Current collector and centrifugal fan and gas water heater comprising same

Abstract

The utility model provides a current collector and a centrifugal fan and a gas water heater comprising the same, an air inlet ring of the current collector comprises a plurality of arc sections which are sequentially and smoothly connected in the circumferential direction, and the ratio of the diameter of at least one arc section to the diameter of an impeller is larger than a first ratio. The ratio of the diameter of at least one arc section to the diameter of the impeller is smaller than a first ratio; the first ratio is the ratio of the diameter of the current collector to the diameter of the impeller when the fan works under the small-flow working condition and the air inlet ring of the current collector is a regular round hole. According to the current collector, the centrifugal fan comprising the current collector and the gas water heater comprising the current collector, the working requirements of the fan under different air inlet flow working conditions can be met through the special-shaped structure, the noise of the fan is prevented from being increased, the adaptability to different working conditions is improved, and therefore the user experience effect is improved.

Description

Technical Field

[0001] This utility model relates to the technical field of water heaters, and in particular to a collector and a centrifugal fan and gas water heater including the collector. Background Technology

[0002] A gas water heater mainly consists of a shell, burner, heat exchanger, fan, and various control valves. The burner mixes gas and air for combustion, releasing heat. The heat exchanger replaces the heat released by the combustion of gas, producing hot water for the user. Current gas water heaters require air to mix with gas for combustion. The required air enters through an opening at the bottom of the shell, is then drawn by the fan, and enters from the bottom of the burner to mix with the gas. The exhaust gas is then discharged outdoors through a flue.

[0003] In addition to normal operating conditions, water heaters exhaust gases outdoors through a flue. When outdoor wind speeds are high (at different wind speed levels), the back pressure in the flue gradually increases. At this time, the fan will operate under low flow conditions, resulting in the following: Figure 1 The PQ curves for the entire unit show that when the outside wind speed is low (i.e., the back pressure of the flue is low), the water heater fan operates under high flow rate conditions; when the outside wind speed is high (i.e., the back pressure of the flue is high), the water heater fan operates under low flow rate conditions. The higher the outdoor wind speed, the slower the intake airflow of the water heater decreases, indicating that the water heater has stronger wind resistance.

[0004] To improve the wind resistance of water heater fans and enable them to operate normally under low flow conditions, the diameter of the fan's inlet diameter is typically designed to be small. Because of the smaller inlet diameter D1, the fan's performance and efficiency are superior under low flow conditions. However, when the fan is operating at high flow rates (i.e., during normal water heater use), the smaller inlet area of ​​the inlet results in a higher airflow velocity, leading to higher noise levels and significantly impacting the user experience.

[0005] Therefore, in current technology, there is a lack of effective technical means to enable water heater fans to withstand different external wind speeds and pressures when operating under different air intake conditions without increasing fan noise. Utility Model Content

[0006] The technical problem to be solved by this utility model is to overcome the defect in the prior art that the fan cannot resist external wind pressure and not increase fan noise when working under different air intake flow conditions. The present invention provides a collector and a centrifugal fan and a gas water heater including the collector.

[0007] The present invention solves the above-mentioned technical problems through the following technical solution:

[0008] A flow collector of a centrifugal fan, the centrifugal fan comprising a volute and an impeller arranged in the volute, the flow collector being arranged at an air inlet of the volute, a ring of the air inlet of the flow collector comprising a plurality of circular arc segments connected smoothly in sequence in a circumferential direction, a ratio of a diameter of at least one of the circular arc segments to a diameter of the impeller being greater than a first ratio, and a ratio of a diameter of at least one of the circular arc segments to the diameter of the impeller being less than the first ratio; wherein the first ratio is a ratio of a diameter of the flow collector to the diameter of the impeller when the fan works in a small flow condition and the ring of the air inlet of the flow collector is a regular circular hole.

[0009] In the present scheme, the flow collector of the centrifugal fan forms a special-shaped structure by the circular arc segments of different diameters at the ring of the air inlet, forming an irregular circular air inlet, so as to meet the working needs of the fan in different air inlet flow conditions. That is, when the fan works in different air inlet flow conditions to resist different wind speed pressures from the outside world, the flow collector with the special-shaped structure can adapt to the irregular circular air inlet, and the size of the air inlet will not limit the wind speed to increase under the same flow demand, so as to avoid increasing the noise of the fan, improve the flow collecting and guiding effect of the flow collector, and improve the user experience. The first ratio set above reflects that when the ring of the air inlet of the flow collector adopts a regular circular hole, the fan works in a small flow condition to resist the wind pressure from the outside world, and the diameter of the flow collector is set as a reference for designing the special-shaped flow collector. On this reference, the ratio of the diameter of at least one circular arc segment to the diameter of the impeller is greater than the first ratio, that is, the air inlet area of the region where the circular arc segment is located is large, and can adapt to the demand of large air inlet flow; the ratio of the diameter of at least one circular arc segment to the diameter of the impeller is less than the first ratio, that is, the air inlet area of the region where the circular arc segment is located is small, and can adapt to the demand of small air inlet flow. The air inlet flow in different conditions can be adjusted in the air inlet region of different circular arc segments, so as to meet the needs of working in different air inlet flow conditions, and improve the adaptability of the flow collector to different conditions.

[0010] Preferably, the first ratio is 0.7.

[0011] In the present scheme, the first ratio adopts the above ratio, which improves the accuracy of the first ratio as a reference (the first ratio is a reference for determining the diameters of different circular arc segments).

[0012] Preferably, the ratio of the diameter of at least one of the circular arc segments to the diameter of the impeller is between 0.8 and 0.9.

[0013] In the scheme, by the above ratio range, the diameter size of at least one circular arc segment is increased, so that more airflow is guided to the air inlet area corresponding to the large-diameter circular arc segment when working in small flow conditions, the air speed can be reduced under the same flow condition, thereby avoiding increasing or reducing the noise caused by high air speed.

[0014] Preferably, the diameter of the impeller is D2, the air inlet ring of the collector includes a first circular arc segment, a second circular arc segment, a third circular arc segment and a fourth circular arc segment which are sequentially and smoothly connected in the circumferential direction; the diameter D3 of the first circular arc segment, the diameter D4 of the second circular arc segment, the diameter D5 of the third circular arc segment and the diameter D6 of the fourth circular arc segment satisfy the following conditions: D3=0.82D2, D4=0.37D2, D5=0.79D2, D6=0.4D2.

[0015] In the scheme, the air inlet ring of the collector passes through the above four circular arc segments which are sequentially and smoothly connected, so that the flow rate of the airflow in the air inlet area where the circular arc segments with different diameters are located can be adjusted according to different flow conditions, which can resist external wind pressure and avoid increasing noise caused by too fast air inlet speed. The diameter D3 of the first circular arc segment adopts the above proportional relationship, so that the air inlet area where the first circular arc segment is located has a large area to adapt to the large flow air inlet demand, while the adjacent second circular arc segment and fourth circular arc segment adopt the above proportional relationship, so that the air inlet area where the second circular arc segment and the fourth circular arc segment are located has a small area to adapt to the small flow air inlet demand. The air inlet areas where the circular arc segments are located neutralize the flow changes, adapt to the changes of external wind pressure, and are beneficial to not increasing or reducing noise.

[0016] Preferably, the diameter of the impeller is D2, the center coordinates of the impeller is O2(0, 0), the center coordinates O3 of the first circular arc segment is the center coordinates O2 of the impeller, the center coordinates O4 of the second circular arc segment is (-0.16D2, 0.12D2), the center coordinates O5 of the third circular arc segment is (-0.1D2, -0.1D2), and the center coordinates O6 of the fourth circular arc segment is (0.09D2, -0.16D2).

[0017] In the scheme, the center coordinates of the four circular arc segments adopt the above proportional relationship, which determines the positions of the four circular arc segments relative to the center of the impeller, and matches the flow changes and flow directions of the airflows between the air inlet areas corresponding to the four circular arc segments and the impeller, which is beneficial to improving the flow guiding effect of the collector.

[0018] Preferably, the third circular arc segment is arranged close to the air outlet area of the volute.

[0019] In the scheme, by the above arrangement, the first circular arc segment and the third circular arc segment with larger diameters better adapt to the shape and structure of the volute.

[0020] Preferably, the air inlet ring of the flow collector comprises a flow guide part; the flow guide part extends in an arc shape from the outside of the flow collector to the inside along the axial direction of the flow collector.

[0021] In this scheme, the flow guide part guides the air flow entering the flow collector from the outside, reduces the sudden change of the air flow, and improves the flow guiding effect.

[0022] Preferably, the material of the flow collector is plastic.

[0023] In this scheme, the flow collector is made of plastic, which is easy to process into arc segments of different diameters and is easy to manufacture.

[0024] A centrifugal fan, comprising a volute, an impeller arranged in the volute, and a flow collector as described above, the flow collector being arranged at an air inlet of the volute.

[0025] In this scheme, the centrifugal fan with the flow collector of the special-shaped structure can meet the working needs of the fan under different air inlet flow conditions, avoids increasing the noise of the fan, improves the adaptability to different working conditions, and thus improves the user experience effect.

[0026] A gas water heater, comprising a centrifugal fan as described above.

[0027] In this scheme, the gas water heater with the centrifugal fan can meet the working needs of the fan under different air inlet flow conditions, avoids increasing the noise of the fan, improves the adaptability to different working conditions, and thus improves the user experience effect.

[0028] The positive progress effect of the flow collector and the centrifugal fan and the gas water heater comprising the same lies in that the centrifugal fan with the flow collector of the special-shaped structure can meet the working needs of the fan under different air inlet flow conditions, avoids increasing the noise of the fan, improves the adaptability to different working conditions, and thus improves the user experience effect. BRIEF DESCRIPTION OF DRAWINGS

[0029] Figure 1 P-Q curve of the whole machine of the water heater in the prior art, wherein P is back pressure and Q is air volume.

[0030] Figure 2 Three-dimensional structure schematic view of the centrifugal fan of the embodiment 1 of the utility model.

[0031] Figure 3 Front view of the centrifugal fan of the embodiment 1 of the utility model.

[0032] Figure 4 Front view of the centrifugal fan of the embodiment 1 of the utility model, wherein the figure showsFigure 3 The collector in the middle is rotated 10 degrees counterclockwise.

[0033] Figure 5 This is a front view of the centrifugal fan according to Embodiment 1 of this utility model, wherein the figure shows... Figure 3 The collector in the middle is rotated 10 degrees clockwise.

[0034] Figure 6 This is a three-dimensional structural schematic diagram of the collector of Embodiment 1 of this utility model.

[0035] Figure 7 This is a side view of the collector of Embodiment 1 of this utility model.

[0036] Figure 8 for Figure 7 A cross-sectional view along the BB direction.

[0037] Figure 9 This is a schematic diagram comparing the air intake speed of the irregularly shaped collector and the regular-shaped collector in Embodiment 1 of this utility model.

[0038] Figure 10 This is a schematic diagram comparing the irregularly shaped collector and the regular-shaped collector in Embodiment 1 of this utility model on the PQ curve, where P is the back pressure and Q is the air volume.

[0039] Explanation of reference numerals in the attached figures:

[0040] Centrifugal fan 1

[0041] Snail Shell 2

[0042] Cochlear tongue 21

[0043] Outer wall of air outlet 22

[0044] Air outlet area 23

[0045] Impeller 3

[0046] Collector 4

[0047] Air intake ring 5

[0048] First arc segment 51

[0049] Second arc segment 52

[0050] Third arc segment 53

[0051] Fourth arc segment 54

[0052] 6 flow guide

[0053] Axial A of the collector Detailed Implementation

[0054] A preferred embodiment is described below in conjunction with the accompanying drawings so as to more clearly and completely understand the present application.

[0055] Embodiment 1

[0056] As shown in Figure 2 and Figure 3 , the present embodiment provides a collector 4 of a centrifugal fan 1 and a centrifugal fan 1 applying the collector 4, the centrifugal fan 1 is used for a gas water heater and extracts air required for combustion of the gas water heater. The centrifugal fan 1 comprises a volute 2, an impeller 3 arranged in the volute 2 and a motor, and the collector 4 is arranged at an air inlet of the volute 2. In operation, the motor drives the impeller 3 to rotate, and air outside the collector 4 is sucked into the volute 2.

[0057] The air inlet ring 5 of the collector 4 comprises a plurality of circular arc segments which are sequentially and smoothly connected in a circumferential direction, a ratio of a diameter of at least one circular arc segment to a diameter of the impeller 3 is greater than a first ratio, and a ratio of the diameter of at least one circular arc segment to the diameter of the impeller 3 is less than the first ratio; the first ratio is a ratio of a diameter of the collector 4 to the diameter of the impeller 3 when the fan 1 works under a small flow condition and the air inlet ring 5 of the collector 4 is a regular circular hole.

[0058] Specifically, as shown in Figures 3-5 , in the present embodiment, the air inlet ring 5 comprises four circular arc segments which are sequentially and smoothly connected in a circumferential direction, namely a first circular arc segment 51, a second circular arc segment 52, a third circular arc segment 53 and a fourth circular arc segment 54, the diameters of the first circular arc segment 51 and the third circular arc segment 53 are relatively large, and a ratio of the diameters to the diameter of the impeller is greater than a first ratio; and the diameters of the second circular arc segment 52 and the fourth circular arc segment 54 are relatively small, and a ratio of the diameters to the diameter of the impeller is less than the first ratio. The first ratio is a ratio of a diameter of the collector 4 to the diameter of the impeller 3 when the fan works under a small flow condition and the air inlet ring of the collector is a regular circular hole. The first ratio is a reference for designing the special-shaped collector, and the diameters of the circular arc segments are all referenced to the first ratio. The reason why the first ratio is set under the small flow condition is that when the external wind pressure is relatively high, the fan can still work against the external wind pressure, and the air inlet flow of the fan is reduced to a small flow state, and in this case, the set diameter of the collector and the first ratio reflect the ability of the fan to resist the external wind pressure. In the present embodiment, according to the working condition, the first ratio is set to 0.7, that is, the diameter of the collector designed with a regular circular hole (hereinafter referred to as a reference diameter D1) is 0.7 times the diameter D2 of the impeller 3, and the diameters of the circular arc segments of the collector 4 in the present embodiment are all referenced to the reference diameter D1 to form circular arc segments with different diameters.

[0059] The collector 4 of the centrifugal fan 1 is formed by different diameter circular arc segments at the air inlet ring 5, and has a special-shaped structure and an irregular circular air inlet, so as to meet the working needs of the fan under different air inlet flow conditions. That is, when the fan works under different air inlet flow conditions in order to resist different external wind pressures, the special-shaped collector 4 can adapt to the irregular circular air inlet, and the air inlet size will not limit the wind speed under the same flow condition, so as to avoid increasing the noise of the fan, improve the collecting and guiding effect of the collector 4, and improve the user experience. The first ratio reflects that when the air inlet ring of the collector has a regular circular hole, the fan works under a small flow condition in order to resist external wind pressure, and the set collector diameter (i.e. the reference diameter D1) is used as a reference for designing a special-shaped collector. Under this reference, the diameter of at least one circular arc segment is greater than the first ratio, that is, the air inlet area of the region where the circular arc segment is located can adapt to the demand of large air inlet flow; the diameter of at least one circular arc segment is less than the first ratio, which can adapt to the demand of small air inlet flow. The air inlet flow under different working conditions can be adjusted in the air inlet area of different circular arc segments, so as to meet the needs of working under different air inlet flow conditions, and improve the adaptability of the collector 4 to different working conditions.

[0060] As described above, in the embodiment, the first ratio is 0.7, that is, the reference diameter D1 and the inlet diameter D2 of the impeller 3 satisfy the condition D1=0.7*D2. By adopting such a proportional relationship, the accuracy of the first ratio as a reference (the first ratio is a reference for determining the diameter of different circular arc segments) is improved. That is, compared with other multiple ratio values, the use of 0.7 as the first ratio makes the performance and efficiency of the centrifugal fan 1 under a small flow condition better. In other embodiments, the first ratio can also be other values according to different working conditions, but the use of 0.7 as the first ratio in the embodiment can obtain the best performance.

[0061] Preferably, in each circular arc segment of the air inlet ring 5, the diameter of at least one circular arc segment is between 0.8D2 and 0.9D2. In this way, the diameter of at least one circular arc segment is increased, so that more airflow is guided to the air inlet area corresponding to the large-diameter circular arc segment when working under a small flow condition, and the wind speed can be reduced under the same flow condition, so as to avoid increasing or reducing the noise caused by high wind speed.

[0062] Specifically, in this embodiment, the diameter D3 of the first circular arc segment 51, the diameter D4 of the second circular arc segment 52, the diameter D5 of the third circular arc segment 53, and the diameter D6 of the fourth circular arc segment 54 satisfy the following conditions: D3 = 0.82D2, D4 = 0.37D2, D5 = 0.79D2, and D6 = 0.4D2. The air inlet ring 5 of the current collector 4 forms an irregular circular air inlet through the four circular arc segments that are sequentially and smoothly connected. The air inlet ring 5 can adjust the flow rate of the air flow in the air inlet area where the circular arc segments with different diameters are located according to different flow conditions, so as to resist external wind pressure and avoid excessive air inlet speed to increase noise. The diameter D3 of the first circular arc segment 51 adopts the above-mentioned proportional relationship, so that the air inlet area where the first circular arc segment 51 is located is large and suitable for large-flow air inlet demand. The diameters D4 and D6 of the second circular arc segment 52 and the fourth circular arc segment 54 adopt the above-mentioned proportional relationship, so that the air inlet area where the second circular arc segment 52 and the fourth circular arc segment 54 are located is small and suitable for small-flow air inlet demand. The air inlet areas where the circular arc segments are located neutralize the flow changes, adapt to the changes of external wind pressure, and are beneficial to not increasing or reducing noise.

[0063] In other embodiments, the diameter D3 of the first circular arc segment 51, the diameter D4 of the second circular arc segment 52, the diameter D5 of the third circular arc segment 53, and the diameter D6 of the fourth circular arc segment 54 can also be adjusted according to different working conditions to obtain better working performance.

[0064] The center coordinates of the impeller 3 are O2(0, 0), which are used as the origin of the center coordinates of the circular arc segments. The center coordinates O3 of the first circular arc segment 51 are consistent with the center coordinates O2 of the impeller 3. The center coordinates O4 of the second circular arc segment 52 are (-0.16D2, 0.12D2). The center coordinates O5 of the third circular arc segment 53 are (-0.1D2, -0.1D2). The center coordinates O6 of the fourth circular arc segment 54 are (0.09D2, -0.16D2). Each coordinate includes two horizontal coordinate parameters and a vertical coordinate parameter. Each horizontal coordinate parameter and each vertical coordinate parameter change based on the impeller diameter D2. For example, when the impeller diameter D2 = 100 mm, in the center coordinates O4 of the second circular arc segment 52, the horizontal coordinate -0.16D2 = -0.16 x 100 mm = -16 mm, and the vertical coordinate 0.12D2 = 0.12 x 100 mm = 12 mm. Therefore, the coordinate value of O4 is (-16 mm, 12 mm).

[0065] In other embodiments, the center coordinates of each arc segment can be adjusted as needed. However, in this embodiment, the center coordinates of the four arc segments are determined by the above-mentioned proportional relationship, which determines the position of the four arc segments relative to the center of the impeller 3. Matching the airflow changes and direction between the air inlet area corresponding to the four arc segments and the impeller 3 is beneficial to improving the airflow guiding effect of the collector 4.

[0066] Among them, such as Figure 3 As shown, the third arc segment 53 is located in the air outlet region 23 near the volute 2, and the first arc segment 51 is positioned opposite to the third arc segment 53. Here, "near" means that the main body of the third arc segment 53 falls within the air outlet region 23 between the volute tongue 21 and the outer wall 22 of the air outlet, where the outer wall 22 is the inner wall of the volute opposite to the volute tongue 21. In application, the circumferential distribution of each arc segment can be adjusted appropriately, for example, as... Figure 4 As shown Figure 3 The collector in the middle is rotated 10 degrees counterclockwise, or as... Figure 5 As shown Figure 3 The collector in the middle is rotated 10 degrees clockwise, slightly adjusting the position of each arc segment on the volute. In this distribution structure, most of the arc segment 53 falls within the air outlet area 23 between the volute tongue 21 and the outer wall 22 of the air outlet. In this structural arrangement, the larger diameter first arc segment 51 and third arc segment 53 better adapt to the shape and structure of the volute 2.

[0067] Among them, such as Figures 6-8 As shown, the air inlet ring 5 of the collector 4 includes a guide section 6; along the axial direction A of the collector 4, the guide section 6 extends in an arc shape from the outside of the collector 4. The collector guides the airflow entering the collector 4 from the outside through the guide section 6, reducing abrupt changes in airflow and improving the guiding effect.

[0068] In this embodiment, the current collector 4 is made of plastic. Of course, in other embodiments, the current collector 4 may be made of other materials, but compared to other materials, the current collector 4 is made of plastic, which makes it easy to process arc segments of different diameters and is easy to manufacture.

[0069] like Figure 9 As shown, Figure 9 The left side shows the wind speed changes at various points on the air inlet ring 5 when using the irregularly shaped collector 4 of this embodiment; Figure 9The right side shows the wind speed variation of the air inlet ring 5 when the regular-shaped current collector 4 (hereinafter referred to as "original current collector 4") is used; wherein red represents high wind speed and blue represents low wind speed. As can be seen from the comparison of the left and right illustrations, the irregular-shaped current collector 4 on the left has a larger area of red high wind speed zone, which represents a larger air inlet, so under the same flow condition, the high wind speed zone on the left has more space to adjust the airflow and reduce the wind speed, thereby avoiding noise; while the original current collector 4 on the right has a small area of red high wind speed zone, and the airflow is concentrated, which is easy to produce noise.

[0070] The centrifugal fan 1 of the embodiment can meet the working needs of the fan under different air inlet flow conditions through the irregular-shaped current collector 4, and also avoids increasing the noise of the fan, improves the adaptability to different working conditions, and thus improves the user experience effect.

[0071] As Figure 10 shown, a comparison schematic diagram of the P-Q curve of the irregular-shaped current collector 4 of the embodiment and the regular-shaped current collector 4 (hereinafter referred to as "original current collector 4") is shown, wherein P is the back pressure and Q is the air volume. As can be seen from the figure, under the same back pressure condition, the irregular-shaped current collector 4 of the embodiment can have a larger air volume when working, and thus can avoid noise.

[0072] Embodiment 2

[0073] The embodiment provides a gas water heater, which comprises the centrifugal fan 1 of embodiment 1. The gas water heater can meet the working needs of the fan under different air inlet flow conditions by using the centrifugal fan 1 of embodiment 1, and also avoids increasing the noise of the fan, improves the adaptability to different working conditions, and thus improves the user experience effect.

[0074] Although the specific embodiments of the present application are described above, those skilled in the art should understand that this is only an example, and the protection scope of the present application is defined by the appended claims. Those skilled in the art can make various changes or modifications to these embodiments without departing from the principles and essence of the present application, and these changes and modifications all fall within the protection scope of the present application.

Claims

1. A collector of a centrifugal fan, the centrifugal fan comprising a volute and an impeller arranged in the volute, the collector being arranged at an air inlet of the volute, characterized in that, the air inlet ring of the collector comprises a plurality of circular arc segments connected smoothly in sequence in a circumferential direction, a ratio of a diameter of at least one of the circular arc segments to a diameter of the impeller is greater than a first ratio, and a ratio of a diameter of at least one of the circular arc segments to the diameter of the impeller is less than the first ratio; wherein the first ratio is a ratio of a diameter of the collector to the diameter of the impeller when the fan works in a small flow condition and the air inlet ring of the collector is a regular circular hole.

2. The current collector of claim 1, wherein The first ratio is 0.

7.

3. The current collector of claim 2, wherein The ratio of the diameter of at least one of the circular arc segments to the diameter of the impeller is between 0.8 and 0.

9.

4. The current collector of claim 3, wherein The diameter of the impeller is D2, the air inlet ring of the collector comprises a first circular arc segment, a second circular arc segment, a third circular arc segment and a fourth circular arc segment connected smoothly in sequence in a circumferential direction; a diameter D3 of the first circular arc segment, a diameter D4 of the second circular arc segment, a diameter D5 of the third circular arc segment and a diameter D6 of the fourth circular arc segment satisfy the following conditions: D3 = 0.82D2, D4 = 0.37D2, D5 = 0.79D2, D6 = 0.4D2.

5. The current collector of claim 4, wherein The diameter of the impeller is D2, the center coordinates of the impeller is O2(0, 0), the center coordinates of the first circular arc segment O3 is the center coordinates of the impeller O2, the center coordinates of the second circular arc segment O4 is (-0.16D2, 0.12D2), the center coordinates of the third circular arc segment O5 is (-0.1D2, -0.1D2), and the center coordinates of the fourth circular arc segment O6 is (0.09D2, -0.16D2).

6. The current collector of claim 5, wherein The third circular arc segment is arranged close to an air outlet area of the volute.

7. The current collector of any one of claims 1-6, wherein, The air inlet ring of the collector comprises a flow guide part; along an axial direction of the collector, the flow guide part extends arcuately inward from an outer part of the collector.

8. The current collector of any one of claims 1-6, wherein, The material of the collector is plastic.

9. A centrifugal fan characterized by The centrifugal fan comprises a volute, an impeller arranged in the volute and the collector according to any one of claims 1-8, the collector being arranged at an air inlet of the volute.

10. A gas water heater, characterized by, The gas water heater comprises the centrifugal fan according to claim 9.

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