Fan blade

Abstract

The invention relates to a fan blade (1) comprising a hub (2) having a rotation axis (XR) and blades (3) extending substantially radially outward from the hub (2), each blade (3) being defined by a span (EN), a leading edge (BA) and a trailing edge (BF), wherein the blade (3) is further defined by a stack of aerodynamic profiles (PA) configured according to a thickness distribution law (LE1) around a neutral line (FN) connecting the leading edge (BA) and the trailing edge (BF) of the blade (3), wherein the neutral line (FN) is characterized by a parameter called chord length (LC) representing the distance between the two ends of the neutral line (FN), wherein the thickness distribution law (LE1) represents the variation of the profile thickness along the neutral line (FN), and wherein the thickness distribution law presents a variation in the span direction (EN) so as to form at least two thickness undulations (3) on the blade (3) spaced apart from each other in the span direction (EN).

Description

Technical Field

[0001] This invention relates to a fan impeller, particularly an axial flow fan. Specifically, the fan is configured to be integrated into the front cooling module of an internal combustion engine vehicle or an electric vehicle. Background Technology

[0002] It is worth noting that the purpose of this invention is to reduce noise in such a fan without affecting its aerodynamic performance. Summary of the Invention

[0003] Therefore, the object of the present invention is to provide a fan impeller comprising a hub having an axis of rotation and blades extending generally radially outward from the hub, each blade being defined by a span, a leading edge, and a trailing edge, the blades being further defined by a stack of aerodynamic profiles constructed according to a thickness distribution pattern around a neutral line connecting the leading and trailing edges of the blades, the neutral line being characterized by a parameter called chord length, which represents the distance between the two ends of the neutral line, the thickness distribution pattern representing the variation of the thickness of the profile along the neutral line, the thickness distribution pattern varying in the span direction, thereby forming at least two thickness ripples spaced apart from each other in the span direction on the blades.

[0004] In this invention, to a certain extent, the thickening or thinning coefficient is controlled on each cross section (aerodynamic profile) forming the blade so as to form ripples when transitioning from one aerodynamic profile to the next.

[0005] Therefore, in this case, the thickness corrugations are formed alternately along the span direction by a thinning section defining the low point of the corrugations and a thickening section defining the high point of the corrugations.

[0006] The applicant has discovered that one or more corrugations on the blade provide acoustic and aerodynamic benefits. In particular, the present invention allows for a reduction in sound level without affecting airflow performance or modifying the manufacturing process. Specifically, the corrugations provide flow coherence by reducing radial airflow effects. The performance improvement can be explained in particular by the fact that the boundary layer can be better maintained at the profile, which reduces separation that could lead to a loss of ventilation performance and reduces any acoustic fluctuations that generate noise.

[0007] As an illustration, the neutral line passes through the center of the blade profile between the leading and trailing edges. The aerodynamic profile specifically corresponds to the circumferential section of the blade at a given radius, which is obtained by the blade intersecting a geometric cylindrical surface at a given radius that is coaxial with the impeller's axis of rotation.

[0008] The stacked aerodynamic profiles can be identical or variable.

[0009] The term "blade span" specifically refers to the length of the blade, measured as a percentage along a straight line passing through the axis of rotation in a plane perpendicular to the impeller's axis of rotation. A value of 0% specifically corresponds to the point of contact between the blade and the hub (referred to as the blade root), and a value of 100% corresponds to the point of contact between the blade and the rim (referred to as the blade tip). The expression "along the span direction" specifically refers to the direction from the blade root to the blade tip.

[0010] In this scenario, with the pressure and suction surfaces symmetrical to each other, the thickness distribution along the neutral line follows this convention: the horizontal axis represents the position of a point considered along the neutral line, expressed as a percentage of the neutral line length, where 0% corresponds to a point on the leading edge and 100% to a point on the trailing edge; the vertical axis represents the blade thickness on one side of the neutral line, expressed as a percentage of the chord length, i.e., the vertical axis is determined by the ratio of the chord length to a given radius. Thickness is measured by using the neutral line as a zero reference. For example, the profile of the suction surface is defined by the thickness variation along the neutral line, which is the distance measured between the neutral line and the suction surface.

[0011] A thickness distribution pattern can be provided to define the pressure surface of the blade. In this case, the thickness is the distance between the neutral line and the pressure surface.

[0012] The suction surface can have one thickness distribution pattern, while the pressure surface can have another thickness distribution pattern.

[0013] According to one aspect of the invention, the corrugations can be defined in the spanwise direction by a low point located between two high points. The low point of the corrugations is specifically located on the thinned section of the blade, and the high point is located on the thickened section of the blade.

[0014] The amplitude of a wave is the difference in thickness between the low and high points of the wave at a given location on the wingspan.

[0015] According to one aspect of the invention, at least for some of the corrugations, the plurality of corrugations on the main surface (suction surface or pressure surface) have the same thickness amplitude.

[0016] According to another aspect of the invention, the multiple corrugations on the main surface (suction surface or pressure surface) have all different thickness amplitudes.

[0017] According to one aspect of the invention, at least some of the corrugations on the main surface (suction surface or pressure surface) have a thickness amplitude that increases as they approach the blade tip. It is noteworthy that the corrugations have a thickness amplitude that increases as they approach the blade tip.

[0018] According to one aspect of the invention, one or more corrugations have a sinusoidal or pseudo-sinusoidal shape along the wingspan.

[0019] The ripples are specifically contained between two envelope curves, which are in particular polynomial curves.

[0020] According to one aspect of the invention, the corrugation includes grooves that extend substantially transversely to the blade's span, particularly along the blade's neutral line.

[0021] According to one aspect of the invention, the corrugations are parallel to each other.

[0022] According to one aspect of the invention, the corrugations are parallel to the neutral line of the blade.

[0023] According to one aspect of the invention, the corrugations are inclined so as to form a positive or negative spiral on the blade.

[0024] In the case of a forward spiral, the radius increases as the impeller blades move forward. This means that points on the impeller blades gradually move away from the central axis.

[0025] However, in the case of a negative spiral, the radius decreases as the impeller blades advance. This means that points on the impeller blades gradually approach the central axis.

[0026] According to one aspect of the invention, corrugations exist only on a portion of the blade span. In other words, corrugations do not exist across the entire span from the blade root to the blade tip. Therefore, on a portion of the span, the blade is corrugated, and the blade thickness is provided by a conventional thickness distribution without imposing thickening or thinning factors on these sections.

[0027] According to one aspect of the invention, corrugations exist on up to 80% of the blade's span length, particularly on up to 60% or 50% of the blade's span length.

[0028] According to one aspect of the invention, the corrugations begin only at a position exceeding 20%, 40%, or 50% of the wingspan length from the blade root.

[0029] Therefore, there are no ripples in the area near the leaf root.

[0030] For example, each blade includes a local area with a series of grooves or corrugations, and the rest of the blade outside this area is free of corrugations and can have a relatively smooth curvature.

[0031] According to one aspect of the invention, each corrugation extends from the leading edge to the trailing edge as a groove.

[0032] According to one aspect of the invention, only the suction surface or the pressure surface has one or more corrugations. The other main surface has no corrugations.

[0033] As a variation, both the suction surface and the pressure surface have one or more corrugations.

[0034] In this case, the ripples on the suction and pressure surfaces can be symmetrical with respect to the neutral line, or, as a variation, can be asymmetrical.

[0035] According to one aspect of the invention, the number of ripples ranges from 3 to 15, for example from 3 to 8.

[0036] According to one aspect of the invention, all blades of the impeller are provided with corrugations according to the invention.

[0037] According to one aspect of the invention, the blade is connected at its blade tip to an axisymmetric rim coaxial with the hub.

[0038] The present invention also relates to an electric fan, particularly an electric fan for motor vehicles, which includes an impeller as described above. Attached Figure Description

[0039] On the one hand, further features, details, and advantages of the invention will become clearer by reading the following description, and on the other hand, by reading several embodiments provided by way of non-limiting examples and by referring to the accompanying schematic diagrams, wherein: Figure 1 This is a representation of an impeller according to an embodiment of the present invention; Figure 2 yes Figure 1 A cross-sectional view of the impeller blades; Figure 3 The instructions are shown and applied to Figure 1 The curve showing the variation of the thickness distribution pattern of the impeller blades; Figure 4 It is a representation of a blade with its characteristic elements; Figure 5 It is a cross-sectional representation of a blade with these characteristic elements; Figure 6 A curve illustrating a simple thickness distribution law is shown; Figure 7 The diagram shows the tilted corrugations used to form a positive spiral. Figure 8 The diagram shows the wavy lines tilted to form a negative spiral. Detailed Implementation

[0040] The features, variations, and various embodiments of the present invention can be combined with each other in various combinations, as long as they are not incompatible or mutually exclusive. In particular, variations of the invention that include only these selected features and not the other features described are conceivable if a feature selected from the following features is sufficient to provide a technical advantage and / or distinguish the present invention from the prior art.

[0041] Figure 1 The impeller 1 is shown mounted on the axial fan 100. The electric motor-driven fan 100 is configured for integration into the front cooling module of an internal combustion engine vehicle or an electric vehicle. Of course, other applications are conceivable.

[0042] The impeller 1 includes a hub 2 having a rotation axis XR and blades 3 extending outward from the hub 2 generally radially (along radius Ra) to the rim 4. The number of blades ranges, for example, between 5 and 20, and in this case, 7. The blades 3 are either uniformly distributed around the hub 2 (with uniform circumferential angular spacing) or non-uniformly distributed around the axis XR, resulting in an asymmetrical distribution.

[0043] like Figure 4 As shown, each blade 3 is defined by the wingspan EN, leading edge BA, and trailing edge BF. The blade 3 is also defined by a stack of aerodynamic profiles PA constructed according to the thickness distribution law LE1, surrounding the neutral line FN that connects the leading edge BA to the trailing edge BF of the blade 3 (see [reference]). Figure 5 The neutral line FN is characterized by a parameter called chord length LC, which represents the distance between the two ends BA and BF of the neutral line FN.

[0044] Figure 6 An example of the thickness distribution pattern LE1 is shown on the bottom curve, which represents the variation of the thickness of the profile PA along the neutral line FN.

[0045] For illustration, the neutral line FN passes through the center of the profile PA of blade 3 between the leading edge BA and the trailing edge BF. The aerodynamic profile PA specifically corresponds to the circumferential section of blade 3 at a given radius Rd (see...). Figure 4 This cross section is obtained by the blade 3 intersecting a geometric cylindrical surface at a given radius that is coaxial with the impeller rotation axis XR.

[0046] Figure 6 The curve LE1 illustrates the thickness distribution law applied to the neutral line FN of the circumferential section at a given radius, in order to define the suction surface curve with the same radius. For example, a ordinate value of zero means that the thickness of blade 3 is zero, and a ordinate value of 2% means that at that point on the neutral line FN of the section, the thickness measured relative to the neutral line FN of blade 3 is 2% of the chord length LC.

[0047] It can also have a thickness distribution pattern to define the pressure surface INT of blade 3. In this case, the thickness is the distance between the neutral line FN and the pressure surface INT.

[0048] The suction surface EXT can have one thickness distribution pattern, while the pressure surface INT can have another. In this case, the neutral line is offset relative to the center of the profile PA.

[0049] The stacked aerodynamic profiles PA can be identical or variable.

[0050] The term "blade span EN" specifically refers to the length of the blade 3, measured as a percentage along a straight line passing through the axis of rotation XR in a plane perpendicular to the axis of rotation XR of the impeller 1. A value of 0% corresponds to the contact point between the blade 3 and the hub 2 (this point is called the blade root PP), and a value of 100% corresponds to the contact point between the blade 3 and the rim 4 (this point is called the blade tip TP).

[0051] In the described example, the thickness distribution pattern LE1 varies along the wingspan (its curve VAR is in...). Figure 3 (as shown in the figure) so that thick corrugations 5 spaced apart from each other in the span direction EN are formed on the blade 3.

[0052] In this invention, to a certain extent, the thickening or thinning coefficient is controlled on each cross section (aerodynamic profile PA) forming the blade 3 so as to form corrugations 5 when transitioning from one aerodynamic profile PA to the next aerodynamic profile PA.

[0053] Therefore, in this case, the thickness corrugation 5 is formed alternately by the thinning section PA2 that defines the low point of the corrugation 5 and the thickening section PA1 that defines the high point of the corrugation 5 along the span direction.

[0054] exist Figure 3 The thickening or thinning coefficient is read from the VAR curve.

[0055] In other words, the variation of the profile PA curve VAR along the wingspan EN of blade 3 gives each aerodynamic profile PA a thickening or thinning coefficient relative to the conventional thickness distribution law that does not produce ripples in the sense of this invention.

[0056] Each corrugation 5 is defined in the spanwise direction EN by a low point located between two high points. The low point of the corrugation is on the thinned section PA2 of the blade 3, and the high point is on the thickened section PA1 of the blade 3.

[0057] The amplitude of corrugation 5 is the thickness difference between the low and high points of the corrugation at a given position on the wingspan EN.

[0058] The ripples 5 along the wingspan EN have a sinusoidal or pseudo-sinusoidal shape.

[0059] The ripple 5 is contained between two envelope curves, ENV1 and ENV2, which are in particular polynomial curves.

[0060] The corrugations 5 form grooves that extend substantially laterally to the wingspan EN of the blade 3.

[0061] The corrugations 5 are parallel to each other and parallel to the neutral line FN of blade 3.

[0062] In other embodiments of the invention, the corrugation 5 has a leading angle so as to form a positive helix on the blade (see [reference]). Figure 7 ) or negative spiral (see Figure 8 ).

[0063] In the case of a positive spiral, the radius increases as the impeller blade 3 advances. This means that points on the impeller blade 3 gradually move away from the central axis XR.

[0064] However, in the case of a negative spiral, the radius decreases as the impeller blade 3 advances. This means that a point on the impeller blade 3 gradually approaches the central axis XR.

[0065] The advance angle (taken on the leading edge BA and measured relative to a straight line tangent to the geometric circle at that leading edge point) is, for example, 1° to 10°.

[0066] Corrugations 5 exist only on a portion 20 of the blade's span EN. In other words, corrugations 5 do not exist across the entire span EN from the blade root PP to the blade tip TP. Therefore, on a portion of the span, the blade has no corrugations, and the blade thickness is provided by a conventional thickness distribution without applying thickening or thinning factors to these sections.

[0067] Corrugations 5 are present at up to 80% of the span length EN of blade 3, and particularly at up to 60% or 50% of the blade's span length.

[0068] Corrugation 5 begins only at a position 20%, 40%, or 50% of the wingspan length EN, measured from the blade root PP.

[0069] Therefore, there are no ripples in the area of ​​the PP near the leaf root.

[0070] In the described example, ripple 5 exists between 40% and 100% of the wingspan starting from the blade root PP, and therefore ripple 5 exists at 60% of the blade's wingspan length.

[0071] Therefore, each blade 3 includes a local area with a series of grooves or corrugations 5, and the rest of the blade outside this area is free of corrugations and can have a relatively smooth curvature.

[0072] Each corrugation 5 extends from the leading edge to the trailing edge as a groove.

[0073] Blade 3 can have a certain installation angle CAL, such as Figure 5 As shown.

Claims

1. A fan impeller (1) comprising a hub (2) having a rotation axis (XR) and blades (3) extending generally radially outward from the hub (2), each blade (3) being defined by a span (EN), a leading edge (BA), and a trailing edge (BF), the blade (3) being further defined by a stack of aerodynamic profiles (PA) constructed according to a thickness distribution law (LE1) surrounding a neutral line (FN) connecting the leading edge (BA) and the trailing edge (BF) of the blade (3), the neutral line (FN) being characterized by a parameter called chord length (LC) representing the distance between the two ends of the neutral line (FN), the thickness distribution law (LE1) representing the variation of the thickness of the profile along the neutral line (FN), the thickness distribution law (LE1) being varied in the spanwise direction (EN), thereby forming at least two thickness ripples (3) spaced apart from each other in the spanwise direction (EN) on the blade (3).

2. The impeller (1) according to claim 1, wherein, The corrugation (5) is defined in the span direction (EN) by a low point located between two high points, wherein the low point of the corrugation (5) is located on the thinned section (PA2) of the blade (3) and the high point is located on the thickened section (PA1) of the blade (3).

3. The impeller (1) according to any one of the preceding claims, wherein, The ripples (5) are present on up to 80% of the wingspan of the blade (3), particularly on up to 60% or 50% of the wingspan of the blade (3).

4. The impeller (1) according to the preceding claim, wherein, The ripples begin only at a position 20%, 40%, or 50% of the wingspan (EN) from the blade root (PP).

5. The impeller (1) according to any one of the preceding claims, wherein, Each blade (3) includes a local area with a series of grooves or corrugations (5), and the rest of the blade outside this area has a relatively smooth curvature.

6. The impeller (1) according to any one of the preceding claims, wherein, The corrugations (5) have a thickness amplitude that increases as they approach the blade tip (TP).

7. The impeller (1) according to any one of the preceding claims, wherein, Each ripple (5) extends from the leading edge (BA) to the trailing edge (BF).

8. The impeller (1) according to any one of the preceding claims, wherein, The number of ripples (5) on each blade (3) ranges between 3 and 15, for example, between 3 and 8.

9. The impeller (1) according to any one of the preceding claims, wherein, The ripples (5) are parallel to each other.

10. A fan (100), particularly a fan for motor vehicles, comprising an impeller according to any one of the preceding claims.

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