Centrifugal fan, air conditioner

Abstract

The present invention provides a centrifugal fan and an air conditioner. The centrifugal fan includes a centrifugal impeller and a volute for accommodating the centrifugal impeller. When projected onto any radial plane of the centrifugal impeller along the axial direction of the centrifugal impeller, the circumferential volute of the volute has at least a first profile line and a second profile line. And at the same spiral involute angle φ, the profile line radius of the circumferential volute becomes smaller and smaller along the direction from the first profile line to the second profile line. The air flow rate of the centrifugal impeller corresponding to the area where the first profile line is located is greater than the air flow rate of the centrifugal impeller corresponding to the area where the second profile line is located, where 40° ≤ φ ≤ 360°. According to the present invention, the volute has a plurality of volute profile lines between the first profile line and the second profile line on its axial direction and the profile line radius becomes smaller and smaller. Since the first profile line and the second profile line are respectively matched with the air flow rate of the centrifugal impeller, it can effectively overcome the deficiency of low efficiency caused by the mismatch between the volute profile line and the air flow rate of the impeller in the prior art.

Description

Technical Field

[0001] The present invention belongs to the technical field of air conditioning, and particularly relates to a centrifugal fan and an air conditioner. Background Art

[0002] According to the fan volute design theory, in accordance with the principle of conservation of angular momentum, the volute profile of the fan is a logarithmic spiral, and its equation is When the fan diameter R 2 , design flow rate q, circumferential velocity c of the impeller outlet 2u and volute width B are determined, the R of the volute profile at different φ angles is determined. The three-dimensional volute is generated by simple stretching according to the aforementioned profile. This volute design method is based on the assumption that inside the volute, the air flow distribution is uniform and the flow rate of each cross-section on the impeller is the same. However, during the actual operation of the impeller, the flow rate of each cross-section on the impeller is not consistent. Its change form is that it gradually increases from the air collector (air flow inlet) to the impeller mid-disk (for example, corresponding to the radial plane at the axial midpoint of the impeller in a double-inlet centrifugal fan (i.e., the blade end disk at the axial center position), corresponding to the blade end disk farthest from the inlet in a single-inlet centrifugal fan), and is the highest near the impeller mid-disk. This leads to a mismatch between the original volute profile and the actual operating conditions, and the fan operating efficiency is reduced. Summary of the Invention

[0003] Therefore, the present invention provides a centrifugal fan and an air conditioner, which can overcome the deficiency that the volute profile in the related art is single and does not match the flow rate in the actual operating conditions of the impeller, resulting in low fan operating efficiency.

[0004] To solve the above problems, the present invention provides a centrifugal fan, including a centrifugal impeller and a volute for accommodating the centrifugal impeller. When projected onto any radial plane along the axial direction of the centrifugal impeller, the circumferential volute of the volute has at least a first profile and a second profile. And at the same spiral involute angle φ, the profile radius of the circumferential volute becomes smaller and smaller along the direction from the first profile to the second profile. The air flow rate of the centrifugal impeller corresponding to the area where the first profile is located is greater than the air flow rate of the centrifugal impeller corresponding to the area where the second profile is located, where 40° ≤ φ ≤ 360°.

[0005] Preferably, at the spiral involute angle φ, the profile radius corresponding to the first profile is R a , wherein, R 2 is the diameter of the centrifugal impeller, in m; e is the natural logarithm, q is the design flow rate of the centrifugal fan, in m 3 / s; c 2uis the circumferential velocity at the outlet of the centrifugal impeller, with the unit of m / s; B is the axial width of the volute, with the unit of m.

[0006] Preferably, at the same spiral involute angle φ as the first profile line, the profile radius corresponding to the second profile line is R b ,

[0007] Preferably, when projected onto any radial plane of the centrifugal impeller along the axial direction of the centrifugal impeller, the circumferential volute further includes a third profile line, which is located between the first profile line and the second profile line. At the same spiral involute angle φ as the first profile line, the profile radius corresponding to the third profile line is R c ,

[0008] Preferably, the centrifugal fan is a single-inlet centrifugal fan. The volute has a first end plate corresponding to the first end disk of the centrifugal impeller and a second end plate corresponding to the second end disk of the centrifugal impeller. The circumferential volute is located between the first end plate and the second end plate. A first inlet is formed on the first end plate. The second profile line is disposed adjacent to the first inlet and the first profile line is disposed adjacent to the second end plate.

[0009] Preferably, in the axial direction of the centrifugal fan, the axial distance between the radial section where the first profile line is located and the radial section where the second profile line is located is b, and the axial distance between the radial section where the first profile line is located and the radial section where the third profile line is located is b1, and b1 = (0.4 - 0.6)b.

[0010] Preferably, the centrifugal fan is a double-inlet centrifugal fan. The volute has a first end plate corresponding to the first end disk of the centrifugal impeller and a second end plate corresponding to the second end disk of the centrifugal impeller. The circumferential volute is located between the first end plate and the second end plate. A first inlet is formed on the first end plate, and a second inlet is formed on the second end plate. The first end plate and the second end plate are symmetric about a first radial plane. There are two second profile lines, and the two second profile lines are symmetrically arranged with respect to the first profile line.

[0011] Preferably, in the axial region of the centrifugal fan between the first profile line and the first end plate, the axial distance between the radial section where the first profile line is located and the radial section where the second profile line is located is b, and the axial distance between the radial section where the first profile line is located and the radial section where the third profile line is located is b1, and b1 = (0.4 - 0.6)b.

[0012] The present invention also provides an air conditioner, including a centrifugal fan, and the centrifugal fan is the above-mentioned centrifugal fan.

[0013] A centrifugal fan and an air conditioner provided by the present invention. The volute has a plurality of volute profiles between the first profile and the second profile on its axial direction, and the profile radius becomes smaller and smaller. Since the first profile and the second profile respectively match the air flow rate of the centrifugal impeller, the deficiency of low efficiency caused by the mismatch between the volute profile and the impeller flow rate in the prior art can be effectively overcome. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 It is a three-dimensional structural schematic diagram of the centrifugal fan according to the embodiment of the present invention;

[0015] Figure 2 is Figure 1 a structural schematic diagram (axonometric view) of the volute in

[0016] Figure 3 is Figure 2 a partial structural schematic diagram of a cross-section along the axis of the volute in

[0017] Figure 4 is Figure 2 a structural schematic diagram of the axial projection of the volute in

[0018] The reference numerals are shown as:

[0019] 1, volute; 11, first axial end plate; 111, first inlet; 12, second axial end plate; 121, second inlet; 13, circumferential volute; 131, first profile; 132, second profile; 133, third profile; 134, outlet; 2, centrifugal impeller. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0020] Referring to Figures 1 to 4 shown, according to an embodiment of the present invention, a centrifugal fan is provided, including a centrifugal impeller 2 and a volute 1 for accommodating the centrifugal impeller 2. The volute 1 has a first axial end plate 11 corresponding to the first axial end disc of the centrifugal impeller 2 and a second axial end plate 12 corresponding to the second axial end disc of the centrifugal impeller 2. The first axial end plate 11 and the second axial end plate 12 are parallel, and the circumferential volute 13 is between them. Projecting along the axial direction of the centrifugal impeller 2 on any radial plane of the centrifugal impeller 2, the circumferential volute 13 of the volute 1 includes at least a first profile 131 and a second profile 132 (such as Figure 4As shown, and at the same spiral involute angle φ, the profile radius of the circumferential volute 13 becomes smaller and smaller along the direction from the first profile 131 to the second profile 132. The air flow rate of the centrifugal impeller 2 corresponding to the area where the first profile 131 is located is greater than the air flow rate of the centrifugal impeller 2 corresponding to the area where the second profile 132 is located, where 40° ≤ φ ≤ 360°. It can be understood that the area of the circumferential volute 13 corresponding to 0° ≤ φ < 40° is the area where the outlet 134 of the centrifugal fan is located, and the starting position of the spiral involute angle φ can be referred to Figure 4 The orientation shown is defined. Specifically, taking the projection of the axis of the centrifugal impeller 2 on any radial plane as the coordinate origin O, and taking the straight line parallel to the lip projection line of the projection of the mouth of the outlet 134 on any radial plane and passing through the O point as the X-axis (the positive direction is towards the air flow outlet side), and the straight line passing through the O point and perpendicular to the X-axis as the Y-axis (the positive direction is towards the air flow outlet side), thus constructing the definition coordinate system of the first profile 131 and the second profile 132. And φ is the angle between the connection line of the points on the first profile 131 and the second profile 132 and the O point and the X-axis. This part of the limitation on φ is common knowledge in the art and will not be further elaborated. In this technical solution, different from the single axial profile of the volute in the prior art, the volute in the present invention has multiple volute profiles between the first profile 131 and the second profile 132 with a decreasing profile radius in its axial direction. Since the first profile 131 and the second profile 132 respectively match the air flow rate of the centrifugal impeller 2, it can effectively overcome the deficiency of low efficiency caused by the mismatch between the volute profile and the impeller flow rate in the prior art.

[0021] In some embodiments, at the spiral involute angle φ, the profile radius corresponding to the first profile 131 is R a , wherein, R 2 is the diameter of the centrifugal impeller 2, with the unit of m; e is the natural logarithm, q is the designed flow rate of the centrifugal fan, with the unit of m 3 / s; c 2u is the circumferential velocity at the outlet of the centrifugal impeller 2, with the unit of m / s; B is the axial width of the volute 1, with the unit of m. It should be noted that through simulation verification, taking the coefficient of q in the previous formula as 1.1 - 1.3 can ensure that the fan efficiency is at a relatively high level. Further, at the same spiral involute angle φ as the first profile 131, the profile radius corresponding to the second profile 132 is R b ,

[0022] It should be noted that through simulation verification, when the coefficient of q in the previous formula takes a value of 0.7 to 0.9, the fan efficiency can be ensured to be at a relatively high level. It should be noted that the first profile 131 is arranged corresponding to the position where the flow rate of the centrifugal impeller 2 is the largest, while the second profile 132 is arranged corresponding to the position where the flow rate of the centrifugal impeller 2 is the smallest. Correspondingly, at this time, on the same axial section of the circumferential volute 13, the position of the first profile 131 is higher than that of the second profile 132. Further, when projected onto any radial plane of the centrifugal impeller 2 along the axial direction of the centrifugal impeller 2, the circumferential volute 13 further includes a third profile 133. The third profile 133 is located between the first profile 131 and the second profile 132. At the same spiral involute angle φ as the first profile 131, the profile radius corresponding to the third profile 133 is R c , That is to say, at this time, on the same axial section of the circumferential volute 13, the position of the first profile 131 is the highest, the position of the second profile 132 is the lowest, and the position of the third profile 133 is between the positions of the first profile 131 and the second profile 132. It should be noted that through simulation verification, when the coefficient of q in the previous formula takes a value of 1 to 1.05, the fan efficiency can be ensured to be at a relatively high level.

[0023] For example, the connection relationship between the first profile 131 and the second profile 132 can be a linearly gradually changing connection extending along the axial direction of the circumferential volute 13. Preferably, the connection relationship between the two is a smoothly curved gradually changing connection relationship, so that the circumferential volute 13 can better match the axial flow rate of the centrifugal impeller 2. When the third profile 133 is further included, the connection relationship among the first profile 131, the third profile 133, and the second profile 132 is also a smoothly curved connection relationship.

[0024] In one embodiment, the centrifugal fan is a single-inlet centrifugal fan. At this time, a first inlet 111 is formed on the first shaft end plate 11. The second profile 132 is arranged adjacent to the first inlet 111, and the first profile 131 is arranged adjacent to the second shaft end plate 12. That is to say, at this time, the profile radius of the circumferential volute 13 gradually decreases along its axial direction from the second shaft end plate 12 to the first shaft end plate 11. It should be noted that for a single-inlet centrifugal fan, the setting position of the first profile 131 corresponds to the inner shaft end disc of the centrifugal impeller 2 (which also corresponds to the second shaft end plate 12), and the air flow rate of the impeller here is the largest. The setting position of the second profile 132 corresponds to the outer shaft end disc of the centrifugal impeller 2 adjacent to the first inlet 111, and the air flow rate of the impeller here is the smallest.

[0025] Correspondingly, in the axial direction of the centrifugal fan, the axial distance between the radial section A where the first profile line 131 is located and the radial section B where the second profile line 132 is located is b, and the axial distance between the radial section A where the first profile line 131 is located and the radial section C where the third profile line 133 is located is b1, where b1 = (0.4 - 0.6)b. In this way, the flow velocity at the corresponding position is closer to the flow velocity generated at the designed flow rate of the fan.

[0026] In another embodiment, the centrifugal fan is a double-inlet centrifugal fan. A first inlet 111 is formed on the first shaft end plate 11, and a second inlet 121 is formed on the second shaft end plate 12. The first shaft end plate 11 and the second shaft end plate 12 are symmetric about the first radial plane. There are two second profile lines 132, and the two second profile lines 132 are symmetrically arranged about the first profile line 131. It can be understood that the first profile line 131 is located on the first radial plane, and there are also two third profile lines 133. The two third profile lines 133 are respectively located between the first profile line 131 and the second profile line 132 and are symmetric about the first profile line 131. It should be noted that for the double-inlet centrifugal fan, the setting position of the first profile line 131 corresponds to the central shaft end plate of the centrifugal impeller 2 (which is the end plate at the middle position of the axial length of the centrifugal impeller 2, also called the blade middle plate), where the air flow rate of the impeller is the largest, and the setting positions of the second profile lines 132 respectively correspond to the side shaft end plates of the centrifugal impeller 2 adjacent to the first inlet 111 and the second inlet 121, where the air flow rate of the impeller is the smallest.

[0027] In the axial region of the centrifugal fan between the first profile line 131 and the first shaft end plate 11, the axial distance between the radial section A where the first profile line 131 is located and the radial section B where the second profile line 132 is located is b, and the axial distance between the radial section A where the first profile line 131 is located and the radial section C where the third profile line 133 is located is b1, where b1 = (0.4 - 0.6)b.

[0028] According to an embodiment of the present invention, there is also provided an air conditioner, including the centrifugal fan as described above.

[0029] It is easy for those skilled in the art to understand that, on the premise of no conflict, the above advantageous ways can be freely combined and superimposed.

[0030] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included within the protection scope of the present invention. The above is only the preferred implementation manner of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the technical principle of the present invention, several improvements and variations can still be made, and these improvements and variations should also be regarded as within the protection scope of the present invention.

Claims

1. A centrifugal fan, comprising a centrifugal impeller (2) and a volute (1) for accommodating the centrifugal impeller (2). Characterized in that, Projected along the axial direction of the centrifugal impeller (2) on any radial plane of the centrifugal impeller (2), the circumferential volute (13) of the volute (1) at least includes a first profile line (131) and a second profile line (132). And at the same spiral involute angle φ, the profile radius of the circumferential volute (13) becomes smaller and smaller along the direction from the first profile line (131) to the second profile line (132). The air flow rate of the centrifugal impeller (2) corresponding to the area where the first profile line (131) is located is greater than the air flow rate of the centrifugal impeller (2) corresponding to the area where the second profile line (132) is located, where 40° ≤ φ ≤ 360°; at the spiral involute angle φ, the profile radius corresponding to the first profile line (131) is R a , wherein, R 2 is the diameter of the centrifugal impeller (2), in m; e is the natural logarithm, q is the designed flow rate of the centrifugal fan, in m 3 / s; c 2u is the circumferential velocity at the outlet of the centrifugal impeller (2), in m / s; B is the axial width of the volute (1), in m; at the same spiral involute angle φ as the first profile line (131), the profile radius corresponding to the second profile line (132) is R b , Projected along the axial direction of the centrifugal impeller (2) on any radial plane of the centrifugal impeller (2), the circumferential volute (13) further includes a third profile line (133). The third profile line (133) is located between the first profile line (131) and the second profile line (132). At the same spiral involute angle φ as the first profile line (131), the profile radius corresponding to the third profile line (133) is R c , 2. The centrifugal fan according to claim 1, Characterized in that, The centrifugal fan is a single-inlet centrifugal fan. The volute (1) has a first end plate (11) corresponding to the first axial end plate of the centrifugal impeller (2) and a second end plate (12) corresponding to the second axial end plate of the centrifugal impeller (2). Between the first end plate (11) and the second end plate (12) is the circumferential volute (13). A first inlet (111) is formed on the first end plate (11). The second profile line (132) is arranged adjacent to the first inlet (111) and the first profile line (131) is arranged adjacent to the second end plate (12).

3. The centrifugal fan according to claim 2, Characterized in that, In the axial direction of the centrifugal fan, the axial distance between the radial section where the first profile line (131) is located and the radial section where the second profile line (132) is located is b, and the axial distance between the radial section where the first profile line (131) is located and the radial section where the third profile line (133) is located is b1, and b1 = (0.4 - 0.6)b.

4. The centrifugal fan according to claim 1, Characterized in that, The centrifugal fan is a double-inlet centrifugal fan. The volute (1) has a first end plate (11) corresponding to the first axial end plate of the centrifugal impeller (2) and a second end plate (12) corresponding to the second axial end plate of the centrifugal impeller (2). Between the first end plate (11) and the second end plate (12) is the circumferential volute (13). A first inlet (111) is formed on the first end plate (11), and a second inlet (121) is formed on the second end plate (12). The first end plate (11) and the second end plate (12) are symmetric about a first radial plane. There are two second profile lines (132), and the two second profile lines (132) are symmetrically arranged about the first profile line (131).

5. The centrifugal fan according to claim 4, Characterized in that, In the axial region of the centrifugal fan between the first profile line (131) and the first end plate (11), the axial distance between the radial section where the first profile line (131) is located and the radial section where the second profile line (132) is located is b, and the axial distance between the radial section where the first profile line (131) is located and the radial section where the third profile line (133) is located is b1, and b1 = (0.4 - 0.6)b.

6. An air conditioner, Characterized in that, Comprising a centrifugal fan, and the centrifugal fan is the centrifugal fan according to any one of claims 1 to 5.

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