Centrifugal fan blade for cooking device and cooking device

Abstract

The centrifugal fan blade for the cooking device comprises a base plate and blades arranged on the surface of one side of the base plate, the blades are perpendicular to the base plate and are evenly arranged at intervals in the circumferential direction with the center of the base plate as the center, and a rotating center area is defined by the blades in the center of the base plate. Each blade sequentially comprises a first blade body and a second blade body from inside to outside relative to the center of the base plate, and a gap is formed between the adjacent ends of the first blade body and the second blade body. Compared with the prior art, on one hand, the radial pressure gradient of the first blade body and the rotating center area near the gap can be increased, on the other hand, airflow in the rotating center area can be promoted to smoothly flow towards the outer sides of the fan blades in the radial direction, and therefore the problem that circumferential flow of the airflow in the rotating center area is poor is solved.

Description

Technical Field

[0001] The utility model relates to the field of cooking devices, in particular to a centrifugal fan blade used for a cooking device and the cooking device. Background Art

[0002] Ovens, steam ovens and other cooking devices with baking functions are equipped with centrifugal blades on their inner pots. In baking mode, the motor drives the centrifugal blades to rotate so that the air in the inner pot enters the hot air chamber, and then flows back to the inner pot under the centrifugal force of the centrifugal blades after being heated in the hot air chamber. The centrifugal blades currently used in cooking devices are generally single-stage centrifugal blades with equal deflection angles. When the blades rotate at high speed, each blade works on the fluid disturbance, generates airflow and throws out the rotating area along the radial velocity air volume, forming a negative pressure area in the rotating area. Relying on the axial pressure gradient between the negative pressure area in this area and the surrounding environment, the surrounding gas is introduced into the blades, and the work is repeated. For example, the Chinese invention patent with patent number ZL202210040203.8 (authorization announcement number CN114468792B), the Chinese utility model patent with patent number ZL202123137912.8 (authorization announcement number CN216776752U), etc.

[0003] However, the existing centrifugal fan blades for cooking devices have the following problems (such as Figure 6 shown):

[0004] (1) For a single-stage centrifugal fan with equal deflection angle, the overall velocity distribution gradient is large from the outer edge to the inner side of the blade, that is, the efficiency of the work done by the outer edge of the blade is higher, while the efficiency of the work done by the disturbance on the inner side is relatively low;

[0005] (2) The direction of the velocity vector on the blade is constant, and the radial component of the velocity vector is also small. The efficiency of the airflow being thrown out in the radial direction is greatly limited, so the efficiency of the work done by the blade disturbance is low;

[0006] (3) The rotation center of the fan blade is the most stable negative pressure area, and its ability to introduce airflow is also relatively strong. However, the airflow in this area can only rotate in a circumferential direction, and the radial outward velocity component is relatively small. Therefore, the ability of the airflow in this area to escape from the rotation area of ​​the fan blade and perform work outward is severely limited. Utility Model Content

[0007] The first technical problem to be solved by the utility model is to provide a centrifugal fan blade with high working efficiency for a cooking device in view of the prior art.

[0008] The second technical problem to be solved by the utility model is to provide a centrifugal fan blade for a cooking device with a large performance expansion space and a firm internal structure in view of the prior art.

[0009] The third technical problem to be solved by the present invention is to provide a cooking device with the centrifugal fan blades according to the prior art.

[0010] The technical solution adopted by the utility model to solve at least one of the above-mentioned technical problems is: a centrifugal fan blade for a cooking device, including a base plate and blades arranged on a surface of one side of the base plate, the blades are perpendicular to the base plate and are evenly arranged at intervals along the circumferential direction with the center of the base plate as the center, and each blade forms a rotation center area at the center of the base plate, characterized in that each of the blades includes a first sheet body and a second sheet body in sequence from the inside to the outside relative to the center of the base plate, and there is a gap between adjacent ends of the first sheet body and the second sheet body.

[0011] Furthermore, the gap includes a first gap along a radial direction or a radial parallel line, and the adjacent ends of the first sheet and the second sheet in each of the blades are spaced opposite to each other along a radial direction or a radial parallel line to form the first gap between the two. The first gap can effectively solve the problem of excessive pressure gradient of linear velocity distribution on the fan blade. In addition, when the fan blade rotates at a high speed, the overall velocity vector of the airflow near the first gap area between the first sheet and the second sheet has a larger radial outward component, thereby being able to more effectively improve the ability of the airflow to escape radially outward and increase the work capacity.

[0012] Furthermore, the gap also includes a second gap along the circumferential direction, and the adjacent ends of the first sheet and the second sheet of each blade are staggered along the circumferential direction, and are spaced inside and outside relative to the center of the substrate to form the first gap and the second gap respectively. The matching design of the first gap and the second gap is conducive to improving the performance of the first gap, and the second gap can be set to control the relative position of the first sheet and the second sheet in the rotation direction according to needs, thereby improving design flexibility.

[0013] Furthermore, the second blades of each blade are located on the same side of the corresponding first blade along the rotation direction, so as to ensure that the second blades can disturb the airflow and guide the airflow in the area of ​​the first blade.

[0014] Furthermore, the second sheet of each blade is located at the rear side of the corresponding first sheet in the clockwise direction, so as to better ensure the second sheet's disturbing effect on the airflow and the guiding effect on the airflow in the first sheet area.

[0015] Furthermore, the angle between the first sheet of each blade and the radial direction is α1, and the angle between the second sheet and the radial parallel line is α2, and α1≥0, α2≥α1. In the utility model, the angle between the first sheet and the radial direction is small, so the overall linear velocity of the area where the first sheet is located is small, so that the first sheet can better transport the airflow in the rotating center area (i.e., the central bladeless area) from the inside to the outside along the radial component more smoothly. Further, since the blades have the same angular velocity, and the linear velocity gradually increases from the inside to the outside along the radial direction, the second sheet in the utility model is mainly used to do work on the airflow disturbance, ensure a larger radial outward component of the airflow, and make the airflow better thrown out of the rotating area (i.e., the fan blade). In this way, when α2≥α1, the radial velocity component of the second sheet increases, thereby increasing the radial negative pressure gradient between the second sheet and the first sheet, and at the same time, the airflow of the first sheet can be better guided radially outward.

[0016] Furthermore, the first gap is recorded as d1, the height of the first body of each blade is h1, and the height of the second body is h2, then:

[0017] 0.025(h1+h2)≤d1≤0.2(h1+h2). In this way, the size of the first gap is related to the height of the first sheet and the second sheet, so that the first gap can better play its function. Preferably, h1=h2.

[0018] Furthermore, the second gap is recorded as d2, the length of the second sheet of each blade is l2, and the angle between the second sheet and the radial parallel line is α2, the diameter of the substrate is D, then: -π(D-l2 cosα2-d1 cosα2) / 2n≤d2≤π(D-l2 cosα2-d1 cosα2) / 2n, where n is the number of blades, when d2>0, the second sheet of each blade is located at the rear side of the corresponding first sheet in the clockwise direction; and when d2<0, the second sheet of each blade is located at the front side of the corresponding first sheet in the clockwise direction. In this way, by limiting the size of the second gap and coordinating the size design of the first gap, the gap in the utility model can better play its function.

[0019] Furthermore, the first body of each blade is trapezoidal and the second body is square, and the inner side of each first body is inclined outward from bottom to top relative to the center of the base plate, while the outer side of each first body extends vertically.

[0020] The technical solution adopted to further solve the third technical problem mentioned above is: a cooking device, characterized in that it includes the centrifugal fan blades for the cooking device as described above.

[0021] Compared with the prior art, the advantage of the utility model is that each blade includes a first sheet and a second sheet in sequence from the inside to the outside relative to the center of the base plate, and a gap is provided between the adjacent ends of the first sheet and the second sheet. In this way, since there is a gap between the first sheet and the second sheet, when the fan blade rotates, the airflow near the gap will generate a relative movement in the opposite direction of the rotation direction of the fan blade through the gap, thereby generating a local negative pressure area near the gap. On the one hand, it can increase the radial pressure gradient between the first sheet and the rotation center area near the gap, and on the other hand, it is conducive to promoting the airflow in the rotation center area to flow smoothly radially toward the outside of the fan blade, thereby improving the problem of poor circumferential flow of the airflow in the rotation center area (such as Figure 5 shown).

[0022] Furthermore, each blade of the fan blade in the utility model is a secondary structure (i.e., including a first sheet and a second sheet), so that the deflection angle and height direction of the first sheet and the second sheet can be controlled separately, so that the available materials for fan blade molding can be better utilized, greatly expanding the design space of the fan blade and maximizing the performance of the fan blade. For example, when the deflection angle of the second sheet is large, the overall height of the fan blade can be reasonably increased, thereby improving the second sheet's ability to disturb the airflow. In addition, the gap between the first sheet and the second sheet is also conducive to alleviating the structural stress and thermal stress energy problems of the fan blade, and improving the stability of the internal structure of the fan blade. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 This is a schematic diagram of the structure of the centrifugal fan blade in Example 1 of the utility model;

[0024] Figure 2 for Figure 1 A schematic diagram of the structure in another direction;

[0025] Figure 3 This is a schematic diagram of the structure of the centrifugal fan blade in Example 2 of the utility model;

[0026] Figure 4 for Figure 3 A schematic diagram of the structure in another direction;

[0027] Figure 5 The velocity vector diagram of the centrifugal fan blade in Example 2 of the utility model;

[0028] Figure 6 It is the velocity vector diagram of the centrifugal fan blade in the prior art. DETAILED DESCRIPTION

[0029] The present invention will be described in further detail below in conjunction with the accompanying drawings.

[0030] In the description of the present utility model, 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", "axial", "radial", "circumferential" and the like indicate the orientation or position relationship based on the orientation or position relationship shown in the drawings, which is only for the convenience of describing the present utility model and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Since the embodiments disclosed in the present utility model can be set in different directions, these terms indicating directions are only for illustration and should not be regarded as limitations. For example, "up" and "down" are not necessarily limited to directions opposite to or consistent with the direction of gravity. In addition, the features defined as "first" and "second" may explicitly or implicitly include one or more of such features.

[0031] like Figures 1 to 5 As shown, Example 1 and Example 2 are preferred embodiments of the centrifugal fan blade in the utility model. The centrifugal fan blade is applied to a cooking device, and is specifically applied to a steam oven in the following embodiments.

[0032] Embodiment 1:

[0033] like Figure 1 and 2 As shown, a centrifugal fan blade for a cooking device comprises a base plate 1 and a blade 2 arranged on a side surface of the base plate 1, the blade 2 is perpendicular to the base plate 1 and is arranged at intervals along the circumferential direction with the center of the base plate 1 as the center, and each blade 2 forms a rotation center area at the center of the base plate 1, characterized in that each of the above blades 2 comprises a first sheet 21 and a second sheet 22 in sequence from the inside to the outside relative to the center of the base plate 1, and there is a gap 3 between the adjacent ends of the first sheet 21 and the second sheet 22. In the utility model, a central hole 10 is opened in the center of the base plate 1 for the fan blade shaft to pass through.

[0034] As can be seen from the above, in the utility model, due to the gap 3 between the first sheet 21 and the second sheet 22, when the fan blade rotates, the airflow near the gap 3 will generate a relative movement opposite to the rotation direction of the fan blade through the gap 3, thereby generating a local negative pressure area near the gap 3, which can increase the pressure gradient in the radial direction between the gap 3 and the first sheet 21 and the rotation center area, and on the other hand, it is conducive to promoting the airflow in the rotation center area to flow smoothly radially toward the outside of the fan blade, thereby improving the problem of poor circumferential flow of the airflow in the rotation center area. Further, in the utility model, each blade 2 of the fan blade is a secondary structure (i.e., including the first sheet 21 and the second sheet 22), so that the deflection angle and height direction of the first sheet 21 and the second sheet 22 can be controlled separately, so that the available materials for fan blade molding can be better used to greatly expand the design space of the fan blade and maximize the performance of the fan blade. For example, when the deflection angle of the second sheet 22 is large, the overall height of the fan blade can be reasonably increased, thereby improving the disturbance ability of the second sheet 22 to the airflow. In addition, the gap 3 between the first sheet 21 and the second sheet 22 is also helpful in alleviating the structural stress and thermal stress energy problems of the fan blades, and improving the stability of the internal structure of the fan blades.

[0035] Furthermore, the gap 3 includes a first gap 31 along a radial direction or a radial parallel line, and the adjacent ends of the first sheet 21 and the second sheet 22 in each of the blades 2 are spaced opposite to each other along a radial direction or a radial parallel line to form the first gap 31 therebetween. The first gap 31 can effectively solve the problem of excessive pressure gradient of linear velocity distribution on the blade. In addition, when the blade rotates at a high speed, the overall velocity vector of the airflow near the first gap 31 area between the first sheet 21 and the second sheet 22 has a larger radial outward component, thereby being able to more effectively improve the ability of the airflow to escape radially outward and increase the work capacity.

[0036] Furthermore, the angle between the first sheet 21 of each of the above-mentioned blades 2 and the radial direction is α1, and the angle between the second sheet 22 and the radial parallel line is α2, and α1≥0, α2≥α1. In the utility model, the angle between the first sheet 21 and the radial direction is small, so the overall linear velocity of the area where the first sheet 21 is located is small, so that the first sheet 21 can better transport the airflow in the rotating center area (i.e., the central area without blades 2) from the inside to the outside along the radial component more smoothly. Further, since the blades 2 have the same angular velocity, and the linear velocity gradually increases from the inside to the outside along the radial direction, therefore, the second sheet 22 in the utility model is mainly used to do work on the airflow disturbance, ensure a larger radial outward component of the airflow, and make the airflow better throw out of the rotating area (i.e., the fan blade). In this way, when α2≥α1, the radial velocity component of the second sheet 22 increases, thereby increasing the radial negative pressure gradient between the second sheet 22 and the first sheet 21, and at the same time, the airflow of the first sheet 21 can be better guided radially outward.

[0037] Embodiment 2:

[0038] like Figures 2 to 5 As shown, different from the embodiment 1, in this embodiment, the gap 3 further includes a second gap 32 along the circumferential direction, and the adjacent ends of the first sheet 21 and the second sheet 22 of each of the blades 2 are staggered along the circumferential direction, and the first gap 31 and the second gap 32 are formed between the two with respect to the center inner and outer spacing of the substrate 1. The matching design of the first gap 31 and the second gap 32 is conducive to improving the performance of the first gap 31, and the second gap 32 is set to control the relative position of the first sheet 21 and the second sheet 22 in the rotation direction according to the needs, thereby improving the design flexibility. Figure 5 is the velocity vector diagram of the centrifugal fan blade in this embodiment, Figure 5 It can be seen that in this embodiment, the radially outward component of the velocity vector direction of each blade 2 increases, the overall velocity on the blade 2 increases, and the distributed velocity gradient on the fan blade decreases, especially the airflow in the rotating center area is effectively output radially outward, thereby improving the efficiency of the fan blade.

[0039] Further, the second sheet 22 of each of the above-mentioned blades 2 is respectively located on the same side of the corresponding first sheet 21 along the rotation direction, so that the second sheet 22 can ensure the disturbing effect of the airflow and the drainage effect of the airflow in the area of ​​the first sheet 21. Preferably, the second sheet 22 of each of the above-mentioned blades 2 is respectively located on the rear side of the corresponding first sheet 21 along the clockwise direction, so that the second sheet 22 can better ensure the disturbing effect of the airflow and the drainage effect of the airflow in the area of ​​the first sheet 21.

[0040] Furthermore, the first gap 31 is denoted as d1, the height of the first body 21 of each blade 2 is h1, and the height of the second body 22 is h2, then:

[0041] 0.025(h1+h2)≤d1≤0.2(h1+h2). In this way, the size of the first gap 31 is related to the height of the first sheet 21 and the second sheet 22, so that the first gap 31 can better perform its function. The utility model determines the lower limit and upper limit of the value of the first gap 31 by the average value of h1 and h2. When the d1 value of the first gap 31 is too small, the resistance of the airflow on the fan blade through the first gap 31 is too large, and the flow rate and speed are both small. The negative pressure intensity of the local negative pressure zone where the first gap 31 is located (relative to the rotation center zone, the rotation center zone is the central negative pressure zone with relatively stable negative pressure) is small, and the negative pressure gradient with the first sheet 21 is small, so the drainage effect is weak; when the d1 value of the first gap 31 is too large, the flow rate passing through the first gap 31 is large, but the speed is not enough, resulting in that the negative pressure intensity of the negative pressure zone is still insufficient, and the drainage effect on the airflow of the first sheet 21 begins to be not obvious. At the same time, d1 is too large, which also occupies too much disturbance area of ​​the blade 2, affecting the disturbance performance of the entire fan blade.

[0042] Furthermore, the second gap 32 is recorded as d2, the length of the second sheet 22 of each of the blades 2 is l2, and the angle between the second sheet 22 and the radial parallel line is α2, the diameter of the substrate 1 is D, then: -πD-l2 cosα2-d1cosα2 / 2n≤d2≤πD-l2 cosα2-d1 cosα2 / 2n, wherein n is the number of blades 2, and in this embodiment n=7, and when d2>0, the second sheet 22 of each of the blades 2 is respectively located at the rear side of the corresponding first sheet 21 in the clockwise direction; and when d2<0, the second sheet 22 of each of the blades 2 is respectively located at the front side of the corresponding first sheet 21 in the clockwise direction. It can be seen from the above formula that the outermost edges of the n first sheets 21 in the fan blade divide the circumferential 360° into arc segments, and the central angle corresponding to each segment is 360 / n. By limiting the d2 value of the second gap 32, the misalignment angle between the innermost edge of the second sheet 22 and the outermost edge of the first sheet 21 is not greater than half of the central angle of each segment, that is, the circumferential gap with the innermost edge of the second sheet 22 is controlled at 180° / n, so as to ensure the continuity of the disturbance performance between the first sheet 21 and the second sheet 22 of each blade 2, and at the same time ensure that when the airflow flows from the first sheet 21 to the second sheet 22, the blade 2 has a radial flow constraint and flow guiding effect on the airflow. In this way, by limiting the size of the second gap 32 in the utility model and coordinating with the size design of the first gap 31, the gap 3 in the utility model can better play its function.

[0043] In addition, the magnitude relationship between the h1 value of the first sheet 21 and the h2 value of the second sheet 22 can control the disturbance capability between the first sheet 21 and the second sheet 22. When h1>h2, the area of ​​the first sheet 21 increases, and the airflow disturbance capability of the first sheet 21 is specifically enhanced; when h1<h2, the area of ​​the second sheet 22 increases, and the airflow disturbance capability of the second sheet 22 is specifically enhanced; however, both of the above two situations require passive matching of the non-uniform cross-section shaped structure of the hot air blower baffle corresponding to the fan blade rotation area; when h1=h2, the performance of the first sheet 21 and the second sheet 22 is relatively balanced, and does not depend on the matching hot air blower baffle surface shape, therefore, in this embodiment, preferably, h1=h2.

Claims

1. A centrifugal fan blade for a cooking device, comprising a base plate (1) and blades (2) arranged on a surface of one side of the base plate (1), the blades (2) being perpendicular to the base plate (1) and being arranged at intervals along the circumferential direction with the center of the base plate (1) as the center, and each blade (2) forming a rotation center area at the center of the base plate (1), characterized in that: Each blade (2) comprises a first sheet (21) and a second sheet (22) in sequence from the inside to the outside relative to the center of the base plate (1), and a gap (3) is provided between adjacent ends of the first sheet (21) and the second sheet (22).

2. The centrifugal fan blade for a cooking device according to claim 1, characterized in that: The gap (3) comprises a first gap (31) along a radial direction or a radially parallel line, and the adjacent ends of the first sheet (21) and the second sheet (22) in each of the blades (2) are spaced opposite to each other along a radial direction or a radially parallel line to form the first gap (31) therebetween.

3. The centrifugal fan blade for a cooking device according to claim 2, characterized in that: The gap (3) further includes a second gap (32) along the circumferential direction, and the adjacent ends of the first sheet (21) and the second sheet (22) of each blade (2) are staggered along the circumferential direction and are spaced inside and outside relative to the center of the base plate (1) to form the first gap (31) and the second gap (32) therebetween.

4. The centrifugal fan blade for a cooking device according to claim 3, characterized in that: The second sheet body (22) of each blade (2) is located on the same side of the corresponding first sheet body (21) along the rotation direction.

5. The centrifugal fan blade for a cooking device according to claim 4, characterized in that: The second sheet body (22) of each blade (2) is located on the rear side of the corresponding first sheet body (21) in the clockwise direction.

6. The centrifugal fan blade for a cooking device according to claim 1, characterized in that: The included angle between the first sheet (21) of each blade (2) and the radial direction is α1, and the included angle between the second sheet (22) and the radial parallel line is α2, and α1≥0, α2≥α1.

7. The centrifugal fan blade for a cooking device according to claim 3, characterized in that: The first gap (31) is denoted as d1, the height of the first body (21) of each blade (2) is h1, and the height of the second body (22) is h2, then: 0.025(h1+h2)≤d1≤0.2(h1+h2).

8. The centrifugal fan blade for a cooking device according to claim 7, characterized in that: The second gap (32) is denoted as d2, the length of the second sheet (22) of each blade (2) is l2, and the angle between the second sheet (22) and the radial parallel line is α2. The diameter of the substrate (1) is D, then: -π(D-l2 cosα2-d1 cosα2) / 2n≤d2≤π(D-l2 cosα2-d1cosα2) / 2n, wherein n is the number of blades (2), and when d2>0, the second sheet (22) of each blade (2) is located at the rear side of the corresponding first sheet (21) in the clockwise direction; and when d2<0, the second sheet (22) of each blade (2) is located at the front side of the corresponding first sheet (21) in the clockwise direction.

9. The centrifugal fan blade for a cooking device according to claim 1, characterized in that: The first sheet (21) of each blade (2) is trapezoidal and the second sheet (22) is square, and the inner side edges of each first sheet (21) are inclined outwards from bottom to top relative to the center of the base plate (1), while the outer side edges of each first sheet (21) extend vertically.

10. A cooking device, characterized in that: It comprises a centrifugal fan blade for a cooking device as claimed in any one of claims 1 to 9.

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