A low noise centrifugal fan

Abstract

The utility model relates to the technical field of centrifugal fans, and discloses a low-noise centrifugal fan, including an axis structure, a circular base and n blades, wherein the axis structure is fixedly connected to the center of the circular base, the blades are fixedly arranged on one side of the circular base, the n blades are arranged at intervals in the circumferential direction about the axis structure, and the side of the n blades facing away from the circular base constitutes the air intake side; the blades are provided with reference points, and the reference points of the n blades are on a concentric circle with the axis structure as the center; the i-th blade is ni, and the line connecting the reference point of the n-th blade and the center of the axis structure is the reference line, and the installation angle of the reference point of the i-th blade relative to the reference line in the circumferential direction is the installation angle of the blade in the circumferential direction conforms to the sine law. Not only does it ensure that the centrifugal fan meets the requirements of dynamic balance, but also the adjacent angles in the circumferential direction are not equal, which significantly weakens the pressure pulsation degree at the rotation frequency of the fan and effectively reduces the noise of high-speed operation.

Description

Technical Field

[0001] The utility model relates to the technical field of centrifugal fans, in particular to a low-noise centrifugal fan. Background Art

[0002] Sweeping robots are often used in our daily lives, and their operating noise has a great impact on the user experience. The noise sources of sweeping robots include: pneumatic noise and mechanical noise when the vacuum fan and motor are working, and friction noise generated by the friction between the wheels and brushes and the ground.

[0003] At present, in order to make the sweeping robot have strong suction, the working speed of the centrifugal fan is very high, usually above 10,000 rpm, but it also produces a lot of noise while achieving strong suction. The noise of the centrifugal fan includes rotation noise and eddy noise. The rotation noise is the noise produced by each blade periodically beating the airflow when the fan is running, and the eddy noise is the eddy structure generated when the air passes through the fan blades. This structure will form an unstable airflow around the fan and generate eddy noise.

[0004] Existing centrifugal fans use a design where multiple blades are evenly spaced, that is, the angles between any two adjacent blades about the axis are equal, thus ensuring the dynamic balance of the fan during operation. However, the blades sweep across a certain point in the air duct at the same time interval, resulting in intense pressure pulsation at that point at the fan's rotation frequency, causing the centrifugal fan to make a lot of noise when running at high speed. Utility Model Content

[0005] The technical problem to be solved by the utility model is that the blades of the existing centrifugal fan sweep over a certain point of the air duct at the same time interval, resulting in violent pressure pulsation at the point under the rotation frequency of the fan, causing the problem of high noise when the centrifugal fan runs at high speed.

[0006] In order to solve the above technical problems, the utility model provides a technical solution of a low-noise centrifugal fan:

[0007] A low-noise centrifugal fan comprises an axial structure, a circular base and n blades, wherein the axial structure is fixedly connected to the center of the circular base, the blades are fixedly arranged on one side of the circular base, the n blades are circumferentially spaced about the axial structure, and the side of the n blades facing away from the circular base constitutes an air intake side;

[0008] The blades are provided with reference points, and the reference points of n blades are located on a concentric circle with the axis structure as the center, and n≥3; the i-th blade is n i , taking the line connecting the reference point of the nth blade and the center of the axial structure as the reference line, the installation angle of the reference point of the i-th blade relative to the reference line in the circumferential direction is

[0009] The formula for the installation angle of the blade in the circumferential direction is as follows:

[0010] k is a constant.

[0011] Furthermore, the constant k=5.1.

[0012] Furthermore, the number n of the blades is an odd number.

[0013] Furthermore, the number n of the blades is any odd number between 5 and 13.

[0014] Furthermore, the blade has a root portion close to the axis structure and a tip portion far away from the axis structure, and the blade is arranged obliquely in a circumferential tangent direction from the root portion to the tip portion.

[0015] Furthermore, the tip of the blade constitutes the reference point, the center of the axis structure is taken as the origin, the straight line where the reference line is located is taken as the X-axis, the vertical line passing through the center of the axis structure and perpendicular to the reference line is taken as the Y-axis, and the quadrant angle of the tip of the i-th blade in the plane coordinate system constitutes the installation angle

[0016] Furthermore, it also includes an annular cover plate, wherein the annular cover plate and the circular base plate are coaxially arranged at intervals in the axial direction of the axial structure, and the plurality of blades are fixedly connected to the annular cover plate.

[0017] Furthermore, the contour shape of the annular cover plate is the same as the outer shape of the circular base plate, and an air inlet is opened in the middle of the annular cover plate, and the plurality of blades are circumferentially spaced and distributed around the air inlet.

[0018] Compared with the prior art, the low-noise centrifugal fan of the utility model has the following beneficial effects: the low-noise centrifugal fan adopts a design form of an axial structure, a circular base and n blades, the axial structure is fixedly connected to the center of the circular base, the blades are fixedly arranged on one side of the circular base, the axial structure is utilized to drive the n blades to rotate about the center of the circular base, and the outside air is sucked into the centrifugal fan through the air inlet side of the n blades, thereby forming an effective negative pressure suction effect.

[0019] The blades are provided with reference points, and the reference points of n blades are located on a concentric circle with the axis structure as the center, and n ≥ 3; the line connecting the reference point of the nth blade and the center of the axis structure is taken as the reference line, and the installation angle of the reference point of the i-th blade relative to the reference line in the circumferential direction is The installation angle formula of the blade is as follows:

[0020] k is a constant.

[0021] Taking the i-th blade and the i-1-th blade as an example (i≤n), the angle a between these two adjacent blades about the axis structure is Substituting into the above formula, we can see that the angle between two adjacent leaves is

[0022] Since k is a constant, it can be inferred that the angle a between two adjacent blades complies with the sinusoidal distribution within the 360° circumference, which not only ensures that the geometric center of the n blades falls exactly on the center of the axis structure, but also ensures that the centrifugal fan meets the requirements of dynamic balance. At the same time, the circumferentially adjacent angles a are not equal. For any point in the air duct, the n blades sweep by at different time intervals, which significantly weakens the pressure pulsation of the point at the rotation frequency of the fan, thereby effectively reducing the noise of the centrifugal fan when running at high speed. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a three-dimensional schematic diagram of a low-noise centrifugal fan in an embodiment of the utility model;

[0024] Figure 2 It is a schematic diagram of the distribution of the low-noise centrifugal fan in the embodiment of the utility model in a plane coordinate system;

[0025] In the figure: 1-axial structure, 10-intake side, 2-circular base plate, 3-blades, 31-root, 32-tip, 4-annular cover plate. DETAILED DESCRIPTION

[0026] The following is a further detailed description of the specific implementation of the present invention in conjunction with the accompanying drawings and examples. The following examples are used to illustrate the present invention, but are not intended to limit the scope of the present invention.

[0027] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise" and the like used in the present invention to indicate the orientation or position relationship are based on the orientation or position relationship shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

[0028] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present utility model, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0029] In the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be directly connected or indirectly connected through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0030] like Figure 1 As shown, a low-noise centrifugal fan according to an embodiment of the utility model comprises an axial structure 1, a circular base 2 and n blades 3, the axial structure 1 is fixedly connected to the center of the circular base 2, the blades 3 are fixedly arranged on one side of the circular base 2, the n blades 3 are circumferentially spaced about the axial structure 1, and the side of the n blades 3 facing away from the circular base 2 constitutes an air intake side 10.

[0031] The blade 3 is provided with a reference point, and the reference points of n blades 3 are located on a concentric circle with the axis structure 1 as the center, and n ≥ 3; the i-th blade 3 is n i , taking the line connecting the reference point of the nth blade 3 and the center of the axial structure 1 as the reference line, the installation angle of the reference point of the i-th blade 3 relative to the reference line in the circumferential direction is The installation angle formula of blade 3 in the circumferential direction is as follows:

[0032] k is a constant.

[0033] The low-noise centrifugal fan adopts a design of an axial structure 1, a circular base 2 and n blades 3. The axial structure 1 is fixedly connected to the center of the circular base 2, and the blades 3 are fixedly arranged on one side of the circular base 2. The axial structure 1 is used to drive the n blades 3 to rotate about the center of the circular base 2, and the outside air is sucked into the centrifugal fan through the air inlet side 10 of the n blades 3, thereby forming an effective negative pressure suction effect.

[0034] The blade 3 is provided with a reference point, and the line connecting the reference point of the nth blade 3 and the center of the axial structure 1 is taken as the reference line. The installation angle of the reference point of the i-th blade 3 relative to the reference line in the circumferential direction is The installation angle formula of blade 3 is as follows:

[0035] k is a constant.

[0036] Taking the i-th blade and the i-1-th blade as an example (i≤n), the angle a between these two adjacent blades about the axis structure 1 is Substituting into the above formula, we can see that the angle between two adjacent leaves is

[0037] Since k is a constant, it can be inferred that the angle a between two adjacent blades 3 complies with the sinusoidal distribution within the circumference of 360°, which not only ensures that the geometric center of the n blades 3 falls exactly on the center of the axis structure 1, but also ensures that the centrifugal fan meets the requirements of dynamic balance. At the same time, the circumferentially adjacent angles a are not equal. For any point in the air duct, the n blades 3 sweep by at different time intervals, which significantly weakens the pressure pulsation degree of the point at the rotation frequency of the fan, thereby effectively reducing the noise of the centrifugal fan when running at high speed.

[0038] In this embodiment, k=5.1, and the number n of the blades 3 is any odd number between 5 and 13. Specifically, the number n of the blades 3 is 9. In addition, the blades 3 have a root 31 close to the axis structure 1 and a tip 32 far from the axis structure 1. The blades 3 are arranged obliquely from the root 31 to the tip 32 in the circumferential tangent direction.

[0039] like Figure 2 As shown, the tip 32 of the blade 3 constitutes a reference point, the center of the axis structure 1 is taken as the origin 0, the straight line where the reference line is located is taken as the X-axis, and the vertical line passing through the center of the axis structure 1 and perpendicular to the reference line is taken as the Y-axis. The quadrant angle of the tip 32 of the i-th blade 3 in the plane coordinate system constitutes the installation angle It is convenient to determine the installation angle of n blades 3 in the centrifugal fan and the angle a between two adjacent blades about the axis structure 1. The distribution law of the blades is as follows:

[0040]

[0041] In addition, the centrifugal fan further includes an annular cover plate 4, which is coaxially spaced with the circular base plate 2 in the axial direction of the axial structure 1, and the plurality of blades 3 are fixedly connected to the annular cover plate 4. The contour shape of the annular cover plate 4 is the same as the shape of the circular base plate 2, and an air inlet is provided in the middle of the annular cover plate 4, and the plurality of blades 3 are circumferentially spaced around the air inlet. Under the rotational movement of the plurality of blades 3 about the axial structure 1, the outside air is sucked into the centrifugal fan from the air inlet of the annular cover plate 4, and an outward air flow is formed through the gap between two adjacent blades 3.

[0042] In other embodiments, k can be other constants, the number of blades n can also be any odd number greater than 3 or 13, or the number of blades n can be any even number greater than 3, which can also ensure that the circumferentially adjacent angles a are not equal. In addition, in order to meet different usage requirements, the centrifugal fan in the above embodiment can be simplified in design, for example, the annular cover plate is omitted and the circular base plate and blades are retained, which can also produce an effective negative pressure suction effect.

[0043] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and substitutions can be made without departing from the technical principle of the present invention. These improvements and substitutions should also be regarded as the protection scope of the present invention.

Claims

1. A low-noise centrifugal fan, characterized in that: It comprises an axial structure, a circular base and n blades, wherein the axial structure is fixedly connected to the center of the circular base, the blades are fixedly arranged on one side of the circular base, the n blades are arranged at intervals in the circumferential direction about the axial structure, and the side of the n blades facing away from the circular base constitutes an air intake side; The blades are provided with reference points, and the reference points of n blades are located on a concentric circle with the axis structure as the center, and n≥3; the i-th blade is n i , taking the line connecting the reference point of the nth blade and the center of the axial structure as the reference line, the installation angle of the reference point of the i-th blade relative to the reference line in the circumferential direction is The formula for the installation angle of the blade in the circumferential direction is as follows: k is a constant.

2. The low-noise centrifugal fan according to claim 1 is characterized in that: The constant k=5.

1.

3. The low-noise centrifugal fan according to claim 1 is characterized in that: The number n of the blades is an odd number.

4. The low-noise centrifugal fan according to claim 1 is characterized in that: The number n of the blades is any odd number between 5 and 13.

5. The low-noise centrifugal fan according to claim 1 is characterized in that: The blade has a root portion close to the axial structure and a tip portion far away from the axial structure, and the blade is arranged inclined in a circumferential tangent direction from the root portion to the tip portion.

6. The low-noise centrifugal fan according to claim 5, characterized in that: The tip of the blade constitutes the reference point, the center of the axis structure is taken as the origin, the straight line where the reference line is located is taken as the X-axis, the vertical line passing through the center of the axis structure and perpendicular to the reference line is taken as the Y-axis, and the quadrant angle of the tip of the i-th blade in the plane coordinate system constitutes the installation angle 7. The low-noise centrifugal fan according to claim 1, characterized in that: It also includes an annular cover plate, wherein the annular cover plate and the circular base plate are coaxially arranged at intervals in the axial direction of the axial structure, and the plurality of blades are fixedly connected to the annular cover plate.

8. The low-noise centrifugal fan according to claim 7, characterized in that: The contour shape of the annular cover plate is the same as the outer shape of the circular base plate, and an air inlet is opened in the middle of the annular cover plate, and a plurality of blades are distributed circumferentially around the air inlet at intervals.

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