Design method of protective structure of range hood

Abstract

The invention relates to a design method of a protective structure of a range hood, the protective structure comprises a protective net located between an air inlet of an exhaust fume collecting hood and a volute, the protective net is provided with at least two long holes, and a part between two adjacent long holes on the protective net is a connecting rib; the design method comprises the following steps: calculating the deformation of the connecting rib in the X direction and the Y direction; setting a judgment condition for failure of the connecting rib in the X direction and a judgment condition for failure of the connecting rib in the Y direction; substituting the deformation amount of the connecting rib in the X direction into a judgment condition of failure of the connecting rib in the X direction to obtain a first inequality; substituting the deformation amount of the connecting rib in the Y direction into a judgment condition of failure of the connecting rib in the Y direction to obtain a second inequality; and solving the first inequality and the second inequality, and taking the larger value in solving results as the minimum width value of the connecting rib. According to the method, the strength of the protective net can be ensured to be qualified under the condition that the long holes in the protective net are as large as possible.

Description

Technical Field

[0001] This invention relates to the field of oil fume purification technology, and in particular to a protective structure design method for a range hood. Background Technology

[0002] Range hoods have become an indispensable kitchen appliance in modern homes. They are generally classified into two types: top-mounted and side-mounted. Top-mounted range hoods are increasingly popular due to their neat appearance, lightweight design, and small footprint. A typical top-mounted range hood includes a smoke collection hood, a fan frame mounted on the hood, and a fan system housed within the fan frame. This fan system comprises a volute, an impeller, and a motor that drives the impeller.

[0003] To prevent users from accidentally touching the high-speed rotating impeller and getting injured, Chinese utility model patent ZL202120741751.4 (authorization announcement number CN 214536397U) discloses a range hood's air mesh installation structure. This structure includes a body, with an inclined plate on the bottom surface of the body. At least one fume inlet is mounted on the inclined plate, and a fume extraction component is installed on the fume inlet. A protective air mesh is located in front of the fume inlet on the body. While the aforementioned range hood can protect users from inserting their fingers through the protective air mesh, it has the following limitations: due to the high airflow velocity at the fume inlet, placing the protective air mesh in front of the inlet generates significant airflow resistance, noise risk, and turbulent energy consumption. Furthermore, to prevent users from inserting their fingers, the gaps in the protective air mesh are relatively small, further degrading airflow performance. Therefore, further improvements to the existing technology are needed. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide a protective structure design method for a range hood that can reduce the impact on airflow and ensure strength, in contrast to the above-mentioned prior art.

[0005] The technical solution adopted by the present invention to solve the above-mentioned technical problems is as follows: a protective structure design method for a range hood, the range hood including a smoke collection hood with an air inlet and a fan system disposed within the smoke collection hood, the fan system including a volute and an impeller rotatably disposed within the volute, the inlet of the volute and the air inlet of the smoke collection hood being in fluid communication, the protective structure including a protective net, characterized in that: the inlet of the volute and the air inlet of the smoke collection hood are offset from each other, the protective net is located between the air inlet of the smoke collection hood and the volute, the protective net has at least two adjacent elongated holes, each elongated hole extending along the length direction of the protective net, the component between two adjacent elongated holes on the protective net is called a connecting rib, and the front-back direction of the connecting rib is called the X direction, and the left-right direction of the connecting rib is called the Y direction;

[0006] The protective structure design method includes:

[0007] Calculate the deformation of the connecting reinforcement in the X and Y directions;

[0008] Set the judgment conditions for failure of the connecting reinforcement in the X direction and the judgment conditions for failure in the Y direction;

[0009] Substituting the deformation of the connecting bar in the X direction into the judgment condition for failure of the connecting bar in the X direction, we obtain the first inequality; substituting the deformation of the connecting bar in the Y direction into the judgment condition for failure of the connecting bar in the Y direction, we obtain the second inequality; solving the first and second inequalities, and taking the larger value between the solutions of the first and second inequalities as the minimum width of the connecting bar.

[0010] In the above scheme, the formula for calculating the deformation ΔX of the connecting reinforcement in the X direction is:

[0011] ΔX=(F x *L 3 ) / (48*E*I x )

[0012] Among them, F x To apply a force perpendicular to the plane containing the front side of the connecting bar at its center, where L is the length of the connecting bar, E is the elastic modulus of the connecting bar, and I... x This represents the moment of inertia of the connecting rib in the X direction.

[0013] Preferably, the F x The value of is: 30N < F x <50N.

[0014] In the above scheme, the condition for determining the failure of the connecting rib in the X direction is:

[0015]

[0016] Where L is the length of the connecting bar, and n is the first preset value.

[0017] In the above scheme, the formula for calculating the deformation ΔY of the connecting reinforcement in the Y direction is:

[0018] ΔY=(F y *L 3 ) / (48*E*I y )

[0019] Among them, F y To apply a force perpendicular to the plane containing the side of the connecting bar at the center of the connecting bar, I y This represents the moment of inertia of the connecting rib in the Y direction.

[0020] Preferably, the F y The value of is: 100N < F y <150N.

[0021] In the above scheme, the condition for determining the failure of the connecting rib in the Y direction is:

[0022]

[0023] Where m is the second preset value.

[0024] Preferably, the back of the protective net has a flange around the outer perimeter of each elongated hole.

[0025] To accommodate the specific requirements of the flanging process, the height B of each flang is the same, with 0 < B ≤ 0.5 * A.

[0026] Preferably, the distance between the two ends of the elongated hole and the corresponding outer side of the protective net along the length direction is a0*A, where a0 is a preset constant. Then, the formula for calculating the length H of the protective net is: H=L+2a0*A.

[0027] Compared with the prior art, the advantages of the present invention are as follows: On the one hand, by setting the protective net between the air inlet of the smoke hood and the volute, the airflow velocity generated by the protective net is lower because the inlet of the volute and the air inlet of the smoke hood are staggered, thus reducing airflow resistance, noise risk, and turbulent energy consumption. In addition, since the protective net does not directly face the inlet of the volute, it can protect the user's safety even if the user's finger is inserted. Therefore, the long holes in the protective net can be larger, which helps to reduce air resistance. On the other hand, by designing the long holes in the protective net to be as large as possible, the strength of the protective net can also be guaranteed to meet the requirements, thus improving the user's experience. Attached Figure Description

[0028] Figure 1 This is a schematic diagram of the structure of the range hood in an embodiment of the present invention;

[0029] Figure 2 for Figure 1 A sectional view;

[0030] Figure 3 This is a schematic diagram of the protective net structure in an embodiment of the present invention;

[0031] Figure 4 for Figure 3 Another perspective structural diagram. Detailed Implementation

[0032] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments.

[0033] like Figures 1-4As shown, in this embodiment, the range hood includes a smoke hood 1 with an air inlet 10, a fan system located within the smoke hood 1, and a protective structure. The fan system includes a volute 31 and an impeller (not shown) rotatably located within the volute 31. The inlet 311 of the volute 31 and the air inlet 10 of the smoke hood 1 are in fluid communication. The protective structure includes a protective net 2 located within the smoke hood 1. The inlet 311 of the volute 31 and the air inlet 10 of the smoke hood 1 are offset from each other. The protective net 2 is located between the air inlet 10 of the smoke hood 1 and the volute 31. The protective net 2 has at least two adjacent elongated holes 21, each extending along the length of the protective net 2. The component between two adjacent elongated holes 21 on the protective net 2 is called a connecting rib 22, and the front-back direction of the connecting rib 22 is called the X direction, and the left-right direction of the connecting rib 22 is called the Y direction. Figure 3 and Figure 4 As shown, there are 7 elongated holes 21 in this embodiment.

[0034] like Figure 2 As shown, in this embodiment, the air inlet 10 of the smoke hood 1 is located near the bottom of the smoke hood 1, the inlet 311 of the volute 31 faces the front side of the smoke hood 1, and the protective net 2 is located inside the smoke hood 1 and between the air inlet 10 and the volute 31.

[0035] In this embodiment, the protective structure is moved to a position far away from the inlet 311 of the volute 31 and with a larger cross-section. According to the continuity equation, the flow velocity is lower, and the airflow resistance, noise risk, and turbulent energy consumption will be reduced. In addition, since the protective structure is far away from the hazard source, it can be safe even if a hand is inserted. Therefore, the long hole of the protective structure can be larger, which is beneficial to reducing air resistance.

[0036] To reduce airflow resistance, it is desirable to have as large an area as possible for the elongated holes 21 on the protective net 2. However, larger elongated holes 21 will inevitably compress the space of the connecting ribs 22 between the elongated holes 21, reducing the strength of the protective structure. Therefore, it is necessary to consider the minimum design width of the connecting ribs 22 to ensure their strength meets requirements. To solve the above technical problems, the protective structure design method in this embodiment includes:

[0037] Calculate the deformation of the connecting reinforcement 22 in the X direction and the deformation in the Y direction;

[0038] Set the judgment conditions for failure of the connecting rib 22 in the X direction and the judgment conditions for failure in the Y direction;

[0039] Substituting the deformation of the connecting rib 22 in the X direction into the judgment condition for the failure of the connecting rib 22 in the X direction, we obtain the first inequality; and substituting the deformation of the connecting rib 22 in the Y direction into the judgment condition for the failure of the connecting rib 22 in the Y direction, we obtain the second inequality; solving the first and second inequalities, and taking the larger value of the solution results, we take it as the minimum width of the connecting rib 22.

[0040] The formula for calculating the deformation ΔX of the connecting rib 22 in the X direction in this embodiment is:

[0041] ΔX=(F x *L 3 ) / (48*E*I x )

[0042] Among them, F x To apply a force perpendicular to the plane containing the front side of the connecting rib 22 at the center of the front side, where L is the length of the connecting rib 22, E is the elastic modulus of the connecting rib 22, and I... x Let 22 be the moment of inertia of the connecting rib in the X direction;

[0043] The formula for calculating the deformation ΔY of the connecting reinforcement 22 in the Y direction is:

[0044] ΔY=(F y *L 3 ) / (48*E*I y )

[0045] Among them, F y To apply a force perpendicular to the plane containing the side of the connecting bar 22 at the center of the side, I y Let 22 be the moment of inertia of the connecting rib in the Y direction;

[0046] In this embodiment, the back of the protective net 2 is provided with flanges 23 around the outer periphery of each elongated hole 21. The height B of each flange 23 is the same. Due to the special nature of the flange processing, the flange height should not exceed 50% of the width of the connecting rib, 0 < B ≤ 0.5 * A, where A is the width of the connecting rib 22. In addition, the distance between the two ends of 21 and the corresponding outer side of the protective net 2 along the length direction of the protective net 2 is a0 * A. The formula for calculating the length H of the protective net 2 is: H = L + 2a0 * A, where a is a preset constant. In this embodiment, B = 0.5A, a0 = 1.5, so L = H - 3A.

[0047] For the connecting reinforcement 22 in this embodiment, its moment of inertia can be approximately regarded as the moment of inertia of a rectangular beam, that is: I x =(A*B 3 ) / 12, I y =(B*A 3) / 12;

[0048] Will I x Substituting the formulas for calculating L and ΔX into the formula for calculating ΔX, we can obtain...

[0049] ΔX=(F x *(H-3A) 3 ) / (4*E*A*(0.5A) 3 )

[0050] Will I y Substituting the formulas for calculating L and ΔY into the formula for calculating ΔY, we can obtain...

[0051] ΔY=(F y *(H-3A) 3 ) / (4*E*A*(0.5A) 3 )

[0052] The value of E mentioned above depends on the material of the protective net. In this embodiment, the commonly used material for the protective net is galvanized sheet, with an elastic modulus of 190 to 210 GPa.

[0053] F x The value of is: 30N < F x <50N, F x This is typically the wiping force. In daily cleaning and wiping, a large amount of force is usually not needed; the force used by a person generally does not exceed 10N. For safety reasons, it is recommended to estimate 30-50N in the design calculations; F y The value of is: 100N < F y <150N.

[0054] F y Grip force is typically measured in kPa (kilopascals). The actual grip force (in Newtons) can be obtained by multiplying the grip force (kPa) by the contact area of ​​the hand (square meters), and then multiplying by a constant of 0.5. The grip force of an adult male during non-violent gripping is in the range of 40-100 kPa. Since the area of ​​a human palm is less than 0.005 square meters, it is obvious that the palm cannot fully contact the structure of this invention. Therefore, we take the contact area as 0.001 square meters, which corresponds to a grip force range of 20-50 Newtons. For safety reasons, it is recommended to use 100-150 N in the design calculations.

[0055] The main failure mode of the protective netting in this embodiment is bending deformation. Failure in the X direction is compression deformation in scenarios such as wiping, i.e., applying F... x The force caused the protective netting to dent; failure in the Y direction was due to the squeezing deformation when gripping the two connecting ribs, i.e., the application of F yThe force causes the baffle to bend left and right. In this embodiment, the protective net is a sheet metal part. When its deformation is small, it is usually elastic deformation and can recover on its own after the force is removed. Therefore, the sheet metal part is considered to have failed only when the deformation of the sheet metal part meets the following conditions:

[0056] The condition for failure of connecting rib 22 in the X direction is:

[0057]

[0058] Where L is the length of the connecting rib 22, and n is the first preset value.

[0059] The condition for failure of connecting reinforcement 22 in the Y direction is:

[0060]

[0061] Where m is the second preset value.

[0062] The values ​​of the first preset value n and the second preset value m are determined based on experiments or experience. In this embodiment, n% = m% = 5%.

[0063] The first inequality is:

[0064]

[0065] Right now:

[0066] EA 4 -40F x (H-3A) 2 ≥0

[0067] EA 4 -360F x A 2 +240HF x A-40F x H 2 ≥0

[0068] The above formula involves finding the roots of a quartic equation in one variable, which is quite complex. It is recommended to use a numerical computer solution. This embodiment provides a solution method (Ferrari method). The general form of the quartic equation is: ax 4 +bx 3 +cx 2 The specific solution process for +dx+e=0 is as follows:

[0069] 1. Transform the equation into standard form:

[0070] x 4 +px 3 +qx 2 +rx+s=0

[0071] where p=b / a, q=c / a, r=d / a, s=e / a

[0072] 2. Transform the equation: Let y = x + p / 4, that is, x = yp / 4. Substitute this into the equation to get:

[0073] y 4 +py 2 +(q-3p 2 / 8)y 2 +(rp 3 / 8)y+(s-pq / 4+p 2 / 16)=0

[0074] 3. Multiplying both sides of the equation by 4, we get:

[0075] 4y 4 +4py 2 +(4q-3p 2 )y 2 +(4r-p 3 )y+(4s-pq+p 2 / 4)=0

[0076] 4. Let z = y 2 Substituting it into the above equation, we get:

[0077] 4z 2 +(4q-3p 2 )z+(4r-p 3 )z+(4s-pq+p 2 / 4)=0.

[0078] 5. Solve for the value of z, and then find the four roots of the equation using y = ±√z and x = yp / 4.

[0079] Because solving quartic equations in one variable is quite complex and may involve complex roots, it is recommended to use a computer or other tools for solving them in practical applications.

[0080] Similarly, the second inequality is solved using the same method described above, and will not be elaborated further here.

[0081] The specification and claims of this invention use terms indicating direction, such as "front," "rear," "upper," "lower," "left," "right," "side," "top," and "bottom," to describe various exemplary structural parts and elements of the invention. However, these terms are used herein merely for ease of explanation and are determined based on the exemplary orientations shown in the accompanying drawings. Since the embodiments disclosed in this invention can be arranged in different orientations, these terms indicating direction are for illustrative purposes only and should not be considered as limitations. For example, "upper" and "lower" are not necessarily limited to directions opposite to or consistent with the direction of gravity.

Claims

1. A protective structure design method for a range hood, the range hood comprising a smoke hood (1) with an air inlet (10) and a fan system disposed within the smoke hood (1), the fan system comprising a volute (31) and an impeller rotatably disposed within the volute (31), the inlet (311) of the volute (31) and the air inlet (10) of the smoke hood (1) being in fluid communication, the protective structure comprising a protective net (2), characterized in that: The inlet (311) of the volute (31) is offset from the air inlet (10) of the smoke hood (1). The protective net (2) is located between the air inlet (10) of the smoke hood (1) and the volute (31). The protective net (2) has at least two adjacent elongated holes (21) on it. Each elongated hole (21) extends along the length of the protective net (2). The component between two adjacent elongated holes (21) on the protective net (2) is called the connecting rib (22). The front-back direction of the connecting rib (22) is called the X direction, and the left-right direction of the connecting rib (22) is called the Y direction. The protective structure design method includes: Calculate the deformation of the connecting reinforcement (22) in the X direction and the deformation in the Y direction; Set the judgment conditions for failure of the connecting reinforcement (22) in the X direction and the judgment conditions for failure in the Y direction; Substituting the deformation of the connecting bar (22) in the X direction into the judgment condition for the failure of the connecting bar (22) in the X direction, we obtain the first inequality; and substituting the deformation of the connecting bar (22) in the Y direction into the judgment condition for the failure of the connecting bar (22) in the Y direction, we obtain the second inequality; we solve the first inequality and the second inequality, and take the larger value of the solution results of the first inequality and the second inequality as the minimum width of the connecting bar (22).

2. The protective structure design method according to claim 1, characterized in that: The formula for calculating the deformation ΔX of the connecting reinforcement (22) in the X direction is: ΔX=(F x *L 3 ) / (48*E*I x ) Among them, F x To apply a force perpendicular to the plane containing the front side of the connecting bar (22) to the center of the front side of the connecting bar (22), where L is the length of the connecting bar (22), E is the elastic modulus of the connecting bar (22), and I... x The moment of inertia of the connecting rib (22) in the X direction.

3. The protective structure design method according to claim 2, characterized in that: The F x The value of is: 30N < F x <50N.

4. The protective structure design method according to claim 3, characterized in that: The condition for determining the failure of the connecting rib (22) in the X direction is: Where L is the length of the connecting bar (22) and n is the first preset value.

5. The protective structure design method according to claim 4, characterized in that: The formula for calculating the deformation ΔY of the connecting reinforcement (22) in the Y direction is: ΔY=(F y *L 3 ) / (48*E*I y ) Among them, F y To apply a force perpendicular to the plane containing the side of the connecting bar (22) at the center of the side, I y Let be the moment of inertia of the connecting rib (22) in the Y direction.

6. The protective structure design method according to claim 5, characterized in that: The F y The value of is: 100N < F y <150N.

7. The protective structure design method according to claim 6, characterized in that: The condition for determining the failure of the connecting reinforcement (22) in the Y direction is: Where m is the second preset value.

8. The protective structure design method according to any one of claims 1 to 7, characterized in that: The back of the protective net (2) has a flange around the outer periphery of each elongated hole (21).

9. The protective structure design method according to claim 8, characterized in that: The height B of each flange is the same, and 0 < B ≤ 0.5 * A.

10. The protective structure design method according to claim 9, characterized in that: The distance between the two ends of the elongated hole (21) along the length direction of the protective net (2) and the corresponding outer side of the protective net (2) is a0*A, where a0 is a preset constant. The formula for calculating the length H of the protective net (2) is: H=L+2a0*A.

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