indoor unit

Abstract

The application relates to the air conditioning technical field, in particular to an indoor unit which comprises a shell, an indoor heat exchanger and a cross-flow fan. The shell internally comprises a first side plate and a second side plate which are arranged at intervals along the length direction of the shell. The first side plate and the second side plate provide connecting fulcrums for the first steel shaft and the second steel shaft of the cross-flow fan. The mass M of the outer rotor cross-flow fan, the first steel shaft diameter D1 and the second steel shaft diameter D2 satisfy the following conditions: when M<=700g, D1=7mm or D2=7mm; when M>700g, D1=0.01M or D2=0.01M. The effect of reducing the frictional abnormal sound between the steel shafts at the two ends of the cross-flow fan and the bearings is achieved, and the problem that the existing outer rotor cross-flow fan is caused to vibrate greatly and the load of the steel shaft and the bearing changes sharply due to non-rigid connection, thereby generating periodic "scraping" sound or "clicking" sound is solved.

Description

Technical Field

[0001] This application relates to the field of air conditioning technology, and more particularly to an indoor unit. Background Technology

[0002] Currently, due to their structural characteristics, external rotor cross-flow fans differ from internal rotor fans, which use a rigid connection to the motor shaft. External rotor fans primarily rely on the electromagnetic force of the magnetic ring on the fan and the interaction between the steel shaft and the motor stator for positioning, rather than being rigidly connected to the motor shaft. This non-rigid connection design results in more pronounced vibrations during actual operation compared to internal rotor fans.

[0003] When the fan is running, especially at low speeds below 700 rpm, the aforementioned vibrations are transmitted through the fan's plastic body to the steel shafts on both sides of the fan, causing significant variations in the load applied to the bearings. These unstable load variations generate frictional noise between the steel shafts and bearings, specifically manifesting as periodic noise near the air outlet close to the bearings at both ends of the fan. This noise directly impacts the user experience.

[0004] Currently, existing technical solutions to this problem have significant shortcomings: existing technologies use a stepped steel shaft design to ensure the smoothness of the steel shaft by avoiding contact between the steel shaft and the bearing during injection molding, thereby reducing the frictional resistance between the steel shaft and the bearing and reducing bearing noise. However, in practical applications, the effect is not significant, and the aforementioned abnormal noise still exists. Utility Model Content

[0005] This application provides an indoor unit, the purpose of which is to eliminate or reduce the abnormal noise caused by friction between the steel shafts at both ends of the cross-flow fan.

[0006] To achieve the above objectives, this application adopts the following technical solution: Firstly, indoor units are provided, including: The outer casing has a first side plate and a second side plate spaced apart along the length of the outer casing inside the casing. An indoor heat exchanger, which is disposed inside an outer casing, is used to exchange heat with the air passing through the indoor heat exchanger. A cross-flow fan, disposed within the housing, draws indoor air into the housing through its operation, which then flows into the room after heat exchange in the indoor heat exchanger; the cross-flow fan includes: A first steel shaft is connected to the first side plate; The second steel shaft is connected to the second side plate; The diameter of the first steel shaft is D1, the diameter of the second steel shaft is D2, and the mass of the cross-flow fan is M; When M≤700g, then D1=7mm, or D2=7mm; When M > 700g, then D1 = 0.01M, or D2 = 0.01M.

[0007] In the above embodiments, when the mass M of the cross-flow fan is ≤700g, D1 or D2 is set to 7mm, increasing the contact area between the steel shaft and the bearing. According to Hertzian contact theory, increasing the contact area can reduce the load per unit area between the steel shaft and the bearing, thereby reducing the friction effect caused by load fluctuations and alleviating periodic abnormal noise.

[0008] When M > 700g, the steel shaft diameter increases proportionally with the fan mass by designing D1 = 0.01M or D2 = 0.01M, ensuring that the load per unit contact area remains within a reasonable range, avoiding excessive load concentration due to increased fan mass, and further suppressing the generation of friction noise.

[0009] In some embodiments of this application, it also includes: The first bearing is disposed on the first side plate, and the contact surface between the first steel shaft and the first bearing is configured as the first connecting surface; The second bearing is disposed on the second side plate, and the contact surface between the second steel shaft and the second bearing is configured as the second connecting surface.

[0010] In the above embodiments, the first and second bearings of this application provide rotational support for the first and second steel shafts, limiting the radial and axial movement of the steel shafts and ensuring the smooth operation of the fan. The bearings distribute the load transmitted by the steel shaft evenly to the side plate, avoiding localized stress concentration caused by direct rigid contact between the steel shaft and the side plate, thus extending the service life of the structure. The bearings can also absorb vibrations generated during the operation of the cross-flow fan to a certain extent, reducing the amplitude of vibration transmission through the steel shaft to the side plate.

[0011] In some embodiments of this application, when M≤700g, the roughness of the first connecting surface and the second connecting surface is less than or equal to 0.07μm, and / or the roundness of the first connecting surface and the second connecting surface is less than or equal to 0.05μm.

[0012] In the above embodiments, the surface roughness of this application characterizes the smoothness of the connecting surface along the axial direction. When the roughness is ≤0.07μm, the microscopic undulations of the contact surface between the steel shaft and the bearing are smaller. According to the friction formula ƒ=μ•F, where μ is the coefficient of friction and F is the normal pressure, a lower roughness can directly reduce the sliding friction coefficient μ, reduce the frictional resistance when the steel shaft and the bearing move relative to each other, and reduce abnormal noise caused by friction.

[0013] The roundness design of ≤0.05μm makes the cross-section of the steel shaft more regular in the circumferential direction, resulting in more uniform contact with the inner surface of the bearing during rotation. This avoids localized pressure concentration caused by the non-circular cross-section of the steel shaft. Uniform contact reduces excessive local friction and lowers the probability of periodic noise generation, making it suitable for the low-speed operation of cross-flow fans with M≤700g.

[0014] In some embodiments of this application, when M > 700g and M < 900g, the roughness of the first connecting surface and the second connecting surface is less than or equal to 0.06μm, and / or the roundness of the first connecting surface and the second connecting surface is less than or equal to 0.04μm.

[0015] In the above embodiments, when the mass of the cross-flow fan is between 700g and 900g, the normal pressure exerted on the steel shaft and bearing is greater than that of a cross-flow fan with M≤700g. By further reducing the roughness to less than or equal to 0.06μm, the microscopic undulations of the connecting surface can be reduced, directly decreasing the sliding friction coefficient μ; simultaneously, the roundness is less than or equal to ≤0.04μm, ensuring more uniform contact between the steel shaft and the inner surface of the bearing during rotation, avoiding concentrated contact pressure caused by local non-roundness. By reducing the sliding friction coefficient μ and optimizing contact uniformity, the increased friction caused by the increased load can be offset, reducing abnormal noise.

[0016] For cross-flow fans weighing 700g < M < 900g, the steel shaft diameter is designed according to D1 = 0.01M or D2 = 0.01M, which reduces the load per unit area by increasing the contact area; while in this embodiment, the abnormal noise generated by friction is suppressed by higher precision roughness and roundness control.

[0017] In some embodiments of this application, when M≥900g, the roughness of the first connecting surface and the second connecting surface is less than or equal to 0.05μm, and / or the roundness of the first connecting surface and the second connecting surface is less than or equal to 0.03μm.

[0018] In the above embodiments, the normal pressure on the steel shaft and bearing reaches its maximum when the fan mass M ≥ 900g. Further reducing the surface roughness to ≤0.05μm reduces the microscopic undulations of the connecting surface, decreasing the sliding friction coefficient μ; increasing the roundness to ≤0.03μm ensures more uniform contact between the steel shaft and the inner surface of the bearing during rotation, avoiding localized pressure concentration caused by minute deformations or vibrations under high mass. This counteracts friction caused by high loads, reducing the intensity and frequency of abnormal noises.

[0019] In some embodiments of this application, a stator is provided on the first side plate or the second side plate; The cross-flow fan also includes: Fan blades, which are arranged circumferentially around the cross-flow fan body; The rotor is configured as a ring structure and is coaxially disposed on one end face of the cross-flow fan body; The rotor is fixed at one end of the fan blade near the stator, and the stator drives the rotor to rotate through magnetic torque. The rotation of the rotor drives the cross-flow fan to rotate.

[0020] In the above embodiments, the external rotor fan of this application relies on the electromagnetic force of the magnetic ring. The steel shaft and stator are matched and limited. During the magnetic torque drive process, the electromagnetic attraction force between the stator and the rotor can drive the fan blades to rotate, reducing the radial or axial movement of the fan during operation. Together with measures such as increasing the diameter of the steel shaft and improving the precision of the contact surface, the bearing noise is suppressed.

[0021] In some embodiments of this application, 0.5mm≤|D2-D1|≤1mm is used to balance the mass at both ends of the cross-flow fan.

[0022] In the above embodiments, in the structure of the external rotor cross-flow fan of this application, the side near the rotor where the magnetic ring and other components are installed has a greater mass than the other side of the rotor where the magnetic ring is not installed. The difference in mass between the two ends, |D2-D1|, is controlled within 0.5-1mm and can be compensated for by the difference in the diameter of the steel shaft. On the side with a larger mass, the contact area between the steel shaft and the bearing can be increased by increasing the diameter, thereby reducing the overall pressure of the fan on the bearing. The balancing effect can reduce the periodic vibration caused by the mass offset, reduce the amplitude of vibration transmitted to the friction pair of the steel shaft and bearing, and reduce friction noise.

[0023] In some embodiments of this application, the distances between the first connecting surface and the second connecting surface along the axial direction of the cross-flow fan are L1 and L2; Wherein, when the second connecting surface is located on the side of the cross-flow fan closer to the rotor, L2 > L1.

[0024] In the above embodiments, the external rotor cross-flow fan of this application has a structural feature where the side closer to the motor has a larger mass due to the installation of the magnetic ring. If the second connecting surface corresponds to the side with the larger mass, L2 being greater than L1 can increase the axial contact length between the steel shaft and the bearing on that side. According to Hertzian contact theory, increasing the contact length can increase the contact area between the steel shaft and the bearing, thereby reducing the load per unit area, alleviating the problem of increased friction caused by the large mass and high load on that side, and reducing bearing noise. The design of L2 being greater than L1 balances the load distribution at both ends of the fan, enhances support stability, reduces bearing friction noise, and improves the quietness of the indoor unit operation.

[0025] In some embodiments of this application, the distances between the first connecting surface and the second connecting surface along the axial direction of the cross-flow fan are L1 and L2; Wherein, when the second connecting surface is located on the side of the cross-flow fan closer to the rotor, D2×L2>D1×L1.

[0026] In the above embodiments, the external rotor cross-flow fan of this application has a structural feature where the mass near the rotor side is greater than that on the other side due to the installation of components such as magnetic rings, resulting in a higher load. The design of D2×L2 > D1×L1 enhances the load-bearing capacity of the second connection surface near the rotor side. According to Hertzian contact theory, the contact area and load-bearing capacity between the steel shaft and the bearing are related to the diameter and contact length. A larger product means a larger overall contact area between the steel shaft and the bearing on that side, which can disperse the unit area pressure under high loads, avoid increased friction caused by the large mass and concentrated load on the rotor side, and reduce bearing noise.

[0027] The second aspect provides an indoor unit, including: The outer casing includes, inside which are first side plates and second side plates spaced apart along the length of the outer casing. An indoor heat exchanger, which is disposed inside an outer casing, is used to exchange heat with the air passing through the indoor heat exchanger. A cross-flow fan, disposed within the housing, draws indoor air into the housing through its operation, which then flows into the room after heat exchange in the indoor heat exchanger; the cross-flow fan includes: A first steel shaft is connected to the first side plate; The second steel shaft is connected to the second side plate; The diameter of the first steel shaft is D1, the diameter of the second steel shaft is D2, and the mass of the cross-flow fan is M; When M ≤ 700g, then D1 = 7mm and D2 = 7mm; When M > 700g, then D1 = 0.01M and D2 = 0.01M.

[0028] In the above embodiments, the diameters of the first and second steel shafts are consistent, which avoids the need for separate production of the left and right steel shafts during manufacturing and reduces assembly errors caused by confusion in steel shaft models. A unified diameter parameter facilitates standardized processing, reduces the frequency of mold changes and parameter adjustments, and improves production efficiency. The uneven load caused by the uneven mass of the cross-flow fan at both ends can be accommodated by setting differentiated lengths L1 and L2 of the contact surface, enhancing the load-bearing capacity of the high-load side. Furthermore, noise is reduced through gradient design of the roughness and roundness of the connecting surface.

[0029] 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

[0030] 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.

[0031] Figure 1 This is a schematic diagram of the overall structure of the indoor unit provided in the embodiments of this application; Figure 2 This is a front view of the indoor unit provided in the embodiment of this application; Figure 3 This is a cross-sectional view of the indoor unit provided in the embodiment of this application in the first direction below the AA section line; Figure 4 This is an enlarged view of part A of the indoor unit provided in the embodiment of this application; Figure 5 This is an enlarged view of part B of the indoor unit provided in the embodiment of this application; Figure 6 This is a cross-sectional view of the indoor unit provided in the embodiment of this application in the second direction; Figure 7 This is a schematic diagram of the cross-flow fan structure of the indoor unit provided in the embodiments of this application; Figure 8 This is a schematic diagram of the first side panel of the indoor unit and its connection structure in a first direction provided in the embodiments of this application; Figure 9 This is a second-direction schematic diagram of the first side panel and its connection structure of the indoor unit provided in the embodiments of this application; Figure 10 This is a schematic diagram of the second side panel of the indoor unit and its connection structure provided in the embodiments of this application.

[0032] In the above figures: the X-axis is defined as the front-to-back direction (vertical), and its arrow points to the front; the Y-axis is defined as the left-to-right direction (horizontal), and its arrow points to the left; the Z-axis is defined as the up-down direction (vertical), and its arrow points to the up.

[0033] In the above figures: 1. Outer shell; 11. First side plate; 111. First bearing; 12. Second side plate; 121. Second bearing; 122. Stator; 2. Cross-flow fan; 21. First steel shaft; 22. Second steel shaft; 23. Rotor; 24. Fan blades; 3. Indoor heat exchanger. Detailed Implementation

[0034] 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. 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.

[0035] 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.

[0036] 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.

[0037] 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.

[0038] 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.

[0039] It should be noted that in the air conditioning industry, currently, external rotor cross-flow fans, due to their structural characteristics, differ from internal rotor fans in that they do not use a rigid connection to the motor shaft. External rotor fans primarily rely on the electromagnetic force of the magnetic ring on the fan and the cooperation between the steel shaft and the motor stator for limiting movement, rather than being rigidly connected to the motor shaft. This non-rigid connection design results in more noticeable vibrations during actual operation compared to internal rotor fans.

[0040] When the fan is running, especially at low speeds below 700 rpm, the aforementioned vibrations are transmitted through the fan's plastic body to the steel shafts on both sides of the fan, causing significant variations in the load applied to the bearings. These unstable load variations generate frictional noise between the steel shafts and bearings, specifically manifesting as periodic noise near the air outlet close to the bearings at both ends of the fan. This noise directly impacts the user experience.

[0041] Currently, existing technical solutions to this problem have significant shortcomings: existing technologies use a stepped steel shaft design to ensure the smoothness of the steel shaft by avoiding contact between the steel shaft and the bearing during injection molding, thereby reducing the frictional resistance between the steel shaft and the bearing and reducing bearing noise. However, in practical applications, the effect is not significant, and the aforementioned abnormal noise still exists.

[0042] Based on this, this application proposes an indoor unit with an external rotor cross-flow fan of mass M, where D1 is the diameter of the first steel shaft and D2 is the diameter of the second steel shaft. When M≤700g, D1=7mm or D2=7mm; when M>700g, D1=0.01M or D2=0.01M. This achieves the effect of reducing frictional noise between the steel shaft and bearing at both ends of the cross-flow fan, and solves the problem of large vibration and drastic load changes on the steel shaft and bearing caused by the non-rigid connection of existing external rotor cross-flow fans, which in turn generates periodic noise.

[0043] In the following, embodiments of this application will be described in detail with reference to the accompanying drawings.

[0044] As attached Figures 1 to 10 As shown, in the first aspect of this application, an indoor unit includes a housing 1, an indoor heat exchanger 3, and a cross-flow fan 2.

[0045] The housing 1 includes a first side plate 11 and a second side plate 12 spaced apart along the length of the housing 1. The first side plate 11 and the second side plate 12 provide connection points for the first steel shaft 21 and the second steel shaft 22 of the cross-flow fan. By fixing the two ends of the steel shaft, the cross-flow fan is stably supported, limiting the radial and axial movement of the fan during operation and reducing vibration amplification caused by unstable support.

[0046] The indoor heat exchanger 3 is installed inside the outer casing 1 and is used to exchange heat with the air passing through it.

[0047] A cross-flow fan is installed inside the housing 1. By operating the cross-flow fan, indoor air is introduced into the housing 1, and after heat exchange by the indoor heat exchanger 3, it flows into the room. The cross-flow fan includes a first steel shaft 21 and a second steel shaft 22.

[0048] One end of the first steel shaft 21 is located at one end along the length of the cross-flow fan, and the other end of the first steel shaft 21 is connected to the first side plate 11. One end of the second steel shaft 22 is located at the end of the cross-flow fan away from the first steel shaft 21, and the other end of the second steel shaft 22 is connected to the second side plate 12.

[0049] The first steel shaft 21 and the second steel shaft 22 serve as the connection structure between the fan and the side plate, transmitting the torque and load during fan operation.

[0050] The diameter of the first steel shaft 21 is D1, the diameter of the second steel shaft 22 is D2, and the mass of the cross-flow fan is M.

[0051] In some embodiments, when M≤700g, then D1=7mm, or D2=7mm.

[0052] When the mass M of the cross-flow fan is less than or equal to 700g, setting D1 or D2 to 7mm increases the contact area between the steel shaft and the bearing. According to Hertzian contact theory, increasing the contact area reduces the load per unit area between the steel shaft and the bearing, thereby reducing the frictional effect caused by load fluctuations and alleviating periodic abnormal noises.

[0053] In some embodiments, when M > 700g, then D1 = 0.01M, or D2 = 0.01M.

[0054] When M > 700g, the steel shaft diameter increases proportionally with the fan mass by designing D1 = 0.01M or D2 = 0.01M, ensuring that the load per unit contact area remains within a reasonable range, avoiding excessive load concentration due to increased fan mass, and further suppressing the generation of friction noise.

[0055] Noise reduction is achieved by optimizing the steel shaft diameter parameters without introducing complex structural modifications, avoiding significant adjustments to existing production processes and reducing implementation costs. Differentiated diameter designs for cross-flow fans of varying quality ensure stable reduction of bearing noise under various indoor operating conditions, expanding the product's applicability.

[0056] like Figure 4 and Figure 5 As shown, in some embodiments, the indoor unit further includes a first bearing 111 and a second bearing 121. The first bearing 111 is disposed on the first side plate 11, and the contact surface between the first steel shaft 21 and the first bearing 111 is configured as a first connecting surface. The second bearing 121 is disposed on the second side plate 12, and the contact surface between the second steel shaft 22 and the second bearing 121 is configured as a second connecting surface.

[0057] The first bearing 111 and the second bearing 121 of this application provide rotational support for the first steel shaft 21 and the second steel shaft 22, which can limit the radial and axial movement of the steel shafts and ensure the smooth operation of the fan. The bearings distribute the load transmitted by the steel shafts evenly to the side plates, avoiding local stress concentration caused by direct rigid contact between the steel shafts and the side plates, and extending the service life of the structure. The bearings can also absorb the vibration generated by the operation of the cross-flow fan to a certain extent, reducing the amplitude of vibration transmitted through the steel shafts to the side plates.

[0058] In some embodiments, when M≤700g, the roughness of the first connecting surface and the second connecting surface is less than or equal to 0.07μm.

[0059] It should be noted that surface roughness refers to the microscopic geometric characteristics of a machined surface, manifested as the peaks and valleys of the surface profile. When the roughness is ≤0.07μm, the microscopic undulations of the contact surface between the steel shaft and the bearing are smaller; if the roughness is too large, there will be greater microscopic undulations, causing abnormal noise. According to the friction formula ƒ=μ•F, where μ is the coefficient of friction and F is the normal pressure, a lower roughness can directly reduce the sliding friction coefficient μ, reducing the frictional resistance during relative movement between the steel shaft and the bearing, and reducing abnormal noise caused by friction.

[0060] In some embodiments, when M≤700g, the roundness of the first connecting surface and the second connecting surface is less than or equal to 0.05μm.

[0061] It should be noted that roundness refers to the degree to which the cross-section of the workpiece approximates a theoretical circle. A roundness of ≤0.05μm makes the cross-section of the steel shaft more regular in the circumferential direction, resulting in more uniform contact with the inner surface of the bearing during rotation, and avoiding localized pressure concentration caused by the non-circularity of the steel shaft cross-section. If the roundness is too large, the cross-section of the steel shaft becomes more irregular in the circumferential direction, leading to uneven contact with the inner surface of the bearing during rotation, which can cause excessive localized friction and abnormal noise. Uniform contact reduces excessive localized friction, lowers the probability of periodic noise, and is suitable for the low-speed operation characteristics of cross-flow fans with M≤700g.

[0062] In some embodiments, when M > 700g, the roughness of the first connecting surface and the second connecting surface is less than or equal to 0.06μm.

[0063] When the mass of the cross-flow fan 2 exceeds 700g, its normal pressure on the steel shaft and bearings is greater than that of a cross-flow fan 2 with a mass of 700g or less. By reducing the roughness to less than or equal to 0.06μm, the micro-undulations of the connecting surface can be reduced, directly decreasing the sliding friction coefficient μ. If the roughness is too large, there will be greater micro-undulations, causing abnormal noise. Reducing the sliding friction coefficient μ can offset the increased friction caused by the increased load, thus reducing abnormal noise.

[0064] In some embodiments, when M > 700g, the roundness of the first connecting surface and the second connecting surface is less than or equal to 0.04μm.

[0065] When the mass of the cross-flow fan 2 exceeds 700g, the normal pressure it exerts on the steel shaft and bearing is greater compared to when the mass of the cross-flow fan 2 is less than or equal to 700g. By ensuring a roundness of less than or equal to 0.04μm, more uniform contact between the steel shaft and the inner surface of the bearing is achieved during rotation. This avoids concentrated contact pressure caused by local non-roundness, and optimizing contact uniformity can offset the increased friction due to increased load, reducing abnormal noise. If the roundness is too large, the cross-section of the steel shaft becomes more irregular circumferentially, resulting in uneven contact with the inner surface of the bearing during rotation, which can cause excessive local friction and abnormal noise.

[0066] In some embodiments, when M < 900g, the roughness of the first connecting surface and the second connecting surface is less than or equal to 0.06μm.

[0067] When the mass of the cross-flow fan 2 is less than 900g, reducing the roughness to less than or equal to 0.06μm can reduce the microscopic undulations of the connecting surface, directly decreasing the sliding friction coefficient μ. If the roughness is too large, there will be greater microscopic undulations, causing abnormal noise. Reducing the sliding friction coefficient μ can offset the increased friction caused by the increased load, thus reducing abnormal noise.

[0068] In some embodiments, when M < 900g, the roundness of the first connecting surface and the second connecting surface is less than or equal to 0.04μm.

[0069] When the mass of the cross-flow fan 2 is less than 900g, by ensuring a roundness of less than or equal to 0.04μm, the steel shaft can achieve more uniform contact with the inner surface of the bearing during rotation. This avoids concentrated contact pressure caused by local non-roundness, and optimizing contact uniformity can offset the increased friction caused by the increased load, thus reducing abnormal noise. If the roundness is too large, the cross-section of the steel shaft will be more irregular along the circumference, resulting in uneven contact with the inner surface of the bearing during rotation, which will produce excessive local friction and abnormal noise.

[0070] When the mass of the cross-flow fan 2 is between 700g and 900g, the normal pressure it exerts on the steel shaft and bearing is greater than that of a cross-flow fan with a mass M≤700g. By further reducing the roughness to less than or equal to 0.06μm, the microscopic undulations of the connecting surface can be reduced, directly decreasing the sliding friction coefficient μ; simultaneously, a roundness of less than or equal to 0.04μm ensures more uniform contact between the steel shaft and the inner surface of the bearing during rotation, avoiding concentrated contact pressure caused by local non-roundness. By reducing the sliding friction coefficient μ and optimizing contact uniformity, the increased friction caused by the increased load can be offset, reducing abnormal noise.

[0071] For cross-flow fans with a weight of 700g < M < 900g, the steel shaft diameter is designed according to D1 = 0.01M or D2 = 0.01M. This reduces the load per unit area by increasing the contact area, and suppresses abnormal noise caused by friction through higher precision roughness and roundness control.

[0072] In some embodiments, when M≥900g, the roughness of the first connecting surface and the second connecting surface is less than or equal to 0.05μm.

[0073] This application further reduces the surface roughness to ≤0.05μm when the fan mass M≥900g. This results in smaller micro-undulations on the connection surface, reduces the sliding friction coefficient μ, counteracts friction caused by high loads, and reduces the intensity and frequency of abnormal noise. If the roughness is too large, there will be greater micro-undulations, causing abnormal noise.

[0074] In some embodiments, when M≥900g, the roundness of the first connecting surface and the second connecting surface is less than or equal to 0.03μm.

[0075] When the mass M of the cross-flow fan 2 is ≥900g, this application improves the roundness to ≤0.03μm, resulting in more uniform contact between the steel shaft and the inner surface of the bearing during rotation. This avoids localized pressure concentration caused by minor deformation or vibration under large mass. It also counteracts friction caused by high loads, reducing the intensity and frequency of abnormal noise. If the roundness is too large, the cross-section of the steel shaft becomes more irregular circumferentially, leading to uneven contact with the inner surface of the bearing during rotation, which can cause excessive localized friction and abnormal noise.

[0076] like Figure 5As shown, in some embodiments, a stator 122 is provided on the first side plate 11 or the second side plate 12. The attached figure of this embodiment... Figure 5 A stator 122 is provided on the second side plate 12. For example... Figure 7 As shown, the cross-flow fan 2 also includes a rotor 23 and a fan blade 24. The fan blade 24 is arranged circumferentially around the cross-flow fan body. The rotor 23 is configured as a ring structure and is coaxially arranged on one end face of the cross-flow fan 2 body. The rotor 23 is fixed to one end of the fan blade 24 near the stator 122. The stator 122 drives the rotor 23 to rotate through magnetic torque. The rotation of the rotor 23 is used to drive the cross-flow fan 2 to rotate.

[0077] The external rotor 23 fan relies on the electromagnetic force of the magnetic ring. The steel shaft and stator 122 cooperate to limit the movement. During the magnetic torque drive process, the electromagnetic attraction between stator 122 and rotor 23 can drive the fan blades 24 to rotate, reducing the radial or axial movement of the fan during operation. Together with measures such as increasing the diameter of the steel shaft and improving the precision of the contact surface, it suppresses bearing noise.

[0078] It should be noted that the relationship between the diameter D of the steel shaft, the contact surface length L between the steel shaft and the bearing, and the mass M of the cross-flow fan is analyzed in detail below: The force exerted on the matching bearing by the single-sided steel shaft is:

[0079] Where g is the acceleration due to gravity.

[0080] The contact area between the steel shaft and the inner surface of the bearing is calculated using Hertz's formula, which is:

[0081]

[0082] Where b is the contact half-width between the steel shaft and the bearing, D is the diameter of the steel shaft, and L is the length of the contact surface between the steel shaft and the bearing. For the equivalent elastic modulus, This refers to the contact area.

[0083] Therefore, the pressure exerted by the steel shaft on the bearing can be obtained as follows:

[0084] As can be seen from the above formula, the pressure P exerted by the steel shaft on the bearing is related to the force F exerted by the steel shaft on its matching bearing, the diameter D of the steel shaft, and the length L of the contact surface between the steel shaft and the bearing.

[0085] In some embodiments, the diameter of the first steel shaft 21 is D1, the diameter of the first steel shaft 22 is D2, the mass of the cross-flow fan 2 is M, and |D2-D1|≥0.5mm. By controlling the absolute value of the diameter difference between the first steel shaft 21 and the second steel shaft 22 to a minimum of 0.5mm, the mass difference at both ends of the cross-flow fan is balanced.

[0086] In some embodiments, |D2-D1|≤1mm. By controlling the absolute value of the diameter difference between the first and second steel shafts to a maximum of 1mm, the mass difference at both ends of the cross-flow fan is balanced.

[0087] In the structure of an external rotor cross-flow fan, the side closer to rotor 23, due to the installation of components such as magnetic rings, has a greater mass than the other side of the rotor without magnetic rings. The difference in mass between the two ends, |D2-D1|, can be controlled within 0.5-1mm and compensated for by the difference in the diameter of the steel shaft. On the side with the greater mass, increasing the diameter increases the contact area between the steel shaft and the bearing, thus reducing the overall pressure exerted by the fan on the bearing. This balancing effect reduces periodic vibrations caused by mass shift, lowers the amplitude of vibration transmitted to the friction pair of the steel shaft and bearing, and reduces frictional noise.

[0088] In some embodiments, the distance between the first connecting surface and the second connecting surface along the axial direction of the cross-flow fan is L1 and L2; wherein, when the second connecting surface is located on the side of the cross-flow fan 2 closer to the rotor, L2 is greater than L1. It should be noted that if the contact surface length L between the steel shaft and the bearing is too long, it will affect the adaptive positioning of the cross-flow fan.

[0089] In the structural features of the external rotor cross-flow fan 2, the side closer to the motor has a larger mass due to the installation of the magnetic ring. If the second connecting surface corresponds to the side with the larger mass, L2 being greater than L1 increases the axial contact length between the steel shaft and the bearing on that side. According to Hertzian contact theory, increasing the contact length increases the contact area between the steel shaft and the bearing, thereby reducing the load per unit area, alleviating the problem of increased friction caused by the large mass and high load on that side, and reducing bearing noise. The design of L2 being greater than L1 balances the load distribution at both ends of the fan, enhances support stability, reduces bearing friction noise, and improves the quietness of the indoor unit operation.

[0090] In some embodiments of this application, the distance between the first connecting surface and the second connecting surface along the axial direction of the cross-flow fan is L1 and L2; wherein, when the second connecting surface is located on the side of the cross-flow fan closer to the rotor, D2×L2>D1×L1.

[0091] The structural characteristics of an external rotor cross-flow fan are such that the side closer to the rotor, due to the installation of components such as magnetic rings, has a greater mass and higher load than the other side. The design of D2×L2 > D1×L1 enhances the load-bearing capacity of the second connection surface closer to the rotor. According to Hertzian contact theory, the contact area and load-bearing capacity between the steel shaft and the bearing are related to the diameter and contact length. A larger product means a larger overall contact area between the steel shaft and the bearing on that side, which can disperse the unit area pressure under high loads, avoid increased friction caused by the large mass and concentrated load on the rotor side, and reduce bearing noise.

[0092] A second aspect of this application provides an indoor unit, including a housing 1, an indoor heat exchanger 3, and a cross-flow fan 2.

[0093] The housing 1 includes a first side plate 11 and a second side plate 12 spaced apart along the length of the housing 1. The first side plate 11 and the second side plate 12 provide connection points for the first steel shaft 21 and the second steel shaft 22 of the cross-flow fan 2. By fixing the two ends of the steel shaft, the cross-flow fan 2 is stably supported, limiting the radial and axial movement of the fan during operation and reducing the vibration amplification caused by unstable support.

[0094] The indoor heat exchanger 3 is installed inside the outer casing 1 and is used to exchange heat with the air passing through it.

[0095] The cross-flow fan 2 is installed inside the housing 1. By operating the cross-flow fan 2, indoor air is introduced into the housing 1, and after heat exchange by the indoor heat exchanger 3, it flows into the room. The cross-flow fan 2 includes a first steel shaft 21 and a second steel shaft 22.

[0096] One end of the first steel shaft 21 is located at one end of the cross-flow fan 2 along its length, and the other end of the first steel shaft 21 is connected to the first side plate 11. One end of the second steel shaft 22 is located at the end of the cross-flow fan 2 away from the first steel shaft 21, and the other end of the second steel shaft 22 is connected to the second side plate 12.

[0097] The first steel shaft 21 and the second steel shaft 22 serve as the connection structure between the fan and the side plate, transmitting the torque and load during fan operation.

[0098] The diameter of the first steel shaft 21 is D1, the diameter of the second steel shaft 22 is D2, and the mass of the cross-flow fan is M; When M≤700g, then D1=7mm and D2=7mm. Maintaining the same diameter for the first and second steel shafts avoids the need for separate production of left and right shafts, reducing assembly errors caused by confusion in shaft models. Uniform diameter parameters facilitate standardized processing, reducing the frequency of mold changes and parameter adjustments, and improving production efficiency. The uneven load caused by the uneven mass of the cross-flow fan at both ends can be accommodated by setting differentiated contact surface lengths L1 and L2, enhancing the load-bearing capacity of the high-load side. Furthermore, the gradient design of the connection surface roughness and roundness reduces noise.

[0099] In some embodiments, when M > 700g, then D1 = 0.01M and D2 = 0.01M. Maintaining the same diameter for the first and second steel shafts avoids the need for separate production of the left and right shafts during manufacturing, reducing assembly errors caused by confusion in shaft models. Uniform diameter parameters facilitate standardized processing, reducing the frequency of mold changes and parameter adjustments, and improving production efficiency. The uneven load caused by the uneven mass of the cross-flow fan at both ends can be accommodated by setting differentiated values ​​for the contact surface lengths L1 and L2, enhancing the load-bearing capacity of the high-load side. Furthermore, the gradient design of the roughness and roundness of the connecting surfaces reduces noise.

[0100] 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 indoor unit, characterized in that, include: The outer casing has a first side plate and a second side plate spaced apart along the length of the outer casing inside the casing. An indoor heat exchanger, which is disposed inside an outer casing, is used to exchange heat with the air passing through the indoor heat exchanger; A cross-flow fan is installed inside the housing. By operating the cross-flow fan, indoor air is introduced into the housing, and after heat exchange by the indoor heat exchanger, it flows into the room. The cross-flow fan includes: A first steel shaft is connected to the first side plate; The second steel shaft is connected to the second side plate; The diameter of the first steel shaft is D1, the diameter of the second steel shaft is D2, and the mass of the cross-flow fan is M; When M≤700g, then D1=7mm, or D2=7mm; When M > 700g, then D1 = 0.01M, or D2 = 0.01M.

2. The indoor unit according to claim 1, characterized in that, Also includes: The first bearing is disposed on the first side plate, and the contact surface between the first steel shaft and the first bearing is configured as the first connecting surface; The second bearing is disposed on the second side plate, and the contact surface between the second steel shaft and the second bearing is configured as the second connecting surface.

3. The indoor unit according to claim 2, characterized in that, When M≤700g, the roughness of the first connecting surface and the second connecting surface is less than or equal to 0.07μm, and / or the roundness of the first connecting surface and the second connecting surface is less than or equal to 0.05μm.

4. The indoor unit according to claim 2, characterized in that, When M > 700g and M < 900g, the roughness of the first connecting surface and the second connecting surface is less than or equal to 0.06μm, and / or the roundness of the first connecting surface and the second connecting surface is less than or equal to 0.04μm.

5. The indoor unit according to claim 2, characterized in that, When M≥900g, the roughness of the first connecting surface and the second connecting surface is less than or equal to 0.05μm, and / or the roundness of the first connecting surface and the second connecting surface is less than or equal to 0.03μm.

6. The indoor unit according to claim 5, characterized in that, A stator is provided on the first side plate or the second side plate; The cross-flow fan also includes: Fan blades, which are arranged circumferentially around the cross-flow fan body; The rotor is configured as a ring structure and is coaxially disposed on one end face of the cross-flow fan body; The rotor is fixed at one end of the fan blade near the stator, and the stator drives the rotor to rotate through magnetic torque. The rotation of the rotor drives the cross-flow fan to rotate.

7. The indoor unit according to claim 6, characterized in that, 0.5mm≤|D2-D1|≤1mm, used to balance the mass at both ends of the cross-flow fan.

8. The indoor unit according to claim 7, characterized in that, The distances between the first connecting surface and the second connecting surface along the axial direction of the cross-flow fan are L1 and L2, respectively. Wherein, when the second connecting surface is located on the side of the cross-flow fan closer to the rotor, L2 > L1.

9. The indoor unit according to claim 7, characterized in that, The distances between the first connecting surface and the second connecting surface along the axial direction of the cross-flow fan are L1 and L2, respectively. Wherein, when the second connecting surface is located on the side of the cross-flow fan closer to the rotor, D2×L2>D1×L1.

10. An indoor unit, characterized in that, include: The outer casing includes, inside which are first side plates and second side plates spaced apart along the length of the outer casing. An indoor heat exchanger, which is disposed inside an outer casing, is used to exchange heat with the air passing through the indoor heat exchanger; A cross-flow fan is installed inside the housing. By operating the cross-flow fan, indoor air is introduced into the housing, and after heat exchange by the indoor heat exchanger, it flows into the room. The cross-flow fan includes: A first steel shaft is connected to the first side plate; The second steel shaft is connected to the second side plate; The diameter of the first steel shaft is D1, the diameter of the second steel shaft is D2, and the mass of the cross-flow fan is M; When M ≤ 700g, then D1 = 7mm and D2 = 7mm; When M > 700g, then D1 = 0.01M and D2 = 0.01M.

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