Air induction fan and gas stove using the same

Abstract

The utility model discloses a kind of air guide fans, including motor, support, volute, wind wheel and heat dissipation fan blade, bearing is respectively installed on the front end cover and rear end cover of motor, rotating shaft support is installed on bearing;The front end cover of motor is installed on volute by support, heat dissipation fan blade is installed between motor and volute, motor rotating shaft, air inlet hole and air outlet hole are set on motor shell, annular side wall is formed on the support, second cavity is formed in annular side wall, annular side wall is provided with exhaust hole, exhaust hole is communicated with second cavity, the heat dissipation fan blade is placed in second cavity, air outlet hole is communicated with second cavity;Blind hole is opened in the rear end surface of rotating shaft, blind hole extends to second cavity, a plurality of through holes are dug out on rotating shaft in the position of second cavity, through hole is communicated with blind hole;It can effectively reduce the working temperature of bearing, prolong the service life of bearing and motor.

Description

Technical Field

[0001] This utility model relates to an induced draft fan and a gas furnace using the same. Background Technology

[0002] In gas furnace systems, the induced draft fan is typically installed at the flue gas outlet. The negative pressure generated at the fan inlet draws air from the outlet, ensuring sufficient air for complete combustion. The flue gas temperature reaches between 60-180℃, and this excessive temperature can easily cause the induced draft fan to fail. The fan bearings are particularly vulnerable to high temperatures, having the shortest lifespan of the entire fan system. While more expensive, high-temperature resistant bearings are required, lifespan remains a significant weakness of the product.

[0003] Existing bearing cooling solutions, such as patent CN200920295851 (named "Utility Model Patent for a Blower Structure"), primarily address heat dissipation for the stator and rotor of the entire motor by adding centrifugal fan blades between the impeller and volute and the motor body. However, no specific heat dissipation design is implemented for the bearings. Research indicates two main reasons for the short bearing lifespan: First, since the shaft is the component directly in contact with high-temperature flue gas within the motor body, the heat transferred first reaches the front bearing, which bears a significant thermal load, accelerating its lifespan. Second, according to the formula Q = -kA·dT / dx—where Q is the heat flow rate (unit: W); k is the thermal conductivity of the material (unit: W / (m·K); and A is the heat transfer area (unit: m²)—... 2 ); dT / dx / / is the temperature gradient (unit: K / m). From the above formula, we can know that the shaft is made of solid metal. Referring to the heat flow rate calculation formula, the heat conduction area is large, which causes more heat to be transferred from the inside of the volute to the motor body, resulting in poor heat dissipation of the bearing.

[0004] In the existing design, the airflow generated by the rotation of the centrifugal fan blades has a poor heat dissipation effect on the bearings, especially the front bearing. The generated low-temperature airflow first carries away the heat from the stator and rotor components, and the actual air temperature has already risen. Then a small amount passes through the front cover of the fixed bearing and the outside of the bearing chamber. Summary of the Invention

[0005] The purpose of this utility model is to provide an induced draft fan and a gas furnace using it, which solves the technical problem that the induced draft fan in the prior art does not have a special heat dissipation design for the bearing, resulting in the front bearing bearing a large heat load, which accelerates the end of the bearing life and affects the life of the motor.

[0006] The technical solution of this utility model is implemented as follows:

[0007] An induced draft fan includes a motor, a bracket, a volute, a fan impeller, and cooling fan blades, wherein:

[0008] The motor includes a rotating shaft, a stator assembly, a rotor assembly, a motor housing, and bearings. The motor housing includes a front cover and a rear cover. The stator assembly is installed inside the motor housing, and the rotor assembly is installed on the rotating shaft. The rotor assembly is fitted inside the stator assembly. The front shaft extension of the rotating shaft extends out of the front cover and enters the first cavity inside the volute and connects to the impeller. The volute is provided with an air inlet and an air outlet. Bearings are installed on the front cover and the rear cover, respectively, and the rotating shaft is supported and installed on the bearings.

[0009] The front end cover of the motor is mounted on the volute via a bracket. Cooling fan blades are installed between the motor and the volute and on the motor shaft. An air inlet and an air outlet are provided on the motor housing. An annular sidewall is formed on the bracket, and a second cavity is formed inside the annular sidewall. An exhaust hole is provided on the annular sidewall, and the exhaust hole communicates with the second cavity. The cooling fan blades are placed inside the second cavity, and the exhaust hole communicates with the second cavity.

[0010] The feature is that a blind hole is opened on the rear end face of the rotating shaft, the blind hole extends into the second cavity, and several through holes are dug on the rotating shaft at the position of the second cavity, the through holes communicating with the blind hole;

[0011] When the induced draft fan is working, the cooling fan blades rotate inside the second cavity. Some of the cold air enters through the blind holes and is discharged into the second cavity through several through holes. The heat inside the bearing and the heat of the rotor assembly are transferred to the rotating shaft and carried away after heat exchange with the cold air flowing through the blind holes.

[0012] Preferably, a plurality of through holes are spaced apart circumferentially along the shaft, and the plurality of through holes are located between the heat dissipation fan blades and the bearing mounted on the front end cover.

[0013] Preferably, there are four through holes, which are evenly distributed along the circumference of the axis of rotation.

[0014] Preferably, a heat dissipation enhancement column is provided inside the blind hole at a position corresponding to the bearing.

[0015] Preferably, the heat dissipation enhancement column includes an outer ring, an inner ring, and a number of heat dissipation ribs connecting the outer ring and the inner ring. Two adjacent heat dissipation ribs form an air duct, and the outer ring is in close contact with the inner wall of the blind hole.

[0016] Preferably, the bearing is a ball bearing, which includes an inner ring, an outer ring, and several balls. The inner ring is mounted on the shaft. When the fan is working, the cooling fan blades rotate inside the second cavity, and another part of the cold air enters the motor from the air inlet provided on the motor housing, carrying away part of the heat from the stator assembly, rotor assembly, and bearing. Then, it enters the second cavity from the air outlet and is finally discharged from the exhaust port.

[0017] Preferably, both the blind hole and the through hole have circular cross-sectional shapes, and the cross-sectional area of ​​the blind hole is larger than that of the through hole.

[0018] A gas-fired furnace includes an induced draft fan, characterized in that: the induced draft fan is the induced draft fan described above.

[0019] Compared with the prior art, this utility model has the following advantages:

[0020] Effect 1: This utility model designs a motor shaft structure by machining a blind hole at the tail end of the shaft, extending to the second cavity near the bottom of the volute. Several through holes are added circumferentially to the shaft between the bearing and the cooling fan on the front cover, reducing the cross-sectional area of ​​the shaft and decreasing the amount of heat transferred from inside the volute through the shaft. The blind hole and through holes on the shaft form an air circuit. When the motor is operating, the rotating cooling fan creates a negative pressure near the through holes, causing the low-temperature air entering from the blind hole at the tail end of the shaft to flow through the blind hole and out through the through holes. This low-temperature air carries away heat from the shaft, bearing, and rotor assembly, effectively extending the service life of the bearing and the motor.

[0021] Effect 2: The through hole reduces the cross-sectional area of ​​the shaft, reducing the amount of heat transferred from inside the volute through the shaft, effectively reducing the thermal load on the bearing and extending its service life.

[0022] Effect 3: A heat dissipation enhancement column is pressed into the blind hole corresponding to the bearing position on the rotating shaft, increasing the heat exchange area between the low-temperature air and this area, thereby enhancing heat dissipation for the bearing. Through the use of through holes to reduce the thermal conductivity area, low-temperature air flowing through the blind holes and through holes for cooling, and heat dissipation enhancement columns to enhance heat exchange, the bearing's heat dissipation problem is solved.

[0023] Other advantages of this invention are described in detail in the embodiments section of the specification. Attached Figure Description

[0024] Figure 1 A perspective view provided for this utility model;

[0025] Figure 2 An exploded view provided for this utility model;

[0026] Figure 3 Another exploded view provided for this utility model;

[0027] Figure 4 This is a partial perspective view of the assembled motor and bracket of this utility model;

[0028] Figure 5 This is the front view of this utility model;

[0029] Figure 6 yes Figure 5 AA section view;

[0030] Figure 7 This is a cross-sectional view of the rotating shaft of this utility model;

[0031] Figure 8 yes Figure 7 BB cross-sectional view;

[0032] Figure 9 This is a diagram of the heat dissipation airflow path of this utility model. Detailed Implementation

[0033] To make the objectives, technical solutions, and advantages of the embodiments of this utility model clearer, the technical solutions of the embodiments of this utility model 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 utility model. All other embodiments obtained by those skilled in the art based on the embodiments of this utility model without creative effort are within the scope of protection of this utility model. Embodiment 1:

[0034] like Figures 1 to 9 As shown, this embodiment provides an induced draft fan, including a motor 1, a bracket 2, a volute 3, a fan wheel 4, and a cooling fan blade 5, wherein:

[0035] The motor 1 includes a rotating shaft 11, a stator assembly 12, a rotor assembly 13, a motor housing, and bearings 16. The motor housing includes a front cover 14 and a rear cover 15. The stator assembly 12 is installed inside the motor housing. The rotor assembly 13 is installed on the rotating shaft 11 and is fitted inside the stator assembly 12. The front shaft extension 112 of the rotating shaft 11 extends out of the front cover 14 and enters the first cavity 30 inside the volute 3 to connect with the impeller 4. The volute 3 is provided with an air inlet 31 and an air outlet 32. Bearings 16 are respectively installed on the front cover 14 and the rear cover 15. The rotating shaft 11 is supported and installed on the bearings 16.

[0036] The front end cover 14 of the motor 1 is mounted on the volute 3 by the bracket 2. A cooling fan 5 is installed between the motor 1 and the volute 3 and on the motor shaft 7. An air inlet 17 and an air outlet 18 are provided on the motor housing. An annular sidewall 21 is formed on the bracket 2. A second cavity 20 is formed inside the annular sidewall 21. An exhaust hole 22 is provided on the annular sidewall 21. The exhaust hole 22 is connected to the second cavity 20. The cooling fan 5 is placed inside the second cavity 20. The air outlet 18 is connected to the second cavity 20.

[0037] The feature is that a blind hole 110 is opened on the rear end face of the rotating shaft 11, the blind hole 110 extends to the second cavity 20, and a plurality of through holes 111 are dug on the rotating shaft 11 at the position of the second cavity 20, the through holes 111 are connected to the blind hole 110.

[0038] When the induced draft fan is working, the cooling fan blades 5 rotate inside the second cavity 20. A portion of the cold air enters through the blind hole 110 and is discharged into the second cavity 20 through several through holes 111. The heat inside the bearing 16 and the heat of the rotor assembly 13 are transferred to the rotating shaft 11 and carried away after heat exchange with the cold air flowing through the blind hole 110.

[0039] Preferably, a plurality of through holes 111 are arranged at intervals along the circumference of the rotating shaft 11. The plurality of through holes 111 are located between the heat dissipation fan blade 5 and the bearing 16 mounted on the front end cover 14. The structure is simple, the layout is reasonable, and it is more conducive to the flow of air.

[0040] Preferably, there are four through holes 111, which are evenly distributed along the circumference of the rotating shaft 11, resulting in a simple structure and easy processing.

[0041] Preferably, a heat dissipation enhancement column 6 is provided in the blind hole 110 at a position corresponding to the bearing 6 to increase the heat dissipation area and facilitate faster heat dissipation of the bearing 6.

[0042] Preferably, the heat dissipation enhancement column 6 includes an outer ring 61, an inner ring 62, and a plurality of heat dissipation ribs 63 connecting the outer ring 61 and the inner ring 62. Two adjacent heat dissipation ribs 63 form an air duct 64. The outer ring 61 is close to the inner wall of the blind hole 110. The structure is simple and easy to process, and the heat dissipation area can be increased to the maximum extent. Cold air passes through the air duct 64 and exchanges heat.

[0043] Preferably, the bearing 16 is a ball bearing, which includes an inner ring, an outer ring, and several balls. The inner ring is mounted on the shaft 11. When the fan is working, the cooling fan blades 5 rotate inside the second cavity 20. Another part of the cold air enters the motor from the air inlet 17 provided on the motor housing and carries away part of the heat from the stator assembly 12, the rotor assembly 13, and the bearing 16. Then it enters the second cavity 20 from the air outlet 18 and is finally discharged from the exhaust port 22.

[0044] Preferably, both the blind hole 110 and the through hole 111 have circular cross-sectional shapes, and the cross-sectional area of ​​the blind hole 110 is larger than that of the through hole 111, which is more conducive to airflow.

[0045] This invention designs a motor shaft structure by machining a blind hole 110 at the tail of the shaft 11, extending to the second cavity 20. Several through holes 111 are added circumferentially between the bearing 16 and the cooling fan 5 on the front cover 14, reducing the cross-sectional area of ​​the shaft 11 and decreasing the heat transferred from the volute 3 through the shaft 11. The blind hole 110 and the through holes 111 form an air circuit. When the motor is working, the rotating cooling fan 5 creates a negative pressure near the through holes 111, causing the low-temperature air entering through the blind hole 110 at the tail of the shaft 11 to flow through the blind hole 110 and out through the through holes 111. This low-temperature air carries away heat from the shaft 11, bearing 16, and rotor assembly 13, effectively extending the service life of the bearing and the motor. The through-hole 111 reduces the cross-sectional area of ​​the shaft 11, decreasing the amount of heat transferred from the inside of the volute 3 through the shaft 11, effectively reducing the thermal load on the bearing 16 and extending its service life. A heat dissipation enhancement column 6 is pressed into the blind hole 110 on the shaft 11 corresponding to the bearing 16 position, increasing the heat exchange area between the low-temperature air and this area, thus enhancing heat dissipation for the bearing 16. Through the thermal barrier of the through-hole 111 reducing the thermal conductivity area, the cooling of the low-temperature air flowing through the blind hole 110 and through-hole 111, and the enhanced heat exchange via the heat dissipation enhancement column 6, the heat dissipation problem of the bearing is solved.

[0046] Example 2:

[0047] A gas-fired boiler includes an induced draft fan, characterized in that: the induced draft fan is the type described in Embodiment 1. It has good bearing heat dissipation and a long motor life.

[0048] The above embodiments are preferred embodiments of the present utility model, but the embodiments of the present utility model are not limited thereto. Any changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and principle of the present utility model are equivalent substitutions and are included within the protection scope of the present utility model.

Claims

1. An induced draft fan, comprising a motor (1), a bracket (2), a volute (3), a fan wheel (4), and cooling fan blades (5), wherein: The motor (1) includes a rotating shaft (11), a stator assembly (12), a rotor assembly (13), a motor housing, and a bearing (16). The motor housing includes a front cover (14) and a rear cover (15). The stator assembly (12) is installed inside the motor housing. The rotor assembly (13) is installed on the rotating shaft (11). The rotor assembly (13) is fitted inside the stator assembly (12). The front shaft extension end (112) of the rotating shaft (11) extends out of the front cover (14) and enters the first cavity (30) inside the volute (3) to connect with the impeller (4). The volute (3) is provided with an air inlet (31) and an air outlet (32). The front cover (14) and the rear cover (15) are respectively equipped with bearings (16). The rotating shaft (11) is supported and installed on the bearings (16). The front end cover (14) of the motor (1) is mounted on the volute (3) by the bracket (2). A cooling fan (5) is installed between the motor (1) and the volute (3) and on the motor shaft (7). An air inlet (17) and an air outlet (18) are provided on the motor housing. An annular sidewall (21) is formed on the bracket (2). A second cavity (20) is formed inside the annular sidewall (21). An exhaust hole (22) is provided on the annular sidewall (21). The exhaust hole (22) is connected to the second cavity (20). The cooling fan (5) is placed inside the second cavity (20). The air outlet (18) is connected to the second cavity (20). The feature is that a blind hole (110) is opened on the rear end face of the rotating shaft (11), the blind hole (110) extends to the second cavity (20), and several through holes (111) are dug on the rotating shaft (11) at the position of the second cavity (20), and the through holes (111) are connected to the blind hole (110). When the induced draft fan is working, the cooling fan blades (5) rotate inside the second cavity (20). A portion of the cold air enters through the blind hole (110) and is discharged into the second cavity (20) through several through holes (111). The heat inside the bearing (16) and the heat of the rotor assembly (13) are transferred to the rotating shaft (11) and carried away after heat exchange with the cold air flowing through the blind hole (110).

2. The induced draft fan according to claim 1, characterized in that: A number of through holes (111) are arranged at intervals along the circumference of the rotating shaft (11), and the number of through holes (111) are located between the heat dissipation fan (5) and the bearing (16) mounted on the front end cover (14).

3. The induced draft fan according to claim 2, characterized in that: There are four through holes (111), which are evenly distributed along the circumference of the axis of rotation (11).

4. An induced draft fan according to claim 1, 2, or 3, characterized in that: A heat dissipation enhancement column (6) is provided in the blind hole (110) at a position corresponding to the bearing (16).

5. The induced draft fan according to claim 4, characterized in that: The heat dissipation enhancement column (6) includes an outer ring (61), an inner ring (62), and several heat dissipation ribs (63) connecting the outer ring (61) and the inner ring (62). Two adjacent heat dissipation ribs (63) form an air duct (64), and the outer ring (61) is in close contact with the inner wall of the blind hole (110).

6. The induced draft fan according to claim 4, characterized in that: The bearing (16) is a ball bearing, which includes an inner ring, an outer ring and several balls. The inner ring is mounted on the shaft (11). When the fan is working, the cooling fan blades (5) rotate inside the second cavity (20). Another part of the cold air enters the motor from the air inlet (17) provided on the motor housing and carries away part of the heat from the stator assembly (12), rotor assembly (13) and bearing (16). Then it enters the second cavity (20) from the air outlet (18) and is finally discharged from the exhaust port (22).

7. An induced draft fan according to claim 1, 2, or 3, characterized in that: Both the blind hole (110) and the through hole (111) have circular cross-sectional shapes, and the cross-sectional area of ​​the blind hole (110) is larger than that of the through hole (111).

8. A gas-fired furnace, comprising an induced draft fan, characterized in that: The induced draft fan is the induced draft fan according to any one of claims 1 to 7.

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