Impeller and fan motor

Abstract

Provided is an impeller capable of effectively reducing noise that accompanies the rotation of blades.　This impeller (160) comprises a plurality of blades (164) that are arranged side by side in the circumferential direction. Among the plurality of blades (164) there are a first blade (164), a second blade (164) that is adjacent to the first blade (164) in the circumferential direction, and a n-th blade (164) that is the n-th blade (164) in the circumferential direction. When the angle pitch of the n-th blade (164) is θn, the angle pitch of the (n +1)-th blade (164) is θn+1, 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 angle pitch θn+1 and the angle pitch θn follows formula 1.

Description

Impeller and fan motor

[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.

[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.

[0004] Patent No. 5183451

[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.

[0006] The present invention comprises a plurality of blades arranged in the circumferential direction, a first blade among the plurality of blades, 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.

[0008] This is a perspective view showing a fan motor according to an embodiment of the present invention. This is a front view showing a fan motor according to an embodiment. This is a cross-sectional view (A) taken along line III-III in Figure 2, and a partially enlarged view (B) of (A). This is a perspective view showing an impeller according to an embodiment. This is a plan view showing an impeller according to an embodiment. This is a cross-sectional view taken along line VI-VI in Figure 5. (A) is a graph showing the relationship between the blade number and the difference in angular pitch in formula (1) of the embodiment, and (B) is a plan view of the impeller. (A) is a graph obtained by substituting numerical values ​​into formula (2) in an embodiment, and (B) is an image diagram showing the arrangement of the blades. (A) is a graph showing the relationship between the blade number and the difference in angular pitch in a modified example of the embodiment, and (B) is an image diagram showing the arrangement of the blades. (A) is a graph showing the relationship between the blade number and the difference in angular pitch in another modified example of the embodiment, and (B) is an image diagram showing the arrangement of the blades.

[0009] Figure 1 is a perspective view showing a fan motor 100 according to an embodiment of the present invention, and Figure 2 is a plan view. The fan motor 100 includes a casing 110 composed of a resin upper casing 120 and a resin lower casing 130. The casing 110 has a rectangular shape (including a substantially square shape) in plan view, but is not limited to this, and may be circular.

[0010] Legs 121 are formed at the four corners of the upper casing 120, projecting downwards. The legs 121 are formed by creating roughly rectangular notches at the corners of the upper casing 120 and extending downwards from the edges of the notches.

[0011] The lower casing 130 has a projection 131 that protrudes upward, and the upper end of the projection 131 is connected to the lower end of the leg 121. The projection 131 has the same axial cross-sectional shape as the leg 121. The upper end of the projection 131 has a step 131a formed on the inner circumference side, which is lowered by one step. On the other hand, the lower end of the leg 121 has a step 121a formed on the inner circumference side, which protrudes by one step downward. The steps 121a and 131a are fitted together and joined to each other, for example, by adhesive.

[0012] A through hole 132 is formed on the radially outer side of the projection 131, 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 in the 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 positioned in the flow path 111 in a rotatable manner. 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. This process may generate noise as wind noise. 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 a 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] 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 periphery of the axially upper surface of the blade 164. This connects the blades 164 to each other. In the radial direction, an annular plate 162 extends to a position midway between the ring 165 and the outer circumferential surface of the cylinder 161. Thus, the blades 164 are firmly connected to the cylinder 161, as they are connected to each other at their periphery by the ring 165 and at their inner circumference by the annular plate 162.

[0024] In this embodiment, the angular pitch of the blades 164 is set as follows. That is, among the plurality of blades 164, the first blade 164, the second blade 164 adjacent to the first blade 164 in the circumferential direction, and the nth blade, the nth blade 164, are set, and the angular pitch of the nth blade 164 is θ n is taken, and when the angular pitch of the (n + 1)th blade 164 is θ n+1 the difference between the angular pitch θ n+1 and the angular pitch θ n is periodically changed.

[0025] In particular, 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).

[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.

[0027] FIG. 7(A) is a graph showing the number of the blades 164 on the horizontal axis and the difference in the angular pitch between adjacent blades 164 on the vertical axis in the formula (1), and (B) is a plan view of the impeller 160 showing the arrangement of the blades 164. As shown in FIG. 7(B), a first region S where the intervals between the blades 164 are sparse and a second region D where the intervals between the blades 164 are dense 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] Further, as shown in FIG. 7(A), when the point where θ n+1 - θ n is 6.1° (exactly, the value obtained by dividing 360° by 59, the number of blades, and rounding to the second decimal place) is used as a reference, when the amplitude A is 2, θ n+1 - θ n It swings by ±2° around 6°. When the amplitude A increases, the sparsity degree of the first region S increases, and the density degree of the second region D increases.

[0029] Fig. 8(A) shows the formula (1) when the number of blades Z = 59, sine wave, vibration frequency F = 3, and amplitude A = 2, and (B) is an image diagram of the blade 164. As shown in Fig. 8(B), since the periodic function f(n) is a sine wave, the center of gravity position of the impeller 160 coincides with the center of the rotation axis of the impeller 160.

[0030] Here, the first region S is the region where the difference between the angular pitch θ n+1 and the angular pitch θ n is larger than the value obtained by dividing 360 by the number of blades Z. Also, the second region D is the region where the difference between the angular pitch θ n+1 and the angular pitch θ n is smaller than the value obtained by dividing 360 by the number of blades Z, and in the circumferential direction, the first region S and the second region D are alternately arranged at the same interval as the period of the periodic function.

[0031] Also, the number of blades Z of the blade 164 is an integer of 4 or more. Further, the vibration frequency F of the periodic function f(n) is an integer that is 2 or more and Z - 2 or less and not Z / 2. When the vibration frequency F of the periodic function f(n) is an even number and Z / 2, the formula (2) becomes as follows and does not hold as a periodic function.

[0032] As described above, in the impeller 160 and the fan motor 100 of the above embodiment, since the difference in the angular pitch of adjacent blades 164 changes periodically, sounds of different frequencies are generated from each blade 164 with different angular pitches. That is, when observing the rotation of the blade 164 at the same location, as the first blade 164 passes and the second blade 164 comes, a wind cut sound is continuously generated. If the difference in the angular pitch of the blade 164 is constant, the wind cut sound of the same frequency is amplified and becomes noise. In the above embodiment, since a wind cut sound of a different frequency is generated every time the blade 164 passes, the wind cut sound is not amplified. Therefore, the noise associated with the operation of the fan motor 100 can be effectively reduced.

[0033] Particularly in the above embodiment, the angular pitch θ n+1and the angular pitch θ n Since the difference from is made to follow the above formula (1), the center of gravity position of the impeller 160 and the center of the rotation axis of the impeller 160 coincide. Therefore, the generation of vibration caused by the rotation of the impeller 160 is suppressed.

[0034] The present invention is not limited to the above-described embodiment, and various modifications can be made as follows. i) FIG. 9 is a graph of the formula (1) when the number of blades Z = 23, a triangular wave, the frequency F = 3, and the amplitude A = 5, and (B) is an image diagram of the blade 164. Even in this example, the triangular wave is a periodic function f(n), and as shown in FIG. 9(B), the arrangement of the blades 164 is such that the first region S and the second region D appear alternately in the circumferential direction. Therefore, the same operation as in the above-described embodiment is exhibited.

[0035] ii) FIG. 10 is a graph of the formula (1) when the number of blades Z = 23, a rectangular wave, the frequency F = 3, and the amplitude A = 5, and (B) is an image diagram of the blade 164. Even in this example, the rectangular wave is a periodic function f(n), and as shown in FIG. 11(B), the arrangement of the blades 164 is such that the first region S and the second region D appear alternately in the circumferential direction. Therefore, the same operation as in the above-described embodiment is exhibited.

[0036] iii) The present invention is not limited to the radial fan motor as in the above-described embodiment, and can be applied to an axial flow fan motor or a centrifugal fan. iv) The present invention is not limited to the periodic function as described above, and any periodic function such as a cosine wave can be applied. v) Further, the angular pitch θ n+1 and the angular pitch θ n If the difference from changes periodically, the change can be arbitrarily set regardless of the periodic function. The main point is that 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 bearing applied to the motor of the present invention is not limited to a ball bearing, and various bearings such as a sliding bearing can be applied. vii) The stator core applied to the motor of the present invention may be an amorphous material.

[0037] The present invention can be used for a fan motor used for blowing, ventilation, cooling, etc. in home electric appliances, OA equipment, industrial and vehicle air conditioners.

[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. The device comprises a plurality of blades arranged in the circumferential direction, a first blade among the plurality of blades, 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 An impeller, in which the difference between [the current state] and [the current state] changes periodically.

2. Let Z be the number of blades, f(n) be the periodic function, and A be the amplitude of the periodic function. Then, the angular pitch θ n+1 and the aforementioned angular pitch θ n The difference is determined by the formula shown in equation 1 below, as described in claim 1.

3. The impeller according to claim 1 or 2, wherein the center of gravity of the impeller coincides with the center of rotation of the impeller.

4. The impeller according to claim 2, wherein the number of blades Z is an integer of 4 or more.

5. The impeller according to claim 2, wherein 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.

6. The angle pitch θ n+1 and the angle pitch θ n The region where the difference from is greater than the value obtained by dividing 360 by the Z is defined as the first region, and the angle pitch θ n+1 and the angle pitch θ n The 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 alternately arranged at the same interval as the period of the periodic function. The impeller according to claim 2.

7. A fan motor comprising: an impeller according to claim 1 or 2; a motor that rotatably supports the impeller; and a casing having a passage through which the fluid generated by the impeller passes.

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