Centrifugal fan impeller, centrifugal fan and ventilation treatment equipment

Abstract

The utility model relates to the technical field of centrifugal fans, and discloses a centrifugal fan impeller, a centrifugal fan and ventilation treatment equipment. The centrifugal fan impeller comprises a wheel disc (1) and a plurality of main blades (2), the multiple main blades (2) are arranged on the surface of one side of the wheel disc (1) and distributed in the circumferential direction of the wheel disc (1) at intervals, each main blade (2) is twisted outwards clockwise or anticlockwise in the radial direction of the wheel disc (1), and in the height direction of the main blades (2), the number of the main blades (2) is larger than that of the main blades (2). And the front edge (21) of the main blade (2) and the part close to the front edge (21) form an arc-shaped part (27) which is sunken towards the pressure surface (22) of the main blade (2). According to the centrifugal fan impeller, the noise reduction effect of a fan can be effectively improved, and due to the fact that noise reduction of the fan comes from improvement of the impeller structure, universality is high.

Description

Technical Field

[0001] The utility model relates to the technical field of centrifugal fans, in particular to a centrifugal fan impeller, a centrifugal fan comprising the centrifugal fan impeller, and ventilation treatment equipment comprising the centrifugal fan. Background Art

[0002] In modern clinical medicine, ventilation therapy equipment, such as a ventilator, is an assisted respiratory therapy device with artificial ventilation function. Respiratory gas is supplied to the patient through a breathing tube through a patient interface, effectively improving the patient's respiratory function by increasing the patient's lung ventilation volume. It is now widely used to treat respiratory diseases such as respiratory failure, respiratory insufficiency, sleep apnea syndrome, chronic obstructive pulmonary disease, and can play an important role in assisting patients' breathing, saving and prolonging their lives.

[0003] As the primary power component within a ventilator, the centrifugal fan often determines its overall performance. With increasing awareness of noise in recent years, low noise levels and quietness have become crucial indicators of product quality. As the primary noise source in ventilators, reducing the noise caused by the high-speed rotation of the centrifugal impeller has become a key research hotspot and challenge.

[0004] Currently, many fan noise reduction methods rely on improvements to the volute. For example, by varying the volute spacing near the volute tongue, the airflow is directed to minimize eddy currents and resonance caused by air impact at different locations. However, this approach is not very effective and only works on specific impellers, making it less universal. Utility Model Content

[0005] In order to solve the above-mentioned problems, the purpose of the present invention is to provide a centrifugal fan impeller, a centrifugal fan including the centrifugal fan impeller, and a ventilation treatment device including the centrifugal fan, so as to enhance the noise reduction effect of the fan by improving the structure of the impeller.

[0006] In order to achieve the above-mentioned purpose, the first aspect of the present invention provides a centrifugal fan impeller, including a wheel disc and a plurality of main blades, wherein the plurality of main blades are arranged on one side surface of the wheel disc and are arranged at intervals along the circumference of the wheel disc, and each of the main blades is twisted clockwise or counterclockwise outward along the radial direction of the wheel disc, and in the height direction of the main blade, the leading edge of the main blade and the part close to the leading edge are formed as an arc-shaped portion concave toward the pressure surface of the main blade.

[0007] In some embodiments, the curvature of the arc-shaped portion is configured to gradually decrease from the leading edge toward the outer periphery of the wheel disc, and the length of the arc-shaped portion is less than 60% of the length of the main blade.

[0008] In some embodiments, the curvature of the leading edge is less than 0.55 radians.

[0009] In some embodiments, a guide portion protruding toward the side where the main blades are located is provided at the center of the wheel disc, and the leading edge extends obliquely away from the wheel disc in a direction from the guide portion toward the outer periphery of the wheel disc.

[0010] In some embodiments, a reinforcement structure is provided on the other side surface of the wheel disc.

[0011] In some embodiments, an upper edge of the main blade facing away from the wheel disk is formed in a curve that bends and extends toward the wheel disk in a direction from the leading edge to the outer peripheral edge of the wheel disk.

[0012] In some embodiments, the wheel disc has a central opening, the guide portion is a conical structure protruding from the periphery of the central opening, and the centrifugal fan impeller further includes a guide cone, which is coaxially mounted on the guide portion.

[0013] In some embodiments, a position where the leading edge meets the upper edge forms a turning point, and the turning point is higher than a top end of the guide portion.

[0014] In some embodiments, the trailing edge of the main blade is in a straight line shape, and the trailing edge extends obliquely toward the wheel disc in a radially outward direction of the wheel disc.

[0015] In some embodiments, a distance is provided between an outer end of the trailing edge and an outer periphery of the wheel disc.

[0016] In some embodiments, splitter blades are further provided between adjacent main blades.

[0017] In some embodiments, the trailing edge of the splitter blade is flush with the trailing edge of the main blade, and the length of the splitter blade is shorter than the length of the main blade.

[0018] In some embodiments, the twisting trend of the splitter blade is consistent with that of the main blade.

[0019] A second aspect of the present invention provides a centrifugal fan, comprising a volute and the centrifugal fan impeller. The volute defines an installation cavity inside, and the centrifugal fan impeller is coaxially installed in the installation cavity.

[0020] In some embodiments, a centrifugal fan inlet connected to the mounting cavity is provided at the top of the volute, and a centrifugal fan outlet connected to the mounting cavity is provided on the circumferential side of the volute, and the centrifugal fan outlet is located below the wheel in the axial direction of the volute.

[0021] In some embodiments, the centrifugal fan includes a motor, and a mounting opening for partially mounting the motor in the mounting cavity is provided at the bottom of the volute, and a motor shaft of the motor is connected to the wheel disc.

[0022] A third aspect of the present invention provides a ventilation treatment device, comprising the above-mentioned centrifugal fan.

[0023] Through the above technical solution, when the impeller of the present invention is applied to a fan, the noise reduction effect of the fan can be effectively improved. Moreover, since the noise reduction of the fan comes from the improvement of the impeller structure, it has high versatility.

[0024] Other features and advantages of the present invention will be described in detail in the subsequent detailed description of the embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] The accompanying drawings, which constitute part of the present invention, are intended to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are intended to explain the present invention and do not constitute an improper limitation of the present invention. In the accompanying drawings:

[0026] Figure 1 This is a front view of an embodiment of the centrifugal fan impeller in the utility model;

[0027] Figure 2 yes Figure 1 Side view of the centrifugal fan impeller;

[0028] Figure 3 yes Figure 2 Schematic diagram with part of the leaves removed;

[0029] Figure 4 yes Figure 3 Stereoscopic image of

[0030] Figure 5 yes Figure 4 A partial enlarged view of

[0031] Figure 6 It is a side view of another embodiment of the centrifugal fan impeller in the utility model;

[0032] Figure 7 yes Figure 6 Exploded view of the centrifugal fan impeller;

[0033] Figure 8 yes Figure 6 Bottom view of the centrifugal fan impeller;

[0034] Figure 9 yes Figure 8 A three-dimensional diagram of the centrifugal fan impeller;

[0035] Figure 10 yes Figure 8 Cross-sectional view of the centrifugal fan impeller;

[0036] Figure 11 This is a front view of an embodiment of the centrifugal fan in the utility model;

[0037] Figure 12 yes Figure 11 AA cross-sectional view of the centrifugal fan;

[0038] Figure 13 yes Figure 11 Exploded view of a centrifugal fan.

[0039] Description of Reference Numerals

[0040] 1-wheel disc, 11-guide part, 12-boss, 13-reinforcement rib, 2-main blade, 21-leading edge, 22-pressure surface, 23-upper edge, 24-turning point, 25-trailing edge, 26-suction surface, 27-arc-shaped part, 3-divergent blade, 4-guide cone, 5-volute, 51-installation cavity, 52-centrifugal fan inlet, 53-centrifugal fan outlet, 54-installation port, 55-upper volute, 56-lower volute, 6-motor, 61-motor shaft. DETAILED DESCRIPTION

[0041] The following detailed description of the embodiments of the present invention is provided in conjunction with the accompanying drawings. The following detailed description of the embodiments and the accompanying drawings are intended to illustrate the principles of the present invention, but are not intended to limit the scope of the present invention. The present invention can be implemented in many different forms and is not limited to the specific embodiments disclosed herein, but rather includes all technical solutions within the scope of the claims.

[0042] The present invention provides these embodiments to make the present invention thorough and complete, and to fully convey the scope of the present invention to those skilled in the art. It should be noted that unless otherwise specifically stated, the relative arrangements of components and steps, material compositions, numerical expressions, and numerical values ​​described in these embodiments should be interpreted as merely exemplary and not as limiting.

[0043] It should be noted that, in the description of this utility model, unless otherwise specified, "plurality" means greater than or equal to two; terms such as "upper," "lower," "left," "right," "inner," and "outer" indicating directions or positional relationships are intended solely to facilitate the description of this utility model and simplify the description. They do not indicate or imply that the devices or components referred to must have a specific orientation, be constructed, or operate in a specific orientation, and therefore should not be construed as limitations on this utility model. When the absolute position of the described object changes, the relative positional relationship may also change accordingly.

[0044] In addition, the terms "first," "second," and similar terms used in this invention do not indicate any order, quantity, or importance, but are simply used to distinguish different parts. "Perpendicular" does not mean perpendicular in the strict sense, but rather means that the positions are within the tolerance range. "Parallel" does not mean parallel in the strict sense, but rather means that the positions are within the tolerance range. "Include" or "comprising" and similar terms mean that the elements listed before the word include the elements listed after the word, and do not exclude the possibility that other elements may also be included.

[0045] It should also be noted that, in the description of this utility model, unless otherwise expressly specified or limited, the terms "installed," "connected," and "connected" should be understood broadly. For example, they can refer to fixed connections, detachable connections, or integral connections; they can refer to direct connections or indirect connections through an intermediary. Those skilled in the art will understand the specific meanings of these terms in this utility model based on the specific circumstances. When a specific device is described as being located between a first device and a second device, there may or may not be an intervening device between the specific device and the first or second device.

[0046] All terms used in this utility model have the same meaning as those understood by ordinary technicians in the field to which this utility model belongs, unless otherwise specifically defined. It should also be understood that terms defined in general dictionaries should be interpreted as having meanings consistent with their meanings in the context of the relevant technology, and should not be interpreted in an idealized or extremely formal sense, unless explicitly defined as such herein.

[0047] Technologies, methods, and equipment known to ordinary technicians in the relevant art may not be discussed in detail, but where appropriate, they should be considered part of the specification.

[0048] A first aspect of the present invention provides a centrifugal fan impeller, comprising a wheel disc 1 and a plurality of main blades 2, wherein the plurality of main blades 2 are arranged on one side surface of the wheel disc 1 and are arranged at intervals along the circumference of the wheel disc 1, and each main blade 2 is twisted clockwise or counterclockwise outward along the radial direction of the wheel disc 1, and in the height direction of the main blade 2, the leading edge 21 of the main blade 2 and the portion close to the leading edge 21 are formed as an arc-shaped portion 27 that is recessed toward the pressure surface 22 of the main blade 2.

[0049] In the above description, it should be noted that the interval between two adjacent main blades 2 forms a main channel for the medium to flow. Figure 1The main blade 2 is a twisted plate-shaped blade, with its convex surface serving as the pressure side (also known as the windward side) 22 and its concave surface serving as the suction side (also known as the leeward side) 26. The clockwise or counterclockwise twisting of the main blade 2 radially outward along the disc 1 can be understood as a radial offset of the main blade 2 relative to the disc 1, while the concavity of the arcuate portion 27 toward the pressure side 22 can be understood as a height offset relative to the main blade. The main blade 2 can be positioned perpendicular to the disc 1 or slightly tilted relative to it.

[0050] The aerodynamic noise generated during the use of centrifugal impellers can be divided into rotational noise and eddy current noise. The eddy current noise mainly consists of the following two aspects: the first is the noise generated by the compression and expansion of the gas when the eddy currents at the blade outlet separate, which is transmitted in the form of sound waves; the second is the noise generated by the pulsation of the blade force caused by the unevenness of the airflow and turbulent pulsation at the impeller inlet. The principle of turbulent pulsation generating noise is that when gas with a certain turbulence enters the impeller, the impact of the airflow disturbance velocity on the leading edge of the blade shows obvious irregular changes. When the angle of attack (i.e., the angle between the overall airflow and the leading edge of the blade, its size depends on the average airflow velocity and the instantaneous disturbance velocity) is too large, the irregular changes are more obvious, making it easier for the leading edge to separate the airflow, thus generating noise.

[0051] The centrifugal fan impeller of the present invention forms an arc shape that is concave toward the pressure surface 22 of the main blade 2 in the height direction of the main blade 2 by making the leading edge 21 of the main blade 2 and the part close to the leading edge 21. There is no concept of attack angle, which can reduce the impact of turbulence on the leading edge 21 and thus reduce the noise generated by turbulent pulsation.

[0052] In some embodiments, the curvature of the arc portion 27 is configured to gradually decrease from the leading edge 21 toward the outer periphery of the disc 1. The length of the arc portion 27 is less than 60% of the length of the main blade 2, preferably 15%-25%, and more preferably 20%. It will be appreciated that the curvature of the arc portion 27 gradually decreases to zero, meaning that the rearward portion of the main blade 2 is not offset relative to the height direction of the main blade 2.

[0053] In some embodiments, the curvature of the leading edge 21 is less than 0.55 radians.

[0054] See also Figure 2-Figure 3 The center of the wheel disc 1 may be provided with a guide portion 11 protruding toward the side where the main blade 2 is located, and the leading edge 21 extends obliquely away from the wheel disc 1 in a direction outward from the guide portion 11 (i.e. toward the outer periphery of the wheel disc 1), i.e. the leading edge is swept back.

[0055] See also Figure 4-Figure 5In some embodiments, the upper edge 23 of the main blade 2 facing away from the wheel disc 1 is formed as a curve extending from the leading edge 21 outward (ie, toward the outer periphery of the wheel disc 1 ) toward the wheel disc 1 .

[0056] Among them, the position where the leading edge 21 meets the upper edge 23 forms a turning point 24, which is the highest point of the main blade 2. The height of the turning point 24 can exceed the top height of the guide part 11, or can be less than or equal to the top height of the guide part 11.

[0057] In some embodiments, see Figure 4 The trailing edge 25 of the main blade 2 is straight and extends obliquely outward from the radial direction of the disc 1 toward the disc 1. This arrangement (i.e., the forward-swept trailing edge) reduces the mass of the impeller, thereby reducing the impeller's moment of inertia, thereby reducing the motor load, suppressing the heat generated by the motor during operation, and effectively extending the motor's service life.

[0058] In some embodiments, see Figure 1 and Figure 4 There is a gap between the outer end of the trailing edge 25 (i.e., the tip of the main blade) and the outer periphery of the impeller 1. In other words, the main blade 2 is configured to extend from the center of the impeller 1 toward the outer periphery of the impeller 1 and terminate inward of the outer periphery. By providing a gap between the tip of the main blade 2 and the edge of the impeller 1, this gap can be used as a material removal portion when correcting the dynamic balance of the impeller.

[0059] In the present invention, the plurality of main blades 2 can be evenly spaced or unevenly spaced. The number of the main blades 2 is not limited, and can be 13, for example.

[0060] In some embodiments, see Figure 1 , splitter blades 3 are further provided between adjacent main blades 2. That is, each main channel is provided with a splitter blade 3 extending in the same direction as the corresponding main blade 2 (i.e., the blade 2 used to define the corresponding main channel). The length of the splitter blade 3 is shorter than that of the main blade 2, and the end of the splitter blade 3 is flush with the end of the main blade 2.

[0061] The splitter blade 3 can separate the outlet of the main channel (i.e., the end of the main channel close to the outer periphery of the wheel disc 1) into two split channels, thereby preventing the vortex formed at the outlet of the main channel from being too large, thereby reducing the vortex noise generated by the first aspect mentioned above.

[0062] In order to balance the airflow in the two diversion channels, reduce the aerodynamic impact on the blades, and prevent the impeller from becoming unstable, it is best to locate the diversion blade 3 on the center line of the main channel, that is, the diversion blade 3 divides the corresponding part of the main channel into two diversion channels.

[0063] See also Figure 1 、 Figure 3 and Figure 4 , the twisting trend of the splitter blade 3 can be consistent with that of the main blade 2.

[0064] In this utility model, see Figure 3-Figure 4 The wheel disc 1 has a central opening, and the guide portion 11 is a conical structure protruding upward through the periphery of the central opening. That is, the wheel disc as a whole is a structure similar to a truncated cone.

[0065] See also Figure 9-10 The bottom surface of the wheel disc 1 is a concave surface, that is, the bottom surface of the wheel disc 1 is concave to form a cavity. A reinforcement structure can be provided on the bottom surface of the wheel disc 1 to ensure the strength of the wheel disc when the impeller rotates and prevent it from deformation.

[0066] Specifically, if Figures 8-10 In the illustrated embodiment, the reinforcement structure may include a cylindrical boss 12 extending axially downward from the inner circumference of the impeller 1, and a plurality of reinforcing ribs 13 extending radially outward from the outer circumference of the boss 12. The plurality of reinforcing ribs 13 are evenly spaced around the circumference of the boss 12. Preferably, the top surface of the reinforcing rib 13 is connected to the bottom surface of the impeller 1, and the bottom surface of the reinforcing rib 13 and the bottom end surface of the cylindrical boss 12 are flush with the bottom end surface of the impeller 1. The reinforcing rib 13 is generally triangular in shape, and the top surface of the reinforcing rib 13 is consistent with the surface profile of the bottom surface of the impeller 1. This allows the reinforcing rib 13 to conform to the bottom surface of the impeller 1, thereby reducing the rotational inertia of the impeller.

[0067] In the present utility model, Figure 6-Figure 7 As shown, the centrifugal fan impeller may further include a guide cone 4, which is coaxially mounted on the guide portion 11. The presence of the guide cone 4 can ensure that the airflow enters the impeller flow channel smoothly and smoothly without airflow impact at the inlet. In order to ensure concentricity, the guide cone 4 is preferably made of metal material, so that the material removal required for static and dynamic balancing of the impeller can be placed at the guide cone. The metal material can ensure that more imbalance is reduced when the material removal volume is the same. Removing material at the guide cone can greatly avoid damage to the impeller during material removal. That is to say, when the guide cone is present, there can be no gap between the end of the main blade 2 and the edge of the wheel disc 1, which can reduce the moment of inertia of the impeller and the relevant dimensions of the volute.

[0068] A second aspect of the present invention provides a centrifugal fan, comprising a volute 5 and the above-mentioned centrifugal fan impeller.

[0069] like Figure 11-13As shown, the volute 5 defines an installation cavity 51 inside, and the centrifugal fan impeller is coaxially installed in the installation cavity 51. The top of the volute 5 is provided with a centrifugal fan inlet 52 connected to the installation cavity 51, and the circumferential side of the volute 5 is provided with a centrifugal fan outlet 53 connected to the installation cavity 51. The centrifugal fan outlet 53 is located below the wheel disc 1 in the axial direction of the volute 5 (see Figure 12 As shown, the centrifugal fan outlet 53 is located below the wheel disc 1).

[0070] In order to reduce the volume of the centrifugal fan, the volute 5 of the present invention may not include a bladeless diffuser, but this will result in the volute being unable to effectively convert a portion of the dynamic pressure into static pressure, that is, it will be unable to further improve the static pressure efficiency; and the increase in dynamic pressure will inevitably lead to increased pressure fluctuations, which will further induce noise caused by pressure fluctuations. In order to solve this problem, the present invention makes the centrifugal fan outlet 53 located below the impeller 1 in the axial direction of the volute 5, increasing the axial space at the bottom of the impeller, so that the impeller generates dynamic pressure and static pressure on the fluid. The fluid will flow downward along the axial direction of the volute due to the obstruction of the inner wall of the volute. During the flow process, the convection diffusion effect will cause the fluid flow rate to decrease and be recovered as static pressure, thereby improving the static pressure efficiency and reducing noise.

[0071] In the present utility model, Figure 11-13 As shown, the centrifugal fan also includes a motor 6. The bottom of the volute 5 is provided with a mounting opening 54 for partially mounting the motor 6 within the mounting cavity 51. The motor shaft 61 of the motor 6 is connected to the impeller 1 to drive the impeller. By partially enclosing the motor 6 within the flow channel of the volute, the present invention allows the motor to dissipate heat in two ways: conduction and convection, thereby achieving better heat dissipation.

[0072] In the present invention, in order to facilitate installation and maintenance, the volute 5 can be formed by connecting an upper volute 55 and a lower volute 56.

[0073] The specific structure and shape of the volute 5 in the utility model can be found in 11- Figure 13 shown.

[0074] A third aspect of the present invention provides a ventilation treatment device, comprising the above-mentioned centrifugal fan.

[0075] The ventilation therapy equipment may be a ventilator, an oxygen therapy device, etc.

[0076] Thus far, various embodiments of the present invention have been described in detail. To avoid obscuring the concept of the present invention, some details well known in the art have not been described. Based on the above description, those skilled in the art can fully understand how to implement the technical solutions disclosed herein.

[0077] Although some specific embodiments of the present invention have been described in detail through examples, those skilled in the art will understand that the above examples are for illustrative purposes only and are not intended to limit the scope of the present invention. Those skilled in the art will understand that the above embodiments may be modified or some technical features may be replaced with equivalents without departing from the scope and spirit of the present invention. In particular, the various technical features described in the various embodiments may be combined in any manner as long as there are no structural conflicts.

Claims

1. A centrifugal fan impeller, characterized in that: The invention comprises a wheel disc (1) and a plurality of main blades (2), wherein the plurality of main blades (2) are arranged on a side surface of the wheel disc (1) and are arranged at intervals along the circumference of the wheel disc (1), each of the main blades (2) is twisted clockwise or counterclockwise outward along the radial direction of the wheel disc (1), and in the height direction of the main blade (2), the leading edge (21) of the main blade (2) and the portion close to the leading edge (21) are formed as an arc-shaped portion (27) that is recessed toward the pressure surface (22) of the main blade (2).

2. The centrifugal fan impeller according to claim 1, characterized in that: The arcuate portion (27) is configured to gradually decrease in radius from the leading edge (21) toward the outer periphery of the wheel disc (1), and the length of the arcuate portion (27) is less than 60% of the length of the main blade (2); and / or The curvature of the leading edge (21) is less than 0.55 radians.

3. The centrifugal fan impeller according to claim 1, characterized in that: The center of the wheel disc (1) is provided with a guide portion (11) protruding toward the side where the main blade (2) is located, and the leading edge (21) extends obliquely away from the wheel disc (1) in a direction from the guide portion (11) toward the outer periphery of the wheel disc (1); and / or A reinforcement structure is provided on the other side surface of the wheel disc (1).

4. The centrifugal fan impeller according to claim 3, characterized in that: The upper edge (23) of the main blade (2) facing away from the wheel disc (1) is formed as a curve extending from the leading edge (21) toward the outer peripheral edge of the wheel disc (1) toward the wheel disc (1); and / or The wheel disc (1) has a central opening, the guide portion (11) is a conical structure protruding from the periphery of the central opening, and the centrifugal fan impeller further includes a guide cone (4), which is coaxially mounted on the guide portion (11).

5. The centrifugal fan impeller according to claim 4, characterized in that: The position where the front edge (21) and the upper edge (23) meet forms a turning point (24), and the turning point (24) is higher than the top end of the guide portion (11).

6. The centrifugal fan impeller according to claim 1, characterized in that: The trailing edge (25) of the main blade (2) is in a straight line shape, and the trailing edge (25) extends obliquely toward the wheel disc (1) in a radially outward direction of the wheel disc (1); and / or There is a distance between the outer end of the trailing edge (25) and the outer peripheral edge of the wheel disc (1).

7. The centrifugal fan impeller according to any one of claims 1 to 6, characterized in that: Splitter blades (3) are further provided between adjacent main blades (2).

8. The centrifugal fan impeller according to claim 7, characterized in that: The trailing edge of the splitter blade (3) is flush with the trailing edge (25) of the main blade (2), and the length of the splitter blade (3) is less than the length of the main blade (2); and / or The twisting trend of the splitter blade (3) is consistent with that of the main blade (2).

9. A centrifugal fan, characterized in that: The invention comprises a volute (5) and a centrifugal fan impeller according to any one of claims 1 to 8, wherein a mounting cavity (51) is defined inside the volute (5), and the centrifugal fan impeller is coaxially mounted in the mounting cavity (51).

10. The centrifugal fan according to claim 9, characterized in that: A centrifugal fan inlet (52) communicating with the mounting cavity (51) is provided at the top of the volute (5), a centrifugal fan outlet (53) communicating with the mounting cavity (51) is provided on one circumferential side of the volute (5), and the centrifugal fan outlet (53) is located below the wheel (1) in the axial direction of the volute (5); and / or The centrifugal fan comprises a motor (6); a mounting opening (54) for partially mounting the motor (6) in the mounting cavity (51) is provided at the bottom of the volute (5); and a motor shaft (61) of the motor (6) is connected to the wheel (1).

11. A ventilation therapy device, characterized in that: Including the centrifugal fan according to claim 9 or 10.

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