Impeller and fan motor
The impeller and fan motor design addresses noise reduction by periodically varying the angular pitch between blades, generating diverse frequencies to mitigate noise amplification and vibrations.
Patent Information
- Authority / Receiving Office
- JP · JP
- Patent Type
- Applications
- Current Assignee / Owner
- MINEBEAMITSUMI INC
- Filing Date
- 2024-12-25
- Publication Date
- 2026-07-07
AI Technical Summary
Existing fan motors generate significant noise due to the rotation of the blades, which is a concern in various applications.
The impeller and fan motor design incorporates a periodic change in the angular pitch between adjacent blades, following a specific formula, to reduce noise by generating different frequencies of wind noise, thereby preventing noise amplification.
This design effectively reduces noise and suppresses vibrations by ensuring that different frequencies of wind noise are generated as each blade passes, rather than amplifying a single frequency, thus minimizing operational noise.
Smart Images
Figure 2026112631000001_ABST
Abstract
Description
[Technical Field]
[0001] This invention relates to impellers and fan motors, and more particularly to a technology for reducing noise generated by the rotation of the blades. [Background technology]
[0002] Fan motors are known as blowers that are widely used for cooling, ventilation, and air conditioning in home appliances, office automation equipment, and industrial equipment, as well as for air conditioning and ventilation in vehicles. One type of fan motor is known in which a rotatable blade support is arranged in a housing, multiple blades are fixed to the blade support, and as the blade support rotates, air is drawn in from the intake port and blown outwards from the housing through exhaust ports formed around the entire circumference of the side of the housing (see, for example, Patent Document 1).
[0003] In the fan motor described in Patent Document 1, each blade is arranged such that the mounting angle between adjacent blades follows an arithmetic progression, which is said to reduce the noise generated when the blades rotate. [Prior art documents] [Patent Documents]
[0004] [Patent Document 1] Patent No. 5183451 [Overview of the Initiative] [Problems that the invention aims to solve]
[0005] In fan motors, there is a strong demand to reduce noise generated by the rotation of the blades as much as possible. One of the objectives of this invention is to provide an impeller and a fan motor that can reduce the noise generated by the rotation of the blades. [Means for solving the problem]
[0006] The present invention comprises a plurality of blades arranged in the circumferential direction, a first blade, a second blade adjacent to the first blade in the circumferential direction, and an nth blade which is the nth blade in the circumferential direction, wherein the angular pitch of the nth blade is θ n Let the angle pitch of the (n+1)th blade be θ. n+1 When this is done, the angular pitch θ n+1 and the aforementioned angular pitch θ n It is an impeller in which the difference between [the current state] and [the current state] changes periodically.
[0007] The impeller and fan motor of the present invention can effectively reduce noise associated with the rotation of the blades. [Brief explanation of the drawing]
[0008] [Figure 1] This is a perspective view showing a fan motor according to an embodiment of the present invention. [Figure 2] This is a front view showing a fan motor of an embodiment. [Figure 3] Figure 2 shows a cross-sectional view along line III-III (A) and a magnified view of a portion of (A) (B). [Figure 4] This is a perspective view showing the impeller in the embodiment. [Figure 5] This is a plan view showing the impeller in the embodiment. [Figure 6] This is a cross-sectional view taken along the line VI-VI in Figure 5. [Figure 7] (A) is a graph showing the relationship between the blade number and the difference in angular pitch in equation (1) of the embodiment, and (B) is a plan view of the impeller. [Figure 8] (A) is a graph obtained by substituting numerical values into equation (2) in an embodiment, and (B) is an image diagram showing the arrangement of the feathers. [Figure 9] (A) is a graph showing the relationship between the blade number and the difference in angular pitch in a modified embodiment, and (B) is an illustrative diagram showing the arrangement of the blades. [Figure 10](A) is a graph showing the relationship between the blade number and the difference in angular pitch in another modification of the embodiment, and (B) is an image diagram showing the blade arrangement.
Mode for Carrying Out the Invention
[0009] 1. Configuration of the Fan Motor FIG. 1 is a perspective view showing a fan motor 100 according to an embodiment of the present invention, and FIG. 2 is a plan view. The fan motor 100 includes a casing 110 composed of an upper casing 120 made of resin and a lower casing 130 made of resin. The casing 110 is square in plan view (including a substantially square shape), but is not limited thereto and may be circular.
[0010] At four corners of the upper casing 120, legs 121 protruding downward are formed. The legs 121 are formed by forming a substantially rectangular notch at the corner of the upper casing 120 and extending downward from the edge of the notch.
[0011] On the lower casing 130, protrusions 131 protruding upward are formed, and the upper ends of the protrusions 131 are connected to the lower ends of the legs 121. The protrusions 131 have the same axial cross-sectional shape as the legs 121. On the upper end of the protrusion 131, a step 131a with the inner peripheral side portion lowered by one step is formed. On the other hand, on the lower end of the leg 121, a step 121a with the inner peripheral side portion protruding downward by one step is formed. Then, the step 121a and the step 131a are fitted to each other, and both are joined to each other by, for example, adhesion.
[0012] On the radially outer side of the protrusion 131, a through hole 132 is formed, and a metal collar 133 is fixed around the through hole 132. The collar 133 is integrally formed with the lower casing 130 by insert molding. For example, a bolt is inserted through the through hole 132 and tightened into a screw hole of a device to which the fan motor 100 is to be mounted.
[0013] A circular intake port 122 is formed in the center of the upper casing 120. Additionally, outlet ports 112 are formed along the entire circumference of the casing 110, excluding the legs 121 and projections 131. In other words, multiple outlet ports 112 are formed between adjacent projections 131. Inside the casing 110, a flow path 111 is formed by the casing, connecting the intake port 122 and the outlet ports 112. An impeller 160 is rotatably positioned in the flow path 111. As the impeller 160 rotates clockwise in the diagram, the blades 164 of the impeller 160 draw air in through the intake port 122. The drawn-in air passes between the blades 164 and is blown radially outward from the impeller 160, passing through the flow path 111 and being discharged from the outlet ports 112. The configuration of the impeller 160 will be described in detail later.
[0014] As shown in Figure 3, a motor 140 is positioned in the center of the casing 110. The motor 140 is an outer rotor type brushless DC motor. In this description, the direction of the motor 140's shaft 141 is referred to as the "axial direction," the direction perpendicular to the axial direction is referred to as the "radial direction," and the direction in which the shaft 141 rotates is referred to as the "circumferential direction." Also, terms indicating directions such as "up" and "down" are based on Figure 3.
[0015] An annular projection 134 is formed in the center of the lower casing 130, projecting upward in the axial direction. A cylindrical metal bearing holder 142 is fixed to the annular projection 134 with adhesive. Ball bearings 143 are fixed to both sides of the bearing holder 142 in the axial direction by means of press-fitting, adhesive, or other means. The shaft 141 is fixed to the ball bearings 143 in a rotatable manner by means of press-fitting, adhesive, or other means.
[0016] A rotor yoke 144 made of soft magnetic material (iron) is fixed to the upper end of the shaft 141 by means of press-fitting or other means. The rotor yoke 144 is a bottomed cylindrical shape, and an annular rotor magnet 145 is fixed to the inner circumferential surface of its cylindrical portion with adhesive. The rotor magnet 145 is magnetized in such a way that the polarity of the magnetic poles alternates between NSNS·· along the circumferential direction. A coil spring 146 is interposed between the rotor yoke 144 and the ball bearing 143 to apply preload to the ball bearing 143.
[0017] A stator 150 is fixed to the outer circumference of the bearing holder 142. The stator 150 consists of a stator core 151, an insulator 152, and a stator coil 153. The stator core 151 has a structure in which multiple thin sheets of soft magnetic material such as electromagnetic steel are laminated and crimped together. The stator core 151 has multiple pole teeth 151b that extend radially outward from a core back portion 151a which has an annular shape.
[0018] A resin insulator 152 is integrally molded onto the stator core 151 by insert molding, and a stator coil 153 is wound around multiple pole teeth 151b via the insulator 152. The insulator 152 insulates the stator core 151 from the stator coil 153. The insulator 152 may be made by bonding together separate parts that are separated in the axial direction.
[0019] The core back portion 151a has an opening that penetrates axially, and the opening of the core back portion 151a is fitted to the outer circumferential surface of the bearing holder 142, and the lower end surface of the core back portion 151a is placed on the annular projection 134 of the lower casing 130, thereby axially positioning the stator core 151. However, this is not the only option; the outer circumferential surface of the bearing holder 142 may be press-fitted into the opening of the core back portion 151a.
[0020] The rotor magnet 145 is positioned opposite the outer circumferential surface of the pole teeth 151b of the stator core 151, with a gap (magnetic gap) between the outer circumferential surface of the pole teeth 151b and the rotor magnet 145. In other words, in the radial direction, the outer circumferential surface of the pole teeth 151b and the rotor magnet 145 face each other with a magnetic gap in between. A circuit board 154 is positioned below the insulator 152. The circuit board 154 is electrically connected to the stator coil 153, and by periodically switching the polarity of the current applied to the stator coil 153 using a drive circuit formed on the circuit board 154, a driving force is generated that causes the rotor magnet 145 to rotate around the shaft 141, and the impeller 160 rotates.
[0021] 2. Impeller configuration The impeller 160 in the embodiment will be described with reference to Figures 4 to 6. In Figure 4, reference numeral 161 denotes a cylinder. The cylinder 161 is a bottomed cylindrical shape, and the impeller 160 is rotatably mounted by the motor 140 by placing the cylinder 161 over the rotor yoke 144 and bonding it. An annular plate 162 is formed on the outer circumferential surface of the cylinder 161, extending radially outward and axially downward. The annular plate 162 has an arc-shaped cross-section that is convex axially downward.
[0022] Multiple blades 164 are integrally formed on the upper surface of the annular plate 162. All blades 164 have the same shape and are arranged in the circumferential direction at an angular pitch defined by the present invention, facing the outer circumference of the cylinder 161 with a constant gap in the radial direction. Furthermore, the blades 164 are backward-facing blades that are curved so as to be concave in the opposite direction to the direction of rotation, and are arranged at a constant angle in the direction of rotation indicated by arrow R in Figure 5 relative to the annular plate 162, and are also arranged at a downward inclination toward the radially outward direction, as shown in Figure 6.
[0023] A ring 165 is integrally formed on the peripheral edge of the upper surface in the axial direction of the blade 164. As a result, the blades 164 are connected to each other. In the radial direction, the annular plate 162 extends to a position intermediate between the ring 165 and the outer peripheral surface of the cylinder 161. Thus, since the blades 164 are connected to each other by the ring 165 at the peripheral edge and by the annular plate 162 at the inner peripheral portion, they are firmly connected to the cylinder 161.
[0024] In this embodiment, the angular pitch of the blades 164 is set as follows. That is, among the plurality of blades 164, a first blade 164, a second blade 164 adjacent to the first blade 164 in the circumferential direction, and an nth blade 164 which is the nth blade in the circumferential direction are set, and the angular pitch of the nth blade 164 is θ n and the angular pitch of the (n + 1)th blade 164 is θ n+1 When this is done, the difference between the angular pitch θ n+1 and the angular pitch θ n is periodically changed.
[0025] Particularly, in the above embodiment, when the number of the plurality of blades 164 is Z, the periodic function is f(n), and the amplitude of the periodic function is A, the difference between the angular pitch θ n+1 and the angular pitch θ n is made to follow the following formula (1).
Equation
[0026] Here, when f(n) is, for example, a sine wave, the periodic function is as follows. In the formula, "F" is the frequency of the periodic function. Specifically, it means that it vibrates F times (repeats reaching 360° F times) until n reaches Z.
Equation
[0027] Figure 7(A) is a graph in equation (1) where the number of the blades 164 is shown on the horizontal axis and the difference in angular pitch between adjacent blades 164 is shown on the vertical axis, and (B) is a plan view of the impeller 160 showing the arrangement of the blades 164. As shown in Figure 7(B), a first region S in which the blades 164 are spaced far apart and a second region D in which the blades 164 are spaced closer together compared to the first region S are formed, and the first region S and the second region D each appear alternately three times in the circumferential direction.
[0028] Also, as shown in Figure 7(A), θ n+1 - θ n If we take the point where the angle is 6.1° (more precisely, the value obtained by dividing 360° by the number of blades, 59, and rounding it to two decimal places) as the reference point, then when the amplitude A is 2, θ n+1 - θ n The amplitude fluctuates by ±2° around 6°. As the amplitude A increases, the degree of abruptness in the first region S increases, and the degree of density in the second region D increases.
[0029] Figure 8(A) shows equation (1) when the number of blades Z=59, the wave is sinusoidal, the frequency F=3, and the amplitude A=2, and (B) is an image of blade 164. As shown in Figure 8(B), since the periodic function f(n) is sinusoidal, the center of gravity of impeller 160 and the center of rotation of impeller 160 coincide.
[0030] Here, the first region S is defined by the angular pitch θ. n+1 and angle pitch θ n This is the region where the difference is greater than the value obtained by dividing 360 by the number of sheets Z. Furthermore, the second region D is defined by the angular pitch θ. n+1 and angle pitch θ n The difference between these two regions is smaller than the value obtained by dividing 360 by the number of sheets Z, and in the circumferential direction, the first region S and the second region D are arranged alternately at intervals equal to the period of the periodic function.
[0031] Furthermore, the number of blades Z of the 164 blades is an integer greater than or equal to 4. In addition, the frequency F of the periodic function f(n) is an integer greater than or equal to 2 and less than or equal to the number of blades Z-2, and not Z / 2. If the frequency F of the periodic function f(n) is an even number and is Z / 2, then equation (2) above becomes as follows, and it no longer holds true as a periodic function.
number
[0032] As described above, in the impeller 160 and fan motor 100 of the above embodiment, the difference in angular pitch between adjacent blades 164 changes periodically, so sounds of different frequencies are generated from each blade 164 with a different angular pitch. In other words, when observing the rotation of the blades 164 at the same location, wind noise is continuously generated as the first blade 164 passes and the second blade 164 comes along, and if the difference in angular pitch between the blades 164 is constant, wind noise of the same frequency is amplified and becomes noise. In the above embodiment, wind noise of a different frequency is generated each time a blade 164 passes, so the wind noise is not amplified. Therefore, the noise associated with the operation of the fan motor 100 can be effectively reduced.
[0033] In particular, in the above embodiment, the angular pitch θ n+1 and angle pitch θ n Since the difference is made to follow the above equation (1), the center of gravity of the impeller 160 and the center of the rotation axis of the impeller 160 coincide. Therefore, the generation of vibrations caused by the rotation of the impeller 160 is suppressed.
[0034] 3. Example of changes The present invention is not limited to the embodiments described above, and various modifications are possible as follows. i) Figure 9 is a graph of equation (1) when the number of blades Z=23, the wave is triangular, the frequency F=3, and the amplitude A=5, and (B) is an image of the 164 blades. In this example as well, the triangular wave is a periodic function f(n), and as shown in Figure 9(B), the arrangement of the 164 blades results in the first region S and the second region D appearing alternately in the circumferential direction. Therefore, it produces the same effect as the embodiment described above.
[0035] ii) Figure 10 is a graph of equation (1) when the number of blades Z=23, the wave is square, the frequency F=3, and the amplitude A=5, and (B) is an image of the blades 164. In this example as well, the square wave is a periodic function f(n), and as shown in Figure 11(B), the arrangement of the blades 164 results in the first region S and the second region D appearing alternately in the circumferential direction. Therefore, it produces the same effect as the embodiment described above.
[0036] iii) The present invention is not limited to radial fan motors as described in the above embodiments, but can also be applied to axial fan motors and centrifugal fans. iv) The present invention is not limited to the periodic functions described above, but can be applied to any periodic function, such as a cosine wave. v) Furthermore, the angular pitch θ n+1 and the aforementioned angular pitch θ n If the difference between the two changes periodically, then that change can be arbitrarily set without being dependent on a periodic function. In short, the arrangement of the blades 164 should be such that the first region S and the second region D appear alternately in the circumferential direction. vi) The bearings applied to the motor of the present invention are not limited to ball bearings; various types of bearings, such as sliding bearings, can be applied. vii) The stator core applied to the motor of the present invention may be made of an amorphous material. [Industrial applicability]
[0037] This invention can be used in fan motors used for air supply, ventilation, cooling, etc., in home appliances, office automation equipment, and air conditioning systems for industrial and vehicle use. [Explanation of Symbols]
[0038] 100...Fan motor, 110...Casing, 111...Flow path, 112...Outlet, 120...Upper casing, 121...Legs, 121a...Step, 122...Inlet, 130...Lower casing, 131...Protrusion, 131a...Step, 132...Through hole, 133...Collar, 134...Annular projection, 137...Recess, 140...Motor, 141...Shaft, 142...Bearing holder, 143...Ball bearing, 1 44...Rotor yoke, 145...Rotor magnet, 146...Coil spring, 150...Stator, 151...Stator core, 151a...Core back section, 151b...Poles, 152...Insulator, 153...Stator coil, 154...Circuit board, 160...Impeller, 161...Cylinder, 162...Annular plate, 164...Blade, 165...Ring, R...Arrow, S...First region, D...Second region.
Claims
1. Multiple feathers arranged in the circumferential direction, Of the plurality of blades, a first blade and a second blade adjacent to the first blade in the circumferential direction, It comprises the nth feather, which is the nth feather in the circumferential direction, The angular pitch of the n blades is θ n Let the angle pitch of the (n+1)th blade be θ. n+1 When this is done, the angular pitch θ n+1 and the aforementioned angular pitch θ n The difference between them changes periodically. Impeller.
2. Let Z be the number of the aforementioned multiple blades. If we let f(n) be a periodic function and A be the amplitude of the periodic function, The aforementioned angular pitch θ n+1 and the aforementioned angular pitch θ n The difference between the two follows the formula in equation 1 below. The impeller according to claim 1. [Math 1]
3. The center of gravity of the impeller and the center of the rotation axis of the impeller coincide. The impeller according to claim 1 or 2.
4. The number of blades Z is an integer greater than or equal to 4. The impeller according to claim 2.
5. The frequency of the periodic function f(n) is 2 or greater and less than or equal to Z-2, and is an integer other than Z / 2 when Z is an even number. The impeller according to claim 2.
6. The aforementioned angular pitch θ n+1 and the aforementioned angular pitch θ n The region where the difference is greater than the value obtained by dividing 360 by Z is defined as the first region. the angle pitch θ n+1 and the angle pitch θ n A region where the difference from is smaller than the value obtained by dividing 360 by the Z is defined as the second region, In the circumferential direction, the first region and the second region are arranged alternately at intervals equal to the period of the periodic function. The impeller according to claim 1 or 2.
7. An impeller according to claim 1 or 2, A motor that rotatably supports the impeller, A casing having a passage through which the fluid generated by the impeller passes, A fan motor equipped with a fan motor.