Fan guard design method

Abstract

The application discloses a fan protective cover design method in the technical field of fan device manufacturing, and comprises the following steps: 1, obtaining the shape and size of the outer frame of the fan protective cover and presetting the size of the center disc; 2, arranging the basic rib between the center disc and the outer frame, the centers of the basic rib, the center disc and the outer frame are overlapped, and a plurality of closed areas are formed in the outer frame; 3, arranging the radial rib in the closed area to be arranged, each radial rib of the protective cover intersects with at least two basic ribs; the starting point of the radial rib and the center line of the outer frame are radial lines, the radial rib satisfies the diverging direction along the center of the protective cover, and the angle between the extension direction of the radial rib and the radial line gradually increases. The radial rib intersects with at least two basic ribs, the radial rib connected with the outer frame at least spans two closed areas, and the radial rib connected with the center disc at least spans two closed areas. The length of the radial rib is long, which is beneficial to the airflow guiding of the radial rib; and the angle between the connecting line of the starting point and the ending point of the radial rib and the radial line is small, which is beneficial to the gathering of the air outlet.

Description

Technical Field

[0001] This invention relates to the field of ventilation device manufacturing technology, and specifically to a design method for a fan protective cover. Background Technology

[0002] In current protective cover designs, the center of the cover is typically located at the motor shaft area of ​​the fan system, while the edges of the cover are away from the motor shaft area. According to safety technical requirements for protective covers, to prevent fingers or other objects from entering the machine body through the cover, the following requirements apply to the mesh size of the cover: the mesh formed by the interlaced ribs of the cover must not allow a cylinder with a diameter of 12.5mm to pass directly through the mesh gaps.

[0003] Based on the above requirements and considering the strength requirements of the protective shield, two design approaches were initially considered in the research and development phase. The first approach uses the center of the protective shield as the center point, designing a dense concentric circular rib structure, and then connecting and fixing it with sparser ribs radiating outwards from the center to the dense concentric ribs, forming an interlaced grid pattern. The second approach uses the center of the protective shield as the center point, designing a dense radial rib pattern extending from the center to the edge; then, sparser concentric ribs or sparser radial ribs intersect with the previously dense radial ribs to form a grid pattern. In both design approaches, the distance between adjacent radial ribs changes continuously as the grid size transitions from the center to the edge. Specifically, as adjacent ribs radiate outwards from the center, the distance between them gradually increases. Therefore, the effective ventilation area of ​​the protective shield decreases near the center.

[0004] With further in-depth research and development of protective cover design, considering factors such as noise and efficiency of the air supply system, the rib structure of the protective cover is no longer limited to the previous straight line form, and its expression is more diversified. For example, Chinese invention patent CN103900167B, entitled "Air Outlet Protective Cover for Fan, Fan and Outdoor Unit of Air Conditioner," discloses an air outlet protective cover. Specifically, this application discloses an air outlet protective cover in which the number of warp strips varies in different warp strip groups, with the warp strip groups closer to the edge of the weft ring having more warp strips. In this application, the warp strips are curved, but the number of warp strips in each group is different, meaning that adjacent groups of warp strips are not continuous curves. Therefore, each group of warp strips has a different air outlet direction, which is not conducive to air concentrating. Summary of the Invention

[0005] To overcome the problem of weak airflow concentration caused by the discontinuity of different groups of warp strips in the existing protective cover mesh design, this invention provides a fan protective cover design method.

[0006] The technical solution adopted by this invention to solve its technical problem is:

[0007] The design method for wind turbine protective covers includes the following steps:

[0008] Step 1: Obtain the shape and size of the outer frame of the fan protective cover, and preset the size of the center plate;

[0009] Step 2: Arrange foundation reinforcement bars between the central plate and the outer frame. The center of the foundation reinforcement bars, the central plate, and the outer frame overlap, forming multiple closed areas within the outer frame.

[0010] Step 3: Arrange radial ribs in the closed area where radial ribs are to be arranged. Each radial rib on the protective cover shall intersect with at least two foundation ribs. The end of the radial rib closest to the center of the outer frame shall be the starting point, and the line connecting the starting point and the center of the outer frame shall be the radial line. The radial ribs shall satisfy the requirement of radiating outward from the center of the protective cover, and the acute angle between the extension direction of the radial ribs and the radial line shall gradually increase.

[0011] In this method, each radial rib intersects with at least two foundation ribs. Therefore, radial ribs connected to the outer frame span at least two enclosed areas, and radial ribs connected to the central disc also span at least two enclosed areas. Relative to the varying number of radial ribs within each enclosed area, the innermost and outermost radial ribs in this method are longer, which is beneficial for their airflow guidance function. Furthermore, considering that the radial ribs radiate outwards from the center of the protective cover, the acute angle between the extension direction of the radial ribs and the radial line gradually increases. The longer the radial ribs, the smaller the angle between the line connecting the start and end points of the radial ribs and the radial line, which is beneficial for airflow convergence.

[0012] Furthermore, step 3, arranging the radial reinforcements, includes the following steps:

[0013] Step 31: Treat several closed areas with the same radial reinforcement as the whole area. If the whole area is a circular area, arrange the radial reinforcement directly in the circular area, so that the shortest distance from any point on the radial reinforcement to the adjacent radial reinforcement in the same closed area does not exceed 5%. If the whole area is not a circular area, proceed to step 32.

[0014] Step 32: With the center of the protective shield as the center, draw a circle with the line connecting the outermost point of the entire area farthest from the center and the center as the radius; with the center of the protective shield as the center, draw a circle with the line connecting the innermost point of the entire area farthest from the center and the center as the radius; the two circles form an annular area;

[0015] Step 33: Arrange radial ribs within the annular area formed in step 32, ensuring that the shortest distance from any point on the radial rib to adjacent radial ribs within the same closed area does not exceed 5%.

[0016] Step 34: Trim the radial ribs that extend beyond the outer edge of the overall area in Step 33, and extend the radial ribs that do not touch the outer edge of the overall area in Step 33 to complete the arrangement of radial ribs within the overall area.

[0017] This method specifies the requirements for arranging radial ribs within the annular area, with the minimum distance variation not exceeding 5%. This is primarily because if the distance between radial ribs were not restricted, the spacing between them would gradually increase as the protective cover extends outwards from its center. Consequently, the length of the radial ribs would be limited due to requirements such as grid gap safety standards. Meeting the aforementioned requirements makes it easier to extend the length of the radial ribs, which is beneficial for improving airflow guidance and concentration. Furthermore, the small variation in distance between adjacent radial ribs allows for a reduction in the number and density of radial ribs, thus increasing the effective ventilation area.

[0018] It's worth noting that the overall area here might not be a circular area because, in practice, the outer frame of the wind turbine protective cover is not limited to a circle. Common shapes include ellipses, circles, several connected arcs, and convex polygons. Therefore, the applicant proposed first creating a circular area based on the overall shape, then arranging radial ribs within the circular area, and finally adjusting the radial ribs to achieve the layout of the radial ribs in the non-circular area.

[0019] Furthermore, the specific steps for arranging radial ribs within the annular area in steps 31 and 33 are as follows:

[0020] Step 301: Let the inner circle of any annular region where radial ribs are to be arranged be C1, the outer circle be C2, the inner diameter be R1, the outer diameter be R2, and the center be O. There are m radial ribs to be arranged. The distance between any point on the radial rib and the adjacent radial ribs in the same annular region is preset to D.

[0021] Step 302: Evenly set s first auxiliary ribs with center O in the annular region, namely circles I1, I2, ... IS, where s is a positive integer ≥ 3, divide the region into s+1 auxiliary annular regions, draw a ray from the center O, and from the center O to the outside, intersect the inner circle, the first auxiliary rib and the outer circle at points A, I1, I2... IS and B respectively.

[0022] Step 303: Calculate the chord lengths LA, LI1, LI2, ..., LIS, LB corresponding to the central angles of circles C1, I1, I2, ..., IS, C2 being 360° / m respectively;

[0023] Set the angles ∠A = acos(D / LA), ∠I1 = acos(D / LI1), ∠I2 = acos(D / LI2), ... ∠IS = acos(D / LIS), ∠B = acos(D / LB);

[0024] Step 304: Starting from point A, draw a ray in the direction away from the center O, forming a ∠A with OB; starting from point I1, draw a ray in the direction away from the center O, forming a ∠I1 with OB; starting from point I2, draw a ray in the direction away from the center O, forming a ∠I2 with OB; ... starting from point IS, draw a ray in the direction away from the center O, forming a ∠IS with OB; starting from point B, draw a ray in the direction away from the center O, forming a ∠B with OB. All of the aforementioned rays are located on the same side of OB.

[0025] Step 305: In each auxiliary ring area, set a second auxiliary rib with center O. The second auxiliary rib is located in the middle of the auxiliary ring area. Extend each ray starting from the outer circle of the auxiliary ring area in the opposite direction until it intersects with the second auxiliary rib in the auxiliary ring area. Rotate the ray after the reverse extension around the center O so that two rays starting from the same auxiliary ring area intersect on the second auxiliary rib in the auxiliary ring area.

[0026] Step 306: Connect point A, the intersection point on the second auxiliary rib, and point B in sequence with a smooth curve to form radial ribs AB. With the center O as the center point, form a circular array of m radial ribs AB into the circular area.

[0027] In this method, the preset minimum distance D is slightly lower than the design standard. For example, when selecting 12.5mm as required by the safety design of the protective cover, the preset minimum distance D can be set to 11.9mm. This leaves a 5% margin for fluctuation relative to 12.5mm, avoiding errors in design and manufacturing that could affect the quality of subsequent products. The number of radial ribs within the annular area can be roughly calculated based on the preset minimum distance D and the inner diameter of the annular area. For example, it can be calculated that m radial ribs divide the inner diameter into m arc segments, with the chord length of each arc segment being greater than or equal to D. This range of radial rib numbers can then be obtained. After completing the overall layout of the radial ribs in the wind turbine protective cover, the number or type of radial ribs can be adjusted according to the overall strength of the wind turbine protective cover.

[0028] Furthermore, when arranging the foundation reinforcement in step 2, ensure that the width of the resulting closed area is greater than or equal to 2D and less than or equal to 4D.

[0029] In this method, the width of the enclosed area is specifically defined, which is also the distance limit between adjacent foundation reinforcement bars, indirectly limiting the length of the radial reinforcement bars within the enclosed area. If the width between the enclosed areas is too long, the cross-sectional dimensions of the radial reinforcement bars must be high to ensure overall strength; if the width between the enclosed areas is too short, the foundation reinforcement bars will be laid out too densely, resulting in high cost and reduced ventilation area.

[0030] Furthermore, in step 3, each radial reinforcement bar intersects with a maximum of four foundation reinforcement bars.

[0031] In this method, the width of the enclosed area, i.e., the distance limit between adjacent foundation reinforcement bars, is used to effectively limit the extension length of the first and second radial reinforcement bars. As mentioned above, the angle between the extension direction of the radial reinforcement bars and the radial line gradually increases along the outward divergence direction from the center of the protective cover. If the length of the radial reinforcement bars is not limited, as the length of the radial reinforcement bars increases, the amount of change in their outward divergence from the center becomes smaller and smaller, which will also increase costs and reduce the effective ventilation area.

[0032] Furthermore, after the radial reinforcement layout is completed in step 3, the size of the foundation reinforcement in the overall area is adjusted so that the length of the radial reinforcement in each closed area is equal.

[0033] In this method, after the radial reinforcement layout of an overall area is completed, the size of the internal base reinforcement is adjusted so that the length of the radial reinforcement in different enclosed areas that make up the overall area is equal. At this time, the grid gap and length formed by the radial reinforcement and base reinforcement are basically the same, and the strength of the enclosed area is basically the same. Under the premise of meeting the strength requirements of the protective cover, the layout of the base reinforcement and radial reinforcement is more regular, and the cross-sectional size of the reinforcement can be optimized accordingly to maximize the reduction of the weight of the protective cover and reduce costs.

[0034] Furthermore, in step 304, at least one set of two adjacent integral regions are located on different sides of OB.

[0035] In this method, when radial ribs are arranged in two adjacent integral areas, the corresponding rays in step 304 are located on different sides of OB. Correspondingly, in the fan shield, the radial ribs in adjacent enclosed areas have different rotation directions. Two adjacent areas with radial ribs rotating in opposite directions actually form reverse winds during operation. The reverse winds mix with each other, reducing the noise during fan operation.

[0036] Furthermore, step 306 specifically includes the following steps:

[0037] Step 306a: Connect point A, the intersection point on the second auxiliary rib and point B in sequence with a smooth curve, and set the angle between straight line AB and straight line OA to be 110°-160°.

[0038] Step 306b: Determine the relationship between the actual angle between lines AB and OA and the preset angle range. If the angle between lines AB and OA falls within the preset angle range, proceed to step 306c. If the angle between lines AB and OA does not fall within the preset angle range, adjust the dimensions of the foundation reinforcement and return to step 31 until the angle between lines AB and OA is consistent with the preset range, and then proceed to step 306c.

[0039] Step 306c: Using the center O as the center point, arrange m radial ribs AB in a ring array into the ring area.

[0040] In this method, the angle between the lines AB and OA connecting the start and end points of the radial ribs is limited. When the angle is less than 110°, the radial ribs extend too long, and the amount of change in their outward divergence along the center becomes smaller and smaller, which will increase costs and reduce the effective ventilation area. When the angle is greater than 160°, the radial ribs extend too short, and the layout of the foundation ribs is too dense, which will also lead to increased costs and reduced ventilation area.

[0041] The beneficial effects of this invention are:

[0042] 1. Applying this method to the design of fan shields can optimize the layout of the shield's ribs. Specifically, the length of the radial rib curves is extended, spanning multiple enclosed areas, which is more conducive to the radial ribs controlling and guiding airflow. Combined with the outward divergence direction along the center of the shield, the acute angle between the extension direction of the radial ribs and the radial line gradually increases. The longer the radial ribs are, the smaller the angle between the inclined line of the radial ribs and the radial line, which is beneficial for concentrating the outflowing air.

[0043] 2. Furthermore, limiting the variation in the shortest distance between radial ribs facilitates the extension of their length, while ensuring that the density of radial ribs can be reduced simultaneously. This not only lowers costs but also increases the effective ventilation area. Limiting the width of the enclosed area and the number of base ribs connecting the radial ribs, or limiting the angle between the inclined and radial lines of the radial ribs, thereby restricting the length of the radial ribs and preventing them from becoming too long, which would increase costs and reduce the effective ventilation area.

[0044] 3. Limiting the variation in the length of radial reinforcements within different enclosed areas, combined with the aforementioned small variation in the shortest distance between radial reinforcements, the strength of the areas enclosed by the foundation reinforcements and radial reinforcements is basically the same. Under the premise of meeting the strength requirements of the protective cover, the layout of the foundation reinforcements and radial reinforcements is more regular, which facilitates the optimization of the cross-sectional dimensions of the reinforcements, maximizes the reduction of the weight of the protective cover, and reduces costs.

[0045] 4. The aforementioned method is provided for the design of wind turbine protective covers with non-circular outer frames, which improves the applicability of the method and can be extended to common wind turbine protective covers, such as elliptical and circular covers, as well as several arc-shaped curves and convex polygons with their ends connected. Attached Figure Description

[0046] Figure 1 This is a step-by-step schematic diagram (a) of an embodiment of the fan protective cover design method of the present invention;

[0047] Figure 2 This is a step-by-step schematic diagram (b) of an embodiment of the fan protective cover design method of the present invention;

[0048] Figure 3 This is a step-by-step diagram illustrating the arrangement of radial ribs within the circular area of ​​the wind turbine protective cover design method of the present invention. Figure 1 ;

[0049] Figure 4 This is a step-by-step diagram illustrating the arrangement of radial ribs within the circular area of ​​the wind turbine protective cover design method of the present invention. Figure 2 ;

[0050] Figure 5 This is a step-by-step diagram illustrating the arrangement of radial ribs within the circular area of ​​the wind turbine protective cover design method of the present invention. Figure 3 ;

[0051] Figure 6 This is a step-by-step diagram illustrating the arrangement of radial ribs within the circular area of ​​the wind turbine protective cover design method of the present invention. Figure 4 ;

[0052] Figure 7 c is a step-by-step schematic diagram of an embodiment of the fan protective cover design method of the present invention;

[0053] Figure 8 d is a step-by-step schematic diagram of Embodiment 1 of the fan protective cover design method of the present invention;

[0054] Figure 9 e is a step-by-step schematic diagram of an embodiment of the fan protective cover design method of the present invention;

[0055] Figure 10 This is a step-by-step schematic diagram (f) of an embodiment of the fan protective cover design method of the present invention;

[0056] Figure 11 g is a step-by-step schematic diagram of an embodiment of the fan protective cover design method of the present invention;

[0057] Figure 12 h is a step-by-step schematic diagram of the first embodiment of the fan protective cover design method of the present invention;

[0058] Figure 13 This is a step-by-step schematic diagram of Embodiment 2 of the fan protective cover design method of the present invention;

[0059] Figure 14 This is a step-by-step schematic diagram (b) of Embodiment 2 of the fan protective cover design method of the present invention;

[0060] Figure 15 This is a step-by-step schematic diagram (c) of Embodiment 2 of the fan protective cover design method of the present invention;

[0061] Figure 16 This is a step-by-step schematic diagram (d) of Embodiment 2 of the fan protective cover design method of the present invention;

[0062] Figure 17 This is a step-by-step schematic diagram (e) of Embodiment 2 of the fan protective cover design method of the present invention;

[0063] Figure 18 This is a step-by-step schematic diagram (f) of Embodiment 2 of the fan protective cover design method of the present invention;

[0064] Figure 19 This is a step-by-step schematic diagram (g) of Embodiment 2 of the fan protective cover design method of the present invention;

[0065] Figure 20 h is a step-by-step schematic diagram of Embodiment 2 of the wind turbine protective cover design method of the present invention.

[0066] The markings in the diagram are: 1-Central plate, 2-First radial reinforcement, 3-Second radial reinforcement, 4-Outer frame, 5-First auxiliary reinforcement, 6-Second auxiliary reinforcement, 51-First foundation reinforcement, 52-Second foundation reinforcement, 53-Third foundation reinforcement, 54-Fourth foundation reinforcement, 55-Fifth foundation reinforcement. Detailed Implementation

[0067] The invention will be further described below with reference to the accompanying drawings.

[0068] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0069] Example 1

[0070] like Figure 1-12 The diagram shown is a schematic of the design process of the fan protective cover in Embodiment 1, which is described in words below.

[0071] Step 1: Obtain the dimensions of the outer frame 4 of the fan protective cover and the preset dimensions of the center plate 1.

[0072] In this step, the dimensions of the outer frame 4 of the fan protective cover are determined according to the fan specifications, and the dimensions of the center plate 1 are preset according to the size of the rotating shaft and the central shaft of the fan blades.

[0073] Step 2: Arrange foundation reinforcement bars between the central plate 1 and the outer frame 4 of the fan protective cover. The center of the foundation reinforcement bars, the central plate 1 and the outer frame 4 overlap, forming multiple closed areas inside the outer frame 4.

[0074] The shape of the foundation reinforcement bars here is consistent with that of the outer frame 4, but the dimensions are different.

[0075] like Figure 1 The diagram shown is a schematic diagram of step 2 in Embodiment 1. In Embodiment 1, the outer frame 4 is circular, and five basic reinforcing bars are arranged between the central plate 1 and the outer frame 4, namely the first basic reinforcing bar 51, the second basic reinforcing bar 52, the third basic reinforcing bar 53, the fourth basic reinforcing bar 54, and the fifth basic reinforcing bar 55.

[0076] Multiple closed areas are formed within the outer frame 4. Specifically, a closed area is formed between the central disc 1 and the first foundation reinforcement 51; a closed area is formed between the first foundation reinforcement 51 and the second foundation reinforcement 52; a closed area is formed between the second foundation reinforcement 52 and the third foundation reinforcement 53; a closed area is formed between the third foundation reinforcement 53 and the fourth foundation reinforcement 54; a closed area is formed between the fourth foundation reinforcement 54 and the fifth foundation reinforcement 55; and a closed area is formed between the fifth foundation reinforcement 55 and the outer frame 4. These form six closed areas.

[0077] Step 3: Arrange radial ribs in the closed area where radial ribs are to be arranged. Each radial rib on the protective cover intersects with at least two basic ribs. The starting point of the radial rib is the end of the radial rib closest to the center of the outer frame 4. The line connecting the starting point and the center of the outer frame 4 is the radial line. The radial ribs satisfy the requirement of radiating outward from the center of the protective cover. The acute angle between the extension direction of the radial rib and the radial line gradually increases.

[0078] Unlike existing technologies where the number of radial ribs varies within each enclosed area, in this application, each radial rib intersects with at least two foundation ribs. Therefore, radial ribs connected to the outer frame span at least two enclosed areas, and radial ribs connected to the central disc also span at least two enclosed areas. Compared to the varying number of radial ribs within each enclosed area, this method ensures that the innermost and outermost radial ribs span at least two enclosed areas, resulting in longer ribs that effectively guide and control airflow. Furthermore, the radial ribs radiate outwards from the center of the protective cover, with the acute angle between the rib extension direction and the radial line gradually increasing. The longer the radial rib, the smaller the angle between the line connecting the start and end points of the rib and the radial line, which is beneficial for concentrating the outflow.

[0079] It is worth noting that, since the aforementioned radial ribs need to extend to intersect with the radial lines, in order to clearly describe the angle change, it is specifically described as the acute angle between the radial ribs and the radial lines gradually increasing; while the radial lines and the inclined lines intersect directly at the starting point of the radial ribs, so the angle between the radial lines and the inclined lines is used directly to describe it.

[0080] Step 31: Treat several closed areas with the same radial reinforcement as the whole area. If the whole area is a circular area, arrange the radial reinforcement directly in the circular area, ensuring that the shortest distance from any point on the radial reinforcement to the adjacent radial reinforcement in the same closed area does not exceed 5%. If the whole area is not a circular area, proceed to step 32.

[0081] As described above, there are six enclosed areas within the outer frame 4. In this embodiment, the six enclosed areas are pre-grouped into three groups of three, that is, the three inner enclosed areas are arranged with continuous radial ribs, temporarily referred to as the first radial rib 2; the three outer enclosed areas are arranged with continuous radial ribs, temporarily referred to as the second radial rib 3. Therefore, in this embodiment, the three inner enclosed areas and the three outer enclosed areas are considered as a whole area, and radial ribs are arranged in each of them.

[0082] Furthermore, in this embodiment, the outer frame 4 is circular, therefore the entire area is an annular area, allowing for the direct placement of radial ribs. For example... Figure 2 As shown, the radial reinforcement arrangement is illustrated using the outer layer as an example. The radial reinforcement is continuous within the three enclosed areas of the outer layer; that is, continuous radial reinforcement is arranged between the third foundation reinforcement 53 and the outer frame 4. For a more intuitive demonstration of the arrangement process, the fourth foundation reinforcement 54 and the fifth foundation reinforcement 55 are omitted. Figure 2 As shown, the overall area formed by the third basic reinforcement 53 and the outer frame 4 is a circular area.

[0083] like Figure 3-6 The diagram shows the specific steps for arranging radial ribs within the annular area in step 3:

[0084] Step 301: Let the inner circle of any annular region where radial ribs are to be arranged be C1, the outer circle be C2, the inner diameter be R1, the outer diameter be R2, and the center be O. There are m radial ribs to be arranged. Any point on the radial rib can be selected. The distance between the radial ribs and the adjacent radial ribs in the same annular region is preset to D.

[0085] In this method, the preset minimum distance D is slightly lower than the design standard. For example, when selecting 12.5mm as required by the safety design of the protective cover, the preset minimum distance D can be set to 11.9mm. This leaves a 5% margin for fluctuation relative to 12.5mm, avoiding errors in design and manufacturing that could affect the quality of subsequent products. The number of radial ribs within the annular area can be roughly calculated based on the preset minimum distance D and the inner diameter of the annular area. For example, it can be calculated that m radial ribs divide the inner diameter into m arc segments, with the chord length of each arc segment being greater than or equal to D. This range of radial rib numbers can then be obtained. After completing the overall layout of the radial ribs in the wind turbine protective cover, the number and / or size specifications of the radial ribs can be adjusted according to the overall strength of the wind turbine protective cover.

[0086] The number of radial ribs within the annular region can be roughly calculated based on the preset shortest distance D and the inner diameter of the annular region. In existing technologies, since the shortest distance between adjacent radial ribs gradually increases from the center outwards, the approximate value is calculated based on the preset shortest distance D and the outer diameter of the annular region. Therefore, in this method, the number and density of radial ribs are lower, resulting in a larger effective air outlet area for the fan shield.

[0087] Step 302: Three first auxiliary ribs 5 with center O are evenly set in the annular region, namely circles I1, I2 and I3, to divide the region into four auxiliary annular regions. Draw a ray from the center O to the outer circle, intersecting the inner circle, the first auxiliary rib 5 and the outer circle at points A, I1, I2, I3 and B respectively.

[0088] like Figure 3 As shown, three first auxiliary ribs 5 are evenly arranged within the annular area where the radial ribs are to be arranged. The first auxiliary ribs 5 are as follows: Figure 3 As shown by the dashed line. Here, the number of first auxiliary ribs 5 is 3. In implementation, the number of first auxiliary ribs 5 can be adjusted according to the required precision.

[0089] Step 303: Calculate the chord length L corresponding to the central angles of circles I1-I3 being 360° / m. A、 L I1、 L I2、 L I3、 L B Set the angle ∠A = acos(D / L) A ), ∠I1=acos(D / L I1 ), ∠I2=acos(D / L I2 ), ∠I3=acos(D / L I3 ), ∠B=acos(D / L B ).

[0090] In this embodiment, m radial ribs are evenly distributed within the annular region, so each circle is divided into m arcs of equal length. The chord lengths corresponding to the divided arcs are defined as LA, LI1, LI2, LI3, and LB, respectively.

[0091] Easy to obtain L A = 2R1 sin(360° / m),

[0092] LI1=2(R1+(R2-R1) / 4)sin(360° / m),

[0093] LI2=2(R1+2*(R2-R1) / 4)sin(360° / m),

[0094] LI3=2(R1+3*(R2-R1) / 4)sin(360° / m),

[0095] LB = 2R2sin(360° / m).

[0096] Step 304: Starting from point A, draw a ray in the direction away from the center O, forming a ∠A with OB; starting from point I1, draw a ray in the direction away from the center O, forming a ∠I1 with OB; ... starting from point I3, draw a ray in the direction away from the center O, forming a ∠I3 with OB; starting from point B, draw a ray in the direction away from the center O, forming a ∠B with OB. All of the aforementioned rays are located on the same side of OB.

[0097] Specifically, such as Figure 3 As shown, starting from point A, ray a is drawn in a direction away from the center O of the circle. The angle between ray a and line OB is ∠A.

[0098] Starting from point I1, draw ray i1 in a direction away from the center O. The angle between ray i1 and line OB is ∠I1.

[0099] Starting from point I2, draw ray i2 in a direction away from the center O. The angle between ray i2 and line OB is ∠I2.

[0100] Starting from point I3, draw ray i3 in a direction away from the center O. The angle between ray i3 and line OB is ∠I3.

[0101] Starting from point B, draw ray i4 in a direction away from the center O. The angle between ray i4 and line OB is ∠B.

[0102] The aforementioned rays are all located on the same side of OB, specifically, they are all to the left or right of OA. In this embodiment, as... Figure 1 As shown, all of the above rays are to the left of OA.

[0103] Step 305: In each auxiliary ring area, a second auxiliary rib 6 with center O is set. The second auxiliary rib 6 is located in the middle of the auxiliary ring area. The ray starting from each auxiliary ring area is extended in the opposite direction until it intersects with the second auxiliary rib 6 in the auxiliary ring area. The ray extended in the opposite direction is rotated around the center O so that the two rays starting from the same auxiliary ring area intersect with the second auxiliary rib 6 in the auxiliary ring area.

[0104] like Figure 4 As shown, three first auxiliary ribs 5 divide the area into four auxiliary annular regions. A second auxiliary rib 6, centered at O, is positioned at the center of each of the four auxiliary annular regions. The second auxiliary rib 6 is as follows... Figure 2 As shown by the dashed line at the midpoint.

[0105] The second auxiliary rib 6 located between circle C1 and circle I1 is now defined as circle AI1.

[0106] The second auxiliary rib 6, located between circle I1 and circle I2, is circle I1I2.

[0107] The second auxiliary rib 6, located between circle I2 and circle I3, is circle I2I3.

[0108] The second auxiliary rib 6, located between circle I3 and circle C2, is circle I3B.

[0109] It is easy to see that the center of circle AI1 is O, and the radius is R1+(R2-R1) / 8.

[0110] The center of circle I1I2 is O, and its radius is R1 + 3*(R2 - R1) / 8.

[0111] The center of circle I2I3 is O, and its radius is R1 + 5*(R2 - R1) / 8.

[0112] The center of circle I3B is O, and the radius is R1+7*(R2-R1) / 8.

[0113] In order for the two rays whose starting points are located within the auxiliary annular region to intersect on the second auxiliary rib 6 within the auxiliary annular region, the rays whose starting points are located on the outer circle of the auxiliary annular region need to be extended in the opposite direction until they intersect with the second auxiliary rib 6 within the auxiliary annular region.

[0114] Now Figure 4 The ray i1 shown is extended in the opposite direction until it intersects with circle AI1.

[0115] Extend ray i2 in the opposite direction until it intersects circle I1I2.

[0116] Extend ray i3 in the reverse direction until it intersects with circle I2I3.

[0117] Extend ray b in the reverse direction until it intersects circle I3B.

[0118] Then fix ray a and rotate the other rays so that in all four auxiliary annular regions, the two rays whose starting points are in the auxiliary annular region intersect on the second auxiliary rib 6 in the annular region.

[0119] like Figure 5 As shown, first rotate the ray i1 around the center O and extend it in the opposite direction, so that the extended ray i1 intersects ray a on the circle AI1.

[0120] Then, rotate the ray i2 around the center O and extend it in the opposite direction so that the extended ray i2 intersects the ray i1 on the circle I1I2.

[0121] Then, rotate the ray i3 around the center O and extend it in the opposite direction so that the extended ray i3 intersects the ray i2 on the circle I2I3.

[0122] Then, rotate the ray b around the center O and extend it in the opposite direction so that the extended ray b intersects the ray i3 on the circle I3B.

[0123] Combination Figure 4 and Figure 5 As can be seen, in this embodiment, ray a is fixed, and rays i1, i2, i3, and b are rotated sequentially from the inside out until the above requirements are met. In specific implementations, it is not limited to fixing any particular ray; the above requirements can be achieved in any way. Furthermore, any point can be arbitrarily fixed within the auxiliary annular region as the point through which the subsequent curve AB passes, and the above requirements can be achieved by rotating the aforementioned rays; specific examples are not shown here.

[0124] Step 306: Connect point A, the intersection point on the second auxiliary rib 6, and point B sequentially using a smooth curve, as shown below. Figure 6 As shown, radial ribs AB are formed, with the center O as the center point, and m radial ribs AB are arranged in a ring array into the ring area.

[0125] With center O as the point, m radial ribs AB are arranged in a ring within the ring area. This completes the arrangement of the radial ribs within the ring area.

[0126] In this embodiment, the line connecting the start and end points of the radial ribs is defined as an inclined line, and the line connecting the start point of the radial ribs and the center of the protective cover is defined as a radial line. The preferred angle between the inclined and radial lines is 110°-160°. When the angle is below 110°, the radial ribs extend too long, and their outward divergence along the center becomes increasingly smaller, increasing costs and reducing the effective ventilation area. When the angle is above 160°, the radial ribs extend too short, and the foundation ribs are laid out too densely, similarly leading to increased costs and reduced ventilation area.

[0127] Following the above steps ensures that the shortest distance between adjacent radial ribs changes little. According to the applicant's practice, when the number of first auxiliary ribs 5 is greater than or equal to 3, the change in distance between radial ribs is less than 5%.

[0128] In this embodiment, the above method is preferentially used to arrange radial ribs within the annular area to ensure that the variation in distance between radial ribs is less than 5%. If the distance between radial ribs is not restricted, the spacing between them will gradually increase as the protective cover extends outward from its center. Therefore, due to requirements such as grid gap safety standards, the length extension of the radial ribs will also be limited. However, when the aforementioned requirements are met, the length extension of the radial ribs is easier to achieve, which is beneficial for improving the airflow concentration effect. Furthermore, the small variation in distance between adjacent radial ribs allows for a reduction in the number and density of radial ribs, which is beneficial for increasing the effective ventilation area.

[0129] In practice, the number of first auxiliary ribs 5 in step 301 can be increased to further reduce the aforementioned spacing variation. Obviously, the number of second auxiliary ribs 6 depends on the number of first auxiliary ribs 5, always increasing by one from the number of first auxiliary ribs 5.

[0130] like Figure 7As shown above, radial reinforcement is arranged between the third foundation reinforcement 53 and the outer frame 4, which is represented as the second radial reinforcement 3 in the figure.

[0131] like Figure 8 As shown, other foundation reinforcements are pre-installed between the third foundation reinforcement 53 and the outer frame 4, namely the fourth foundation reinforcement 54 and the fifth foundation reinforcement 55.

[0132] like Figure 9 As shown, in this embodiment, the positions of the fourth basic reinforcement 54 and the fifth basic reinforcement 55 are adjusted so that the lengths of the radial reinforcements are equal in the three enclosed areas.

[0133] At this point, the distance between the aforementioned radial ribs changes very little. The width and length of the multiple grids enclosed by the base ribs and radial ribs are roughly the same, and the strength of the enclosed area is basically the same. Under the premise of meeting the strength requirements of the protective cover, the layout of the base ribs and radial ribs is more regular, and the cross-sectional dimensions of the ribs can be optimized accordingly to maximize the reduction of the weight of the protective cover and reduce costs.

[0134] Obviously, in this embodiment, the basic reinforcement bars in the aforementioned overall area can be pre-arranged, or the basic reinforcement bars can be added to the overall area after the radial reinforcement bars in the overall area are arranged.

[0135] The applicant points out that, in the arrangement of the foundation reinforcement, the preferred approach is to ensure that the width of the enclosed area is greater than or equal to 2D and less than or equal to 4D. This specific limitation on the width of the enclosed area, i.e., the distance limit between adjacent foundation reinforcement bars, indirectly limits the length of the radial reinforcement bars within the enclosed area. If the width between enclosed areas is too long, high requirements are placed on the cross-sectional dimensions of the radial reinforcement bars to ensure overall strength; if the width between enclosed areas is too short, the foundation reinforcement layout is too dense, resulting in high cost and reduced ventilation area.

[0136] Based on this, the applicant points out that each radial rib here preferably intersects with a maximum of four foundation ribs. Combined with the aforementioned width of the enclosed area, i.e., the distance limit between adjacent foundation ribs, this effectively limits the extension length of the first and second radial ribs. Furthermore, as described above, the angle between the extension direction of the radial ribs and the radial line gradually increases along the outward divergence direction from the center of the protective cover. If the length of the radial ribs is not limited, as the length of the radial ribs increases, the amount of change in outward divergence from the center becomes smaller, which will also increase costs and reduce the effective ventilation area.

[0137] At this point, the radial reinforcement arrangement of the outer layer is complete, such as... Figure 10 As shown, radial ribs need to be arranged in the entire inner layer area.

[0138] Since the specific arrangement is the same as described above, involving radial reinforcement within a circular area, it will not be repeated here. Figure 11As shown, the first radial reinforcement 2 is arranged between the central plate 1 and the third foundation reinforcement 53. Figure 12 As shown, the first foundation rib 51 and the second foundation rib 52 are adjusted so that the lengths of the radial ribs in the three enclosed areas of the inner layer are equal. This completes the arrangement of the ribs of the fan protective cover in Embodiment 1.

[0139] When arranging radial ribs in different overall areas, the applicant pointed out that in step 304, the rays in two adjacent overall areas can be located on different sides of OB. Structurally, this manifests as the radial ribs in adjacent enclosed areas having different rotation directions. Adjacent areas with radial ribs rotating in opposite directions actually generate reverse winds during operation. These reverse winds mix with each other, reducing noise during fan operation.

[0140] Example 2

[0141] like Figure 13-20 The diagram shown is a schematic of the design process of the fan protective cover in Embodiment 2, which is described in words below.

[0142] Step 1: Obtain the dimensions of the outer frame 4 of the fan protective cover and the preset dimensions of the center plate 1.

[0143] In this step, the dimensions of the outer frame 4 of the fan protective cover are determined according to the fan specifications, and the dimensions of the center plate 1 are preset according to the size of the rotating shaft and the central shaft of the fan blades.

[0144] Step 2: Arrange foundation reinforcement bars between the central plate 1 and the outer frame 4 of the fan protective cover. The center of the foundation reinforcement bars, the central plate 1 and the outer frame 4 overlap, forming multiple closed areas inside the outer frame 4.

[0145] The shape of the foundation reinforcement bars here is consistent with that of the outer frame 4, but the dimensions are different.

[0146] like Figure 13 The diagram shown is a schematic diagram of step 2 in Embodiment 2. In Embodiment 2, the outer frame 4 is circular, and four basic reinforcing bars are arranged between the central plate 1 and the outer frame 4, namely the first basic reinforcing bar 51, the second basic reinforcing bar 52, the third basic reinforcing bar 53 and the fourth basic reinforcing bar 54.

[0147] Multiple closed areas are formed within the outer frame 4. Specifically, a closed area is formed between the central disc 1 and the first foundation reinforcement 51; a closed area is formed between the first foundation reinforcement 51 and the second foundation reinforcement 52; a closed area is formed between the second foundation reinforcement 52 and the third foundation reinforcement 53; a closed area is formed between the third foundation reinforcement 53 and the fourth foundation reinforcement 54; and a closed area is formed between the fourth foundation reinforcement 54 and the outer frame 4. These form five closed areas.

[0148] Step 3: Arrange radial ribs in the closed area where radial ribs are to be arranged. Each radial rib on the protective cover intersects with at least two basic ribs. The starting point of the radial rib is the end of the radial rib closest to the center of the outer frame 4. The line connecting the starting point and the center of the outer frame 4 is the radial line. The radial ribs satisfy the requirement of radiating outward from the center of the protective cover. The acute angle between the extension direction of the radial rib and the radial line gradually increases.

[0149] The main difference between this embodiment and Embodiment 1 is that the shape of the outer frame 4 is different, resulting in a non-circular enclosed area. Common forms of the outer frame 4 include ellipses, circles, several connected arc segments, and convex polygons. The applicant proposes a design concept for a wind turbine protective cover with a non-circular outer frame 4. This is illustrated below. Figure 13 The outer frame 4 shown is a protective shield design composed of four arc-shaped curves, as illustrated below.

[0150] Step 31: Treat several closed areas with the same radial reinforcement as the whole area. If the whole area is a circular area, arrange the radial reinforcement directly in the circular area, ensuring that the shortest distance from any point on the radial reinforcement to the adjacent radial reinforcement in the same closed area does not exceed 5%. If the whole area is not a circular area, proceed to step 32.

[0151] As described above, there are five enclosed areas within the outer frame 4. In this embodiment, continuous radial ribs are arranged in the three outer enclosed areas, tentatively referred to as the second radial ribs 3, and continuous radial ribs are arranged in the two inner enclosed areas, tentatively referred to as the first radial ribs 2. Therefore, in this embodiment, the two inner enclosed areas and the three outer enclosed areas are considered as a whole area, and radial ribs are arranged accordingly.

[0152] like Figure 14 As shown, in this embodiment, radial reinforcement is first arranged within the overall area formed by the second foundation reinforcement 52 and the outer frame 4. In this embodiment, the overall area is a non-circular area, and step 32 is executed.

[0153] Step 32: With the center of the protective shield as the center, draw a circle with the line connecting the outermost point of the entire area farthest from the center and the center as the radius; with the center of the protective shield as the center, draw a circle with the line connecting the innermost point of the entire area farthest from the center and the center as the radius; the two circles form an annular area.

[0154] like Figure 15 As shown, the overall area shape is first transformed into a circular region. In this embodiment, the outer frame 4 is composed of four arc-shaped curves connected end to end, forming the circular region as shown. Figure 15 In some embodiments, the outer frame 4 is a convex polygon. Due to the limitations of the wind turbine's usage scenarios, it is often a regular polygon. In this case, the circle drawn above is its circumcircle.

[0155] Step 33: Arrange radial ribs within the annular area formed in step 32, ensuring that the shortest distance from any point on the radial rib to adjacent radial ribs within the same closed area does not exceed 5%.

[0156] like Figure 16 As shown, radial ribs are arranged within the annular region, similar to that in Example 1. Figure 2-6 The steps for arranging radial ribs within the circular area shown are the same and will not be repeated here.

[0157] Step 34: Trim the radial ribs that extend beyond the outer edge of the overall area in Step 33, and extend the radial ribs that do not touch the outer edge of the overall area in Step 33 to complete the arrangement of radial ribs within the overall area.

[0158] Combination Figure 16 and 17 As shown, the radial ribs formed in step 33 are trimmed and extended to connect the inner and outer rings of the entire area.

[0159] This completes the layout of the second radial rib 3 within the outer layer of Example 2.

[0160] like Figure 18 As shown, the overall area also includes a third foundation reinforcement 53 and a fourth foundation reinforcement 54. Similarly, the positions of the third foundation reinforcement 53 and the fourth foundation reinforcement 54 can be adjusted to ensure that the radial reinforcement lengths are the same in different enclosed areas.

[0161] like Figure 19 As mentioned above, radial ribs still need to be installed within the overall area formed by the two enclosed areas in the inner layer. This part is similar to the previous one and will not be repeated here.

[0162] like Figure 20 The inner layer is completed by placing a type of radial rib 2 throughout the entire area. This completes the arrangement of the ribs in the fan protective cover of Embodiment 1.

[0163] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for designing a fan protective cover, characterized in that, Includes the following steps: Step 1: Obtain the shape and size of the outer frame (4) of the fan protective cover, and preset the size of the center plate (1); Step 2: Arrange foundation reinforcement between the central plate (1) and the outer frame (4). The center of the foundation reinforcement, the central plate (1) and the outer frame (4) overlaps, and multiple closed areas are formed inside the outer frame (4). Step 3: Arrange radial ribs in the closed area where radial ribs are to be arranged. Each radial rib on the protective cover intersects with at least two basic ribs. The end of the radial rib closest to the center of the outer frame (4) is the starting point. The line connecting the starting point and the center of the outer frame (4) is the radial line. The radial ribs satisfy the outward divergence direction along the center of the protective cover. The acute angle between the extension direction of the radial ribs and the radial line gradually increases. Step 3, arranging the radial reinforcements, includes the following steps: Step 31: Treat several closed areas with the same radial reinforcement as the whole area. If the whole area is a circular area, arrange the radial reinforcement directly in the circular area, so that the shortest distance from any point on the radial reinforcement to the adjacent radial reinforcement in the same closed area does not exceed 5%. If the whole area is not a circular area, proceed to step 32. Step 32: With the center of the protective shield as the center, draw a circle with the line connecting the outermost point of the entire area farthest from the center and the center as the radius; with the center of the protective shield as the center, draw a circle with the line connecting the innermost point of the entire area farthest from the center and the center as the radius; the two circles form an annular area; Step 33: Arrange radial ribs within the annular area formed in step 32, ensuring that the shortest distance from any point on the radial rib to adjacent radial ribs within the same closed area does not exceed 5%; Step 34: Trim the radial ribs that extend beyond the outer edge of the overall area in Step 33, and extend the radial ribs that do not touch the outer edge of the overall area in Step 33 to complete the arrangement of radial ribs within the overall area. The specific steps for arranging radial ribs within the annular area in steps 31 and 33 are as follows: Step 301: Let the inner circle of any annular region where radial ribs are to be arranged be C1, the outer circle be C2, the inner diameter be R1, the outer diameter be R2, and the center be O. There are m radial ribs to be arranged. The distance between any point on the radial rib and the adjacent radial ribs in the same annular region is preset to D. Step 302: Evenly set s first auxiliary ribs (5) with center O in the annular region, namely circles I1, I2, ... IS, where s is a positive integer ≥ 3, divide the region into s+1 auxiliary annular regions, draw a ray from the center O, and from the center O to the outside, intersect the inner circle, the first auxiliary rib (5) and the outer circle at points A, I1, I2... IS and B respectively; Step 303: Calculate the chord length L corresponding to the central angle of circles C1, I1, I2, ..., IS, C2 being 360° / m. A、 L I1、 L I2、… L IS、 L B； Set the angle ∠A = acos(D / L) A ), ∠I1=acos(D / L) I1 ), ∠I² = acos(D / L) I2 ), ...∠IS=acos(D / L IS ), ∠B = acos(D / L) B ); Step 304: Starting from point A, draw a ray in the direction away from the center O, forming a ∠A with OB; starting from point I1, draw a ray in the direction away from the center O, forming a ∠I1 with OB; starting from point I2, draw a ray in the direction away from the center O, forming a ∠I2 with OB; ... starting from point IS, draw a ray in the direction away from the center O, forming a ∠IS with OB; starting from point B, draw a ray in the direction away from the center O, forming a ∠B with OB. All of the aforementioned rays are located on the same side of OB. Step 305: In each auxiliary ring area, a second auxiliary rib (6) with center O is set. The second auxiliary rib (6) is located in the middle of the auxiliary ring area. The rays starting from each point on the outer circle of the auxiliary ring area are extended in the opposite direction until they intersect with the second auxiliary rib (6) in the auxiliary ring area. The rays extended in the opposite direction are rotated around the center O so that the two rays starting from the same auxiliary ring area intersect with the second auxiliary rib (6) in the auxiliary ring area. Step 306: Connect point A, the intersection point on the second auxiliary rib (6) and point B in sequence with a smooth curve to form radial ribs AB. With the center O as the center point, form a circular array of m radial ribs AB to the circular area.

2. The fan protective cover design method according to claim 1, characterized in that, When arranging the foundation reinforcement in step 2, ensure that the width of the resulting closed area is greater than or equal to 2D and less than or equal to 4D.

3. The fan protective cover design method according to claim 1, characterized in that, In step 3, each radial reinforcement bar intersects with a maximum of four foundation reinforcement bars.

4. The fan protective cover design method according to claim 1, characterized in that, After completing the radial reinforcement layout in step 3, adjust the dimensions of the foundation reinforcement within the overall area so that the length of the radial reinforcement in each closed area is equal.

5. The fan protective cover design method according to claim 1, characterized in that, In step 304, the rays in at least one pair of adjacent whole regions are located on different sides of OB.

6. The fan protective cover design method according to claim 1, characterized in that, Step 306 specifically includes the following steps: Step 306a: Connect point A, the intersection point on the second auxiliary rib (6) and point B in sequence with a smooth curve, and set the angle between straight line AB and straight line OA to be 110°-160°. Step 306b: Determine the relationship between the actual angle between lines AB and OA and the preset angle range. If the angle between lines AB and OA falls within the preset angle range, proceed to step 306c. If the angle between lines AB and OA does not fall within the preset angle range, adjust the dimensions of the foundation reinforcement and return to step 31 until the angle between lines AB and OA is consistent with the preset range, and then proceed to step 306c. Step 306c: Using the center O as the center point, arrange m radial ribs AB in a ring array into the ring area.

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