Horizontal concealed fan coil unit

Abstract

This invention discloses a horizontal concealed fan coil unit, relating to the field of fan coil technology. It includes a chassis and a pair of volutes mounted on one side of the chassis, as well as an annular flow guide assembly installed at the air inlet of each volute. The annular flow guide assembly includes multiple inclined blades evenly arranged circumferentially. The roots of the inclined blades are hinged to the air inlet of the volute via a hinge shaft, and they swing obliquely around the hinge shaft to adaptively adjust the air inlet opening according to the internal air pressure of the volute. A pair of sound-absorbing chambers are also included, respectively arranged in the near-wall boundary layer region on both sides of the inner wall of the volute. This invention, by setting an annular flow guide assembly at the air inlet of the volute and utilizing the hinged structure between the inclined blades and the air inlet, allows the blades to adaptively swing around the hinge shaft according to the internal air pressure of the volute, achieving automatic adjustment of the air inlet opening. When the fan is running at high speed, the lateral component of the axial airflow pushes the blades to swing, increasing the air inlet opening and reducing airflow resistance.

Description

Technical Field

[0001] This invention relates to the field of fan coil unit technology, specifically to horizontal concealed fan coil unit units. Background Technology

[0002] As the core terminal equipment of central air conditioning systems, horizontal concealed fan coil units are widely used in various building spaces such as residences, office buildings, and hotels. They undertake the key tasks of indoor air temperature regulation and airflow organization. Their operational stability, energy efficiency, and noise control directly affect indoor environmental comfort and building energy consumption performance.

[0003] The existing patent application, with publication number CN205425186U and publication date August 3, 2016, is titled "A Horizontal Concealed Fan Coil Unit." This patent includes two side plates, a heat exchanger connected between the two side plates, a water collection tray connected to the lower part of the two side plates, and a fan connected to the air inlet of the heat exchanger. The lower parts of both ends of the two side plates are connected to the left and right sides of the groove in the water collection tray. The key feature is that there is a gap between the bottom of the two side plates and the bottom surface of the groove in the water collection tray, with a gap height of 15-20 mm. The advantages of this utility model are: high side plate strength, effectively preventing deformation of the side plates due to excessive force.

[0004] The aforementioned application has shortcomings. It only focuses on optimizing the strength of the unit structure and does not address improvements to core performance aspects such as fan intake regulation and noise control. On the one hand, when the fan operates at high speed, the fixed opening of the air inlet limits the effective air intake area, leading to aerodynamic noise and even inlet whistling due to excessively high airflow velocity and turbulent flow. On the other hand, when the fan operates at low speed, an excessively large air inlet opening can cause the air intake to be too dispersed, forming vortices in the volute flow channel. Especially in the boundary layer area of ​​the volute wall, the intensified vortices generate significant low-frequency noise. This low-frequency humming is particularly prominent in quiet environments such as at night, seriously affecting the user experience. Moreover, low-frequency noise is often coupled with equipment vibration and is mostly propagated by simply laying sound-absorbing materials inside the chassis or volute. However, the noise fluctuates with changes in wind speed. When the wind speed increases, the low-frequency noise from overall vibration becomes more severe. Furthermore, the impact of airflow inside the volute makes the flexible sound-absorbing materials more susceptible to damage, reducing the durability of noise reduction. Summary of the Invention

[0005] The purpose of this invention is to provide a horizontal concealed fan coil unit to overcome the shortcomings of the prior art.

[0006] To achieve the above objectives, the present invention provides the following technical solution: A horizontal concealed fan coil unit includes a chassis and a pair of volutes mounted on one side of the chassis. It also includes an annular airflow guide assembly installed at the air inlet of each volute. The annular airflow guide assembly includes multiple inclined blades evenly arranged circumferentially. The roots of the inclined blades are hinged to the air inlet of the volute via a hinge shaft, and they swing obliquely around the hinge shaft to adaptively adjust the air inlet opening according to the air pressure inside the volute. A pair of sound-absorbing chambers are respectively arranged in the near-wall boundary layer region on both sides of the inner wall of the volute, and each sound-absorbing chamber is equipped with a sound-absorbing structure. When the wind speed increases, the inclined blades swing under the lateral force of the axial airflow, increasing the air inlet opening and simultaneously increasing the volume of the sound-absorbing chambers. When the wind speed decreases, the inclined blades return to their original position, narrowing the air inlet opening and simultaneously decreasing the volume of the sound-absorbing chambers.

[0007] Preferably, the air inlet of the volute is provided with an annular mounting part, and multiple mounting seats are fixedly mounted on the annular mounting part, and the hinge shaft is rotatably mounted in the corresponding mounting seat.

[0008] Preferably, a pair of return torsion springs are fitted on the hinge shaft. One end of the return torsion spring is fixedly connected to the hinge shaft, and the other end is fixedly connected to the mounting base. It is used to provide a return spring force when the wind speed decreases, driving the tilting blades to swing around the hinge shaft to narrow the air inlet opening.

[0009] Preferably, the sound-absorbing chamber is formed by a side sound-absorbing plate and the inner wall of the volute. The side sound-absorbing plate is arc-shaped, and its arc-shaped contour matches the arc-shaped contour of the inner wall of the volute. A return spring is installed between the side sound-absorbing plate and the inner wall of the volute.

[0010] Preferably, the inner surface of the side muffler plate is provided with a plurality of helical racks arranged in a ring, and one end of the hinge shaft is fixedly connected with a sector tooth that meshes with the helical racks.

[0011] Preferably, an inclined water receiving tray is installed at the bottom of the chassis, and a movable base plate is installed inside the inclined water receiving tray. The movable base plate has a sealing strip on its edge. The movable base plate is connected to the side sound-absorbing plate. The movable base plate is tilted by the side sound-absorbing plate to realize the adaptive adjustment of the water receiving volume of the inclined water receiving tray.

[0012] Preferably, a telescopic transmission rod is fixedly connected to the bottom end of the side silencing plate, a guide rail for inserting the telescopic transmission rod is fixedly connected to one side of the top surface of the movable base plate, and a guide protrusion that abuts against the telescopic transmission rod is fixedly connected to the top of the inclined water receiving tray.

[0013] Preferably, the sound-absorbing structure includes a sound-absorbing cotton layer and a perforated plate. The sound-absorbing cotton layer fills the interior of the sound-absorbing cavity and is tightly attached to the perforated plate and the inner wall of the volute.

[0014] Preferably, the annular mounting portion is fixedly connected to an anti-deviation limiting bracket through which the helical rack passes.

[0015] Preferably, the outer surface of the inclined blade is coated with a smooth, wear-resistant coating, and the edges of the inclined blade are rounded.

[0016] In the above technical solution, by setting an annular flow guide component at the volute inlet and utilizing the hinged structure between the inclined blades and the volute inlet, the blades can adaptively swing around the hinge axis according to the air pressure inside the volute, achieving automatic adjustment of the inlet opening. When the fan is running at high speed, the lateral component of the axial airflow pushes the blades to swing, increasing the inlet opening, reducing airflow resistance, and reducing fan power consumption. When the fan is running at low speed, the blades return to their original position, narrowing the inlet, suppressing eddy current generation, and reducing low-frequency noise. At the same time, suction devices that can adjust their volume synchronously with the blade swing are set in the near-wall boundary layer region on both sides of the volute inner wall. The acoustic chamber increases in volume at high speeds, enhancing mid-to-low frequency noise reduction capabilities while preventing the sound-absorbing layer from being damaged by high-speed airflow. At low speeds, the volume shrinks, effectively absorbing noise while ensuring smooth flow and reducing local resistance. Furthermore, the acoustic chamber is positioned in the low-speed turbulent region near the wall boundary layer, so volume adjustments only slightly occupy the flow channel cross-section, having minimal impact on the airflow in the high-speed mainstream area. The smooth transition of the acoustic chamber's inner wall effectively prevents airflow separation and eddy current intensification, eliminating the generation of additional aerodynamic noise. The overall noise reduction effect is significantly better than the slight aerodynamic impact caused by flow channel shrinkage.

[0017] It should be understood that the foregoing general description and the following detailed description are exemplary and illustrative only, and are not intended to limit this disclosure.

[0018] This application provides an overview of various implementations or examples of the technology described in this disclosure, and is not a full disclosure of the entire scope or all features of the disclosed technology. Attached Figure Description

[0019] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in this invention. For those skilled in the art, other drawings can be obtained based on these drawings.

[0020] Figure 1 This is a schematic diagram of the overall structure of the present invention. Figure 1 ; Figure 2 This is a schematic diagram of the overall structure of the present invention. Figure 2 ; Figure 3 This is an overall sectional view of the present invention; Figure 4 This is a schematic diagram of the internal structure of the volute of the present invention; Figure 5 This is a schematic diagram of the transmission of the annular flow guide assembly and the side noise reduction plate of the present invention; Figure 6 for Figure 5 Enlarged view of the structure at point A in the image; Figure 7 This is a schematic diagram of the inclined water receiving tray of the present invention; Figure 8 for Figure 7 Enlarged view of the structure at point B in the image.

[0021] Explanation of reference numerals in the attached figures: 1. Chassis; 2. Volute; 201. Annular mounting section; 202. Anti-deviation limit bracket; 3. Annular flow guide assembly; 301. Inclined blades; 302. Hinge shaft; 303. Return torsion spring; 304. Sector tooth; 4. Sound absorption chamber; 401. Side sound-absorbing plate; 402. Return spring; 403. Helical rack; 404. Telescopic transmission rod; 5. Sound-absorbing structure; 501. Sound-absorbing cotton layer; 502. Perforated plate; 6. Mounting base; 7. Inclined water receiving tray; 701. Movable base plate; 702. Sealing strip; 703. Guide rail; 704. Guide protrusion; 8. Coil heat exchanger; 9. Fan motor; 901. Impeller. Detailed Implementation

[0022] To make the objectives, technical solutions, and advantages of the embodiments of this disclosure clearer, the technical solutions of the embodiments of this disclosure will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this disclosure. All other embodiments obtained by those skilled in the art based on the described embodiments of this disclosure without creative effort are within the scope of protection of this disclosure.

[0023] Please see Figures 1-8 The horizontal concealed fan coil unit provided in this embodiment of the invention includes a casing 1 and a pair of volutes 2 installed on one side of the casing 1. It also includes an annular flow guide assembly 3, which is installed at the air inlet of the volute 2. The annular flow guide assembly 3 includes multiple inclined blades 301 evenly arranged circumferentially. The roots of the inclined blades 301 are hinged to the air inlet of the volute 2 through a hinge shaft 302. They swing obliquely around the hinge shaft 302 to adaptively adjust the air inlet opening according to the wind pressure inside the volute 2. A pair of sound-absorbing chambers 4 are respectively arranged in the near-wall boundary layer area on both sides of the inner wall of the volute 2. The sound-absorbing chambers 4 are provided with a sound-absorbing structure 5. When the wind speed increases, the inclined blades 301 swing under the action of the lateral component of the axial air intake, increasing the air inlet opening and increasing the volume of the sound-absorbing chambers 4. When the wind speed decreases, the inclined blades 301 return to their original position and narrow the air inlet opening, decreasing the volume of the sound-absorbing chambers 4.

[0024] Specifically, the horizontal concealed fan coil unit is mainly used for indoor terminal heat exchange and ventilation in building air conditioning systems. It adopts a horizontal concealed design, allowing it to be embedded inside the ceiling without occupying usable indoor space, balancing practicality and aesthetics. The casing 1, serving as the mounting carrier and protective shell for the entire unit, is made of cold-rolled steel sheet through a single stamping process. An internal installation chamber is reserved. Two symmetrically arranged mounting openings are provided on one side wall of the casing 1, which are adapted to the shape of the volute 2 for fixing a pair of volutes 2. The pair of volutes 2 are symmetrically fixed at the mounting openings of the casing 1. In addition, the casing 1 also houses conventional components such as the coil heat exchanger 8 and the fan motor 9. The coil heat exchanger 8 is connected to the air outlet of the volute 2 for cooling or... Heating is provided, and an inclined water collection tray 7 is located below the heat exchanger to collect condensate generated during the heat exchange process. An impeller 901, located inside the volute 2, is mounted on the output shaft of the fan motor 9 to power the airflow. The installation method of these conventional components is consistent with existing horizontal concealed fan coil units, and will not be elaborated further here. After the unit starts, the fan motor 9 drives the impeller 901 inside the volute 2 to rotate at high speed. The rotation of the impeller 901 generates negative pressure, causing outside air to enter the volute 2 through the air inlet. After being guided by the volute 2, the airflow is sent to the coil heat exchanger 8 inside the casing 1. The airflow exchanges heat with the cold / hot water in the coil heat exchanger 8, and then is sent into the room through the air outlet of the casing 1 to regulate the indoor temperature. The condensate generated during the heat exchange process falls into the... The condensate pan is drained through the drain pipe, completing the entire heat exchange and ventilation cycle. An annular flow guide assembly 3 is installed at the air inlet of each volute 2. The annular flow guide assembly 3 consists of multiple inclined blades 301 evenly arranged around the circumference of the air inlet. The root of each inclined blade 301 is hinged to the mounting structure at the air inlet via a hinge shaft 302. The axis of the hinge shaft 302 also forms a certain angle with the tangent direction of the air inlet of the volute 2, allowing the inclined blades 301 to swing obliquely around the hinge shaft 302. This ensures effective adjustment of the air inlet opening and avoids excessive blade swing leading to airflow turbulence. A pair of sound-absorbing chambers 4 are respectively arranged on both sides of the inner wall of each volute 2 in the near-wall boundary layer region. The near-wall boundary layer region is the low-speed turbulent flow region between the inner wall of the volute 2 and the mainstream airflow. This area is the main region for airflow separation, vortex generation, and noise radiation. Placing the sound-absorbing chamber 4 here can achieve targeted noise reduction. The sound-absorbing chamber 4 is linked with the inclined blades 301. When the inclined blades 301 swing, they can synchronously drive the sound-absorbing chamber 4 to expand and contract, thereby adjusting the volume of the sound-absorbing chamber 4. The silencing structure 5 is set inside the sound-absorbing chamber 4 to adapt to the operating environment of the fan coil unit. When the indoor load is large and the temperature needs to be adjusted quickly, the fan motor 9 operates in high-speed mode, the impeller 901 rotates faster, the negative pressure in the volute 2 increases, and the outside air enters the air inlet of the volute 2 at a higher speed along the axial direction. At this time, the axial air intake generates a lateral force on the inclined blades 301. This lateral force is greater than the weight of the blades themselves and the friction at the hinge.The inclined blades 301 are pushed to swing obliquely inward around the hinge shaft 302, increasing the gap between the multiple inclined blades 301, i.e., increasing the air inlet opening. With the increased air inlet opening, the air inlet resistance is significantly reduced, allowing airflow to enter the volute 2 more smoothly, reducing the load on the fan motor 9 and lowering fan power consumption. Simultaneously, it prevents high-speed airflow from congesting at the air inlet, reducing aerodynamic noise. At the same time, the inclined blades 301 synchronously stretch the sound-absorbing chamber 4, increasing its volume. The noise generated by the high-speed operation of the fan is mainly in the low and mid frequencies. The increased volume of the sound-absorbing chamber 4 enhances its ability to absorb low and mid-frequency noise caused by vibration of the casing 1. Simultaneously, the sound-absorbing chamber 4 is located in the near-wall boundary layer region of the inner wall of the volute 2, which is a low-speed turbulent flow area where high-speed airflow is mainly concentrated in the central mainstream region. The increased volume of the sound-absorbing chamber 4 only slightly occupies the flow channel cross-section, having minimal impact on the airflow in the central high-speed mainstream region and not increasing the inlet resistance. Furthermore, it prevents high-speed airflow from directly impacting the silencing structure 5, thus preventing noise reduction. To prevent damage to sound-absorbing materials and extend their service life, when the indoor temperature approaches the set temperature, the fan motor 9 operates in low-speed mode, the impeller 901 rotates slower, the negative pressure inside the volute 2 decreases, and the axial air intake speed decreases. The lateral force generated by this on the inclined blades 301 also decreases. When the lateral force is less than the weight of the blades themselves and the elastic restoring force at the hinge, the inclined blades 301 swing outwards obliquely around the hinge axis 302 under their own action, restoring and narrowing the air inlet opening. After the air inlet opening is narrowed, it can effectively suppress the generation of eddies between the high-speed mainstream area and the edge of the air inlet, reducing the radiation of low-frequency noise. At the same time, the narrowed air inlet can keep the airflow speed within a reasonable range, avoiding turbulence generated by low-speed airflow, further reducing noise. Simultaneously, it drives the sound-absorbing chamber 4 to shrink synchronously, reducing its volume. At this time, the sound-absorbing chamber 4 with reduced volume can specifically absorb low-frequency noise, while avoiding the sound-absorbing chamber 4 occupying too much flow channel cross-section, ensuring smooth airflow, reducing local resistance, and ensuring the stability of airflow when the fan is running at low speed. Furthermore, the smooth transition of the inner wall of the sound-absorbing chamber 4 effectively prevents airflow separation at the chamber edges, eliminating additional aerodynamic noise and ensuring noise reduction without affecting the unit's aerodynamic performance.

[0025] Compared with the prior art, the embodiments of the present invention, by setting an annular flow guide component 3 at the air inlet of the volute 2, and utilizing the hinge structure between the inclined blade 301 and the air inlet of the volute 2, allow the blade to adaptively swing around the hinge axis 302 according to the wind pressure inside the volute 2, thereby achieving automatic adjustment of the air inlet opening. When the fan is running at high speed, the lateral component of the axial air intake pushes the blade to swing, increasing the air inlet opening, reducing air intake resistance, and reducing fan power consumption. When the fan is running at low speed, the blade returns to its original position, narrowing the air inlet, suppressing eddy current generation, and reducing low-frequency noise. At the same time, near-wall boundary layer regions on both sides of the inner wall of the volute 2 are provided with components that can swing synchronously with the blade. The volume of the dynamically adjustable sound-absorbing chamber 4 increases at high speeds, enhancing mid-to-low frequency noise reduction capabilities while preventing the sound-absorbing layer from being damaged by high-speed airflow. At low speeds, the volume shrinks, effectively absorbing noise while ensuring smooth flow and reducing local resistance. Furthermore, the sound-absorbing chamber 4 is positioned in the low-speed turbulent region near the wall boundary layer, so the volume adjustment only slightly occupies the flow channel cross-section, having minimal impact on the airflow in the middle high-speed mainstream area. The smooth transition of the inner wall of the sound-absorbing chamber 4 effectively prevents airflow separation and eddy current amplification, eliminating the generation of additional aerodynamic noise. The overall noise reduction effect is significantly better than the slight aerodynamic impact caused by flow channel shrinkage.

[0026] In a further embodiment of the present invention, an annular mounting part 201 is integrally provided at the air inlet of the volute 2. The annular mounting part 201 is fixedly mounted on the inner wall of the sound absorption chamber 4 with multiple mounting seats 6. The hinge shaft 302 is rotatably mounted in the corresponding mounting seat 6. Specifically, the annular mounting part 201 is an annular structure integrally formed with the inner side of the air inlet. Multiple mounting seats 6 are evenly spaced along the outer circumference of the annular mounting part 201. Each mounting seat 6 is equipped with a corresponding inclined blade 301, which provides stable mounting support for the hinge shaft 302, ensures the stability of the inclined blade 301 during the swing process, prevents swaying and deviation, improves the accuracy of opening adjustment, and avoids airflow turbulence caused by blade misalignment.

[0027] In a further embodiment of the present invention, a pair of reset torsion springs 303 are fitted on the hinge shaft 302. One end of the reset torsion spring 303 is fixedly connected to the hinge shaft 302, and the other end is fixedly connected to the mounting base 6. It is used to provide reset elastic force when the wind speed decreases, driving the tilting blade 301 to swing around the hinge shaft 302 to narrow the air inlet opening. Specifically, when the fan is running at high speed, when the tilting blade 301 swings inward, it will drive the hinge shaft 302 to rotate in the mounting base 6. The reset torsion spring 303 will then undergo elastic torsion, accumulating reset elastic force. When the fan speed decreases and the lateral force of the air inlet decreases, the reset torsion spring 303 releases the accumulated elastic force, assisting in pushing the hinge shaft 302 to rotate in the opposite direction, driving the tilting blade 301 to quickly reset and narrow the air inlet, avoiding reset delay due to insufficient blade weight, ensuring the response speed of air inlet opening adjustment, adapting to the dynamic changes of fan speed, and improving the reliability of adaptive adjustment.

[0028] In a further embodiment of the present invention, the sound-absorbing chamber 4 is formed by a side silencing plate 401 and the inner wall of the volute 2. The side silencing plate 401 is arc-shaped, and its arc contour is adapted to the arc contour of the inner wall of the volute 2. A return spring 402 is installed between the side silencing plate 401 and the inner wall of the volute 2. Specifically, the side silencing plate 401 can slide along the radial direction of the volute 2. One end of the return spring 402 is fixed to the inner wall of the volute 2, and the other end is fixed to the outer side of the side silencing plate 401, providing a pulling force to the side silencing plate 401 towards the outer side of the volute 2. By sliding the side silencing plate 401, the volume of the sound-absorbing chamber 4 can be changed. The structure is simple and the adjustment is flexible. Moreover, the outer wall of the arc-shaped side silencing plate 401 is adapted to the contour of the inner wall of the volute 2, and no gap will appear during the sliding process, ensuring the airtightness of the sound-absorbing chamber 4.

[0029] In a further embodiment of the present invention, a plurality of helical racks 403 are distributed in a ring on the inner side of the side silencing plate 401. One end of the hinge shaft 302 is fixedly connected to a sector tooth 304 that meshes with the helical rack 403. Specifically, when the inclined blade 301 is pressed and drives the hinge shaft 302 to rotate, the sector tooth 304 at the end of the hinge shaft 302 rotates synchronously, meshing and driving the matching helical rack 403 to move radially along the volute 2. The helical rack 403 is fixed on the inner side of the side silencing plate 401, thereby driving the side silencing plate 401 to slide synchronously, realizing the linkage between the swing of the inclined blade 301 and the volume adjustment of the sound absorption chamber 4. No additional power drive components are required, the structure is compact, the transmission is reliable, and the volume adjustment can be completed by using the swing power of the inclined blade 301 without increasing additional energy consumption and structural complexity.

[0030] In a further embodiment of the present invention, an inclined water receiving tray 7 is installed at the bottom of the chassis 1, with a drain outlet at one end. A movable base plate 701 is hinged inside the inclined water receiving tray 7. A sealing strip 702 is provided on the edge of the movable base plate 701. The movable base plate 701 is connected to a side sound-absorbing plate 401 away from the drain outlet. The side sound-absorbing plate 401 drives the movable base plate 701 to tilt, thereby realizing the adaptive adjustment of the water receiving volume of the inclined water receiving tray 7. Specifically, the inclined water receiving tray 7 is a rectangular open water receiving structure. The movable base plate 701 divides the interior of the water receiving tray into an upper water receiving area and a lower cavity. The upper water receiving area is used to collect condensate. When the side sound-absorbing plate 401 slides, it drives the movable base plate 701 to move. When the fan operates at high speed... When the fan is running, the side silencer plate 401 slides inward toward the volute 2. The heat exchange load of the unit is large and the amount of condensate produced is large. The movement of the side silencer plate 401 pulls the movable end of the movable base plate 701 downward, increasing the water volume of the upper water receiving area and preventing condensate from overflowing. When the fan is running at low speed, the side silencer plate 401 slides outward toward the volute 2. The amount of condensate produced is small, pushing the movable base plate 701 to tilt upward, reducing the volume of the upper water receiving area and raising the water level to facilitate the rapid discharge of condensate and prevent the long-term accumulation of a small amount of condensate from producing odor. The sealing strip 702 on the edge of the movable base plate 701 can seal the gap between the movable base plate 701 and the inner wall of the water receiving tray to prevent condensate from leaking into the lower cavity.

[0031] In a further embodiment of the present invention, a telescopic transmission rod 404 is fixedly connected to the bottom end of the side silencing plate 401, a guide rail 703 for inserting the telescopic transmission rod 404 is fixedly connected to one side of the top surface of the movable base plate 701, and a guide protrusion 704 that abuts against the telescopic transmission rod 404 is fixedly connected to the top of the inclined water receiving tray 7. The telescopic transmission rod 404 slides and seals with the housing 1. Specifically, when the side silencing plate 401 slides radially along the volute 2, it drives the telescopic transmission rod 404 at the bottom end to move synchronously. The telescopic transmission rod 404 is inserted into the guide rail 703 at its bottom end. During the movement, it moves along the inclined guide protrusion 704. The inclined surface of the guide protrusion 704 will squeeze the telescopic transmission rod 404, causing it to synchronously drive the guide rail 703 to shift downward or upward during the horizontal movement. Finally, it will drive the movable base plate 701 to rotate around the hinge shaft 302 to adjust the tilt angle, so as to realize the adaptive change of water volume and rate. This transmission structure is simple and reliable, and the adjustment is completed directly by the sliding power of the side silencing plate 401.

[0032] In a further embodiment of the present invention, the sound-absorbing structure 5 includes a sound-absorbing cotton layer 501 and a perforated plate 502. The sound-absorbing cotton layer 501 fills the interior of the sound-absorbing chamber 4 and is tightly fitted to the inner wall of the volute 2. The perforated plate 502 is fixed to the inner surface of the side sound-absorbing plate 401. Specifically, a plurality of through-holes are uniformly opened on the surface of the perforated plate 502. The sliding of the side sound-absorbing plate 401 increases the volume of the sound-absorbing chamber 4. The sound-absorbing cotton layer 501 and the perforated plate 502... Simultaneously, it plays an efficient noise reduction role. When the volume of the sound-absorbing chamber 4 is reduced, the sound-absorbing cotton layer 501 is uniformly compressed, but it can still maintain a tight fit with the inner wall of the chamber. It will not become loose or hollow due to compression, ensuring a stable noise reduction effect under different volumes. The perforated plate 502 can guide the sound waves entering the sound-absorbing chamber 4, and at the same time, it can limit and protect the sound-absorbing cotton layer 501, preventing the sound-absorbing cotton from being directly washed away by the airflow and extending the service life of the sound-absorbing structure 5.

[0033] In a further embodiment of the present invention, an anti-deviation limiting bracket 202 for the oblique rack 403 to pass through is fixedly connected to the annular mounting part 201. Specifically, the anti-deviation limiting bracket 202 is provided with a limiting sliding hole that matches the cross section of the oblique rack 403. After the oblique rack 403 passes through the limiting sliding hole, it meshes with the fan-shaped tooth 304. When the side sound-absorbing plate 401 drives the oblique rack 403 to slide radially, the limiting sliding hole will restrict the movement direction of the oblique rack 403, so as to avoid the oblique rack 403 from deviating and shaking during the transmission process, ensuring that the fan-shaped tooth 304 and the oblique rack 403 always maintain stable meshing, improving the stability of the transmission process, preventing linkage failure due to meshing misalignment, and ensuring that the volume adjustment of the sound absorption chamber 4 can reliably follow the swing of the inclined blade 301 synchronously.

[0034] In a further embodiment of the present invention, the outer surface of the inclined blade 301 is coated with a smooth wear-resistant coating, and the edge of the inclined blade 301 is rounded. Specifically, the smooth wear-resistant coating can reduce the surface roughness of the inclined blade 301, reduce the frictional resistance when the airflow passes over the blade, prevent dust accumulation on the blade surface, improve the wear resistance of the blade, and extend the service life of the blade. The rounded edge design can prevent airflow separation and eddies caused by sharp edges when the airflow passes over the blade edge, reduce the generation of additional aerodynamic noise from the source, and further improve the noise reduction effect.

[0035] The foregoing has only described certain exemplary embodiments of the present invention by way of illustration. Undoubtedly, those skilled in the art can modify the described embodiments in various ways without departing from the spirit and scope of the present invention. Therefore, the foregoing drawings and descriptions are illustrative in nature and should not be construed as limiting the scope of protection of the claims of the present invention.

Claims

1. A horizontal concealed fan coil unit, comprising a casing (1) and a pair of volutes (2) mounted on one side of the casing (1), characterized in that, Also includes: An annular flow guide assembly (3) is installed at the air inlet of the volute (2). The annular flow guide assembly (3) includes multiple inclined blades (301) evenly arranged in the circumferential direction. The root of the inclined blades (301) is hinged to the air inlet of the volute (2) through a hinge shaft (302). The blades swing obliquely around the hinge shaft (302) to adaptively adjust the air inlet opening according to the wind pressure inside the volute (2). A pair of sound-absorbing chambers (4) are respectively arranged in the near-wall boundary layer region on both sides of the inner wall of the volute (2), and a sound-absorbing structure (5) is provided in the sound-absorbing chamber (4). When the wind speed increases, the tilting blade (301) swings under the lateral force of the axial air intake, increasing the air inlet opening and causing the volume of the sound absorption chamber (4) to increase synchronously. When the wind speed decreases, the tilting blade (301) returns to its original position and narrows the air inlet opening, causing the volume of the sound absorption chamber (4) to decrease synchronously.

2. The horizontal concealed fan coil unit according to claim 1, characterized in that, The volute (2) has an annular mounting part (201) at the air inlet, and multiple mounting seats (6) are fixedly installed on the annular mounting part (201). The hinge shaft (302) is rotatably installed in the corresponding mounting seat (6).

3. The horizontal concealed fan coil unit according to claim 2, characterized in that, A pair of reset torsion springs (303) are fitted on the hinge shaft (302). One end of the reset torsion spring (303) is fixedly connected to the hinge shaft (302), and the other end is fixedly connected to the mounting base (6). It is used to provide reset force when the wind speed decreases, and drive the tilting blade (301) to swing around the hinge shaft (302) to narrow the opening of the air inlet.

4. The horizontal concealed fan coil unit according to claim 3, characterized in that, The sound-absorbing chamber (4) is formed by the side sound-absorbing plate (401) and the inner wall of the volute (2). The side sound-absorbing plate (401) is arc-shaped, and its arc-shaped contour matches the arc-shaped contour of the inner wall of the volute (2). A return spring (402) is installed between the side sound-absorbing plate (401) and the inner wall of the volute (2).

5. The horizontal concealed fan coil unit according to claim 4, characterized in that, The inner side of the side muffler plate (401) is provided with a plurality of helical racks (403) arranged in a ring, and one end of the hinge shaft (302) is fixedly connected with a fan-shaped tooth (304) that meshes with the helical racks (403).

6. The horizontal concealed fan coil unit according to claim 4, characterized in that, The bottom of the chassis (1) is equipped with an inclined water receiving tray (7), and a movable base plate (701) is installed inside the inclined water receiving tray (7). The edge of the movable base plate (701) is provided with a sealing strip (702). The movable base plate (701) is connected to the side silencing plate (401) for transmission. The movable base plate (701) is tilted by the side silencing plate (401) to realize the adaptive adjustment of the water receiving volume of the inclined water receiving tray (7).

7. The horizontal concealed fan coil unit according to claim 6, characterized in that, The bottom end of the side silencing plate (401) is fixedly connected to a telescopic transmission rod (404), and the top side of the movable base plate (701) is fixedly connected to a guide rail (703) for the telescopic transmission rod (404) to be inserted. The top of the inclined water receiving tray (7) is fixedly connected to a guide protrusion (704) that abuts against the telescopic transmission rod (404).

8. The horizontal concealed fan coil unit according to claim 4, characterized in that, The sound-absorbing structure (5) includes a sound-absorbing cotton layer (501) and a perforated plate (502). The sound-absorbing cotton layer (501) is filled inside the sound-absorbing chamber (4), and the sound-absorbing cotton layer (501) is tightly attached to the perforated plate (502) and the inner wall of the volute (2).

9. The horizontal concealed fan coil unit according to claim 5, characterized in that, An anti-deviation limiting bracket (202) for the oblique rack (403) to pass through is fixedly connected to the annular mounting part (201).

10. The horizontal concealed fan coil unit according to claim 1, characterized in that, The outer surface of the inclined blade (301) is coated with a smooth wear-resistant coating, and the edges of the inclined blade (301) are rounded.

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