CN108105154A - Fan and micro-wave oven - Google Patents

Abstract

The invention discloses a fan and a microwave oven. The fan comprises a blade (22) and a hub (21). The hub profile (211) of the hub includes a wavy line segment. ), the leading edge point of the blade root of the blade coincides with the starting point of the wavy line segment, the trailing edge point of the blade root coincides with the end point of the wavy line segment, and the wavy line segment at least includes a radially concave front A concave segment (211a) and a radially convex rear convex segment (211b). The fan of the present invention adopts a hub profile with a front concave segment and a rear convex segment with a wavy segment, the purpose of which is to reduce the blockage caused by the separation of the angular area of the hub of a small axial flow fan, and improve the acoustic performance of the fan by means of flow control , to reduce the noise of the fan. At the same time, the adoption of the solution of the present invention can effectively suppress the development of the horseshoe vortex, so that the aerodynamic performance and acoustic performance of the fan are greatly improved.

Description

fan and microwave

technical field

The invention relates to the field of household appliances, in particular to a fan and a microwave oven.

Background technique

A microwave oven is a modern cooking stove that uses microwaves to heat food. In the microwave oven, the magnetron is used to generate microwaves to heat the food in the cavity, and a transformer or frequency converter supplies power to the magnetron. The interior of the microwave oven mainly uses the axial flow fan assembly to dissipate heat from components such as transformers, frequency converters, and magnetrons. The axial flow fan assembly mainly includes fan blades, a collector cover, a fan bracket and a motor. During the operation of the axial flow fan, there is a positive correlation between the flow and the noise. When the fan speed increases and the flow rate increases, its noise level will also increase accordingly, and the high speed of the motor will increase the loss of the motor, increase the cost, and also cause reliability and safety problems. With the substantial improvement of people's living standards, the noise of fans has attracted more and more attention. High air volume and low noise are the development trend of fan products.

For a conventional fan, as shown in FIG. 1 , the blades of the fan are arranged on the hub, and the outer ring portion of the hub is obtained by rotating the hub profile (original profile) of the straight section around the central axis for one turn. During the high-speed rotation of the blade, the incoming flow collides with the leading edge of the blade root to form a horseshoe vortex. In the process of downstream development, the horseshoe vortex continuously entrains the low-energy boundary layer fluid on the suction surface and the outer ring surface of the hub, and its size continues to grow. The growth will cause blockage of the flow passage at the root of the blade. On the one hand, this increases the flow loss and reduces the work efficiency of the fan; on the other hand, it generates turbulent noise, which affects the comfort of users.

Contents of the invention

The purpose of the present invention is to provide a fan which has the advantages of good heat dissipation effect and low noise.

In order to achieve the above object, the present invention provides a fan, including a blade and a hub, the hub profile of the hub includes a wavy line segment, the blades are arranged on the outer ring part formed by the rotation of the wavy line segment, the blades The leading edge point of the blade root coincides with the starting point of the wavy line segment, and the trailing edge point of the blade root coincides with the end point of the wavy line segment, and the wavy line segment at least includes radially inwardly concave toward the central axis of the hub Anterior concave segment and radially convex posterior convex segment.

Preferably, the wavy line segment is an S-shaped line segment.

Preferably, the S-shaped line segment includes a start position, a concave point position, a convex point position and an end position which are sequentially spaced in the axial direction, the base radius of the hub is r ₀ , and the radius of the start position and the end point position is r ₀ , the concave point radius of the concave point position is r ₂ , the convex point radius of the convex point position is r ₃ , satisfying:

Preferably,

Preferably,

Preferably, the S-shaped line segment includes a start position, a concave point position, a convex point position and an end position which are sequentially spaced in the axial direction, the length of the profile axis between the starting point position and the end point position is b, and the concave point The axial offset distance of the concave point between the position and the starting point is b ₂ , the axial offset distance of the convex point between the position of the convex point and the end point is b ₃ , satisfying: b ₂ /b≤45%, b ₃ /b≤45%.

Preferably, 25%≤b ₂ /b≤35%, 25%≤b ₃ /b≤35%.

Preferably, the fan includes a plurality of blades with the same shape, and the plurality of blades are arranged at equal intervals along the circumference of the outer ring portion of the hub and are offset along the axial direction of the hub.

Preferably, the entire circumference of the fan includes multiple sets of blades arranged alternately, and the blades include several blades arranged at equal intervals in the circumferential direction and at the same axial position. The axial directions are misaligned with each other.

Preferably, the axial chord length of the tip of each blade is d, and the maximum axial misalignment distance C between the blade groups, said C=(15%-25%)*d.

In addition, the present invention also provides a microwave oven, which includes the above-mentioned fan.

Through the above technical solution, the fan of the present invention adopts the hub profile with the wavy line segment of the front concave section and the rear convex section. The purpose is to reduce the blockage caused by the separation of the corner area of the hub of the small axial flow fan. Through the method of flow control, The acoustic performance of the fan is improved, and the noise of the fan is reduced. In the wavy line segment, the design of the front concave section can reduce the speed of the leading edge of the blade and increase the pressure at the front of the flow channel; at the same time, the design of the rear convex section can accelerate the speed of the trailing edge of the blade and reduce the flow path of the air channel Rear pressure. The strong reverse pressure gradient in the axial direction on the outer ring part of the hub is effectively improved, which is beneficial to reducing the accumulation of low-energy fluid, thereby reducing losses. At the same time, the hub obtained from the hub shape of the wavy line can effectively restrain the development of the horseshoe vortex, and greatly improve the aerodynamic performance and acoustic performance of the fan.

Other features and advantages of the present invention will be described in detail in the detailed description that follows.

Description of drawings

The accompanying drawings are used to provide a further understanding of the present invention, and constitute a part of the description, together with the following specific embodiments, are used to explain the present invention, but do not constitute a limitation to the present invention. In the attached picture:

Fig. 1 is a perspective view of an existing fan, and the original molded line is a straight line;

2 is a perspective view of a fan according to a specific embodiment of the present invention;

Fig. 3 shows the relevant parameters of the hub profile of the fan of the present invention;

Fig. 4 is a structural schematic diagram of a fan according to a specific embodiment of the present invention, showing that the blades are arranged in a misalignment along the axial direction of the hub;

5 is a schematic diagram of the internal structure of a microwave oven according to a specific embodiment of the present invention;

Figure 6 is an exploded view of the fan assembly.

Explanation of reference signs

1 chamber 2 fan assembly

3 Backplane 4 Transformer

5 Power cord fork 6 Rear panel

7 Magnetron

20 Fan 21 Hub

22 Vane 24 Cowl

25 Bracket 26 Motor

211 Hub Profile 212 Outer Ring

P Start position M Dimple position

N bump position K end position

211a front concave section 211b back convex section

211c Original profile 201 Central axis

Δr The distance of each point corresponding to the hub profile line offset from the original profile line

d Axial chord length of blade tip

C Axial misalignment spacing between blade groups

Detailed ways

Specific embodiments of the present invention will be described in detail below in conjunction with the accompanying drawings. It should be understood that the specific embodiments described here are only used to illustrate and explain the present invention, and are not intended to limit the present invention.

In the present invention, unless stated to the contrary, the used orientation words such as "up, down, top, bottom" generally refer to the directions shown in the drawings or refer to the vertical, perpendicular or gravitational directions The terms used to describe the mutual positional relationship of the various components mentioned above.

In the existing fan, the hub profile is usually the straight original profile 211c as shown in Figure 1. When the fan is rotating at high speed, the angular area formed by the suction surface of the blade 22 and the outer ring of the hub 21 There will be a three-dimensional separation phenomenon in the corner area. This separation will greatly increase the blockage of the air duct, seriously affect the aerodynamic performance of the fan, increase the loss of air volume, and greatly reduce the heat dissipation effect of the fan. For this, the present invention provides a kind of novel fan, as shown in Figure 2, this fan 20 comprises blade 22 and wheel hub 21, and the wheel hub shape line 211 of wheel hub 21 comprises wavy line segment, and blade 22 is arranged on the wavy line segment rotational molding On the outer ring portion 212 of the blade 22, the leading edge point of the blade root of the blade 22 coincides with the starting point of the wavy line segment, and the trailing edge point of the blade root coincides with the end point of the wavy line segment. A concave front concave section 211a and a radially convex rear convex section 211b.

It can be seen that the fan 20 (usually an axial flow fan) of the present invention adopts a wavy line segment with a front concave section 211a and a rear convex section 211b to replace the existing linear original line 211c, in order to reduce the size of the small axial flow fan. The blockage caused by the separation of the corner area of the hub improves the heat dissipation performance of the fan 20 , and the acoustic performance of the fan 20 is improved by means of flow control, thereby reducing the noise of the fan 20 . In the wavy line segment of the present invention, the design of the front concave section 211a can reduce the speed of the leading edge of the blade 22 and increase the pressure at the front of the flow channel; meanwhile, the design of the rear convex section 211b can accelerate the speed of the blade 22 trailing edge, Reducing the pressure at the rear of the flow channel of the air channel effectively improves the strong reverse pressure gradient in the axial direction on the outer ring part 212 of the hub 21, which is beneficial to reducing the accumulation of low-energy fluid, thereby reducing the loss of air volume. At the same time, the hub 21 obtained by the wavy segment hub profile 211 can effectively restrain the development of the horseshoe vortex, and greatly improve the aerodynamic performance and acoustic performance of the fan 20 .

Preferably, the wavy line segment is an S-shaped line segment. Not only the aerodynamic and acoustic performances of the fan 20 are better, but also the overall effect of the fan 20 is more beautiful.

As shown in Figure 3, the S-shaped line segment includes the starting position P, the concave point position M, the convex point position N and the end position K which are sequentially spaced in the axial direction, the reference radius of the hub 21 is r0, and the radius is r0, the concave point radius of the concave point position M is r2, and the convex point radius of the convex point position N is r3, satisfying: The present invention has determined the hub profile 211 of the present invention through a large number of model tests, that is, the optimal position parameters of the concave points and convex points of the S-shaped hub profile. Assuming that the S-shaped line segment of the present invention is obtained by deforming the original profiled line 211c of the existing fan, and Δr is the radial distance from each point on the S-shaped line segment to the original profiled line 211c, then the Δr of the concave point position M is preferably Δr greater than the bump position N, to ensure that the flow channel area of the S-shaped hub is larger than that of the existing original linear fan.

And satisfy:

Further, it may be preferably:

At the same time, as shown in Figure 3, the S-shaped line segment includes a starting point P, a concave point M, a convex point N, and an end point K that are sequentially spaced in the axial direction. is b, the concave point axis offset distance between the concave point position M and the starting position P is b2, and the convex point axis offset distance between the convex point position N and the end position K is b3, satisfying: b ₂ /b≤45% , b ₃ /b≤45%.

Further, it may be preferably: 25%≤b ₂ /b≤35%, 25%≤b ₃ /b≤35%.

In addition, in the fan 20 of the present invention, as shown in FIG. 4 , the fan 20 includes a plurality of blades 22 of the same shape. The axial direction forms a dislocation. Therefore, in the fan 20 of the present invention as shown in FIG. 4 , by reasonably controlling the misalignment distance of the blades 22 along the axial direction of the hub 21 , the fundamental frequency of the original fan can be dispersed to different frequencies. Use this method to destroy the airflow resonance generated when the blade 22 interferes with the fixed obstacles upstream and downstream (in a microwave oven, refer to the support 25 shown in Figure 5, the transformer 4 or frequency converter, the magnetron 7, etc.) At the same time, it disperses the distribution of energy, which plays a good role in controlling the discrete noise of the fan 20. At the same time, it can also improve the aerodynamic performance of the fan 20 to a certain extent, and finally further obtain the redistribution of noise energy. and a reduction in the overall sound power level.

Further, the blades 22 are axially dislocated in groups, that is, the entire circumferential circle of the fan 20 includes multiple sets of blade groups alternately arranged, and the blade groups include several blades 22 arranged at equal intervals in the circumferential direction and at the same axial position. The blade groups are misaligned with each other along the axial direction. Taking the 6-blade fan as an example, it can be divided into 2 or 3 blade groups, that is, the number of blades 22 in each group is 3 or 2 blades 22, and the grouping and equal interval arrangement can also help the dynamic balance performance of the fan 20 to be better. it is good.

As shown in Figure 4, the axial chord length of the tip of each blade 22 is d, the maximum axial misalignment distance C between the blade groups, the axial misalignment distance C between the blade groups should not be too large, preferably C =15%～25%*d. Similarly, when there are multiple sets of blades, the maximum distance between the sets of blades should also satisfy C=15%˜25%*d, so that the air volume of the fan 20 is larger and the noise is lower.

In addition, the present invention also provides a microwave oven. As shown in FIG. 5 , the microwave oven is provided with the above-mentioned fan 20 . Therefore, the microwave oven also includes all the advantages of the fan 20 of the present invention, which will not be repeated one by one.

The microwave oven includes a base plate 3 , a rear plate 6 , a magnetron 7 , a transformer 4 or a frequency converter, a microwave oven heating cavity 1 , a power line bifurcation 5 , a high voltage diode and a fan assembly 2 . As shown in FIG. 6 , the fan assembly 2 includes a fan 20 , a collector cover 24 , a bracket 25 and a motor 26 . Usually the transformer 4 or frequency converter is used to supply power to the magnetron 7, the magnetron 7 generates microwaves to heat the food in the cavity 1, and the fan assembly 2 dissipates heat to the magnetron 7 and the transformer 4 or frequency converter. Wherein, the cavity 1 and the transformer 4 or the frequency converter are fixed on the base plate 3, the magnetron 7 is fixed on the cavity 1, the support 25 is fixed on the back plate 6 by screws, the motor 26 is fixed on the support 25, and the motor 26 The shaft of the fan passes through the shaft installation part of the fan 20.

During the experiment, tests were carried out on the fan with the existing linear hub and the fan 20 using the S-shaped hub of the present invention. Table 1 shows the application of the two kinds of fans in the microwave oven and the data of the temperature rise test of the main components inside the microwave oven. It can be seen that the heat dissipation performance of the fan 20 of the S-shaped hub profile of the present invention has been enhanced, and the temperature rise of the main components inside the microwave oven has been improved to varying degrees. Therefore, the fan 20 of the present invention can effectively suppress the separation phenomenon of the corner area, reduce the accumulation of low-energy fluid, improve the flow characteristics of the corner area, and reduce the aerodynamic loss of the fan.

Table 1

Simultaneously, also carry out the test of sound power level for the fan of existing straight-line type wire hub and the fan of S-type wire hub of the present invention, table 2 has provided the existing fan under different voltages and adopts the S of this scheme. The test data of the 20 sound power level of the hub type line fan. It can be seen from Table 2 that the acoustic performance of the S-shaped hub-shaped fan is better, and most of the sound power levels can be reduced by more than 2dB under different voltages.

Table 2

The preferred embodiment of the present invention has been described in detail above in conjunction with the accompanying drawings, but the present invention is not limited to the specific details of the above embodiment, within the scope of the technical concept of the present invention, various simple modifications can be made to the technical solution of the present invention, These simple modifications all belong to the protection scope of the present invention.

In addition, it should be noted that the various specific technical features described in the above specific implementation manners may be combined in any suitable manner if there is no contradiction. In order to avoid unnecessary repetition, various possible combinations are not further described in the present invention.

In addition, various combinations of different embodiments of the present invention can also be combined arbitrarily, as long as they do not violate the idea of the present invention, they should also be regarded as the disclosed content of the present invention.

Claims (11)

1. A fan, comprising a blade (22) and a hub (21), characterized in that, the hub profile (211) of the hub (21) comprises a wave-shaped line segment, and the blade (22) is arranged on the wave On the outer ring portion (212) formed by rotating the shaped line segment, the blade root leading edge point of the blade (22) coincides with the starting point of the wave-shaped line segment, and the blade root trailing edge point coincides with the end point of the wave-shaped line segment, so The wavy line segment at least includes a radially inwardly concave front segment (211a) facing the central axis (201) of the hub (21) and a radially convex rear segment (211b). 2. The fan according to claim 1, wherein the wavy line segment is an S-shaped line segment. 3. The fan according to claim 2, characterized in that, the S-shaped line segment includes a start position (P), a concave point position (M), a convex point position (N) and an end point position (K ), the reference radius of the hub (21) is r0, the radius of the starting position (P) and the end position (K) is r0, the concave point radius of the concave point position (M) is r2, the convex The bump radius at point position (N) is r3, which satisfies: 4. The fan according to claim 3, characterized in that, 5. The fan according to claim 3, characterized in that, 6. The fan according to claim 2, characterized in that, the S-shaped line segment includes a start position (P), a concave point position (M), a convex point position (N) and an end point position (K ), the profile line axis length between the starting point position (P) and the end point position (K) is b, and the concave point axis offset distance between the concave point position (M) and the starting point position (P) is b2, and the axial offset distance of the bump between the bump position (N) and the end point (K) is b3, satisfying: b ₂ /b≤45%, b ₃ /b≤45%. 7. The fan according to claim 6, characterized in that 25%≤b ₂ /b≤35%, 25%≤b ₃ /b≤35%. 8. The fan according to any one of claims 1-7, characterized in that, the fan (20) comprises a plurality of blades (22) of the same shape, and the plurality of blades (22) are arranged along the hub ( 21) the outer ring portion (212) is arranged at equal intervals in the circumferential direction and forms a misalignment along the axial direction of the hub (21). 9. The fan according to claim 8, characterized in that, the entire circumferential circle of the fan (20) includes a plurality of sets of blades arranged alternately, and the blades are arranged at equal intervals in the circumferential direction and have the same axial position There are several blades (22), and the blade groups are misaligned with each other along the axial direction. 10. The fan according to claim 9, characterized in that, the axial chord lengths of the tip of each of the blades (22) are d, the maximum axial misalignment distance C between the blade groups, the C=(15%～25%)*d. 11. A microwave oven, characterized in that the microwave oven comprises the fan (20) according to any one of claims 1-10.