Compact low-noise circulating cooling unit

Abstract

The invention relates to a compact low-noise circulating cooling unit which comprises a fan shell, a first-stage impeller and a last-stage impeller are arranged at the air inlet end and the air outlet end matched with the fan shell respectively and arranged outside a front-end output shaft and a tail-end output shaft of a motor in a sleeving mode respectively, and a rectification assembly matched with the fan shell is arranged on the outer side of the motor; the first-stage impeller, the last-stage impeller, the motor and the rectification assembly are coaxial; a front silencing device is arranged at the air inlet end matched with the fan shell and comprises an air inlet cavity, the air inlet cavity comprises a mounting base and an air inlet channel formed in the mounting base, and a composite silencing assembly is arranged in cooperation with the air inlet channel. On the same size and weight index level, the performance index of the fan exceeds that of a common fan, and on the same air volume, air pressure and other performance index levels, the size and the weight of the fan are reduced or reduced compared with those of the common fan; the vibration resistance of the unit is improved, the manufacturing process is simplified, the overall stability is improved, and the fan efficiency is effectively improved; pressure loss is reduced, and noise is lowered.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of non-variable displacement pumps or air conditioning, in particular to a compact low-noise circulating cooling unit. BACKGROUND

[0002] ‌The circulating cooling unit is an industrial heat dissipation device, which reduces the equipment operating temperature through forced air circulation, and the power source is generally an axial flow fan. The axial flow fan is a fan in which the airflow is parallel to the shaft of the fan. It is usually used in places where the flow requirement is high and the pressure requirement is low. When the impeller rotates, the gas enters the impeller axially from the inlet, is pushed by the blades on the impeller to increase the energy, and then flows into the guide vane. The guide vane changes the direction of the deflected airflow to axial flow, and at the same time guides the gas into the diffuser pipe to further convert the kinetic energy of the gas into pressure energy, and finally introduces it into the working pipeline. Axial flow fans are widely used in metallurgy, chemical industry, light industry, food, pharmaceutical equipment, mechanical equipment and civil buildings for ventilation and heat dissipation.

[0003] However, with the improvement of performance parameters such as air volume and air pressure, the size and weight of the existing axial flow fan will also increase accordingly, so its adaptability to related scenes, especially special scenes such as nuclear power, is relatively lacking under many working conditions. In addition, in some situations where high requirements are required, its noise index is often difficult to meet, especially when applied to continuous working conditions, it often has a large noise problem.

[0004] A kind of energy-saving axial flow fan with silencing function is disclosed in Chinese patent with publication number CN207673584U, including fan, fan blade is connected to motor by shaft, tail of fan is connected to silencing device, silencing device includes silencing guide sleeve and silencing pipe, multiple air guide openings are arranged on the end surface of silencing guide sleeve, air guide openings are communicated with silencing channel in silencing pipe, silencing channel is concave-convex long channel, silencing channel is filled with silencing material, silencing guide sleeve and silencing pipe are made of multilayer silencing composite material, and flow holes are arranged on fan blade;This technical solution sets silencing device at the end of fan, which solves part of the noise problem of fan, but actually does not solve the air resistance of front end and the influence on front end of fan due to airflow condensation. SUMMARY

[0005] The present application solves the problems in the prior art and provides a compact low-noise circulating cooling unit.

[0006] The technical scheme adopted by the present application is a compact low-noise circulating cooling unit, comprising a fan shell, a first-stage impeller and a last-stage impeller arranged at the air inlet end and the air outlet end of the fan shell respectively, the first-stage impeller and the last-stage impeller in the fan shell being sleeved outside the front end shaft and the tail end shaft of a motor respectively, and a rectifier assembly being arranged outside the motor and matched with the fan shell; the first-stage impeller, the last-stage impeller, the motor and the rectifier assembly are coaxially arranged; a front-mounted sound attenuation device is arranged at the air inlet end of the fan shell, the front-mounted sound attenuation device comprising an air inlet cavity, the air inlet cavity comprising a mounting base and an air inlet channel arranged on the mounting base, and a composite sound attenuation assembly being arranged at the air inlet channel.

[0007] Preferably, the rectifier assembly comprises a rectifier cylinder coaxially arranged outside the motor, a plurality of space guide vanes being arranged in a ring shape outside the rectifier cylinder, and the rectifier cylinder, the space guide vanes and the fan shell being fixedly connected; the number of blades of the first-stage impeller, the number of blades of the last-stage impeller and the number of space guide vanes are prime numbers with respect to each other, and the number of blades of the first-stage impeller is greater than the number of blades of the last-stage impeller.

[0008] Preferably, the first-stage impeller and the last-stage impeller each comprise a hub and blades, a plurality of mounting grooves being arranged on the hub, and a mounting bracket matched with the mounting grooves being arranged on the blade side facing the hub; a plurality of mounting through holes are correspondingly arranged between the mounting grooves and the mounting bracket.

[0009] Preferably, the included angle between the outer edge front end and the outer edge rear end of the blade of the first-stage impeller and the central axis of the first-stage impeller and the last-stage impeller is α, the included angle between the outer edge front end and the outer edge rear end of the blade of the last-stage impeller and the central axis of the first-stage impeller and the last-stage impeller is β, and α>β; the blades of the first-stage impeller and the last-stage impeller are equal in length along the fan axis from the front end to the rear end and are arranged in an arch shape towards the air inlet end.

[0010] Preferably, the front end and the rear end of the space guide vane are parallel to the central axis of the rectifier assembly, the middle part of the space guide vane is arranged in an arch shape, and the arch direction of the space guide vane is opposite to the radial component of the arch direction of the blades of the first-stage impeller and the last-stage impeller.

[0011] Preferably, the composite sound attenuation assembly comprises outer layer sound attenuation louvers and inner layer sound attenuation louvers; the blades of the outer layer sound attenuation louvers and the inner layer sound attenuation louvers are micro-perforated plates, the airflow frequency flowing through the corresponding blades of the outer layer sound attenuation louvers and the inner layer sound attenuation louvers is collected, a relationship curve between thickness and opening rate is established, and the micro-perforated plates are configured based on the relationship curve.

[0012] Preferably, the outer layer sound attenuation louvers and the inner layer sound attenuation louvers are inclined outward from bottom to top towards the air inlet cavity, the included angle between the outer layer sound attenuation louvers and the central axis of the air inlet cavity is smaller than the included angle between the inner layer sound attenuation louvers and the central axis of the air inlet cavity.

[0013] Preferably, a fairing is arranged at the outlet of the air inlet cavity, and the fairing is covered with a sound-absorbing cotton layer, and the flow direction surface of the fairing is arranged at an angle with the inner layer sound-absorbing louvers.

[0014] Preferably, a heat exchanger is arranged between the outer layer sound-absorbing louvers and the inner layer sound-absorbing louvers, the heat exchanger comprises a plurality of groups of cooling coils, a pair of water supply and return pipelines are arranged for any group of cooling coils, and an inclined water collecting tray is arranged below any group of cooling coils; the cooling coils are provided with heat dissipation fins outside; and a wire mesh is arranged for the heat exchanger.

[0015] Preferably, the composite sound-absorbing assembly further comprises a rigid connecting rod and a flexible spring vibration isolator arranged at the air outlet end of the fan housing and the air inlet cavity, respectively, and the rigid connecting rod is arranged at an angle with the horizontal plane.

[0016] The application relates to a compact low-noise circulating cooling unit, which comprises a fan housing, a primary impeller and a final impeller arranged at the air inlet end and the air outlet end of the fan housing, respectively, the primary impeller and the final impeller in the fan housing are arranged outside the front end outgoing shaft and the tail end outgoing shaft of a motor, respectively, and a rectifier assembly is arranged outside the motor and cooperates with the fan housing; the primary impeller, the final impeller, the motor and the rectifier assembly are coaxially arranged; a front sound-absorbing device is arranged at the air inlet end of the fan housing, the front sound-absorbing device comprises an air inlet cavity, the air inlet cavity comprises a mounting base and an air inlet channel arranged on the mounting base, and a composite sound-absorbing assembly is arranged for the air inlet channel.

[0017] The application has the following beneficial effects: (1) The performance indexes such as air volume and air pressure of the fan exceed those of general fans under the same size and weight index level; and the size and weight of the fan are reduced by more than 20% compared with those of ordinary fans under the same air volume and air pressure performance index level. (2) The front composite sound-absorbing assembly effectively strengthens the overall structural strength of the fan, improves the vibration resistance of the unit, improves the vibration indexes of the machine shell cylinder, effectively reduces the influence of the vibration of the fan on the unit, simplifies the manufacturing process and improves the stability of the whole machine. (3) The inlet flow state of the fan is adjusted, the efficiency of the fan is effectively improved, the aerodynamic efficiency of the front sound-absorbing device is effectively improved, the pressure loss is reduced, and the noise is reduced. (4) The noise performance of the fan is greatly superior to that of the same type of product, and the noise index is reduced by more than 4dB compared with that of the same type of product. BRIEF DESCRIPTION OF DRAWINGS

[0018] Figure 1 The figure is a front view structural schematic diagram of the application; Figure 2 The figure is a front view structural schematic diagram of the application; Figure 1 The figure is an A-A sectional view structural schematic diagram of the application; Figure 3 It is a perspective structural schematic diagram of the present application; Figure 4 It is a top view structural schematic diagram of the present application. DETAILED DESCRIPTION

[0019] The present application will be further described in detail below in combination with examples, but the scope of protection of the present application is not limited thereto.

[0020] Example 1 The present embodiment relates to a compact low-noise circulating cooling unit, comprising a fan shell 1, a first-stage impeller 2 and a last-stage impeller 3 are respectively arranged at the air inlet end and the air outlet end of the fan shell 1, the first-stage impeller 2 and the last-stage impeller 3 in the fan shell 1 are respectively sleeved outside the front end shaft and the tail end shaft of a motor 4, and a rectifier assembly is arranged outside the motor 4 and matched with the fan shell 1; the first-stage impeller 2, the last-stage impeller 3, the motor 4 and the rectifier assembly are coaxially arranged; a front-mounted silencing device is arranged at the air inlet end of the fan shell 1, and the front-mounted silencing device comprises an air inlet cavity 5, the air inlet cavity 5 comprises a mounting base 6 and an air inlet channel arranged on the mounting base 6, and a composite silencing assembly is arranged at the air inlet channel.

[0021] In the present embodiment, the air inlet end (port) of the fan shell 1, the first-stage impeller 2, the rectifier assembly, the motor 4, the shaft line of the last-stage impeller 3 and the air outlet end (port) of the fan shell 1 are all on the same straight line, i.e. the fan shaft line, and by increasing the last-stage impeller 3, the airflow which has been converted into pressure energy can be better rectified and introduced into the subsequent air passage.

[0022] On this premise, a front-mounted composite silencing device is arranged in front of the air inlet end of the fan shell 1, the airflow enters the air inlet cavity 5 from the air inlet channel of the composite silencing device, and the silencing is realized from the aspects of reducing air resistance, preventing water mist and impurities from being sucked into the fan interior, and soft and hard combination vibration prevention, the pre-treatment of the airflow is realized in this process, the rectified airflow is delivered to the double-stage impeller of the fan and works in a circulating manner, and the improvement of air volume and air pressure, the reduction of size and weight, and the reduction of noise of the fan are realized in a balanced and coordinated manner.

[0023] In the specific implementation, the composite silencing assemblies are all spliced by using modular rectangular sheet metal design structures, which facilitates installation and processing, facilitates maintenance and replacement, and the spliced device as a whole has a rectangular structure, meeting the requirements of equipment silencing, noise reduction, heat exchange and the like.

[0024] Example 2 On the basis of embodiment 1, the rectifying assembly comprises a rectifying cylinder 7 coaxially arranged outside the motor 4, a plurality of space guide vanes 8 are arranged on the outer ring of the rectifying cylinder 7, and the rectifying cylinder 7, the space guide vanes 8 and the fan shell 1 are fixedly connected; the number of blades of the primary impeller 2, the number of blades of the final-stage impeller 3 and the number of space guide vanes 8 are prime numbers to each other, and the number of blades of the primary impeller 2 is greater than the number of blades of the final-stage impeller 3.

[0025] In this embodiment, the arrangement makes the vibration of the motor 4 effectively isolated by the cylinder wall of the rectifying cylinder 7, the flow guiding of the space guide vanes 8 is not affected, and the airflow flowing through the fan is not affected by the additional structural space, so that turbulence is avoided; in actual application, the rectifying cylinder 7 is provided with a mounting hole 9, the mounting hole 9 is arranged in cooperation with a mounting seat 10 of the motor 4, and the relative static state of the motor 4 and the rectifying assembly is realized.

[0026] Regarding the number of blades of the primary impeller 2, the number of blades of the final-stage impeller 3 and the number of space guide vanes 8, a configuration data is given in this embodiment, that is, the number of blades of the primary impeller 2 is 10, the number of blades of the final-stage impeller 3 is 7, and the number of space guide vanes 8 is 11, which is a relatively reasonable configuration; in actual application, the number of blades of the primary impeller 2 needs to be greater than the number of blades of the final-stage impeller 3, so that the primary impeller 2 can push and squeeze the airflow as much as possible to increase the pressure, and the space guide vanes 8 with a prime number of blades of the primary impeller 2 can reduce the strength of dynamic and static interference and better rectify the airflow, and finally the final-stage impeller 3 with a prime number of space guide vanes 8 can guide the airflow out to reduce vibration and noise.

[0027] In this embodiment, the rectifying cylinder 7, the space guide vanes 8 and the fan shell 1 are integrally welded to better arrange the airflow between the primary impeller 2 and the final-stage impeller 3; on this basis, the air-permeable holes arranged on the rectifying cylinder 7 allow part of the airflow to carry away the heat generated by the motor, thereby achieving a partial heat dissipation effect of the motor; in the specific implementation process, the air-permeable hole has a length of 200 mm with an allowable deviation of ±10%, a width of 50 mm with an allowable deviation of ±5%, and a semicircular arc at both ends, that is, a waist-shaped hole.

[0028] Embodiment 3 On the basis of embodiment 1 or 2, the primary impeller 2 and the final-stage impeller 3 respectively comprise a hub 21 and a blade 22, a plurality of mounting grooves are arranged on the hub 21, and the blade 22 is provided with a mounting bracket 23 matched with the mounting grooves towards the hub 21 side; a plurality of mounting through holes 24 are correspondingly arranged between the mounting grooves and the mounting bracket 23.

[0029] In this embodiment, the fillet radius of the root center point of each blade 22 is 35 mm, with an allowable deviation of ±10%, ensuring the structural strength; the blades 22 of the primary impeller 2 and the final-stage impeller 3 are T-shaped blades, that is, the blade width gradually and uniformly narrows from the root of the blade unit to the top along the radial direction of the impeller, ensuring the guidance and pressurization effect of the air flow.

[0030] There are respectively four groups of mounting through holes 24 on the mounting groove and the mounting bracket 23, which are installed by means of countersunk head bolts, and the matching diameter of the two is 125 mm, with an allowable deviation of ±2%, ensuring the structural strength; this structure can realize the four structural forms of the primary impeller 2 or the final-stage impeller 3 through simple disassembly and assembly, and the combination of the 16 matching modes can be applied to different scenes to form different air flow fields.

[0031] The structure of this embodiment further ensures the improvement of the equipment maintenance efficiency, and the maintenance and repair can be realized by replacing a single blade 22, greatly reducing the production and maintenance costs.

[0032] Embodiment 4 On the basis of embodiment 2, the included angle between the outer edge front end and the outer edge rear end of the blade of the primary impeller 2 and the central axis of the primary impeller 2 and the final-stage impeller 3 is α, the included angle between the outer edge front end and the outer edge rear end of the blade of the final-stage impeller 3 and the central axis of the primary impeller 2 and the final-stage impeller 3 is β, and α>β; the blades of the primary impeller 2 and the final-stage impeller 3 are equal in length along the fan axis from the front end to the rear end and are arranged in an arch towards the air inlet end.

[0033] In the specific implementation process, α satisfies 20°<α<30°, β satisfies 10°<β<20°, more preferably, α satisfies 24.5°<α<27.5°, and β satisfies 17.0°<β<19.5°; The axial section thickness of each blade of the primary impeller 2 and the final-stage impeller 3 gradually thickens from the top of the blade unit to the root of the blade unit (T-shaped blade), and the two sides of each blade 22 are the leading edge and the trailing edge, respectively, and the blade region between the leading edge and the trailing edge is arched, wherein the side close to the air inlet end (port) is the leading edge, and the side away from the air inlet end (port) is the trailing edge; the included angle between the vertex of the blade tip of the leading edge of each blade 22, the vertex of the blade tip of the trailing edge of each blade 22, and the fan axis is 36°, with a deviation allowance of 3%; according to the design principle of fluid mechanics, this angle directly affects the aerodynamic performance of the fan, and if it changes, the design flow and wind pressure of the fan will change, and the best working point and the aerodynamic performance curve will be offset; by setting the primary impeller 2 and the final-stage impeller 3 as a three-dimensional flow blade type, the three-dimensional flow blade type can have a more obvious effect on air work under the condition of the same size and speed, and the aerodynamic performance of the fan is improved.

[0034] Embodiment 5 On the basis of Embodiment 2, the front end and the rear end of the space guide vane 8 are parallel to the central axis of the rectifying assembly, and the middle part of the space guide vane 8 is arched, and the arching direction of the space guide vane 8 is opposite to the radial component of the arching direction of the blades of the first-stage impeller 2 and the last-stage impeller 3.

[0035] In the embodiment, the purpose of the front end and the rear end of the space guide vane 8 being parallel to the central axis of the rectifying assembly is to make the airflow direction through this section as along the fan axis direction as possible, and the middle part being arched is because the airflow after being worked by the first-stage impeller 2 has a deflection vector from the fan axis direction, which is corrected by the arched structure of the space guide vane 8, and then flows to the last-stage impeller 3, so that the last-stage impeller 3 can further work on the airflow to present the required optimal vector component and optimal angle when receiving the airflow; in this way, the vector component of the airflow after flowing through the first-stage impeller 2 and the better matching effect of the space guide vane 8 are better, and similarly, the vector component of the airflow after flowing through the space guide vane 8 and the better matching effect of the last-stage impeller 3 for further working on the airflow are better.

[0036] Embodiment 6 On the basis of Embodiment 1, the composite sound-absorbing assembly comprises outer sound-absorbing louvers 11 and inner sound-absorbing louvers 12; the blades of the outer sound-absorbing louvers 11 and the inner sound-absorbing louvers 12 are micro-perforated plates, the airflow frequency flowing through the blades of the corresponding outer sound-absorbing louvers 11 and inner sound-absorbing louvers 12 is collected, a relationship curve between thickness and opening rate is established, and the micro-perforated plates are configured based on the relationship curve.

[0037] More importantly, the outer sound-absorbing louvers 11 and the inner sound-absorbing louvers 12 are inclined outward from the air inlet cavity 5 from bottom to top, and the included angle between the outer sound-absorbing louvers 11 and the central axis of the air inlet cavity 5 is smaller than the included angle between the inner sound-absorbing louvers 12 and the central axis of the air inlet cavity 5.

[0038] In the embodiment, the micro-perforated plate is used as the material plate of the outer sound-absorbing louvers 11 and the inner sound-absorbing louvers 12, and the sound-absorbing mechanism based on the Helmholtz resonance principle is used, when sound waves pass through the micro-perforated plate, the air in the hole vibrates, and the air layer behind the plate forms resonance, thereby achieving the sound-absorbing effect; by analyzing the airflow frequency flowing through the inner and outer micro-perforated plates, the correlation between different thicknesses and opening rates can be established, and then the micro-perforated plates can be optimized in actual application, so that the sound-absorbing coefficient of the outer sound-absorbing louvers 11 and the inner sound-absorbing louvers 12 at the specified frequency can be improved.

[0039] In this embodiment, the outer layer of sound-absorbing louvers 11 and the inner layer of sound-absorbing louvers 12 are both outwardly opened towards the side away from the mounting base 6. Generally, the inclination angle of the outer layer of sound-absorbing louvers 11 is 70°-75° relative to the horizontal plane, and the inclination angle of the inner layer of sound-absorbing louvers 12 is 50°-55°. The angle difference between the outer layer of sound-absorbing louvers 11 and the inner layer of sound-absorbing louvers 12 can affect the flow velocity of the gas flowing through the louver surface, and thus by adjusting the angle difference, the sound absorption efficiency of the outer layer of sound-absorbing louvers 11 and the inner layer of sound-absorbing louvers 12 in the composite sound-absorbing assembly can be improved.

[0040] Embodiment 7 On the basis of Embodiment 6, a flow guide cover (only shown by a dashed line in the figure) is arranged at the outlet of the air inlet cavity 5, the flow guide cover is covered with a sound-absorbing cotton layer, and the flow guide surface of the flow guide cover is arranged at an angle to the inner layer of sound-absorbing louvers 12.

[0041] In the specific implementation process, in order to better increase the wind pressure and reduce the airflow loss, a flow guide cover is arranged, the outer diameter of the outer edge of the flow guide cover is equal to the outer diameter of the hub of the first-stage impeller 2, and the flow guide cover is fixedly connected with the hub of the first-stage impeller 2.

[0042] In this embodiment, a flow guide cover is used at the outlet of the air inlet cavity 5. Generally, the flow guide cover is also arranged in the structure of a micro-perforated plate, and the surface of the flow guide cover is filled with sound-absorbing cotton. By cooperating with the angle of the outlet of the inner layer of sound-absorbing louvers 12, the inlet flow state of the subsequent axial flow fan can be adjusted, the aerodynamic noise of the fan can be effectively reduced, and generally, the outlet surface of the inner layer of sound-absorbing louvers 12 is arranged at an angle of 50°-55°.

[0043] Embodiment 8 On the basis of Embodiment 6, a heat exchanger 13 is arranged between the outer layer of sound-absorbing louvers 11 and the inner layer of sound-absorbing louvers 12. The heat exchanger 13 includes a plurality of groups of cooling coils, a pair of water supply and return pipelines 14 is arranged in cooperation with any group of cooling coils, and an inclined water collecting tray is arranged below any group of cooling coils. Radiating fins are arranged outside the cooling coils. A metal mesh 15 is arranged in cooperation with the heat exchanger 13.

[0044] In this embodiment, the heat exchanger 13 uses finned tube type coil, arranged in counter flow, with a short drain pipe and a gas release nozzle; each group of cooling coil section is provided with a pair of water supply and return pipe 14, and a condensate collection tray and a drain interface are arranged below each group of cooling coil to collect the condensate of the coil, the collection tray is inclined to the drain interface, and a drain pipe is welded at the lowest part of the collection tray; the heat exchanger 13 is set as known in the art, and the heat exchanger 13 here can be purchased as an integrated product; through this setting, the high wind speed through the return air outlet can blow the condensate generated by the cooling coil of the heat exchanger 13 along the angle of the outer sound attenuation louver 11 to the upper surface of the heat exchanger 13, thereby effectively collecting the condensed water in the circulating air, preventing the water mist from being sucked into the fan and affecting the normal operation of the fan; Further, the heat exchanger 13 is arranged between the outer sound attenuation louver 11 and the inner sound attenuation louver 12, and the angles of the outer sound attenuation louver 11 and the inner sound attenuation louver 12 are different, which can more effectively collect the water mist that cannot be collected by the collection tray and further prevent the water mist from being brought into the fan. In the specific implementation process, the face wind speed of the heat exchanger 13 should not exceed 2.5 m / s and be perpendicular to the airflow direction.

[0045] In actual application, the metal mesh 14 (grating) arranged at the air inlet of the heat exchanger 13 can effectively prevent sundries and garbage from being sucked into the cooling coil during operation of the unit; here, the metal mesh 14 can be arranged on the windward side or the leeward side of the outer sound attenuation louver 11 according to the demand, and in this embodiment, the metal mesh 14 is arranged on the windward side of the outer sound attenuation louver 11. According to the properties of the garbage that may exist in the environment, the grid size of the metal mesh 14 is set to 25 mm x 25 mm, and the diameter of the metal wire is 3 mm; of course, it can also be replaced with a size that is more suitable for actual demand according to actual situation.

[0046] Embodiment 9 On the basis of embodiment 1, the composite sound attenuation assembly further comprises a rigid connecting rod (not shown in the figure) and a flexible spring vibration isolator 16 arranged at the air outlet end of the fan housing 1 and the air inlet cavity 5 respectively, and the rigid connecting rod is arranged at an angle to the horizontal plane.

[0047] Specifically, the fan shell 1 is installed at the air outlet end of the top of the air inlet cavity 5, the damping structure includes rigid connecting rods and flexible spring isolators 16, only the hinged ring 17 for installing the rigid connecting rod is shown in the figure, and the skilled in the art can selectively install the rigid connecting rod according to the needs; generally, the rigid connecting rod is 60° (or adjusted by the skilled in the art according to the actual situation) with the horizontal plane, and accurately, the air outlet end of the air inlet cavity 5 is generally also provided with a reinforced support frame 18, the rigid connecting rod is arranged between the fan shell 1 and the reinforced support frame 18, and the inclination swing of the axial flow fan that may be generated in the use process is effectively supported, and the flexible spring isolator 16 is also arranged between the fan shell 1 and the air inlet cavity 5 (or the reinforced support frame 18 outside the air inlet cavity 5) and is annularly arranged, the allowable load is twice the weight of the fan, and the transmission of high-frequency vibration of the fan is effectively isolated. The vibration of the fan set mainly includes high-frequency vibration generated by the fan impeller and low-frequency vibration generated by the fan silencer affected by airflow, and the vibration generated by the fan can be effectively absorbed through the soft and hard combined damping assembly, and through the two-stage damping structure, the vibration and noise performance of the entire fan set is effectively controlled.

[0048] Further, in the embodiment, the fan can also be filled with a sound-absorbing filler, including but not limited to sound-absorbing cotton, which acts on the noise transmission of the fan body and reduces the noise generated by the fan, and the skilled in the art can set it according to the needs.

[0049] The above only describes the preferred embodiments of the present application and is not used to limit the present application, although the present application is described in detail with reference to the foregoing embodiments, the skilled in the art can still modify the technical solutions recorded in the foregoing embodiments, or make equivalent replacement for part of the technical features. Any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the present application shall be included in the protection scope of the present application.

Claims

1. A compact, low-noise circulating cooling unit, characterized in that: The device includes a fan housing, with a first-stage impeller and a last-stage impeller respectively located at the inlet and outlet ends of the fan housing. The first-stage and last-stage impellers inside the fan housing are respectively fitted onto the front and rear output shafts of the motor. A rectifier assembly is located on the outside of the motor in conjunction with the fan housing. The first-stage impeller, last-stage impeller, motor, and rectifier assembly are coaxially arranged. A pre-silencing device is located at the inlet end of the fan housing, and the pre-silencing device includes an air inlet chamber, which includes a mounting base and an air inlet channel on the mounting base. A composite silencer assembly is located in conjunction with the air inlet channel.

2. The compact, low-noise circulating cooling unit according to claim 1, characterized in that: The rectifier assembly includes a rectifier cylinder coaxially disposed outside the motor. The outer ring of the rectifier cylinder is provided with a plurality of spatial guide vanes. The rectifier cylinder, the spatial guide vanes and the fan casing are fixedly connected. The number of blades of the first-stage impeller, the number of blades of the last-stage impeller and the number of spatial guide vanes are all pairwise prime numbers. The number of blades of the first-stage impeller is greater than the number of blades of the last-stage impeller.

3. A compact, low-noise circulating cooling unit according to claim 1 or 2, characterized in that: The first-stage impeller and the last-stage impeller each include a hub and blades. The hub is provided with several mounting grooves, and the blades are provided with mounting brackets that mate with the mounting grooves on the side facing the hub. Several mounting through holes are provided between the mounting grooves and the mounting brackets.

4. A compact, low-noise circulating cooling unit according to claim 2, characterized in that: The angle between the front and rear ends of the outer edge of the blades of the first-stage impeller and the central axis of the first-stage and last-stage impellers is α, and the angle between the front and rear ends of the outer edge of the blades of the last-stage impeller and the central axis of the first-stage and last-stage impellers is β, where α > β; the blades of the first-stage and last-stage impellers are of equal length along the fan axis from the front end to the rear end and are both arched towards the air inlet.

5. A compact, low-noise circulating cooling unit according to claim 2, characterized in that: The front and rear ends of the spatial guide vane are parallel to the central axis of the rectifier assembly. The middle part of the spatial guide vane is arched, and the arching direction of the spatial guide vane is opposite to the radial component of the arching direction of the blades of the first-stage impeller and the last-stage impeller.

6. A compact, low-noise circulating cooling unit according to claim 1, characterized in that: The composite noise reduction component includes an outer noise reduction louver and an inner noise reduction louver; the blades of the outer and inner noise reduction louvers are micro-perforated plates. The airflow frequency passing through the corresponding blades of the outer and inner noise reduction louvers is collected, and a relationship curve between thickness and opening ratio is established. The micro-perforated plates are configured based on the relationship curve.

7. A compact, low-noise circulating cooling unit according to claim 6, characterized in that: The outer and inner sound-absorbing louvers are inclined outward from the bottom to the top of the air inlet cavity, and the angle between the outer sound-absorbing louver and the central axis of the air inlet cavity is smaller than the angle between the inner sound-absorbing louver and the central axis of the air inlet cavity.

8. A compact, low-noise circulating cooling unit according to claim 6, characterized in that: A flow guide shroud is provided at the outlet of the air inlet cavity. The flow guide shroud is covered with a sound-absorbing cotton layer, and the flow guide surface of the flow guide shroud is set at an angle to the inner sound-absorbing louvers.

9. A compact, low-noise circulating cooling unit according to claim 6, characterized in that: A heat exchanger is provided between the outer and inner sound-absorbing louvers. The heat exchanger includes several sets of cooling coils. A pair of supply and return water pipes are provided with each set of cooling coils. An inclined water collection tray is provided below each set of cooling coils. Heat dissipation fins are distributed on the outside of the cooling coils. A metal wire mesh is provided with the heat exchanger.

10. A compact, low-noise circulating cooling unit according to claim 1, characterized in that: The composite noise reduction assembly also includes a rigid connecting rod and a flexible spring vibration isolator respectively configured to cooperate with the air outlet end of the fan housing and the air inlet cavity. The rigid connecting rod is set at an angle to the horizontal plane.

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