Premixed combustion fan for wall-hung boiler

Abstract

This utility model relates to the field of wall-hung boiler technology, and in particular to a premixed combustion fan for wall-hung boilers. A premixed combustion fan for wall-hung boilers includes a volute and a motor mounted on one side wall of the volute. An impeller is disposed inside the volute. The motor includes a mounting base and a motor body. The mounting base is connected to the side wall of the volute. The motor body includes a shaft, a rotor core, and a stator assembly. The rotor core is fixed to the shaft. The stator assembly includes a square stator core and a support frame for fixing the stator core. The support frame is connected to the mounting base. A cooling fan is mounted at one end of the shaft, and the impeller is press-fitted to the other end of the shaft. This utility model effectively solves problems related to vibration and noise, motor heat dissipation, impeller connection reliability, gas mixing efficiency, and ease of assembly.

Description

Technical Field

[0001] This utility model relates to the field of wall-hung boiler technology, and in particular to a premixed combustion fan for wall-hung boilers. Background Technology

[0002] As a highly efficient and convenient heating device, the performance of the premixed combustion fan, one of the core components of a wall-hung boiler, directly determines its combustion efficiency, noise level, and operational reliability. The premixed combustion fan is responsible for precisely mixing air and natural gas in a specific ratio and delivering it into the combustion chamber. Its mixing effect and delivery stability are crucial for achieving complete combustion and reducing nitrogen oxide emissions.

[0003] Currently, most wall-hung boiler combustion fans on the market adopt traditional structures, which have several shortcomings. First, their motors are usually directly fixed to the volute via rigid connectors. Vibrations from the motor during operation are directly transmitted to the volute, generating significant noise. Long-term operation can easily lead to loosening of the connectors, affecting reliability. Second, the motor's heat dissipation design is inadequate, especially for high-speed motors driving the fan. The stator windings generate a lot of heat, and heat accumulation can easily lead to overheating, demagnetization, or damage, shortening the motor's lifespan. Third, the impeller and motor shaft are often connected using keyways or screws, which have insufficient connection strength or low dynamic balance accuracy. Under high-speed conditions, they are prone to loosening or producing abnormal noise. Simultaneously, the impeller itself has a simple structure, poor gas guiding effect, large flow losses, and efficiency needs improvement.

[0004] Furthermore, the existing blower's gas path design is relatively simple, with air and natural gas mixing relying mainly on simple convergence within the pipes, resulting in insufficient mixing and low combustion efficiency. Some designs attempt to use Venturi tubes for gas injection, but their installation location and structure are not integrated with the blower body for optimized design, limiting the improvement in mixing effect and making it difficult to precisely control the air-fuel ratio. Regarding the motor's assembly structure, the connection methods between the stator assembly and the mounting base, as well as the fixing methods for the control PCB board, in existing technologies are cumbersome, lacking rapid positioning and error-proofing mechanisms. This not only hinders automated production but may also lead to misalignment during assembly, causing motor rubbing and other malfunctions.

[0005] Therefore, there is an urgent need for a premixed combustion fan for wall-hung boilers that is reasonably designed and has a compact structure, which can effectively solve a series of problems such as vibration and noise, motor heat dissipation, impeller connection reliability, gas mixing efficiency and assembly convenience. Utility Model Content

[0006] The technical problem to be solved by this utility model is: in order to solve the problems of high vibration and noise, insufficient motor heat dissipation, poor impeller connection reliability, gas mixing efficiency and assembly convenience in the prior art mentioned above, a premixed combustion fan for wall-hung boilers is provided.

[0007] The technical solution adopted by this utility model to solve its technical problem is: a premixed combustion fan for a wall-hung boiler, including a volute and a motor disposed on one side wall of the volute. An impeller is provided inside the volute. The motor includes a mounting base and a motor body. The mounting base is connected to the side wall of the volute. The motor body includes a rotating shaft, a rotor core, and a stator assembly. The rotor core is fixed on the rotating shaft. The stator assembly includes a square stator core and a support frame for fixing the stator core. The support frame is connected to the mounting base. A cooling fan is installed at one end of the rotating shaft, and the impeller is press-fitted onto the other end of the rotating shaft.

[0008] Compared to round stator cores, square stator cores are more advantageous for maximizing installation space and achieving motor miniaturization. The support frame not only secures the stator core but also serves as the structural skeleton of the entire motor body, providing precise positioning and support for the connection with the mounting base, supporting the PCB board, and accommodating the rotor, ensuring the motor's internal coaxiality and structural stability. The impeller, as the working end, generates airflow; the cooling fan, as the non-working end, constructs an independent internal cooling airflow channel. Airflow passes over the motor stator windings and PCB board, effectively removing the large amount of heat generated during operation, solving the common heat dissipation problem faced by high-speed motors, and significantly improving the motor's reliability and service life.

[0009] According to one embodiment of the present invention, the impeller includes a hub, blades, an annular base plate, and a guide ring. The hub has a conical structure, with the large-diameter edge of the bottom of the hub connected to the inner side of the blades. The outer side of the blades is connected to the annular base plate, and the upper part of the blades is connected to the guide ring. The top of the hub has a shaft hole for cooperating with a rotating shaft.

[0010] The conical hub reduces wind resistance and vortex generation during air inflow, allowing airflow to enter the blade's working area more smoothly and efficiently, reducing inlet impact losses and improving turbine efficiency. The annular base plate enhances the radial stiffness of the blades, preventing outward bending deformation during high-speed rotation; the guide ring enhances the axial stiffness of the blades and effectively constrains gas leakage at the blade tips, reducing secondary flow losses. The shaft hole serves as the interface between the impeller and the motor shaft, ensuring the precision of the power transmission path.

[0011] According to one embodiment of the present invention, the hub is provided with a plurality of heat dissipation holes, the number of blades is 15 to 20, and the installation angle of the blades is 15° to 35°.

[0012] The heat dissipation holes prevent heat from accumulating inside the sealed volute. The number of blades within this range provides enough working units to ensure sufficient airflow and pressure head, while avoiding excessively dense blades that could lead to channel blockage and increased friction loss. The installation angle range of 15° to 35° ensures that the blades have high working efficiency and good airflow guidance at high speeds.

[0013] According to one embodiment of the present invention, the ratio of the diameter to the height of the impeller is 2:1.

[0014] By limiting the ratio of the impeller's diameter to its height, the impeller can generate a higher outlet pressure, ensuring that a sufficient amount of mixed air is delivered into the combustion chamber at a sufficiently high pressure to achieve stable and efficient premixed combustion.

[0015] According to one embodiment of the present invention, the end of the rotating shaft used for pressing the impeller is provided with knurling.

[0016] During the press-fitting process, the raised knurling slightly cuts or squeezes the inner wall material of the impeller shaft hole, achieving a mechanical interlock based on the plastic deformation of the material. This prevents the impeller from sliding or loosening relative to the shaft during high-speed start-up or sudden load changes, ensuring the reliability of power transmission.

[0017] According to one embodiment of the present invention, the top of the support frame is connected to a PCB board, and the PCB board has a reserved hole in the middle for the airflow of the cooling fan to pass through.

[0018] The PCB board of the drive motor is directly fixed to the support frame of the motor body, which shortens the wiring distance between the motor wires and the PCB board, reducing interference and energy loss; the reserved holes provide a channel for the airflow of the cooling fan, ensuring that the cooling air can be blown directly to the power components and motor windings on the PCB board, achieving precise heat dissipation.

[0019] According to one embodiment of the present invention, the mounting base has a pair of upwardly protruding protrusions at diagonal positions, and a limiting baffle at another pair of diagonal positions; the outer wall of the support frame has a connecting post, the inner side of the connecting post has a notch for the limiting baffle to be inserted, and the PCB board has a mounting through hole adapted to the connecting post.

[0020] The protruding pillars are used for the initial positioning and support of the PCB board; the cooperation between the limiting plate and the notch improves assembly efficiency and consistency, and ensures the normal operation of the motor.

[0021] According to one embodiment of the present invention, the motor is covered with a housing, and the top surface of the housing has bolt holes corresponding to the mounting through holes.

[0022] The bolt holes and fasteners on the top surface of the casing allow for the clamping and securing of the PCB board, support frame, and mounting base. The casing serves to protect internal electrical components, prevent foreign object intrusion, and guide cooling airflow.

[0023] According to one embodiment of the present invention, the outer wall of the mounting base is provided with a plurality of retaining rings, an elastic guide sleeve is fitted inside the retaining rings, and a screw connected to the side plate of the volute is provided inside the elastic guide sleeve.

[0024] The elastic guide sleeve forms a highly damped, flexible vibration isolation layer between the motor and the volute, effectively absorbing high-frequency vibrations generated during motor operation and preventing them from being transmitted to the volute and amplified into noise. Meanwhile, the snap ring connection method avoids direct tapping on the mounting base, improving structural strength and assembly convenience.

[0025] According to one embodiment of the present invention, an air inlet section is formed by radially protruding outward from the center of the side wall away from the motor of the volute. A venturi tube is provided in the air inlet section. A natural gas inlet pipe is connected to the lower part of the air inlet section near the volute and is arranged perpendicularly thereto. The natural gas inlet pipe is connected to the air inlet section. A mixed gas outlet is also provided on the volute. A diffusion extension section with a progressively increasing pipe diameter is provided on the mixed gas outlet.

[0026] The Venturi tube utilizes the Venturi effect to generate negative pressure at the throat, automatically injecting the gas from the natural gas inlet pipe in a precise ratio. The extension section converts the kinetic energy of the high-speed, high-pressure gas flow from the impeller into static pressure energy, further increasing the pressure of the outlet gas to overcome downstream resistance. At the same time, the gradually expanding structure also facilitates the final uniform mixing of the gas, ensuring that a homogeneous and stable mixture enters the combustion chamber.

[0027] The beneficial effects of this utility model are: (1) The use of a conical hub reduces intake resistance; a specific number of blades with a specific installation angle ensures efficient and sufficient energy exchange of the gas; the ratio of diameter to height enables the impeller to generate sufficient pressure to overcome subsequent resistance. The built-in venturi tube automatically injects and premixes natural gas while delivering air, realizing active and preliminary homogeneous mixing of the airflow, which provides a basis for complete combustion in the subsequent combustion chamber, significantly improving combustion efficiency and thermal efficiency, and helping to reduce harmful emissions such as nitrogen oxides; (2) The cooling fan driven by the rotating shaft forms an independent air duct, and the airflow directly cools the heat-generating components such as the motor stator and PCB board, effectively controlling the motor temperature rise and avoiding problems such as magnet demagnetization, aging or failure of electronic components caused by overheating, thus extending the service life and operational reliability of the motor and the whole machine. (3) The impeller and the shaft are press-fitted and knurled at the shaft end. The mechanical interlocking of the materials forms a connection with strong anti-torsion ability, which prevents the impeller from loosening or slipping under high-speed start-stop and load changes, and ensures the absolute reliability of power transmission. (4) The elastic guide sleeve and the retaining ring form a vibration damping installation structure, forming a flexible vibration isolation layer between the motor and the volute, effectively blocking the transmission path of high-frequency vibration of the motor to the volute and the whole machine, reducing the air-borne noise and structural noise during the operation of the fan, and improving the overall durability of the equipment. Attached Figure Description

[0028] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0029] Figure 1 This is a schematic diagram of the structure of this utility model.

[0030] Figure 2 yes Figure 1 A schematic diagram of the structure from another direction.

[0031] Figure 3 This is a schematic diagram of the structure of the motor in this utility model.

[0032] Figure 4 This is a schematic diagram of the installation of the impeller of this utility model.

[0033] Figure 5 This is a schematic diagram of the impeller structure in this utility model.

[0034] In the diagram: 1. Volute; 11. Air inlet section; 12. Natural gas inlet pipe; 13. Mixed gas outlet; 14. Diffusion extension section; 2. Motor; 21. Mounting base; 211. Protruding column; 212. Baffle plate; 213. Snap ring; 22. Motor body; 221. Shaft; 222. Rotor core; 223. Stator assembly; 2231. Stator core; 2232. Support frame; 22321. Connecting column; 223211. Notch; 224. PCB board; 2241. Reserved hole; 2242. Mounting through hole; 225. Cooling fan; 24. Elastic guide sleeve; 4. Cover; 41. Bolt hole; 5. Impeller; 51. Hub; 511. Shaft hole; 512. Heat dissipation hole; 52. Blade; 53. Annular base plate; 54. Guide ring. Detailed Implementation

[0035] The present invention will now be described in further detail with reference to the accompanying drawings. These drawings are simplified schematic diagrams, illustrating only the basic structure of the present invention, and therefore only show the components relevant to the present invention.

[0036] like Figure 1 and Figure 2As shown, a premixed combustion fan for a wall-mounted boiler includes a volute 1 and a motor 2 mounted on one side wall of the volute 1. An air inlet section 11 is formed by radially protruding outward from the center of the side wall away from the motor 2. A venturi tube is provided inside the air inlet section 11. A natural gas inlet pipe 12 is connected to the lower part of the air inlet section 11 near the volute 1 and is perpendicular to it. The natural gas inlet pipe 12 is connected to the air inlet section 11. A mixed gas outlet 13 is also provided on the volute 1, and a diffusion extension section 14 with a progressively increasing diameter is provided on the mixed gas outlet 13.

[0037] The air inlet section 11 is equipped with a Venturi tube. Utilizing the Venturi effect, a negative pressure is automatically generated at the throat when the air flows. This negative pressure can automatically inject the gas from the natural gas inlet pipe 12 according to the hydrodynamic ratio without additional power. The mixed gas outlet 13 is equipped with a diffusion extension section 14, which can efficiently convert the kinetic energy of the high-speed airflow accelerated by the impeller 5 into static pressure, ensuring that the mixed gas can be stably and sufficiently delivered into the combustion chamber, preventing backfire or unstable combustion, and also facilitating the final homogenization of the gas.

[0038] like Figure 3 As shown, the motor 2 includes a mounting base 21 and a motor body 22. The mounting base 21 is connected to the side wall of the volute 1. The motor body 22 includes a rotating shaft 221, a rotor core 222, and a stator assembly 223. The rotor core 222 is fixed on the rotating shaft 221. The stator assembly 223 includes a square stator core 2231 and a support frame 2232 for fixing the stator core 2231. The support frame 2232 is connected to the mounting base 21. A cooling fan 225 is installed at one end of the rotating shaft 221.

[0039] The motor body 22 is separate from the mounting base 21, facilitating production and maintenance while providing a structural basis for vibration isolation. The square stator core 2231 helps to fully utilize space, enabling the miniaturization of the motor 2. The support frame 2232 serves as a fixing element, forming the structural skeleton of the entire motor body 22 and ensuring coaxiality and overall rigidity during assembly. The cooling fan 225 rotates with the shaft 221, generating reliable airflow to ensure good heat dissipation for the motor 2 in a closed environment, thereby improving the power density and long-term operational reliability of the motor 2.

[0040] Specifically, the top of the support frame 2232 is connected to the PCB board 224, and the PCB board 224 has a reserved hole 2241 in the middle for the airflow of the cooling fan 225. The mounting base 21 has a pair of upwardly protruding protrusions 211 at opposite diagonal positions, and a limiting baffle 212 at another pair of opposite diagonal positions. The outer wall of the support frame 2232 has a connecting post 22321, the inner side of which has a notch 223211 for the limiting baffle 212 to be inserted. The PCB board 224 has mounting through holes 2242 that fit the connecting post 22321. The outer wall of the mounting base 21 has several retaining rings 213, each retaining ring 213 holding an elastic guide sleeve 24. The elastic guide sleeve 24 contains screws for connection to the side plate of the volute 1. Figure 1 The motor 2 is covered with a cover 4, and the top surface of the cover 4 has bolt holes 41 corresponding to the mounting through holes 2242.

[0041] By directly fixing the PCB board 224 to the motor 2, the power wiring harness is shortened, electromagnetic interference and energy loss are reduced, and the control response speed is improved. The reserved hole 2241 ensures that the cooling airflow can accurately penetrate the PCB board 224 and directly cool the power components on it, resulting in high heat dissipation efficiency.

[0042] like Figure 4 As shown, the volute 2 contains an impeller 5, such as Figure 5 As shown, the impeller 5 includes a hub 51, blades 52, an annular base plate 53, and a guide ring 54. The hub 51 has a conical structure. The large-diameter edge of the bottom of the conical hub 51 is connected to the inner side of the blades 52, and the outer side of the blades 52 is connected to the annular base plate 53. The upper part of the blades 52 is connected to the guide ring 54. The top of the hub 51 has a shaft hole 511 for mating with the rotating shaft 221. The impeller 5 is press-fitted onto the end of the rotating shaft 221 away from the cooling fan 225, and the end of the rotating shaft 221 used for press-fitting the impeller 5 is knurled.

[0043] The conical hub 51 reduces intake resistance and turbulence, allowing airflow to enter the impeller 5 flow channel smoothly and evenly, reducing inlet impact losses and improving fan efficiency. The annular base plate 53 enhances the radial stiffness of the blades 52, preventing them from expanding outwards during high-speed rotation; the guide ring 54 enhances axial stiffness and effectively seals the gap between the blade 52 tip and the volute 1, reducing leakage of high-pressure gas into the low-pressure area, improving strength, and directly translating into higher aerodynamic efficiency and pressure output. The knurled raised texture embeds into the shaft hole 511 material, generating a strong mechanical interlocking force and extremely high torsional resistance, ensuring that the impeller 5 is absolutely free from slippage and loosening under high-speed, variable-load conditions, guaranteeing the reliability of power transmission and dynamic balance accuracy.

[0044] Specifically, the hub 51 has several heat dissipation holes 512, and the number of blades 52 is 15 to 20, with an installation angle of 15° to 35°. Preferably, the ratio of the diameter to the height of the impeller 5 is 2:1.

[0045] The heat dissipation holes 512 eliminate heat dissipation dead zones, further improving heat dissipation reliability. The 15-20 blades 52 provide sufficient working units to ensure air pressure and airflow while avoiding excessive density that could lead to flow channel blockage and frictional losses. The 15°-35° installation angle ensures efficient energy exchange between the blades 52 and the gas. The ratio of impeller diameter to height 5 overcomes the resistance from the venturi tube and combustion system, stably outputting the high-pressure gas required for premixed combustion, ensuring stable operation of the entire system.

[0046] Specific working principle: When the wall-hung boiler control system issues a start command, the power is transmitted to the PCB board 224 integrated on the motor body 22. The drive circuit on the PCB board 224 converts the mains power into precisely controlled three-phase AC power and supplies it to the stator winding. The energized stator winding generates a rotating magnetic field, which drives the rotor core 222 to rotate, thereby driving the rotating shaft 221 to rotate at high speed. The rotating shaft 221 drives the impeller 5 to rotate. The high-speed rotating impeller 5 generates a strong suction force within the volute 1, drawing air in from the air inlet section 11. Before entering the impeller 5, the air flows through the venturi tube. According to the Venturi effect, the air velocity increases sharply as it flows through the throat, causing a sudden drop in static pressure and creating a localized, strong vacuum negative pressure zone. The negative pressure signal is transmitted to the diaphragm chamber of the gas valve or a pressure sensor via a negative pressure sampling tube. The force generated by the negative pressure acting on the diaphragm directly overcomes the spring resistance, driving the valve stem displacement, or the sensor feeds back the pressure signal to the main controller, which then outputs a command to drive the electric valve. Therefore, this negative pressure automatically and intelligently controls the opening of the gas valve on the natural gas inlet pipe 12, injecting natural gas at a precise volume ratio matched to the air flow. The two gases undergo preliminary, vigorous, and constant-ratio mixing in the throat of the venturi tube and the subsequent diffuser section, ensuring the optimal air-fuel ratio. The premixed gas is drawn into the impeller 5 flow channel. The rotation of the impeller 5 does work on it, giving it higher kinetic energy and pressure. After the work is done, the gas is thrown into the vortex chamber of the volute 1. After collection and guidance, it is discharged from the mixed gas outlet 13. The diffusion extension section 14 at the outlet, with its diameter increasing sequentially, acts as a diffuser, further converting the high-speed kinetic energy of the gas into static pressure energy, outputting a well-pressurized, uniformly mixed, and precisely proportioned mixed gas.

[0047] In addition, the PCB board 224 integrated on top of the support frame 2232 not only provides the driving function, but its onboard circuitry also typically integrates components such as Hall sensors to monitor parameters such as the speed and current of the motor 2 in real time. This data is then fed back to the main control board of the wall-hung boiler. The main control board compares this data with the combustion requirements and can perform precise closed-loop adjustment of the motor 2's speed. By controlling the speed, the main control board indirectly but precisely controls the intake negative pressure intensity generated by the impeller 5, thereby achieving precise control of the gas intake volume and ensuring that the air-fuel ratio is always maintained within the optimal range.

[0048] Based on the above-described preferred embodiments of this utility model, and through the foregoing description, those skilled in the art can make various changes and modifications without departing from the technical concept of this utility model. The technical scope of this utility model is not limited to the contents of the specification, but must be determined according to the scope of the claims.

Claims

1. A wall-hanging stove premixed combustion blower, comprising a volute (1) and a motor (2) arranged on one side wall of the volute (1), wherein an impeller (5) is arranged in the volute (1), characterized in that: The motor (2) includes a mounting base (21) and a motor body (22). The mounting base (21) is connected to the side wall of the volute (1). The motor body (22) includes a rotating shaft (221), a rotor core (222), and a stator assembly (223). The rotor core (222) is fixed on the rotating shaft (221). The stator assembly (223) includes a square stator core (2231) and a support frame (2232) for fixing the stator core (2231). The support frame (2232) is connected to the mounting base (21). A cooling fan (225) is installed at one end of the rotating shaft (221), and the impeller (5) is press-fitted onto the other end of the rotating shaft (221).

2. The hydronic heater premix combustion blower of claim 1, wherein: The impeller (5) includes a hub (51), blades (52), an annular base plate (53), and a guide ring (54). The hub (51) has a conical structure. The bottom edge of the hub (51) with a large diameter is connected to the inner side of the blade (52). The outer side of the blade (52) is connected to the annular base plate (53). The upper part of the blade (52) is connected to the guide ring (54). The top of the hub (51) is provided with a shaft hole (511) for cooperating with the rotating shaft (221).

3. The hydronic heater premix combustion blower of claim 2, wherein: The hub (51) has several heat dissipation holes (512), and the number of blades (52) is 15 to 20, with the blade (52) having an installation angle of 15° to 35°.

4. The hydronic heater premix combustion blower of claim 2, wherein: The ratio of the diameter to the height of the impeller (5) is 2:

1.

5. The hydronic heater premix combustion blower of claim 2 or 3, wherein: The shaft (221) is knurled at one end used for pressing the impeller (5).

6. The hydronic heater premix combustion blower of claim 1, wherein: The top of the support frame (2232) is connected to the PCB board (224), and the PCB board (224) has a reserved hole (2241) in the middle for the airflow of the cooling fan (225).

7. The hydronic heater premix combustion blower of claim 6, wherein: The mounting base (21) has a pair of diagonally opposite protruding posts (211) and a pair of diagonally opposite limiting plates (212); the outer wall of the support frame (2232) has a connecting post (22321), the inner side of the connecting post (22321) has a notch (223211) for the limiting plate (212) to be inserted, and the PCB board (224) has a mounting through hole (2242) adapted to the connecting post (22321).

8. The hydronic heater premix combustion blower of claim 7, wherein: The motor (2) is covered with a cover (4), and the top surface of the cover (4) is provided with bolt holes (41) corresponding to the mounting through holes (2242).

9. The hydronic heater premix combustion blower of claim 1, wherein: The mounting base (21) has several retaining rings (213) on its outer side wall. An elastic guide sleeve (24) is fitted inside the retaining ring (213). A screw connected to the side plate of the volute (1) is provided inside the elastic guide sleeve (24).

10. The hydronic heater premix combustion blower of claim 1, wherein: The volute (1) has an air inlet section (11) that protrudes radially outward from the center of the side wall away from the motor (2). The air inlet section (11) is provided with a Venturi tube. The lower part of the air inlet section (11) is connected to a natural gas inlet pipe (12) that is perpendicular to it. The natural gas inlet pipe (12) is connected to the air inlet section (11). The volute (1) is also provided with a mixed gas outlet (13). The mixed gas outlet (13) is provided with a diffusion extension section (14) with a gradually increasing pipe diameter.

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