, the airflow converts dynamic pressure into static pressure under the contraction and expansion of the flow channel.

[0007] Secondly, a total heat exchanger is provided, comprising: The casing contains a fresh air duct and an exhaust air duct. A heat exchange core is disposed within the housing; it is used to achieve heat exchange between indoor exhaust air and outdoor fresh air. A fan, disposed within the housing, is used to drive airflow in the fresh air duct or the exhaust air duct; wherein the fan includes an impeller; The impeller includes: Roulette; Multiple fan blades are spaced apart circumferentially along the wheel. The fan blades are arc-shaped, and the ratio of the inner diameter to the outer diameter of the fan blade is 0.78 to 0.82. The end of the fan blade closer to the center of the wheel is the leading edge, and the end closer to the peripheral wall of the wheel is the trailing edge. From the leading edge to the trailing edge, N wave units are arranged on the suction surface of the fan blade, where N ≥ 2 and N is an integer. In this design, a trough is set between the i-th wave unit and the (i+1)-th wave unit, and the i-th wave unit and its adjacent trough are smoothly transitioned by an arc; where 1≤i≤N, and i is an integer; When the airflow passes through the fan blade, the airflow close to the surface of the fan blade is disturbed by the i-th wave unit, and then exchanges kinetic energy with the outer high-speed airflow away from the surface of the fan blade; at the same time, the airflow converts dynamic pressure into static pressure under the contraction and expansion of the flow channel.

[0008] In the above embodiments, this application achieves a balance between airflow obstruction and the working area of ​​the fan blades by controlling the ratio of the inner and outer diameters of the fan blades to 0.78~0.82, thus narrowing the traditional ratio range. This balance maintains sufficient working area to ensure fan efficiency while avoiding airflow obstruction caused by excessively long flow channels. Simultaneously, the wave units on the suction surface of the fan blades effectively agitate the airflow, prompting the low-speed airflow close to the fan blade surface to exchange kinetic energy with the outer high-speed airflow, reducing the velocity difference between airflow layers. This not only prevents the low-speed airflow close to the fan blade surface from failing to follow the fan blade contour due to insufficient kinetic energy, thus avoiding separation from the fan blade surface and the formation of vortices that generate significant aerodynamic noise, but also prevents the high-speed airflow from driving the surrounding low-speed airflow to form a large cyclone when the velocity difference between airflow layers is too large. This cyclone, occupying space in the flow channel, obstructs the smooth passage of subsequent airflow, thereby reducing noise and airflow obstruction. Furthermore, the protrusions of the wave units create flow channel contraction and expansion, which in turn converts airflow pressure into static pressure. In summary, this embodiment improves the fan's resistance to static pressure and reduces noise, achieving an overall noise reduction of over 2 dBA.

[0009] In some embodiments of this application, the central arc of the fan blade is composed of 2 to 5 arc segments, and the connection point of two adjacent arc segments is the tangent point of the two segments.

[0010] In the above embodiments, the middle arc of this application is composed of 2 to 5 arc segments with adjacent arc segments being tangent. By combining multiple arc segments, the aerodynamic performance of the fan blade is optimized, avoiding abnormal noise generated by a single arc blade shape in a complex flow field, reducing airflow separation and backflow phenomena, and improving the stability of fan operation.

[0011] In some embodiments of this application, among the multiple arc segments of the central arc of the fan blade, the ratio of the fan area of ​​the arc near the leading edge to the adjacent arc near the trailing edge is 0.24 to 0.67.

[0012] In the above embodiments, the ratio of the sector area of ​​the multi-segment arc of the middle arc of this application is controlled at 0.24~0.67, which can avoid severe backflow of the fan blade at the volute and the severe separation of airflow in the flow channel of the fan blade, ensure that the airflow flows within a reasonable range, and reduce static pressure resistance and airflow attenuation.

[0013] In some embodiments of this application, the radii of multiple arc segments on the middle arc line of the fan blade increase sequentially from the leading edge to the trailing edge.

[0014] In the above embodiments, the radius of the multiple arc segments on the middle arc of this application increases sequentially from the leading edge to the trailing edge, causing the fan blade flow channel to gradually expand, forming a progressive diffuser flow channel, reducing airflow resistance, optimizing the distribution of airflow on the fan blade surface, and optimizing the conversion efficiency of dynamic pressure to static pressure.

[0015] In some embodiments of this application, the radius of the first arc segment on the middle arc line of the fan blade in the direction from the leading edge to the trailing edge is 7~12 mm; the radius difference between any two adjacent arc segments is 6~10 mm.

[0016] In the above embodiments, the radius of the first arc segment of this application is 7~12 mm and the difference between the radii of adjacent arc segments is 6~10 mm. Combined with the design of increasing radius of multiple arc segments, the expansion degree of the fan blade flow channel is precisely controlled, so as to achieve efficient conversion of dynamic pressure to static pressure while ensuring structural strength and improving the overall performance of the fan.

[0017] In some embodiments of this application, a trough is provided between two adjacent wave units; From the leading edge to the trailing edge, the crest of the first wave unit of the blade is located at 0.83 times the outer diameter of the blade; the distance between the crest of any wave unit and its adjacent trough is 0.01 to 0.035 times the outer diameter of the blade.

[0018] In the above embodiments, the peak of the first wave unit of this application is located at 0.83 times the outer diameter of the fan blade, and the distance between the peak and the adjacent trough is 0.01 to 0.035 times the outer diameter of the fan blade. The precise design of the peak and trough positions enhances the airflow disturbance effect, promotes the kinetic energy exchange between low-speed and high-speed airflow, effectively reduces the separation of airflow at the front edge of the suction head, improves the static pressure resistance and reduces noise.

[0019] In some embodiments of this application, the ratio of the thickness of the fan blade at any wave crest of the wave unit to the thickness of the fan blade at the wave crest of the wave unit adjacent to and close to the leading edge of the wave unit is 0.73 to 0.91.

[0020] In the above embodiments, the ratio of the thickness at the wave crest of the wave unit to the thickness at the adjacent leading edge crest is 0.73 to 0.91. The reasonable thickness ratio design promotes the kinetic energy exchange between low-speed and high-speed airflow, effectively reduces airflow separation at the leading edge of the suction line, improves static pressure resistance, and reduces noise.

[0021] In some embodiments of this application, the ratio of the thickness of the fan blade at any of the troughs to the thickness of the fan blade at the crest of the wave unit adjacent to the trough and close to the leading edge is 0.64 to 0.82.

[0022] In the above embodiments, the ratio of the thickness at the trough to the thickness at the adjacent leading edge crest is 0.64 to 0.82. Combined with the crest thickness ratio design, the airflow distribution on the fan blade surface is optimized, reducing airflow separation and vortex breakage. This improves static pressure resistance while achieving low-noise operation, resulting in a significant overall noise reduction effect.

[0023] In some embodiments of this application, the thickness of the fan blade at the crest of the first wave unit is 2 to 2.5 mm in the direction from the leading edge to the trailing edge.

[0024] In the above embodiments, this application optimizes the airflow disturbance effect by precisely controlling the crest thickness, while ensuring the strength of the fan blade and the feasibility of demolding, so that the fan blade can still maintain stable operation and effectively reduce noise under high static pressure conditions.

[0025] It should be understood that the above general description and the following detailed description are exemplary and explanatory only, and do not limit this application. Attached Figure Description

[0026] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0027] Figure 1 This is a schematic diagram of the overall structure of the total heat exchanger provided in the embodiments of this application; Figure 2 This is a first-view perspective perspective view of the fan provided in the embodiments of this application; Figure 3 This is a second-view perspective perspective view of the fan provided in the embodiments of this application; Figure 4 This is a first-view perspective perspective view of the impeller provided in an embodiment of this application; Figure 5 This is a second-view perspective perspective view of the impeller provided in an embodiment of this application; Figure 6 This is a first-view perspective perspective view of the fan blade provided in the embodiments of this application; Figure 7 This is a second-view perspective perspective view of the fan blade provided in the embodiments of this application; Figure 8 This is a cross-sectional schematic diagram of the fan blade provided in an embodiment of this application; Figure 9 This is a schematic diagram of the mid-arc line of the fan blade provided in the embodiment of this application; Figure 10 This is a top view of a traditional impeller with unequal thickness; Figure 11 yes Figure 10 Enlarged view of part A in the middle.

[0028] In the above figures: 100, shell; 110, fresh air inlet; 120, return air inlet; 130, supply air outlet; 140, exhaust air outlet; 150, heat exchange core; 200, fan; 210, volute; 211, top plate; 212, enclosure plate; 220, bottom plate; 230, motor; 240, impeller; 241, wheel; 242, leading edge ring; 243, trailing edge ring; 244, fan blade; 244a, leading edge; 244b, trailing edge; 244c, first arc segment; 244d, second arc segment; 244e, first peak; 244f, first trough; 244g, second peak. Detailed Implementation

[0029] In the description of this application, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc., indicating the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, are only for the convenience of describing this application 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, and therefore should not be construed as a limitation of this application.

[0030] In this application, unless otherwise expressly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection, an electrical connection, or a connection that allows communication between components; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication between two components or the interaction between two components, unless otherwise expressly limited. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0031] In this application, unless otherwise expressly specified and limited, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature is in indirect contact with the second feature through an intermediate medium. Furthermore, "above," "on top of," and "over" the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0032] In this application, the terms "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to a specific feature, structure, material, or characteristic described in connection with that embodiment or example, which is included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0033] Additionally, if the meaning of "and / or" in the text is that it includes three parallel options, taking "A and / or B" as an example, it includes option A, option B, or an option that satisfies both A and B.

[0034] The present application 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.

[0035] It should be noted that a total heat exchanger is an energy-saving ventilation device that can recover and utilize the sensible and latent heat carried by the air while exchanging indoor and outdoor air. It is widely used in various buildings such as residences, office buildings, and shopping malls. By recovering exhaust air energy, it reduces the energy consumption of the air conditioning system while ensuring the freshness of indoor air.

[0036] In the field of total heat exchangers, the fan is the core power component, and its performance directly affects the ventilation efficiency, air volume stability, and energy consumption level of the equipment. Since total heat exchangers are mostly installed indoors or near living areas, there are specific requirements for the fan: first, stable air volume; second, low noise to avoid noise pollution to the indoor environment; and third, high static pressure resistance. As the core of a multi-blade centrifugal fan, the ratio of its inner diameter to its outer diameter is a key design parameter. The traditional range is 0.74 to 0.86. When the ratio is too small, the working area of ​​the fan blade is large, but the flow channel is long, the friction resistance is high, and the airflow blockage is serious, which is suitable for high static pressure design. When the ratio is too large, the flow channel is short and the airflow blockage is small, but the working area of ​​the fan blade is small, which is suitable for low static pressure design. To balance the contradiction between airflow blockage and working area, traditional designs often use a single circular arc blade shape (the middle arc is a single segment of circular arc) and increase the number of blades to improve static pressure resistance.

[0037] like Figure 10 , 11As shown, in the existing technology, a single circular arc blade profile cannot adapt to complex flow fields, causing airflow to easily separate on the blade surface. Especially under high static pressure conditions, abnormal noises such as BPF (blade pass frequency) and low-frequency noise will be generated. Even if the airflow turning angle is increased and a large chord length blade profile is used, the increased airflow turning angle will exacerbate airflow separation, negatively impacting aerodynamic noise and making it difficult to avoid the problem of obvious BPF noise. In extreme cases, surge may also occur. Although increasing the number of blades can improve static pressure resistance, it will increase material costs, exacerbate airflow interference between blades, and lead to increased airflow loss and noise amplification, forming a dual problem of "increased cost and deteriorated performance". It is difficult to meet the requirements of total heat exchangers for stable airflow, low noise, and high static pressure resistance.

[0038] Based on this, this application proposes a total heat exchanger. By controlling the ratio of the inner diameter to the outer diameter of the multi-blade centrifugal fan blade 244 to 0.78~0.82, sufficient working area is retained to ensure fan efficiency, while avoiding airflow blockage caused by excessively long flow channels. At the same time, the multi-peak and trough design of the fan blade 244 promotes the exchange of kinetic energy between the low-speed airflow close to the surface of the fan blade 244 and the high-speed airflow on the outer layer, reducing the speed difference between airflow layers. This solves the contradiction between airflow blockage and the difficulty in balancing the working area of ​​the existing fan blade 244, thereby achieving high static pressure and low noise.

[0039] In the following, embodiments of this application will be described in detail with reference to the accompanying drawings.

[0040] As attached Figures 1 to 9 As shown in an illustrative embodiment of this application, the total heat exchanger includes a housing 100, on which a fresh air inlet 110, a return air inlet 120, an exhaust air outlet 140, and a supply air outlet 130 are provided. A fresh air duct and an exhaust air duct are provided inside the housing 100. The fresh air inlet 110 is connected to the supply air outlet 130 through the fresh air duct, and the return air inlet 120 is connected to the exhaust air outlet 140 through the exhaust air duct.

[0041] Among them, the fresh air inlet 110 is connected to the outside through a duct and is used to draw in fresh air from the outside (fresh air); the supply air outlet 130 is connected to the inside through a duct and is used to deliver the fresh air that has undergone heat exchange and purification into the room to replenish the fresh air in the room; the return air outlet 120 is connected to the inside through a duct and is used to draw air from the room (exhaust air), and this exhaust air is the air that needs to be discharged from the room; the exhaust air outlet 140 is connected to the outside through a duct and is used to discharge the exhaust air that has completed energy exchange to the outside, which is the final outlet for the indoor polluted air to leave the system.

[0042] In some embodiments, a heat exchange core 150 is also provided inside the housing 100. The heat exchange core 150 is the core where the fresh air duct and the exhaust air duct meet. The heat exchange core 150 is used to realize heat exchange between indoor exhaust air and outdoor fresh air. In addition, it is necessary to ensure that the fresh air duct and the exhaust air duct are isolated from each other to avoid crossflow between fresh air and exhaust air.

[0043] Specifically, the operating principle of the heat exchange core 150 is as follows: outdoor fresh air and indoor exhaust air flow in opposite or vertical cross directions inside the core, and energy exchange is completed in a non-contact manner. In terms of sensible heat exchange, when there is a temperature difference between exhaust air and fresh air, heat will be conducted through the heat exchange plate to achieve temperature regulation between the two. In terms of latent heat exchange, when there is a humidity difference between exhaust air and fresh air, water vapor will diffuse through the moisture-permeable material to achieve humidity regulation between the two. Ultimately, the temperature and humidity of the fresh air are close to the indoor exhaust air state, reducing the energy consumption of the air conditioning system.

[0044] It should be noted that the specific structure of the heat exchange core 150 (including its layered or honeycomb / corrugated structure, overall frame, and connection with the fresh air duct and exhaust air duct, etc.) and the operating principle of the heat exchange core 150 (such as energy recovery between fresh air and exhaust air through sensible heat transfer and latent heat transfer, and heat exchange completed by fresh air and exhaust air flowing in opposite or cross directions in the core, etc.) are all prior art, and their technical details are well known to those skilled in the art. Therefore, they need not be described in detail in this application. The improvement point of this application is only in the impeller 240 of the fan 200, specifically the fan blade 244, and does not involve any improvement to the existing structure and operating principle of the heat exchange core 150 itself; the same applies below, and will not be described in detail again.

[0045] In some embodiments, a filter assembly is also provided within the housing 100. This filter assembly is a crucial component of the total heat exchanger for air purification. Its core function is to remove impurities such as particulate matter, dust, pollen, and odors from the incoming fresh air, ensuring the cleanliness of the fresh air supplied indoors. It also provides some filtration for the exhaust air, preventing pollutants from entering the environment. Common types of filter assemblies include pre-filters and medium-efficiency filters. Pre-filters typically use materials such as non-woven fabric and metal mesh to filter larger dust and debris particles. Medium-efficiency filters often use materials such as glass fiber and polypropylene to further filter smaller pollutant particles. Some total heat exchangers are also equipped with high-efficiency filters to meet even higher air cleanliness requirements. Within the housing 100, the filter assembly is typically installed at the inlet of the fresh air duct. When outdoor fresh air enters the housing 100, it first flows through the filter assembly and is then filtered before entering the heat exchange core 150 for energy exchange. This effectively prevents impurities in the fresh air from contaminating the heat exchange core 150, ensuring the heat exchange efficiency and service life of the core, while also ensuring that the treated fresh air meets indoor air quality standards.

[0046] It should be noted that the specific structure of the above-mentioned filter components (including the composition of pre-filters, medium-efficiency filters or high-efficiency filters, etc., and their installation positions and connection relationships at the inlet of the fresh air channel and the inlet of the exhaust air channel inside the housing 100) and the operating principle of the filter components (such as removing particulate matter, dust and other impurities in the air through the interception and adsorption of non-woven fabrics, glass fibers and other materials to achieve air purification, etc.) are all existing technologies, and their technical details are well known to those skilled in the art. Therefore, there is no need to elaborate on them in this application.

[0047] In some embodiments, the housing 100 is further provided with two fans 200, which are respectively located in the fresh air duct and the exhaust air duct, and are used to drive the airflow in the fresh air duct and the exhaust air duct respectively.

[0048] In some embodiments, such as Figure 2 and 3 As shown, the fan 200 includes a volute 210, a base plate 220, a motor 230, and an impeller 240. The volute 210 is fixed to one side of the base plate 220, the motor 230 is fixed to the other side of the base plate 220 away from the volute 210, and the impeller 240 is placed in the volute chamber formed by the volute 210 and the base plate 220. The drive shaft of the motor 230 is connected to the impeller 240. When working, the motor 230 drives the impeller 240 to rotate, and the rotation of the impeller 240 drives the air, thereby driving the airflow.

[0049] Furthermore, the volute 210 includes a top plate 211 and a surrounding plate 212, with the top plate 211 fixed to the surrounding plate 212. The top plate 211 has an air inlet, which serves as an airflow inlet and connects to the fresh air inlet 110 or the return air inlet 120. The center of the air inlet is both the center of the fan 200 and the axis of the impeller 240. The surrounding plate 212 is helical or approximately helical in shape and has two ends. One end, closer to the axis of the fan 200, is connected to a volute tongue, and the other end is connected to an upper extension plate. The space between the upper extension plate and the volute tongue forms the air outlet duct of the volute 210, which serves as an airflow outlet and connects to the supply air outlet 130 or the exhaust air outlet 140.

[0050] In some embodiments, the impeller 240 includes a disk 241, a plurality of blades 244, a leading edge ring 242, and a trailing edge ring 243, such as Figure 4 and 5As shown. The impeller 241 is a disc-shaped structure, assembled within the volute chamber and parallel to the base plate 220. The drive shaft of the motor 230 passes through the base plate 220 and connects to the axis of the impeller 241, thus transmitting power. Multiple fan blades 244 are evenly distributed along the circumference of the impeller 241, and all fan blades 244 are mounted on the same circumference. Along the axis of the impeller 240, a leading edge ring 242 and a trailing edge ring 243 are fixed to both ends of the fan blades 244, respectively, to connect and fix the ends of all fan blades 244. This prevents the ends of the fan blades 244 from vibrating when the impeller 240 rotates, thereby avoiding noise caused by vibration and preventing damage to the fan blades 244 during high-speed rotation.

[0051] In some embodiments, the projection shape of the fan blade 244 onto the plane of the disk 241 is generally arc-shaped, and the ratio of the inner diameter to the outer diameter of the fan blade 244 is strictly controlled within 0.78 to 0.82. This ratio range is determined based on a comprehensive balance and optimization of core performance aspects such as airflow obstruction, working area, and static pressure resistance. By precisely defining this ratio range, this application avoids problems such as excessively long flow channels, severe obstruction, and soaring energy consumption and noise caused by an excessively small ratio, while also solving defects such as insufficient working area, weak static pressure resistance, and unstable airflow caused by an excessively large ratio. This lays a solid foundation for the high static pressure, low noise, and high efficiency operation of the total heat exchanger.

[0052] Specifically, when the ratio is less than 0.78 (i.e., the inner diameter is smaller and the outer diameter is relatively larger), the flow channel length of fan blade 244 increases significantly, resulting in a longer airflow path within the channel and a substantial increase in friction resistance. Simultaneously, an excessively long flow channel easily leads to airflow accumulation and vortex phenomena at bends, further exacerbating airflow blockage, causing increased airflow loss and decreased ventilation efficiency. To maintain the target airflow, fan 200 needs to consume more energy to overcome greater friction resistance and airflow blockage, which contradicts the energy-saving requirements of the total heat exchanger. Furthermore, an excessively long flow channel also prolongs the friction time between the airflow and the surface of fan blade 244, and the turbulence and vortices caused by blockage are more intense, easily generating high-frequency noise and abnormal sounds, thus compromising the requirements for low-noise operation.

[0053] Furthermore, when the ratio is greater than 0.82 (i.e., the inner diameter is relatively large and the outer diameter is relatively small), the effective working area of ​​the fan blade 244 (i.e., the area where the blade participates in driving the airflow) is significantly reduced, resulting in a weakening of the driving force of the fan blade 244 on the airflow. In the complex air duct of the total heat exchanger (such as the resistance brought by the heat exchange core 150 and the filter components), this design is difficult to overcome the system static pressure, resulting in a significant decrease in airflow and failing to meet the requirements for stable ventilation. At the same time, insufficient working area will reduce the "control" of the fan blade 244 over the airflow, making the velocity distribution of the airflow in the flow channel more turbulent, increasing the difference between local high-speed and low-speed areas, easily causing airflow separation and turbulent noise, which in turn exacerbates the noise problem. In addition, the total heat exchanger needs to achieve efficient energy recovery within a limited space. An excessively large inner diameter ratio will cause the overall size of the fan blade 244 to be mismatched with the internal air duct of the equipment, further deteriorating the airflow organization and even affecting the energy recovery efficiency of the heat exchange core 150.

[0054] It should be noted that for the fan blade 244, the end closer to the center of the disk 241 is the leading edge 244a, and the end closer to the peripheral wall of the disk 241 is the trailing edge 244b. The distance from the leading edge 244a of the fan blade 244 to the center of the disk 241 is defined as the inner diameter of the fan blade 244, and the distance from the trailing edge 244b of the fan blade 244 to the center of the disk 241 is defined as the outer diameter of the fan blade 244.

[0055] In some embodiments, such as Figures 6-8 As shown, at least two wave units are arranged on the suction surface of the fan blade 244 from the leading edge 244a to the trailing edge 244b; a trough is arranged between two adjacent wave units, and any wave unit and its adjacent trough are smoothly transitioned by an arc to ensure smooth airflow. Here, the trough refers to the thinnest part of the fan blade 244 located between two adjacent wave units.

[0056] Specifically, when airflow passes over fan blade 244, the airflow close to the surface of fan blade 244 is disturbed by the wave unit, and then exchanges kinetic energy with the outer high-speed airflow away from the surface of fan blade 244; reducing the velocity difference between airflow layers: this not only avoids the problem that the low-speed airflow close to the surface of fan blade 244 cannot follow the contour of fan blade 244 due to insufficient kinetic energy, thus separating from the surface of fan blade 244 and forming vortices that generate significant aerodynamic noise; it also prevents the high-speed airflow from driving the surrounding low-speed airflow to form a large cyclone when the velocity difference between airflow layers is too large, and the cyclone occupies space in the flow channel, obstructing the smooth passage of subsequent airflow, thus achieving the effect of reducing noise and reducing airflow obstruction. At the same time, the protrusion of the wave unit causes the flow channel to contract, and the contraction and expansion of the flow channel realizes the conversion of dynamic pressure to static pressure, further improving the fan's anti-static pressure capability and reducing noise, with an overall noise reduction of more than 2 dBA.

[0057] In some embodiments, the mid-arc line of the fan blade 244 is composed of 2 to 5 circular arcs, and the connection point of two adjacent circular arcs is the tangent point between them. This design is to optimize the aerodynamic performance of the fan blade 244, making the airflow flow more smoothly on the surface of the fan blade 244, reducing airflow separation and eddy current generation, thereby reducing noise, improving static pressure resistance, and ensuring the adaptability and operational stability of the fan blade 244 design in complex flow fields.

[0058] If the middle arc has fewer than two segments (i.e., only one arc segment), it is a single arc blade. This design is simple but cannot adapt to complex flow fields. The airflow is prone to separation on the blade surface, especially under high static pressure conditions, which will produce abnormal noises such as BPF sound and low-frequency sound, making it difficult to meet the low noise requirements of the total heat exchanger.

[0059] If there are more than five arc segments, the design of the fan blade 244 will be too complex, increasing the difficulty and cost of processing and manufacturing. At the same time, too many arc segments may cause frequent changes and disturbances in the airflow on the surface of the fan blade 244, which may easily lead to new airflow separation and eddies, which is not conducive to the smooth flow of airflow. This will affect the fan's anti-static pressure capability and noise reduction effect, and may also make it difficult to guarantee the strength and stability of the fan blade 244 due to the complex structure.

[0060] In some embodiments, among the multiple arcs of the central arc of the fan blade 244, the ratio of the sector area of ​​the arc near the leading edge 244a to the adjacent arc near the trailing edge 244b is 0.24 to 0.67; wherein, the sector area of ​​the arc refers to the area of ​​the figure (i.e., the sector) enclosed by an arc and two radii passing through the two ends of the arc. When the ratio of any set of adjacent arcs is less than 0.24, meaning the arc near the leading edge 244a is smaller and the adjacent arc near the trailing edge 244b is larger, the airflow entering the fan blade 244 channel will have insufficient guiding ability from the arc near the leading edge 244a. The airflow will struggle to adapt quickly to the channel's direction, leading to severe backflow at the volute tongue of the volute 210, resulting in a decrease in both static pressure resistance and flow rate. When the ratio of any set of adjacent arcs is greater than 0.67, meaning the arc near the leading edge 244a is larger and the adjacent arc near the trailing edge 244b is larger, the airflow will have insufficient guiding ability from the arc near the leading edge 244a. This will cause the airflow to have difficulty adapting quickly to the channel's direction, leading to severe backflow at the volute tongue of the fan blade 244, resulting in a decrease in both static pressure resistance and flow rate. The arc ratio of 44b is relatively small. When the airflow enters the flow channel, the sharp bend of the arc near the leading edge 244a will generate a large centrifugal force, causing the airflow to detach from the blade surface on the fan blade 244 surface (especially in the transition area between the leading edge 244a and the middle section) (airflow separation). This exacerbates the airflow separation phenomenon in the flow channel within the fan blade 244, resulting in flow loss and increased noise. However, when the ratio of all adjacent arcs is in the range of 0.24 to 0.67, the problems of severe backflow and aggravated airflow separation can be effectively controlled, ensuring that the airflow is within a reasonable flow range throughout the entire flow channel.

[0061] In some embodiments, the radii of multiple arc segments on the mid-arc line of the fan blade 244 increase sequentially from the leading edge 244a to the trailing edge 244b.

[0062] Furthermore, from the leading edge 244a to the trailing edge 244b, the radius of the first arc segment on the mid-arc line of the fan blade 244 is 7~12 mm; the radius difference between any two adjacent arc segments is 6~10 mm. The core function of this design is to achieve precise guidance of airflow and stable control of the flow state by optimizing the "gradient bending morphology" of the flow channel.

[0063] Specifically, the initial arc radius near the leading edge 244a is relatively small (7~12mm), resulting in a relatively gentle curvature in the leading edge 244a region. This avoids severe impacts caused by sharp bends when the airflow enters the fan blade 244 channel, reducing initial flow turbulence and ensuring a smooth entry of the airflow into the channel. From front to back, the arc radius increases progressively, with the radius difference between adjacent segments fixed at 6~10mm. This design gradually reduces the curvature of the channel (the larger the radius, the gentler the arc). This "gradient change" guides the airflow to gradually adapt to the channel's direction during flow, preventing airflow separation (such as local vortices) caused by abrupt changes in curvature. This ensures continuous airflow adhesion along the blade surface, reducing energy loss. Simultaneously, the fixed radius difference (6~10mm) prevents the channel expansion rate from being too fast or too slow: excessive expansion leads to rapid airflow deceleration, easily forming a low-pressure area and causing backflow; excessive expansion fails to effectively utilize the channel length to increase pressure. Ultimately, a balanced expansion rhythm achieves a match between pressure and flow velocity. In addition, due to the smooth transition of the flow channel curvature, the friction and impact between the airflow and the blade surface are significantly reduced, thereby reducing the turbulent noise caused by airflow disturbance.

[0064] In some embodiments, from the leading edge 244a to the trailing edge 244b, the crest of the first wave unit of the fan blade 244 is located at 0.83 times the outer diameter of the fan blade 244; the distance between the crest of any wave unit and its adjacent trough is 0.01 to 0.035 times the outer diameter of the fan blade 244.

[0065] Specifically, the area 0.83 times the outer diameter of blade 244 is a critical region where airflow transitions from the inlet to the middle channel, and it is also a sensitive location where airflow is prone to separation due to changes in pressure gradient. Setting the crest of the first wave unit at this location utilizes the local convexity of the wave structure to create a "lifting" effect on the airflow, enhancing the adhesion between the airflow and the blade surface. This suppresses early airflow separation (such as eddies or flow separation), reduces energy loss caused by airflow separation, and improves the airflow capture efficiency of blade 244. Simultaneously, limiting the distance between the crest and adjacent trough of any wave unit to 0.01~0.035 times the outer diameter of blade 244 represents a micro-scale fluctuation. This range can both disrupt the stability of the airflow boundary layer through perturbation of the wave surface, preventing airflow separation due to an excessively thick boundary layer, and avoid severe airflow turbulence due to excessive fluctuation amplitude. This "micro-perturbation" design guides the airflow smoothly along the wave profile, maintaining the attached flow state within the channel and effectively reducing flow loss.

[0066] In some embodiments, the ratio of the thickness of the blade 244 at the crest of any wave element to the thickness of the blade 244 at the crest of a wave element adjacent to and near the leading edge 244a is 0.73 to 0.91. This design balances structural stability and airflow smoothness by gradually decreasing the thickness of the crests from front to back, maintaining a thicker structure near the leading edge 244a to withstand the initial airflow impact and ensure structural strength, while moderately thinning the structure at the rear to reduce airflow obstruction. This avoids vibration due to excessive thinness or disturbance caused by excessive thickness.

[0067] In some embodiments, the ratio of the thickness of the fan blade 244 at any trough to the thickness of the fan blade 244 at the crest of the wave unit adjacent to the trough and close to the leading edge 244a is 0.64 to 0.82. This design achieves efficient dynamic pressure to static pressure conversion by making the trough thickness thinner than the leading crest, thus forming a moderate flow channel expansion, which, combined with the flow channel contraction at the crest, reduces abrupt thickness changes, making the airflow transition smoother and avoiding backflow due to excessive expansion or insufficient expansion affecting static pressure conversion.

[0068] In some embodiments, the thickness of the fan blade 244 at the crest of the first wave unit is 2~2.5mm in the direction from the leading edge 244a to the trailing edge 244b. The maximum thickness of the fan blade 244 is located at the first wave crest, and its value is related to the blade height (the dimension along the axis of the fan 200). This design ensures that the fan blade 244 has a certain draft angle and structural strength.

[0069] In some embodiments, such as Figure 8 and 9As shown in the figure, D represents the outer diameter of the fan blade 244, d represents the inner diameter of the fan blade 244, and the ratio of the inner diameter to the outer diameter of the fan blade 244 is 0.8. The central arc of the fan blade 244 is composed of two arc segments, and the connection point of the two adjacent arc segments is the point of tangency between them; from the leading edge 244a to the trailing edge 244b, these two arc segments are the first arc segment 244c and the second arc segment 244d, respectively; the ratio of the sector area of ​​the first arc segment 244c to the sector area of ​​the second arc segment is 0.24~0.67. At the same time, the fan blade 244 has two wave units, both located on the first arc segment 244c; from the leading edge 244a to the trailing edge 244b, the wave crests of the two wave units are the first wave crest 244e and the second wave crest 244g, respectively, and the trough between the two wave crests is the first wave trough 244f. The first peak 244e is located at 0.83D, the first trough 244f is located at 0.86D, and the second peak 244g is located at 0.89D.

[0070] Furthermore, the maximum thickness of the fan blade 244 is located at the first peak 244e, and its thickness value is related to the blade height: when the blade height of the fan blade 244 is 0.6D and the fan blade 244 is divided into five parts by the wheel 241, the maximum thickness needs to be controlled between 2 and 2.5 mm to ensure that the fan blade 244 has a certain draft angle and structural strength.

[0071] Furthermore, if the maximum thickness W of the fan blade 244 at the first peak 244e is 2.2 mm, then the thickness of the fan blade 244 at the first trough 244f is 0.64W~0.82W, and the thickness at the second peak 244g is 0.73W~0.91W. It should be noted that these two thickness ranges correspond—when the thickness of the first trough 244f is 0.64W, the thickness of the second peak 244g is 0.73W; when the thickness of the first trough 244f is 0.82W, the thickness of the second peak 244g is 0.91W; the intermediate values ​​also correspond one-to-one. This design allows for a smoother transition from peak to trough, and the airflow vortex formed at the trough can generate a driving force on the overall airflow, thereby improving the fan's static pressure resistance and reducing noise, achieving an overall noise reduction of over 2 dBA.

[0072] 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. A total heat exchanger, characterized in that, include: The casing contains a fresh air duct and an exhaust air duct. A heat exchange core is disposed within the housing; It is used to achieve heat exchange between indoor exhaust air and outdoor fresh air; A fan, disposed within the housing, is used to drive airflow in the fresh air duct or the exhaust air duct; wherein the fan includes an impeller; The impeller includes: Roulette; Multiple fan blades are spaced apart along the circumference of the wheel. The fan blades are arc-shaped, and the ratio of the inner diameter to the outer diameter of the fan blade is 0.78 to 0.

82. The end of the fan blade near the center of the wheel is the leading edge, and the end near the peripheral wall of the wheel is the trailing edge. From the leading edge to the trailing edge, at least two wave units are provided on the suction surface of the fan blade. When the airflow passes through the fan blades, the airflow close to the surface of the fan blades is disturbed by the wave unit, and then exchanges kinetic energy with the outer high-speed airflow away from the surface of the fan blades; at the same time, the airflow converts dynamic pressure into static pressure under the contraction and expansion of the flow channel.

2. The total heat exchanger according to claim 1, characterized in that, The central arc of the fan blade is composed of 2 to 5 arc segments, and the connection point of two adjacent arc segments is the point of tangency between them.

3. A total heat exchanger according to claim 2, characterized in that, In the multiple arc segments of the central arc of the fan blade, the ratio of the sector area of ​​the arc near the leading edge to the adjacent arc near the trailing edge is 0.24 to 0.

67.

4. A total heat exchanger according to claim 3, characterized in that, From the leading edge to the trailing edge, the radii of the multiple arc segments on the middle arc of the fan blade increase sequentially.

5. A total heat exchanger according to claim 4, characterized in that, From the leading edge to the trailing edge, the radius of the first arc segment on the middle arc line of the fan blade is 7~12 mm; the radius difference between any two adjacent arc segments is 6~10 mm.

6. A total heat exchanger according to any one of claims 1 to 5, characterized in that, A trough is provided between two adjacent wave units; From the leading edge to the trailing edge, the crest of the first wave unit of the blade is located at 0.83 times the outer diameter of the blade; the distance between the crest of any wave unit and its adjacent trough is 0.01 to 0.035 times the outer diameter of the blade.

7. A total heat exchanger according to claim 6, characterized in that, The ratio of the thickness of the fan blade at any wave crest of the wave unit to the thickness of the fan blade at the wave crest of the wave unit adjacent to and close to the leading edge of the wave unit is 0.73 to 0.

91.

8. A total heat exchanger according to claim 7, characterized in that, The ratio of the thickness of the fan blade at any of the troughs to the thickness of the fan blade at the crest of the wave unit adjacent to the trough and close to the leading edge is 0.64 to 0.

82.

9. A total heat exchanger according to claim 8, characterized in that, From the leading edge to the trailing edge, the thickness of the fan blade at the crest of the first wave unit is 2~2.5mm.

10. A total heat exchanger, characterized in that, include: The casing contains a fresh air duct and an exhaust air duct. A heat exchange core is disposed within the housing; It is used to achieve heat exchange between indoor exhaust air and outdoor fresh air; A fan, disposed within the housing, is used to drive airflow in the fresh air duct or the exhaust air duct; wherein the fan includes an impeller; The impeller includes: Roulette; Multiple fan blades are spaced apart circumferentially along the wheel. The fan blades are arc-shaped, and the ratio of the inner diameter to the outer diameter of the fan blade is 0.78 to 0.

82. The end of the fan blade closer to the center of the wheel is the leading edge, and the end closer to the peripheral wall of the wheel is the trailing edge. From the leading edge to the trailing edge, N wave units are arranged on the suction surface of the fan blade, where N ≥ 2 and N is an integer. In this design, a trough is set between the i-th wave unit and the (i+1)-th wave unit, and the i-th wave unit and its adjacent trough are smoothly transitioned by an arc; where 1≤i≤N, and i is an integer; When the airflow passes through the fan blade, the airflow close to the surface of the fan blade is disturbed by the i-th wave unit, and then exchanges kinetic energy with the outer high-speed airflow away from the surface of the fan blade; at the same time, the airflow converts dynamic pressure into static pressure under the contraction and expansion of the flow channel.

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