Cooling fan shroud with highly skewed stator

Abstract

The invention discloses a cooling fan shroud with a highly skewed stator. A cooling fan assembly includes a fan, a motor driving the fan, and a shroud enclosing the fan. The shroud has: a plenum portion; a cylinder portion; a motor-support structure; and a stator spanning an annular region disposed between the barrel and the motor-support structure. The skew angle of at least one stator of the assembly is highly skewed.

Description

Background Technology

[0001] The purpose of an automotive cooling fan assembly is to draw in ambient air from around the vehicle and pass it through one or more heat exchangers. A typical automotive cooling fan assembly includes a fan, a motor, and a shroud.

[0002] The shield structure can be a one-piece injection-molded part comprising: an air-guiding chamber portion that docks with the heat exchanger; a cylindrical portion that surrounds the fan; a motor support structure; and multiple support arms (“stators”) that connect the cylindrical portion to the motor support structure and provide physical support and centering to the motor support structure. In some cases, the cylindrical portion is a separate injection-molded part attached to the air chamber portion.

[0003] The stator shroud occupies a roughly annular space between the inner diameter of the cylinder and the outermost part of the motor support structure. Since the airflow from the fan passes through this annular region, the stator has the potential to influence the aerodynamic efficiency of the fan and stator system. If the stators are properly designed for the environment in which they operate, it is possible to improve aerodynamic efficiency by recovering energy from the airflow. If the stators are not optimized for the environment, they may exhibit aerodynamic blockages that degrade the aerodynamic efficiency of the fan.

[0004] As motor vehicles have evolved, the space under the hood for equipment, including cooling fans, has continued to shrink. The trend towards tighter under-hood vehicle packaging has increased obstruction of fan airflow and has a detrimental effect on fan assembly efficiency. When vehicle mounting creates significant axial obstruction or impediment to the fan flow field, the flow streamlines that follow the path of least resistance are forced to become more radial to avoid axial obstruction. As the flow streamlines become more radial, the stator may no longer align with the previously more axially oriented streamlines. This suboptimal stator alignment results in an undesirable loss of aerodynamic efficiency.

[0005] A shroud stator design is needed that improves the aerodynamic performance of automotive cooling fan assemblies, especially when the outlet streamline has a large radial velocity component. Summary of the Invention

[0006] A cooling fan assembly includes a fan, a motor, and a shroud. The shroud is an injection-molded portion comprising: an air-guiding chamber portion that interfaces with a heat exchanger; a cylindrical portion that surrounds the fan; a motor support structure; and a plurality of stators that connect the cylindrical portion to the motor support structure. Under certain conditions, the stator described herein improves aerodynamic performance by reducing undesirable aerodynamic obstruction effects caused by surrounding fixed structures in the airflow path, thereby outperforming some prior art stators, while providing a robust physical structure to support the motor and fan. In particular, the skew angle of at least one stator of the cooling fan assembly is highly skewed, resulting in a shroud stator design that improves the aerodynamic performance of the automotive cooling fan assembly, especially when the outlet streamline has a large radial velocity component.

[0007] This can be compared to some existing stators, as well as others, which have thick cross-sections that result in significant blocking effects, and which add additional reinforcements to increase rigidity at the expense of increased aerodynamic blocking (e.g., circular stator reinforcing rings). Other existing stators have streamlined cross-sections, but are not well aligned with the fan exhaust in at least part of the shroud-cylinder annular flow region. Attached Figure Description

[0008] Figure 1 This is a perspective view of a conventional cooling fan assembly.

[0009] Figure 2 yes Figure 1 An exploded perspective view of the cooling fan assembly.

[0010] Figure 3 This is a perspective view of a conventional fan as seen from upstream and downstream, illustrating the three-dimensional components of the velocity. The direction of fan rotation is indicated by arrows.

[0011] Figure 4 This is a front view of a prior art cooling fan assembly as seen from upstream and downstream of the fan, illustrating the location of section line A-A. The direction of fan rotation is indicated by arrows.

[0012] Figure 5 This is a rear view of a prior art cooling fan assembly as seen from downstream of the motor and looking upstream, illustrating two of the three components of speed. The direction of fan rotation is indicated by arrows.

[0013] Figure 6 It is as seen along line A-A Figure 4A cross-sectional view of the cooling fan assembly, illustrating two of the three components of speed. The direction of fan rotation is indicated by solid arrows, and the direction of airflow is indicated by broken arrows.

[0014] Figure 7A This is a front view of a prior art motor support as seen from upstream to downstream, illustrating the conventional stator sweep angle. The fan has been omitted for clarity, and if shown, it would rotate clockwise as indicated by the narrow arrows. A wide arrow at one point in the stator illustrates the local velocity vector.

[0015] Figure 7B This is a perspective view of a prior art motor support as seen from upstream to downstream, illustrating the conventional stator sweep angle. The fan has been omitted for clarity, and if shown, it would rotate clockwise. A broad arrow at one point in the stator illustrates the local velocity vector.

[0016] Figure 8A This is a front view of the motor support as seen from upstream to downstream, illustrating the optimized stator sweep angle. The fan has been omitted for clarity, and if shown, it would rotate clockwise. A broad arrow at one point in the stator illustrates the local velocity vector.

[0017] Figure 8B This is a perspective view of the motor support as seen from upstream to downstream, illustrating the optimized stator sweep angle. The fan has been omitted for clarity, and if shown, it would rotate clockwise as indicated by the narrow arrows. A wide arrow at one point in the stator illustrates the local velocity vector.

[0018] Figure 9 The illustration shows the cross-section of a non-arc stator as seen at various locations along the stator length, where the percentages represent the relative distance between the stator tip (100%) and the stator root (0%).

[0019] Figure 10 The diagram illustrates the cross-section of the curved stator as seen at various locations along the stator length, where the percentage represents the relative distance between the stator tip (100%) and the stator root (0%). On the 0% cross-section, the amount of curvature is indicated by arrows, the mean line is shown in dashed lines, and the nose-to-tail (“NT”) line is shown in dotted lines.

[0020] Figure 11AThis is a front view of the motor support as seen from upstream to downstream, illustrating the section line A-A through the stator. Although the fan is omitted for clarity, the direction of fan rotation is indicated by the arrow. In this view, the stator is optimized to allow the fan to rotate clockwise.

[0021] Figure 11B Is it like along Figure 11A The diagram shows a schematic cross-sectional view of an isolated streamlined stator as seen along line A-A, with its reference center axis shown and illustrating the stator angles and azimuth positions of the stator cross-section. Wide arrows indicate the direction of the flow streamlines.

[0022] Figure 12 It is a front view of the motor support as seen from upstream to downstream, showing the radial reference line indicated by the dotted line, the stator center chord indicated by the dashed line, and the stator sweep defined as the local tangent of the stator at the stator tip, or sweep = d(skew) / d(r).

[0023] Figure 13A This is a front view of the motor support as seen from upstream to downstream, illustrating the first section line A-A, the second section line B-B, and the third section line C-C passing through the stator. The direction of fan rotation is indicated by arrows. The skewing of section A-A corresponds to the arc extending between the radial line passing through the center chord of section A-A and the radial reference line passing through the center chord of the stator root. The skewing of section B-B corresponds to the arc extending between the radial line passing through the center chord of section B-B and the radial reference line passing through the center chord of the stator root. The skewing of section C-C corresponds to the arc extending between the radial line passing through the center chord of section C-C and the radial reference line passing through the center chord of the stator root.

[0024] Figure 13B This is a schematic illustration of three cross-sections of an isolated streamlined stator, with its reference central axis shown and the skew angles and azimuth positions of these stator cross-sections illustrated. The first cross-section is as follows along... Figure 13A As seen along line C-C, the second cross section is as follows: Figure 13A As seen along line A-A, and the third cross-section is as follows... Figure 13A As you can see from line B-B.

[0025] Figure 14This is a partial view of the motor support structure, stator, and housing projected onto a plane perpendicular to the central axis, as seen from upstream to downstream of the motor support. Although the fan is omitted for clarity, the arrows indicate the direction of fan rotation. The image illustrates the stator's centerline (shown in dashed lines), a first reference radial line (shown in solid lines and passing through the centerline at the stator root), a second reference radial line (shown in solid lines and passing through the centerline at the stator tip), a first arc representing the average angular pitch of the stator, and a second arc extending between the first and second reference radial lines and representing the stator tip-to-root pitch of the highly skewed stator.

[0026] Figure 15 This is a front view of the motor support as seen from upstream to downstream, illustrating the highly skewed stators and the auxiliary support structures that pass through these stators and provide reinforcement.

[0027] Figure 16 The segmented map illustrates the cross-section of the arcuate stator as seen at various locations along the stator length (meridian sweep view), where percentages refer to the relative distance between the stator tip (100%) and the stator root (0%) for a stator with a constant chord length from the stator root to the stator tip.

[0028] Figure 17 The illustration shows a cross-section of an arc-shaped stator as seen at various locations along the stator length (meridian sweep view), where the percentage refers to the relative distance between the stator tip (100%) and the stator root (0%) for a stator having a chord length that increases from the stator tip to the stator root as the stagger angle decreases.

[0029] Figure 18 This is a graph showing fluid velocity (m³ / s) versus pressure (Pascal, shown as a solid line) and static efficiency (percentage, shown as a broken line) for a highly skewed stator (shown in red) and a prior art stator (shown in blue). Detailed Implementation

[0030] refer to Figure 1 and Figure 2A cooling fan assembly 10 can be used in a vehicle as part of a vehicle thermal control system that provides cooling to various components of the vehicle. The cooling fan assembly 10 includes a fan 50, an electric motor 28 driving the fan 50, and a shroud 12. In the illustrated embodiment, the shroud 12 is an injection-molded portion having: an air-guiding chamber portion 14 that interfaces with a heat exchanger (e.g., a radiator) 40; a cylindrical portion 18 that surrounds the fan 50; a motor support structure 26; and a plurality of stators 80 that connect the cylindrical portion 18 to the motor support structure 26. The cooling fan assembly 10 draws air through the radiator 40 and exhausts it in an indicated direction. The stator 80 described herein improves the aerodynamic performance of the cooling fan assembly, at least in part, due to its highly skewed configuration, compared to some prior art stators. This reduces undesirable aerodynamic blockage effects caused by surrounding fixed structures in the airflow path. The highly skewed stator provides a robust physical structure to support the motor and fan. The cooling fan assembly 10, including the highly skewed stator 80, will now be discussed in detail.

[0031] The fan 50 is at least partially surrounded by the shroud body portion 18 and includes a plurality of blades 54 projecting radially outward from the hub 52. In addition, the fan 50 includes a band 56 that surrounds the hub 52 and connects the tip 55 of each blade 54 to prevent the blades 54 from deforming during fan operation.

[0032] Hub 52 is a hollow cylinder, which is closed at one end by an end surface perpendicular to the fan rotation axis 51. The outer circumference of hub 52 faces hoop 56.

[0033] Each blade 54 includes a root 53 connected to a hoop-facing surface of the hub 52, and a tip 55 spaced apart from the root 53. Each tip 55 is connected to a hub-facing surface of the hoop 56. The airflow guiding surface of each blade 54 has a complex three-dimensional curvature determined by the requirements of the specific application. The blade configuration (including the number of blades 54 employed by the fan 50, the shape of the blades 54, the blade spacing, etc.) is also determined by the requirements of the specific application.

[0034] Hub 52, blade 54, and hoop 56 can be formed as a single piece, for example, in an injection molding process. The outer surface of hoop 56 is fixed to the inner surface of the cylindrical portion 18.

[0035] The fan 50 is rotated by a rotational force transferred from an electric motor to the hub 52 via a motor shaft (not shown) that coincides with the fan's rotation axis 51. In the illustrated embodiment, the fan 50 is relative to... Figure 2 The view shown is rotated clockwise around the fan rotation axis 51, and the airflow direction, indicated by the wide arrow, is parallel to the fan rotation axis 51.

[0036] The direction of the airflow discharged from fan 50 depends at least in part on the blade curvature and includes a substantial axial flow component. As used herein, the term "axial flow component" refers to the component of airflow that flows in a direction parallel to the fan's axis of rotation 51.

[0037] Fan 50 is driven by an electric motor 28 mounted on motor support structure 26 to rotate about rotation axis 51. Motor support structure 26 is supported by a plurality of stators 80 extending outward from motor support structure 26 and connected to the inner surface of cylinder portion 18 at a location downstream of clamp 56. Thus, motor support structure 26 and stators 80 together provide a motor support positioned downstream of fan 50. Details of the structure of stator 80 are described below.

[0038] The shroud 12 is a tubular structure comprising a flared air chamber portion 14 and a cylindrical shell portion 18 disposed downstream of the air chamber portion 14. The air chamber portion 14 facilitates smooth airflow into the shell portion 18. The shell portion 18 is attached to the air chamber portion 14 such that the inner walls of the shell portion 18 and the air chamber portion 14 form smooth surfaces. In most embodiments, the shape and size of the air chamber portion 14 correspond to the shape and size of the heat exchanger 40, which is often rectangular. The radial dimension of the inner surface of the upstream end of the air chamber portion 14 is greater than the radial dimension of the inner surface of the shell portion 18, thereby enabling the shroud 12 to accelerate airflow into the cooling fan assembly 10. The shroud 12 both guides and contains a volume of air at a lower pressure than the air surrounding the shroud 12. In other embodiments, the air chamber portion 14 may extend over a smaller or larger portion of the shell portion 18, or even over the entire shell portion 18.

[0039] The cylindrical portion 18 may be generally cylindrical. When molded as a plastic part, the required draft angle may specify that the radial dimension of the cylindrical portion 18 varies slightly along the axial range. The sidewall 22 of the cylindrical portion is coaxial with the central axis 34 of the cylindrical portion, and the inner diameter of the sidewall 22 passes through the central axis 34. The cylindrical portion 18 is arranged such that the central axis 34 is coaxial with the fan rotation axis 51.

[0040] The fan 50 is supported in a housing by the motor shaft of the electric motor 28. The electric motor 28 is mounted on the motor support structure 26. Furthermore, the motor support structure 26 is supported by stators 80, which reside in the annular space between the motor support structure 26 and the cylindrical portion 18.

[0041] refer to Figure 11A and Figure 11BEach stator includes a leading edge (or "nose") 82 and a trailing edge (or "tail") 84. Each stator 80 includes a stator root 88 corresponding to the location where the stator 80 terminates at the outer surface of the motor support structure 26. Each stator 80 includes a stator tip 89 corresponding to the location where the stator 80 terminates at the inner surface of the cylindrical portion 18.

[0042] Each stator 80 has a cross-section with an aerodynamic shape. As used herein, the term "aerodynamic shape" refers to a streamlined shape (a shape designed to minimize drag associated with fluid flowing around that shape). Specifically, the cross-section of the aerodynamic stator 80 will have an axis of symmetry along its longer length dimension, terminating upstream at the nose 82 and downstream at the tail 84. A chord line (or "nose-tail (NT) line") 86 corresponds to a straight line extending between the nose 82 and the tail 84 of the stator 80. The chord line 86 has a chord length c, which is the length of the chord line 86.

[0043] In the illustrated embodiment, the chord length c is approximately equal to the maximum thickness t. max Six times the maximum thickness t. The stator leading edge 82 is circular, and the thickness at the stator trailing edge 84 is less than the maximum thickness t. max The given size and shape of the stator 80 can reduce the severity of the viscous wake downstream of the stator, thereby reducing the stator drag and the noise generated as the fan blades 54 move through the wake.

[0044] Refer again Figure 1 and Figure 2 The degree of parasitic blockage exhibited by the stator 80 is related to the cross-sectional shape of the stator 80 and its alignment with the surrounding airflow streamlines exiting the fan 50. These streamlines are also affected by the presence of downstream objects, with the greater the influence of the object on the streamline trajectory the closer the object is to the stator 80.

[0045] The fan 50, electric motor 28, and shroud body 18 share a common central axis 34. The orientation of the central axis 34 identifies upstream / downstream directions, where upstream refers to a position along the central axis 34 where airflow has not yet entered the fan 50, and downstream refers to a position along the central axis 34 where airflow has traveled through the fan 50.

[0046] refer to Figure 3-6The flow field downstream of fan 50 is three-dimensional and varies with points within the domain. The velocity at any point in the flow field can be characterized by three (3) orthogonal velocity components (axial, radial, and tangential). The axial velocity is parallel to the central axis 34, the radial velocity is perpendicular to the central axis 34 and directed outward away from the central axis 34, and the tangential velocity is directed in azimuth coordinates. The rotating fan 50 imparts axial, radial, and tangential velocities at the fan outlet. The imparted tangential velocity is in the same direction as the fan's rotation.

[0047] refer to Figure 7A and Figure 7B The velocity downstream of fan 50 is a function of the fan's design, its operating point, and any objects(s) in the flow domain that present obstructions to the flow. Any object that obstructs or impedes the flow from the fan has the potential to reduce the aerodynamic efficiency of the fan system. Since the motor-support stator 80 is located downstream of and very close to fan 50, stator 80 has the potential to affect the aerodynamic efficiency of the fan-stator system.

[0048] refer to Figure 8A , Figure 8B and Figure 9 By using streamlined stator cross sections and aligning these streamlined cross sections with the local flow field velocity along the spanwise stator coordinates (e.g., along the stator at a location between the stator root 88 and the stator tip 89), the performance degradation caused by the stator 80 can be minimized.

[0049] A streamlined cross-section is a cross-section designed to present minimal resistance or drag to the oncoming flow when aligned with the flow direction. A streamlined cross-section can generally be described as having a long axis parallel to the flow direction and a shorter axis intersecting the oncoming flow direction at an angle. The long axis is typically an axis of symmetry. For optimal performance, the ratio of the longer axis to the shorter axis should be practically high, but at least 3:1.

[0050] The spanwise stator coordinates can be expressed as a percentage of the total span (e.g., radial dimension) between the outer surface of the motor support structure 26 and the inner surface of the cylinder portion 18, where the stator root 88 corresponds to 0% of the total span dimension and the stator tip 89 corresponds to 100%.

[0051] refer to Figure 10In some cases, additional aerodynamic efficiency gains can be made possible by recovering some energy from the air flowing across the stator by adding curvature to the cross-section. Under certain conditions, lift can be generated from a streamlined shape by adding curvature to the profile. As used herein, the term "curvature" refers to a measure of the curvature of the shape. In the context of the aerodynamic cross-section of the stator, curvature can be quantified as the distance from the nose-to-tail line to the bisector.

[0052] Adding curvature to a streamlined cross-section involves adding curvature to the "long axis" while maintaining equidistant distances from the section boundary on both sides of the curve. Since this curve lies in the middle of the section thickness, it is called the "bisector" of the section. If the section has zero curvature, the bisector is collinear with the nose-tail line.

[0053] When the streamlined cross section is not aligned with the incoming flow, the increase in drag is considered "small" as long as the angular deviation is within a few degrees.

[0054] An aerodynamic cross section is a cross section designed to generate lift while minimizing drag. Lift can come from a cross section with an angle of attack to the oncoming flow, or from adding curvature to the cross section.

[0055] refer to Figure 11A and Figure 11B As flow field streamlines become more radial, it becomes possible to design stators to minimize the blocking effects that degrade efficiency by optimizing both the stator's stagger angle and sweep angle. As used herein, the term "stagger angle" refers to a angular measurement describing the angle formed by the axis of the strut / stator / support cross-section and a line parallel to the central axis. The stagger angle Ɵ can be defined in the horizontal plane as the angle between the local stator NT line 86 and the central axis 34. A stagger angle Ɵ of zero degrees means that the angle of the stator nose-tail line 86 is parallel to the central axis 34.

[0056] refer to Figure 9 and Figure 12 As used herein, the term "sweep angle" refers to an angular measurement describing the slope of stator skew. Sweep = d(skew) / dr, where r is the radial dimension. The sweep angle can also be defined as the local slope of stator skew in a plane perpendicular to the central axis 34. In equation form, sweep = d_skew / d_radius.

[0057] Since the flow field is three-dimensional, the optimization is based on the spanwise coordinates of stator 80. Figure 9 The function is ), and stator optimization can vary across a set of stators.

[0058] refer to Figures 13A-13BThe azimuth position of each stator 80 can be defined in a plane perpendicular to the central axis 34. The reference angle of the stator 80 is a first radial line 108 extending from the central axis 34 and intersecting the midpoint of the stator root section NT line. For each spanwise section, a second radial line 110 is defined from the central axis and intersecting the midpoint of the local section NT line. The angle between these two radial lines is the skew angle β.

[0059] refer to Figure 14 The skew angle α between the radial line 112, which intersects the midpoint of the nose-tail line of the stator tip section (e.g., the outer endpoint 102), and the radial line 114, which intersects the midpoint of the nose-tail line of the stator root section (e.g., the inner endpoint 100), is also called the azimuth range of the stator and is measured in degrees.

[0060] The average angular spacing between stators is defined as 360 degrees divided by the number of stators. For example, a casing with 10 stators will have an average angular spacing of 36 degrees.

[0061] In some embodiments, the term "height skew" refers to a stator 180 having a skew angle α at least equal to the average stator angular spacing. In some embodiments, a height-skewed stator corresponds to a stator 180 in which the skew angle α is at least 70% of the average stator angular spacing. In some embodiments, a height-skewed stator corresponds to a stator 180 in which the skew angle α is at least 80% of the average stator angular spacing. In some embodiments, a height-skewed stator corresponds to a stator 180 in which the skew angle α is at least 90% of the average stator angular spacing.

[0062] Figure 14 The diagram illustrates a stator 180 that is highly skewed such that the skew angle α of the at least one stator is at least equal to the average stator angular pitch. In this embodiment, the angular displacement from the inner endpoint 100 to the outer endpoint 102 is along the same angular direction as the rotation direction of the fan 50. The skew angle α of the stator 180 is defined between the first radial line 112 and the second radial line 114, and in this example, the skew angle α is 42 degrees. In this embodiment, the average stator angular pitch is 30 degrees, thereby making the stator 180 highly skewed.

[0063] exist Figure 14 In the embodiment illustrated, all stators 180 are highly skewed. However, in other embodiments, a subset of stators used in component 10 may be highly skewed, while the remaining stators are normally skewed or not skewed.

[0064] Refer again Figure 7A and Figure 8AAs discussed above, the presence of downstream axial blockage will affect the fan's exit streamline by reducing the axial component of the velocity and increasing the radial component. To optimize the stator for this blockage condition, the importance of the stagger angle becomes less significant, while the importance of the sweep angle becomes more crucial. Under these conditions, overall stator optimization will favor stators with reduced stagger angles and increased sweep angles.

[0065] Under certain conditions, it can be achieved by adjusting the cross-section of the stator ( Figure 10 Add curvature to achieve additional aerodynamic efficiency.

[0066] refer to Figure 15 As the stator interlacing decreases and the stator sweep angle becomes more extreme, the mechanical stiffness of stator 180 decreases. This decrease in stiffness can be offset by adding a stator 180 interlacing with a stator 280 having reduced interlacing and increased sweep.

[0067] refer to Figure 16-18 Another way to increase stator stiffness is to increase the axial range of the stator 180. If the chord length of the stator profile is fixed, the axial range of the stator 180 decreases as the stator crossover angle increases, which in turn reduces the axial stiffness. This loss of axial stiffness can be offset by increasing the chord length of the stator profile.

[0068] When the stator 180 has been optimized for axial blockage conditions as described above, its aerodynamic efficiency will be improved. Figure 18 The fan performance of an automotive cooling fan assembly with a prior art stator in an axially blocked environment is shown compared to an assembly using an optimized, highly skewed stator.

[0069] The foregoing has described, in some detail, an illustrative embodiment of a cooling fan assembly including a highly skewed stator. It should be understood that only structures deemed necessary for illustrating the assembly have been described herein. Other conventional structures, as well as the structures of supplementary and auxiliary components to the assembly, are considered known and understood by those skilled in the art. Furthermore, while working examples of the assembly have been described above, the assembly is not limited to the working examples described above, but various design changes may be implemented without departing from the assembly set forth in the claims.

Claims

1. A cooling fan assembly comprising: The protective shield includes: Air guiding chamber, A hollow, cylindrical body having sidewalls centered on the body's axis, the sidewalls having an inner diameter. Motor-support structure, and The stator spans an annular region disposed between the cylindrical portion and the motor-support structure; A motor supported by the motor support structure, the motor having a motor shaft defining a central axis that coincides with the axis of the cylinder; and A fan at least partially surrounded by the cylinder, the fan comprising: The hub, which is driven to rotate by the motor and centered on the central axis, and Blades that protrude from the hub and are arranged around the central axis; in, The projection plane can be drawn perpendicular to the central axis, and the projection plane is upstream of the cylindrical portion of the shield. When the stator, the motor-support structure, and the cylinder are projected onto the projection plane, the projection of at least one of the stators onto the projection plane corresponds to a first stator line extending between the motor support structure and the cylinder sidewall, a second stator line extending between the motor support structure and the cylinder sidewall, and a mid-chord line disposed between the first stator line and the second stator line and equidistant from each of the first stator line and the second stator line. The chord of at least one of the stators intersects the projection of the inner diameter of the cylinder at its outer endpoint and intersects the projection of the outer portion of the motor-support structure at its inner endpoint. The angular displacement from the inner endpoint to the outer endpoint is along the same angular direction as the rotation direction of the fan. The skew angle of at least one stator is limited between the first radial line and the second radial line, and The skew angle of at least one stator is at least equal to the average angular spacing of the stators. in The first radial line extends from the central axis to the outer endpoint, and the second radial line extends from the central axis to the inner endpoint. The average stator angular pitch corresponds to 360 degrees divided by the number of stators used in the automotive cooling fan assembly.

2. The cooling fan assembly according to claim 1, wherein, The skew angle of the at least one stator is at least 70% of the average angular spacing of the stators.

3. The cooling fan assembly according to claim 1, wherein, The skew angle of the at least one stator is at least 80% of the average angular spacing of the stators.

4. The cooling fan assembly according to claim 1, wherein, The skew angle of the at least one stator is at least 90% of the average angular spacing of the stators.

5. The cooling fan assembly according to claim 1, wherein, The at least one stator has an aerodynamic cross section.

6. The cooling fan assembly according to claim 5, wherein, The chord length of the cross section of the at least one stator increases in the region where the stagger angle increases.

7. The cooling fan assembly according to claim 1, wherein, The at least one stator has an alternating angle that varies along the chord of the at least one stator.

8. The cooling fan assembly according to claim 1, wherein, The at least one stator has an alternation angle that decreases from the midpoint of the chord of the at least one stator to the point where the chord intersects the cylinder.

9. The cooling fan assembly according to claim 1, wherein, The cross-section of at least one stator has curvature.

10. The cooling fan assembly of claim 1, wherein, The at least one stator intersects with an auxiliary support structure configured to support the at least one stator.

11. The cooling fan assembly of claim 10, wherein, The auxiliary support structure has an inner endpoint at the motor-support structure and an outer endpoint at the protective cover cylinder.

12. The cooling fan assembly of claim 1, wherein, The central region of at least one stator is mechanically connected to the central region of another stator.

13. The cooling fan assembly of claim 12, wherein, The deflection angle of the other stator is different from the deflection angle of the at least one stator.

14. The cooling fan assembly of claim 12, wherein, The at least one stator intersects with another stator at a position spaced apart from both the tip and the root of the at least one stator.

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