CN220302357U - Centrifugal fan and breathing machine - Google Patents

Abstract

The application provides a centrifugal fan and a respirator, wherein the centrifugal fan comprises a shell and an impeller, an accommodating space is formed in the shell, an air outlet is formed in one side of the shell, a volute tongue connected with the air outlet is further arranged on the shell, and the plane of the volute tongue is perpendicular to the air flow direction of the air outlet; the impeller is arranged in the accommodating space, and a gap is reserved between the impeller and the volute tongue; the closest point of the volute tongue and the impeller is a first point, the included angle between the straight line where the connecting line of the first point and the center of the impeller is located and the first straight line is smaller than or equal to 75 degrees and larger than or equal to 60 degrees, the first straight line passes through the center of the impeller and is vertical to the airflow direction of the air outlet, the connecting line and the first straight line are located in the same plane, and the plane is vertical to the rotation axis of the impeller. The centrifugal fan and the breathing machine can improve the working efficiency of the centrifugal fan and reduce the pneumatic noise of the centrifugal fan.

Description

Centrifugal fan and breathing machine

Technical Field

The application relates to the technical field of medical equipment, in particular to a centrifugal fan and a breathing machine.

Background

As a normal physiological respiratory device capable of effectively replacing, controlling or assisting a person, a ventilator has been widely used in respiratory failure due to various reasons, anesthesia respiratory management during major surgery, respiratory support treatment and emergency resuscitation, and has taken a very important place in the field of modern medicine.

The centrifugal fan is one of important parts of the breathing machine and mainly comprises a motor, a shell and an impeller arranged in the shell. In the related art, due to the self-structure limitation of the centrifugal fan, the working efficiency of the centrifugal fan is low, and noise is easy to generate in the working process.

Disclosure of Invention

Based on the above, there is a need to provide a centrifugal fan and a respirator, which aim to improve the working efficiency of the centrifugal fan and reduce the pneumatic noise of the centrifugal fan.

The embodiment of the first aspect of the application provides a centrifugal fan, which comprises a shell and an impeller, wherein an accommodating space is formed in the shell, an air outlet is formed in one side of the shell, a volute tongue connected with the air outlet is further arranged on the shell, and the plane of the volute tongue is perpendicular to the air flow direction of the air outlet; the impeller is arranged in the accommodating space, and a gap is formed between the impeller and the volute tongue; the point that the volute tongue is closest with the impeller is the first point, the line that the first point was located with the centre of a circle of impeller is less than or equal to 75 and is equal to or more than 60 with first straight line contained angle, first straight line pass through the centre of a circle of impeller and with air outlet air current direction is perpendicular, the line with first straight line is in the coplanar, the plane with the axis of rotation of impeller is perpendicular.

In this embodiment, the straight line that the centre of a circle of first point and impeller is located is less than or equal to 75 and is greater than or equal to 60 with the contained angle of first straight line, the angle at minimum clearance between volute tongue and the impeller is 60 to 75 promptly, the structural style of volute tongue is adjusted through the setting of this angle, can optimize the air current trend in the centrifugal fan, make in the working process of centrifugal fan, the volute tongue reduces the blocking of the air current by casing inside flow direction air outlet, make the air current in the casing can smooth flow direction air outlet, thereby make the air current reduce along the flow that the clearance between volute tongue and the impeller flows back to the casing, improve centrifugal fan's work efficiency, and make centrifugal fan's work efficiency curve mild, still can reduce the probability of producing vortex phenomenon in the centrifugal fan, reduce centrifugal fan's pneumatic noise. And the volute tongue is perpendicular to the airflow outlet direction of the air outlet, so that the trend of airflow in the centrifugal fan can be optimized, the impact of the airflow on the volute tongue is reduced, and the reliability and the working stability of the centrifugal fan are improved.

In some embodiments, the spacing between the first point and the impeller is less than or equal to 0.1 times the diameter of the impeller and greater than or equal to 0.05 times the diameter of the impeller.

In some embodiments, a first arc transition structure is provided at a connection between the volute tongue and the air outlet.

In some embodiments, the radius of the arc of the first arc transition structure is less than or equal to 0.06 times the diameter of the impeller and greater than or equal to 0.03 times the diameter of the impeller.

In some embodiments, a second arc transition structure is arranged at the connection part of one side of the volute tongue far away from the air outlet and the shell, and the arc radius of the second arc transition structure is less than or equal to 3mm and greater than or equal to 1mm.

In some embodiments, the casing includes a first casing and a second casing, an air inlet communicating with the air outlet is arranged at the center of the first casing, and an annular air passage is arranged in the casing along the circumferential direction of the impeller.

In some embodiments, the impeller comprises a plurality of evenly distributed blades along the circumference of the impeller, and a flow passage is arranged between every two adjacent blades, wherein the flow passage is communicated with the air inlet and the annular air passage.

In some embodiments, the centrifugal fan further comprises a motor disposed on a side of the second housing away from the first housing, the motor having a rotation shaft, the impeller center being provided with a first mounting hole, the rotation shaft being disposed in the first mounting hole.

In some embodiments, the housing is a resin housing and the impeller is a resin impeller.

Embodiments of the second aspect of the present application provide a ventilator comprising a centrifugal fan as described in any of the above.

In the centrifugal fan that this breathing machine included, the place angle of minimum clearance between volute tongue and the impeller is 60 to 75, the structural style of volute tongue is adjusted through the setting of this angle, can optimize the air current trend in the centrifugal fan, make in the course of the work of centrifugal fan, the volute tongue reduces the blocking of the air current of flowing to the air outlet by inside casing, make the air current in the casing can smooth and easy flow to the air outlet, thereby make the air current reduce along the flow that the clearance between volute tongue and the impeller flows back to the casing, improve centrifugal fan's work efficiency, and make centrifugal fan's work efficiency curve mild, still can reduce the probability of producing vortex phenomenon in the centrifugal fan, reduce centrifugal fan's pneumatic noise. And the volute tongue is perpendicular to the airflow outlet direction of the air outlet, so that the trend of airflow in the centrifugal fan can be optimized, the impact of the airflow on the volute tongue is reduced, and the reliability and the working stability of the centrifugal fan are improved.

Drawings

FIG. 1 is a partial structural top view of a centrifugal fan in an embodiment of the present application;

reference numerals: the centrifugal fan-100, the shell-1, the air outlet-11, the volute tongue-12, the first point-121, the second shell-13, the annular air passage-14, the impeller-2, the blades-21, the first straight line-22, the runner-23 and the first mounting hole-24.

Detailed Description

In order to facilitate an understanding of the present application, a more complete description of the present application will now be provided with reference to the relevant figures. Preferred embodiments of the present application are shown in the drawings. This application may, however, be embodied in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete.

Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein in the description of the application is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. The term "and/or" as used herein includes any and all combinations of one or more of the associated listed items.

In describing positional relationships, when an element such as a layer, film or substrate is referred to as being "on" another element, it can be directly on the other element or intervening elements may also be present unless otherwise indicated. Further, when a layer is referred to as being "under" another layer, it can be directly under, or one or more intervening elements may also be present. It will also be understood that when a layer is referred to as being "between" two layers, it can be the only layer between the two layers, or one or more intervening elements may also be present.

Where the terms "comprising," "having," and "including" are used herein, another component may also be added unless explicitly defined as such, e.g., "consisting of … …," etc. Unless mentioned to the contrary, singular terms may include plural and are not to be construed as being one in number.

It will be understood that, although the terms "first," "second," etc. may be used herein to describe various elements, these elements should not be limited by these terms. These terms are only used to distinguish one element from another element. For example, a first element could be termed a second element, and, similarly, a second element could be termed a first element, without departing from the scope of the present application.

It will be further understood that when interpreting an element, although not explicitly described, the element is intended to include the range of errors which should be within the acceptable limits of deviation from the particular values identified by those skilled in the art. For example, "about," "approximately," or "substantially" may mean within one or more standard deviations, and is not limited herein.

Further, in the specification, the phrase "planar distribution diagram" refers to the drawing when the target portion is viewed from above, and the phrase "cross-sectional diagram" refers to the drawing when the cross section taken by vertically cutting the target portion is viewed from the side.

Further, the drawings are not 1:1, and the relative dimensions of the various elements are drawn by way of example only in the drawings and are not necessarily drawn to true scale.

As a normal physiological respiratory device capable of effectively replacing, controlling or assisting a person, a ventilator has been widely used in respiratory failure due to various reasons, anesthesia respiratory management during major surgery, respiratory support treatment and emergency resuscitation, and has taken a very important place in the field of modern medicine. The centrifugal fan is one of important parts of the breathing machine and mainly comprises a motor, a shell and an impeller arranged in the shell. Centrifugal fans are a major source of ventilator noise, particularly for home ventilators, which has a significant impact on both the user's rest and therapeutic effect.

In the related art, due to the self-structure limitation of the centrifugal fan, the working efficiency of the centrifugal fan is low, and noise is easy to generate in the working process. Specifically, for a centrifugal fan, after the air flow is accelerated by an impeller rotating at a high speed, most of the air flow flows out through an air outlet of the centrifugal fan, and a small part of the air flow flows back to the shell along a gap between the volute tongue and the impeller. The impact of high-speed air flow on the volute tongue can generate higher pneumatic noise, so that the structural form and the position of the volute tongue have great influence on the efficiency and the noise of the centrifugal fan.

When the volute tongue is of a flat tongue structure, the plane of the volute tongue is tangent to the shell, the plane of the volute tongue is perpendicular to the direction of an air flow outlet in the air outlet of the centrifugal fan, and the centrifugal fan of the flat tongue structure has the advantages of flat efficiency curve and low noise. However, compared to centrifugal fans having a sharp-tongue, deep-tongue, and short-tongue structure, more airflow flows back to the housing along the gap between the volute tongue and the impeller under the influence of the flat-tongue structure, resulting in a centrifugal fan having a flat-tongue structure that is less efficient.

Based on the above-mentioned problem, this application provides a centrifugal fan and breathing machine, aims at improving centrifugal fan's work efficiency, reduces centrifugal fan's pneumatic noise.

The embodiment of the first aspect of the present application provides a centrifugal fan 100, as shown in fig. 1, including a casing 1 and an impeller 2, where an accommodating space is provided in the casing 1, an air outlet 11 is provided on one side of the casing 1, a volute tongue 12 connected with the air outlet 11 is further provided on the casing 1, and a plane where the volute tongue 12 is located is perpendicular to an airflow direction of the air outlet 11; the impeller 2 is arranged in the accommodating space, and a gap is reserved between the impeller 2 and the volute tongue 12; the closest point of the volute tongue 12 and the impeller 2 is a first point 121, an included angle theta between a straight line where the first point 121 is connected with the center of the impeller 2 and the first straight line 22 is less than or equal to 75 degrees and more than or equal to 60 degrees, the first straight line 22 passes through the center of the impeller 2 and is perpendicular to the airflow direction of the air outlet 11, the connecting line and the first straight line 22 are in the same plane, and the plane is perpendicular to the rotation axis of the impeller 2.

In this embodiment, as shown in fig. 1, the casing 1 includes a first casing and a second casing 131, the center of the first casing is provided with an air inlet communicated with the air outlet 11, along the circumference of the impeller 2, an annular air passage 14 is provided in the casing 1, and the air inlet is communicated with the air outlet 11 through the annular air passage 14. Under the action of the impeller 2 rotating at a high speed, air flow enters the shell 1 from the air inlet on the first shell, kinetic energy and internal energy are obtained through the work of the impeller 2, the air flow is further converted into required high-pressure air flow through the annular air passage 14, and finally the required high-pressure air flow flows out from the air outlet 11 and is connected into the next-stage equipment of the breathing machine. In order to improve the rotation efficiency of the impeller 2, the casing 1 is mostly designed in a spiral shape; the annular air passage 14 can optimize the air flow direction in the centrifugal fan 100, further improve the rotation efficiency of the impeller 2 and improve the working efficiency of the centrifugal fan 100.

In this embodiment, as shown in fig. 1, the volute tongue 12 is a "tongue-shaped" structure formed by the wall of the casing 1 at the connection between the casing 1 and the air outlet 11 of the centrifugal fan 100, and is used for preventing part of the airflow from circulating in the casing 1. When the impeller 2 rotates, the airflow in the annular air passage 14 passes near the volute tongue 12, the volute tongue 12 divides the airflow into two parts, most of the airflow flows to the air outlet 11 of the centrifugal fan 100 along the annular air passage 14, and the small part of the airflow flows back to the accommodating space of the casing 1 through the gap between the volute tongue 12 and the impeller 2, and returns to the volute tongue 12 to participate in new flow division after rotating once again along with the impeller 2 in the accommodating space. The shape, geometry and size of the gap between the volute tongue 12 and the periphery of the impeller 2 have a large influence on the noise of the centrifugal fan 100.

In this embodiment, as shown in fig. 1, the closest point between the volute tongue 12 and the impeller 2 is a first point 121, the included angle θ between the straight line where the first point 121 is located and the center of the impeller 2 is less than or equal to 75 ° and greater than or equal to 60 ° and the first straight line 22, the first straight line 22 passes through the center of the impeller 2 and is perpendicular to the airflow direction of the air outlet 11, the straight line and the first straight line 22 are in the same plane, the plane is perpendicular to the rotation axis of the impeller 2, that is, the angle where the minimum gap between the volute tongue 12 and the impeller 2 is located is 60 ° to 75 °, and the volute tongue 12 is perpendicular to the airflow outlet direction of the air outlet 11 but is not tangential to the casing 1. The plane in which the connection line and the first straight line 22 are located may be a parting plane of the first case and the second case 131. The volute tongue 12 is perpendicular to the airflow outlet direction of the air outlet 11, so that the trend of airflow in the centrifugal fan 100 can be optimized, the impact of the airflow on the volute tongue 12 is reduced, the pulsation is reduced, and the reliability and the working stability of the centrifugal fan 100 are improved.

In this embodiment, as shown in fig. 1, the angle of the minimum gap between the volute tongue 12 and the impeller 2 is 60 ° to 75 °, and the structural form of the volute tongue 12 is adjusted by the setting of the angle, so that the trend of the airflow in the centrifugal fan 100 can be optimized, the blocking of the volute tongue 12 to the airflow flowing from the inside of the casing 1 to the air outlet 11 is reduced in the working process of the centrifugal fan 100, so that the airflow in the casing 1 can smoothly flow to the air outlet 11, thereby reducing the flow of the airflow flowing back to the casing 1 along the gap between the volute tongue 12 and the impeller 2, improving the working efficiency of the centrifugal fan 100, and making the working efficiency curve of the centrifugal fan 100 gentle, and also reducing the probability of vortex phenomenon in the centrifugal fan 100, and reducing the aerodynamic noise of the centrifugal fan 100.

In some embodiments, as shown in fig. 1, the spacing T between the first point 121 and the impeller 2 is less than or equal to 0.1 times the diameter D of the impeller 2 and greater than or equal to 0.05 times the diameter D of the impeller 2. This interval T's setting can avoid because of interval T between first point 121 and the impeller 2 is too little, leads to centrifugal fan 100 to appear efficiency decline, noise increase scheduling problem, influences centrifugal fan 100 work effect to and avoid because of interval T between first point 121 and the impeller 2 is too big, leads to centrifugal fan 100 to appear noise and efficiency all decline scheduling problem, influences centrifugal fan 100's work efficiency, thereby under the influence of guaranteeing centrifugal fan 100's work efficiency, reduce the pneumatic noise that centrifugal fan 100 produced. Alternatively, the spacing T between the first point 121 and the impeller 2 may be 0.07 times the diameter D of the impeller 2; when the diameter D of the impeller 2 is 200mm, the distance T between the first point 121 and the impeller 2 ranges from 10mm to 20mm. The distance T between the first point 121 and the impeller 2 may be set according to practical requirements, which is not limited in this application.

In some embodiments, as shown in fig. 1, a first arc transition structure is disposed at a connection position between the volute tongue 12 and the air outlet 11 near one side of the impeller 2, and an arc radius R1 of the first arc transition structure is less than or equal to 0.06 times and more than or equal to 0.03 times a diameter D of the impeller 2. Specifically, the first arc transition structure is arranged on the inner side of the shell 1, namely, the first arc transition structure is arranged on the inner edge of the joint of the volute tongue 12 and the air outlet 11, so that the joint of the volute tongue 12 and the air outlet 11 is smooth in transition, the trend of air flow in the centrifugal fan 100 is optimized, the impact of the air flow on the volute tongue 12 is reduced, the pneumatic noise of the centrifugal fan 100 is reduced on the premise of ensuring the efficiency of the centrifugal fan 100, and the reliability and the working stability of the centrifugal fan 100 are improved. Alternatively, the radius R1 of the first arc transition structure may be 0.045 times the diameter D of the impeller 2, and when the diameter D of the impeller 2 is 200mm, the radius R1 of the first arc transition structure may be 9mm. The arc radius R1 of the first arc transition structure may be set according to practical requirements, which is not limited in this application.

In some embodiments, as shown in fig. 1, a second arc transition structure is disposed at the connection position between the side of the volute tongue 12 away from the air outlet 11 and the casing 1, where the arc radius R2 of the second arc transition structure is less than or equal to 3mm and greater than or equal to 1mm. The second arc transition structure is also arranged on the inner side of the shell 1, namely, the inner edge of the joint of one side of the volute tongue 12 far away from the air outlet 11 and the shell 1 is provided with the second arc transition structure R2, so that the joint of one side of the volute tongue 12 far away from the air outlet 11 and the shell 1 is smooth in transition, the trend of air flow in the centrifugal fan 100 is optimized, the impact of the air flow on the volute tongue 12 is reduced, the pneumatic noise of the centrifugal fan 100 is reduced on the premise of ensuring the efficiency of the centrifugal fan 100, and the reliability and the working stability of the centrifugal fan 100 are improved. Alternatively, the radius R2 of the second arc transition structure may be 2.5mm. The arc radius R2 of the second arc transition structure may be set according to practical requirements, which is not limited in this application.

In some embodiments, as shown in fig. 1, the impeller 2 includes a plurality of evenly distributed blades 21 along the circumference of the impeller 2, and a flow passage 23 is provided between adjacent blades 21, and the flow passage 23 communicates with the air inlet and the annular air passage 14. When the air inlet is a circular through hole, the air flow can uniformly enter the centrifugal fan 100, the flow loss of the air flow is reduced, the blades 21 are positioned in the accommodating space and uniformly arranged around the axis of the air inlet, when the rotating shaft of the motor drives the blades 21 to rotate, the air flow flows into the flow channel 23 from the air inlet, then flows to the annular air channel 14 under the driving of the blades 21, and finally flows to the outside of the shell 1 from the air outlet 11 communicated with the annular air channel 14, and finally flows to the next-stage equipment of the breathing machine.

In some embodiments, the centrifugal fan 100 further includes a motor disposed on a side of the second housing 131 remote from the first housing, the motor having a rotation shaft, the impeller 2 being centrally provided with the first mounting hole 24, the rotation shaft being disposed in the first mounting hole 24. The rotation of the rotating shaft of the motor drives the impeller 2 to rotate. Motors include, but are not limited to, slotless, brushless coreless motors with low inertia, high rotational speed, and low torque ripple.

In some embodiments, the second housing 131 is centrally provided with a second mounting hole, the second mounting hole and the first mounting hole 24 are coaxially disposed, and the rotation shaft is disposed in the first mounting hole 24 through the second mounting hole. The second mounting hole can enable the rotating shaft to extend into the shell 1 to be connected with the impeller 2, and air flow in the shell 1 can be utilized to radiate heat for the motor, so that the service life of the motor is prolonged.

In some embodiments, the housing 1 is a resin housing 1 and the impeller 2 is a resin impeller 2. The first casing and the second casing 131 can be formed by integral injection molding of a resin material, and the impeller 2 can also be formed by integral injection molding of a resin material, so that the preparation flow of the casing 1 and the impeller 2 can be simplified, and the production cost of the centrifugal fan 100 can be reduced. Alternatively, the first and second housings 131 may be integrally injection-molded of a plastic material, and the impeller 2 may be integrally injection-molded of a plastic material. The materials and preparation methods of the casing 1 and the impeller 2 can be set according to practical requirements, which are not limited in this application.

Embodiments of the second aspect of the present application provide a ventilator comprising a centrifugal fan 100 as described in any of the above. Centrifugal blower 100 is a critical component of a ventilator, and centrifugal blower 100 may provide compressed air to the ventilator at a pressure and flow rate such that a mixed flow of oxygen and at a desired flow rate is established in the ventilator as required for clinical treatment. Specifically, under the action of the impeller 2 rotating at a high speed, air flow enters the centrifugal fan 100 from the air inlet, kinetic energy and internal energy are obtained through the work of the impeller 2, the air flow is further converted into required high-pressure air flow through the flow channel 23 between the adjacent blades 21, and finally the required high-pressure air flow flows out from the air outlet 11 of the centrifugal fan 100 and is connected into the next-stage equipment of the respirator.

In the centrifugal fan 100 included in the breathing machine in this embodiment, as shown in fig. 1, the angle of the minimum gap between the volute tongue 12 and the impeller 2 is 60 ° to 75 °, the structural form of the volute tongue 12 is adjusted through the setting of the angle, so that the trend of airflow in the centrifugal fan 100 can be optimized, the blocking of the volute tongue 12 to the airflow flowing from the inside of the casing 1 to the air outlet 11 is reduced in the working process of the centrifugal fan 100, the airflow in the casing 1 can smoothly flow to the air outlet 11, the flow of the airflow flowing back to the casing 1 along the gap between the volute tongue 12 and the impeller 2 is reduced, the working efficiency of the centrifugal fan 100 is improved, the working efficiency curve of the centrifugal fan 100 is gentle, the probability of generating vortex phenomenon in the centrifugal fan 100 can be reduced, and the pneumatic noise of the centrifugal fan 100 is reduced. And the volute tongue 12 is perpendicular to the airflow outlet direction of the air outlet 11, so that the trend of airflow in the centrifugal fan 100 can be optimized, the impact of the airflow on the volute tongue 12 is reduced, and the reliability and the working stability of the centrifugal fan 100 are improved.

The technical features of the above-described embodiments may be arbitrarily combined, and all possible combinations of the technical features in the above-described embodiments are not described for brevity of description, however, as long as there is no contradiction between the combinations of the technical features, they should be considered as the scope of the description.

The above examples merely represent a few embodiments of the present application, which are described in more detail and are not to be construed as limiting the scope of the utility model. It should be noted that it would be apparent to those skilled in the art that various modifications and improvements could be made without departing from the spirit of the present application, which would be within the scope of the present application. Accordingly, the scope of protection of the present application is to be determined by the claims appended hereto.

Claims (10)

1. A centrifugal fan, comprising:

the shell is internally provided with an accommodating space, one side of the shell is provided with an air outlet, the shell is also provided with a volute tongue connected with the air outlet, and the plane of the volute tongue is perpendicular to the air flow direction of the air outlet;

the impeller is arranged in the accommodating space, and a gap is reserved between the impeller and the volute tongue;

the point that the volute tongue is closest with the impeller is the first point, the line that the first point was located with the centre of a circle of impeller is less than or equal to 75 and is equal to or more than 60 with first straight line contained angle, first straight line pass through the centre of a circle of impeller and with air outlet air current direction is perpendicular, the line with first straight line is in the coplanar, the plane with the axis of rotation of impeller is perpendicular.

2. The centrifugal fan of claim 1, wherein a distance between the first point and the impeller is 0.1 times or less and 0.05 times or more a diameter of the impeller.

3. The centrifugal fan of claim 1, wherein a first arc transition structure is provided at a junction of the volute tongue and the air outlet.

4. A centrifugal fan according to claim 3, wherein the radius of the first arc transition structure is 0.06 times or less and 0.03 times or more the diameter of the impeller.

5. The centrifugal fan according to claim 1, wherein a second arc transition structure is arranged at a joint of one side of the volute tongue away from the air outlet and the shell, and the arc radius of the second arc transition structure is less than or equal to 3mm and greater than or equal to 1mm.

6. The centrifugal fan according to claim 1, wherein the housing comprises a first housing and a second housing, an air inlet communicated with the air outlet is formed in the center of the first housing, and an annular air passage is formed in the housing along the circumferential direction of the impeller.

7. The centrifugal fan of claim 6, wherein the impeller includes a plurality of evenly distributed blades along a circumference of the impeller, and wherein adjacent blades have flow passages therebetween, the flow passages being in communication with the air inlet and the annular air passage.

8. The centrifugal fan of claim 6, further comprising a motor disposed on a side of the second housing remote from the first housing, the motor having a shaft, the impeller center being provided with a first mounting hole, the shaft being disposed in the first mounting hole.

9. The centrifugal fan of claim 1, wherein the housing is a resin housing and the impeller is a resin impeller.

10. A ventilator comprising a centrifugal fan as claimed in any one of claims 1 to 9.