Improved fan assembly for a range hood

Abstract

A fan assembly (1) for a hood for extraction of cooking fumes, used above a cooking hob in a kitchen, comprising a casing (2) and an impeller (22) driven by an electric motor (20), said casing having an internal cavity (4) delimited by a wall (3) and suitable for housing said impeller (22) and said electric motor (20), said impeller (22) being located in said internal cavity (4) in such a way as to define with said wall of said internal cavity a helical duct (25) for the entry of vapours into said internal cavity, said helical duct opening into a terminal outlet (5), and the casing (2) being open on opposite sides (6, 7) (at 8, 9) to favour the entry of vapours at opposite heights of said impeller (22). Said wall (3) of said casing comprises a plurality of portions (30, 31, 32, 33, 34, 35, 36) having different radii or radial configurations from one another.

Description

[0001] According to the foregoing clauses, the subject of this invention is a fan assembly for a kitchen range hood.

[0002] As we all know, the fan assembly is an important component of a kitchen range hood. It is designed to be installed above the stove to draw in the steam (containing fumes, grease, and oil) generated when food is being prepared on the stove. The steam is then drawn in by the fan assembly after being filtered and directed to the range hood outlet, which can either connect to the external environment of the kitchen or return the drawn-in and filtered steam to the kitchen.

[0003] In this article, "fan assembly" refers to a component of a kitchen range hood, including a housing containing an impeller and a corresponding electric motor that drives the impeller. When the aforementioned fan assembly is in operation, steam generated on the cooking stove is drawn into the housing of the fan assembly and then sent to the exhaust port of the range hood.

[0004] More specifically, the kitchen range hood fan assembly includes a housing having an inner cavity defined by the housing walls, an impeller, and an adjacent electric motor that axially drives the impeller located within the inner cavity. The impeller is positioned laterally within the housing to form a helical duct with the housing walls, which terminates at the exhaust port of the range hood. Furthermore, the impeller draws in steam from opposing openings on the fan housing, which are typically provided with a grille with radial ribs that begin at the edges of their respective openings and end at a relative height at the center of the openings, where these ribs connect to end rings. One of these rings, located on one side of the housing, is close to the electric motor and is typically connected to the electric motor in a manner that supports it.

[0005] In kitchen range hoods, a fan with a high level of noise suppression during operation is crucial. A fan with high hydrodynamic efficiency is also important to reduce energy consumption when using the range hood (resulting in high energy efficiency).

[0006] As we already know, a quiet and efficient range hood can be obtained through proper design of its impeller and electric motor.

[0007] EP0985829 describes a fan assembly for a range hood used in a kitchen, comprising a housing having an inner cavity suitable for housing an impeller and an electric motor. The impeller is positioned within the inner cavity of the housing to define, together with the walls of the inner cavity, a helical conduit for drawing steam from a cooking oven into the inner cavity. The helical conduit opens at an end outlet from which steam exits after being filtered by a known method.

[0008] The shell has openings on opposite sides to allow the intake steam to enter.

[0009] The housing comprises multiple sections with different radial configurations.

[0010] CN110966257, EP1156224, CN104047895 and CN207080414 also describe a fan assembly for a kitchen range hood, the fan assembly having a housing assembled from a plurality of parts having different radial configurations from each other.

[0011] The purpose of this invention is to provide a fan assembly for a range hood that has high hydrodynamic efficiency and thus high energy efficiency, but does not act on the moving parts (impeller and electric motor) of the range hood fan assembly.

[0012] Therefore, the object of the present invention is to provide a fan assembly that has such efficiency characteristics (an improvement over what can be achieved with known solutions) due to its fixed and structural components.

[0013] In particular, the object of the present invention is to provide an improved fan assembly having a housing manufactured in a manner that can improve the hydrodynamic and energy efficiency of a range hood.

[0014] Another object of the present invention is to provide a fan assembly in which the structural and dimensional features of the housing not only increase hydrodynamic and energy efficiency, but also reduce the noise generated by the fan itself during operation.

[0015] These and other objectives will be obvious to those skilled in the art and are achieved by means of the attached fan.

[0016] To enhance the understanding of the invention, the following drawings are attached by way of indication rather than limitation, wherein:

[0017] Figure 1 A perspective view of one side of the fan assembly housing according to the present invention is shown;

[0018] Figure 2 yes Figure 1 An exploded 3D view of the shell;

[0019] Figure 3 yes Figure 1 A three-dimensional view of the shell from another angle;

[0020] Figure 4 yes Figure 3 An exploded 3D view of the shell;

[0021] Figure 5 This is a side view of the fan assembly of the present invention;

[0022] Figure 6 It is along Figure 5 A cross-sectional view along line 6-6;

[0023] Figure 7 It is along Figure 5 A cross-sectional view of line 7-7;

[0024] Figure 8 It is along Figure 5 A sectional view along line 8-8;

[0025] Figure 9 It is along Figure 5 A cross-sectional view of line 9-9;

[0026] Figure 10 yes Figure 5 A top view of the fan assembly;

[0027] Figure 11 It is along Figure 5 A cross-sectional view of line 11-11;

[0028] Figure 12 yes Figure 11 The image shown is a magnified view of the details of M.

[0029] Figure 13 It is along Figure 5 A cross-sectional view of line 13-13;

[0030] Figure 14 yes Figure 13 A magnified view of the details, represented as N; and

[0031] Figure 15 It is along Figure 10 The cross-sectional view along line 15-15, according to the fan assembly of the present invention, shows some parts omitted for clarity.

[0032] Referring to the above-referenced figures, the fan assembly 1 includes a housing 2, which defines an inner cavity 4 opening at a terminal outlet 5 at the top via its wall 3 (see figure). Figures 1-3 The inner cavity also opens on its opposite sides 6 and 7, providing side openings or openings 8 and 9 for drawing in steam (steam intake or inlet opening). Grilles 10 and 11 are located on the side openings 8 and 9, and grilles 10 and 11 have ribs 12 and 13 respectively, which converge toward end rings 14 and 15 at the center of their respective side openings 8 and 9.

[0033] The housing 2 houses an electric motor 20 with an output or drive shaft 21. An impeller 22 is keyed onto the output or drive shaft 21. Both the impeller 22 and the electric motor 20 are of known type and will not be described further. The electric motor 20 is connected to the end ring 15 of the grille 11 via a connector 23.

[0034] In a known manner, the electric motor 20 and impeller 22 are located within the housing 2, defining a helical duct 25 together with the wall 3. This helical duct 25 has a helical cross-section beginning at a portion 40 of the housing 2 referred to as the "blower cut-off," which gradually increases towards the terminal outlet 5, as will be described later. Through the latter, a shroud with a fan assembly 1 is located at the relative height of the stove. Steam generated on the stove is drawn in by side (inlet) openings 8 and 9 and directed into the helical duct 25, and discharged from the terminal outlet 5.

[0035] The housing 2 is defined by a plurality of transverse portions, which include at least the peripheral edge of each opening 8 and 9, and each portion defines a transverse portion of the housing wall 3. "Peripheral edge" refers to the portion around each opening, which will be described later.

[0036] The aforementioned parts can be manufactured independently of each other, or they can be components of a larger portion of the housing.

[0037] Starting from terminal outlet 5, i.e., from blower cut-off section 40, moving along spiral duct 25, terminal outlet 5 and section 40 are part of the first section 30 of housing 2; other consecutive and adjacent sections along spiral duct 25 are designated 31, 32, 33, 34, 35, 36. Thus, these sections are assembled together in a manner known per se to define housing 2 with side openings 8 and 9. Alternatively, at least some sections may be components of two half-shells, each half-shell having a complete side opening of the housing (not part of the housing), and joined together in a plane K perpendicular to the axis W of drive shaft 21 (see...). Figure 1 Then, parallel to the opening. In a further alternative, the portions may be paired or in varying numbers as component parts of the housing 2, and then assembled to each other in a manner known per se. The portions of plastic material are obtained independently by molding; alternatively, they may be made of aluminum or aluminum alloy by die casting.

[0038] At least some, but preferably all, or at least some of the portions 30 and 32-36 have angles 31A, 32A, 33A, 34A, 35A, and 36A with radii of curvature different from each other. The radii of curvature are in... Figure 5 Let A, B, C, D, E, and F be the numbers in the set, and let them have the following values:

[0039] A is between 1 and 5 mm, preferably between 2 and 4 mm, and advantageously between 3 and 3.5 mm.

[0040] B is between 2 and 8 mm, preferably between 3 and 7 mm, and advantageously between 5 and 5.5 mm.

[0041] C is between 3 and 12 mm, preferably between 5 and 10 mm, and advantageously between 8 and 8.5 mm.

[0042] D is between 10 and 30 mm, preferably between 15 and 25 mm, and advantageously between 15 and 18 mm.

[0043] E is between 20 and 40 mm, preferably between 25 and 35 mm, and advantageously between 30 and 32 mm.

[0044] F is between 90 and 120 mm, preferably between 95 and 115 mm, and advantageously between 100 and 110 mm.

[0045] The geometric values ​​of the various radii of curvature defining the portions of housing 2—namely, the geometric values ​​of the radii connecting side surfaces 31B, 32B, 33B, 34B, 35B, and 36B (whose free edges 32B1, 33B1, 34B1, 35B1, and 36B1, together with the free edge 30B1 of side surface 30, defining the circumferential edges of openings 8 and 9) and the radii of transverse surfaces 31C, 32C, 33C, 34C, 35C, and 36C—allow housing 2 to follow a helical path that provides optimal hydrodynamic performance and reduces noise from the fan assembly during operation. Surprisingly, the aforementioned effects are found to be closely related to the different structures of portions 31-36 of the housing, which can be obtained during housing production using methods that do not affect the overall production cost.

[0046] It should be noted that the special structure of the housing 2 obtained by producing the housing portions 31-36 as described above allows for the creation of a helical duct 25, which can be defined by a mathematical formula (this formula is for the fan assembly and impeller):

[0047] r(ψ) = r_1*(1+Kψ)

[0048] in:

[0049] r(ψ) = the general distance between the center of the impeller 22 and the wall 3 of the casing, as a function of the angle calculated from a segment along the plane of symmetry P of the impeller, starting from the point connecting the center G of the impeller 22 itself to the point of the casing closest to the center (as described below); the angle increases in the direction of increasing cross-sectional area of ​​the helix defined by the helical pipe 25;

[0050] r_1 = the minimum distance between impeller 22 and wall 3;

[0051] K = a constant value for a specific fan assembly and a specific impeller, which is calculated based on r_1 and the radius (r4) at 270° of the housing. These values ​​are set during the preliminary design phase.

[0052] ψ = the arc unfolding value expressed in degrees (or unfolding angle).

[0053] The spiral duct is thus defined in such a way that it is possible to increase (by a value of up to close to 10%) the hydrodynamic efficiency of the fluid flowing within it and reduce the noise generated by the fan assembly during use.

[0054] Figure 15 The display shows some distances r (basically starting from r_1, which are 0°, 90°, 180°, and 270°).

[0055] The radius r_1 is calculated relative to the aforementioned segment connecting the center G of the impeller 22 to the (inner) wall 3 of the housing 2 closest to said center. In particular, the radius r_1 is calculated relative to the aforementioned portion 40 of the housing 2 (which is known in itself and is typically located within the fan assembly of a range hood), referred to as the "blower cutoff," which, as is well known, plays a role in reducing the hydrodynamic noise of the blower. Surprisingly, it was found that extending the central end 41 of the component beyond the longitudinal plane of symmetry P of the impeller (see [reference needed]) within the portion 36 near the terminal outlet 5... Figure 15 This can reduce the noise by at least 10% and improve the fluid dynamic efficiency by more than 5-6%.

[0056] More specifically, the angle α formed between the connecting line (or connecting segment) connecting the end 41 and the center G of the impeller 22 is between 3.3° and 5.0°, advantageously between 3.7° and 4.5°, and preferably equal to 4°.

[0057] This section 40 is an arc-shaped, semi-circular structure (see...). Figure 10 ), has an inclined upper wall 42, which is perpendicular to plane P (see Figure 15 The angle β formed is between 45° and 70°, preferably around 60°.

[0058] By making the diameter of each inlet opening 8 and 9 the same as the diameter of the impeller 22, a surprising further reduction in noise and an increase in efficiency were achieved. Due to this feature, noise was reduced by almost 1%, while hydrodynamic efficiency increased by 3%.

[0059] The dimensional characteristics of openings 8 and 9 were not obtained based on simple design choices, but rather on careful hydrodynamic studies of the fan assembly, contrary to the normal design approach of providing inlet openings with a diameter larger than the impeller diameter to facilitate steam intake. This study shows that air drawn in through openings 8 and 9 and pressurized within the helical duct 25 of the impeller 22 tends to be drawn back to the outside of the housing 2 along the extreme edges of the impeller and discharged from the outer periphery of the openings. This effect, known as "backflow" in turbomachinery, has also been found to occur in range hood assemblies. Due to the diameter configuration of openings 8 and 9 and the impeller 22, the aforementioned "backflow" effect, if not completely eliminated, is at least significantly reduced.

[0060] Since the propagation of BPF (blade pass frequency) noise associated with the movement of the impeller blades 22 to the outside of the housing 2 is avoided, the tone of the noise generated by motor starting and impeller rotation is also improved.

[0061] Furthermore, the ribs 12 of the grille 10 facing the single impeller 22 are structurally spiral, which helps to create optimal flow when steam is drawn into the impeller. The ribs 12 are located on the truncated conical surface S protruding from the casing 2 (see...). Figure 11 and 13 ).For example, Figure 14 The angle of the truncated cone, denoted as γ, is between 25 and 30°.

[0062] The special structure of the grille helps optimize the hydrodynamics of the steam flow and reduce the latter’s losses, thereby improving the efficiency of fan assembly 1.

[0063] A similar observation can be made regarding the grille 11 located at a relative height to the inlet opening 9, where the electric motor 20 (included in the impeller 22) also faces the inlet opening.

[0064] In this configuration, the grid 11 is flat but still has spiral ribs 13, similar to the ribs 12 of the (single) impeller front grid 10. This structure also helps reduce steam intake losses and improve the efficiency of the fan assembly 1.

[0065] As a result of the present invention, it has been unexpectedly discovered that by modifying the fixed and structural components of the fan assembly 1, significant benefits can be obtained not only in terms of the energy and hydrodynamic performance of the fan assembly, but also in terms of the noise generated during the use of the fan assembly.

Claims

1. A fan assembly (1) for a range hood used above a stove in a kitchen, the fan assembly comprising a housing (2) and an impeller (22) and an electric motor (20) contained within the housing, the housing (2) having an inner cavity (4) defined by a wall of the housing (2), the impeller (22) being located in the inner cavity (4) such that the impeller and the wall of the inner cavity (4) define a helical duct (25) starting from a blower cut-off portion (40), the helical duct (25) For steam to enter the inner cavity, the spiral pipe leads to the terminal outlet (5), and the housing (2) has side openings (8, 9) on opposite sides (6, 7) to facilitate steam entry at a relative height of the impeller (22), starting from the blower cut-off section (40) and moving along the spiral pipe. The wall (3) of the housing comprises multiple sections (30, 31, 32, 33, 34, 35, 36) having different radii or radial structures from each other. The portion defines the transverse portion of the wall (3) of the housing (2), the first portion (30) includes the terminal outlet (5) of the helical pipe (25), the portions (30, 31, 32, 33, 34, 35, 36) have side surfaces (30B, 31B, 32B, 33B, 34B, 35B, 36B) connected to the transverse surface (30C, 31C, 32C, 33C, 34C, 35C, 36C), the side surfaces having It has free edges (30B1, 31B1, 32B1, 33B1, 34B1, 35B1, 36B1) that, during assembly, define the peripheral edges of the side openings (8, 9) of the housing (2), and the angles (30A, 31A, 32A, 33A, 34A, 35A, 36A) between the side surfaces and the transverse surfaces are set with corresponding radii of curvature (A, B, C, D, E, F) having the following values, characterized in that... The angles (30A, 31A, 32A, 33A, 34A, 35A, 36A) include at least a first angle, a second angle, and a third angle, which are arranged sequentially along the direction of gradually increasing cross-section of the shell. The first corner includes a portion having a first radius of curvature (A) and connecting to a corresponding side surface, the first radius of curvature (A) being between 2 and 4 mm; and the first corner includes another portion having a third radius of curvature (C) and connecting to a corresponding transverse surface, the third radius of curvature (C) being between 5 and 10 mm; The second angle includes a portion having a second radius of curvature (B) and connecting to a corresponding side surface, the second radius of curvature (B) being between 2 and 8 mm; and the second angle includes another portion having a fifth radius of curvature (E) and connecting to a corresponding transverse surface, the fifth radius of curvature (E) being between 20 and 40 mm; and The third corner includes a portion having a fourth radius of curvature (D) and connecting to a corresponding side surface, the fourth radius of curvature (D) being between 10 and 30 mm; and the third corner includes another portion having a sixth radius of curvature (F) and connecting to a corresponding transverse surface, the sixth radius of curvature (F) being between 90 and 120 mm; One end (41) of the blower cut-off section (40) extends beyond the plane of symmetry (P) of the impeller (22), and the segment connecting the end (41) to the center (G) of the impeller forms an angle (α) between 3.3° and 5.0° with the plane of symmetry.

2. The fan assembly according to claim 1, characterized in that, At least some of the portions (32, 33, 34, 35, 36) are components of two half-shells that define the housing (2) when assembled along a plane (K) perpendicular to the drive shaft (21) of the electric motor (20).

3. The fan assembly according to claim 2, characterized in that, Each half-shell has a side opening (8, 9) of the shell (2).

4. The fan assembly according to claim 1, characterized in that, The assembled portions (30, 31, 32, 33, 34, 35, 36) of the wall (3) defining the housing, together with the impeller (22), define a helical conduit having a path mathematically defined by the following formula: r(ψ) = r_1*(1+Kψ) in: r = the distance between the center (G) of the impeller and the wall (3) of the housing, as a function of the angle along the spiral pipe (25) in the housing, where the radius is calculated; r_1 = the minimum distance between the center (G) of the impeller and the wall (3) of the housing; K = A constant value determined during the design of the wind turbine assembly based on a specific value relating to the distance at 270° between the center of the impeller (22) and the wall (3) of the casing (2). ψ = arc expansion value, in degrees.

5. The fan assembly according to claim 4, characterized in that, The distance between the center (G) of the impeller (22) and the wall (3) of the housing is minimum at the relative height of the blower cut-off section (40) of the fan assembly, near the terminal outlet (5) of the spiral duct (25) of the housing (2), the segment connecting the end (41) to the center (G) of the impeller forms an angle (α) between 3.3° and 5.0° with the plane of symmetry, the blower cut-off section (40) has an arcuate structure with an inclined upper wall (42) forming an angle (β) between 45° and 70° with the plane of symmetry.

6. The fan assembly according to claim 5, characterized in that, The segment connecting the end (41) to the center (G) of the impeller forms an angle (α) between 3.7° and 4.5° with the plane of symmetry.

7. The fan assembly according to claim 6, characterized in that, The segment connecting the end (41) to the center (G) of the impeller forms an angle (α) of 4° with the plane of symmetry.

8. The fan assembly according to claim 5, characterized in that, The inclined upper wall forms an angle (β) of approximately 60° with the plane of symmetry.

9. The fan assembly according to claim 1, characterized in that, The diameter of the side openings (8, 9) of the housing (2) is equal to the diameter of the impeller (22).

10. The fan assembly according to claim 1, characterized in that, At the relative height of each side opening (8, 9) of the housing (2), there is a grid (10, 11) with ribs (12, 13) along a spiral route.

11. The fan assembly according to claim 10, characterized in that, The ribs (12) of the grid (10) located on the opening facing the single impeller (22) are located on the truncated conical surface (S).

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