DE-102025145621-A1 - Cooling fan support frame with strongly angled guide vanes

Abstract

A cooling fan assembly comprises a fan, a motor driving the fan, and a support frame enclosing the fan. The support frame has a plenum section, a casing section, a motor support structure, and guide vanes extending over an annular area located between the casing section and the motor support structure. The helix angle of at least one guide vane of the assembly is steeply inclined.

Inventors

• Yoonshik Shin

Assignees

• Robert Bosch Gesellschaft mit beschränkter Haftung

Dates

Publication Date

20260513

Application Date

20251106

Priority Date

20241108

Claims (14)

1. Cooling fan assembly comprising: a support frame comprising: an air-guiding plenum, a hollow cylindrical shell with a side wall centered on a shell axis, the side wall having an inner diameter, a motor support structure, and guide vanes extending over a space between the extending from the shell section and the annular area arranged in the motor support structure; a motor supported by the motor support structure, the motor having a motor shaft defining a central axis, the central axis being coincident with the shell axis; and a fan being at least partially enclosed by the shell, the fan comprising: a hub driven to rotate by the motor and centered on the central axis, and impeller blades projecting from the hub and arranged around the central axis; wherein a projection plane can be placed perpendicular to the central axis and the projection plane lies upstream of the shell section of the support frame when the guide vanes, the motor support structure and the shell are projected onto the projection plane, the projection of at least one of the guide vanes onto the projection plane corresponds to a first guide vane line extending between the motor support structure and the shell side wall, and a second guide vane line extending between the motor support structure and the shell side wall, as well as a central chord line arranged between the first guide vane line and the second guide vane line and equidistant from both the first and second guide vane lines, the chord line of the at least one of the guide vanes intersects the projection of an inner diameter of the shell at an outer endpoint and intersects the projection of an outer section of the motor support structure at an inner endpoint, an angular displacement from the inner endpoint to the outer endpoint lies in the same angular direction as a direction of rotation of the fan, a helix angle of the at least one guide vane is defined between a first radial line and a second radial line, and the helix angle of the at least one guide vane is at least equal to a mean angular division of the guide vanes, wherein 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, and the mean angular division of the guide vanes is equal to 360 degrees divided by the number of guide vanes used in the automotive cooling fan arrangement.
2. Cooling fan arrangement according to Claim 1 , wherein the helix angle of at least one guide vane is at least 70% of the mean angular division of the guide vanes.
3. Cooling fan arrangement according to Claim 1 , wherein the helix angle of at least one guide vane is at least 80% of the mean angular division of the guide vanes.
4. Cooling fan arrangement according to Claim 1 , wherein the helix angle of at least one guide vane is at least 90% of the mean angular division of the guide vanes.
5. Cooling fan arrangement according to Claim 1 , wherein at least one guide vane has an aerodynamic cross-section.
6. Cooling fan arrangement according to Claim 5 , wherein a chord length of the cross-section of the at least one guide vane is increased in areas where the step angle is increased.
7. Cooling fan arrangement according to Claim 1 , wherein the at least one guide vane has a variable step angle along a chord line of the at least one guide vane.
8. Cooling fan arrangement according to Claim 1 , wherein the at least one guide vane has a decreasing step angle from a midpoint of a chord line of the at least one guide vane to the point where the chord line intersects the surface.
9. Cooling fan arrangement according to Claim 1 , wherein a cross-section of at least one guide vane has a curvature.
10. Cooling fan arrangement according to Claim 1 , wherein the at least one guide vane intersects an auxiliary support structure designed to support the at least one guide vane.
11. Cooling fan arrangement according to Claim 10 , wherein the auxiliary support structure has an inner end on the engine support structure and an outer end on the support frame shell.
12. Cooling fan arrangement according to Claim 1 , wherein a central area of at least one guide vane is mechanically connected to a central area of another guide vane.
13. Cooling fan arrangement according to Claim 12 , wherein the additional guide vane has a helix angle that differs from a helix angle of the at least one guide vane.
14. Cooling fan arrangement according to Claim 12 , wherein the at least one guide vane intersects another guide vane at a position that is both from a tip of the at least one guide vane as well as from a foot that is spaced at least one guide vane apart.

Description

State of the art The purpose of a motor vehicle cooling fan assembly is to draw ambient air from the area around a vehicle through one or more heat exchangers. A typical motor vehicle cooling fan assembly includes a fan, a motor, and a support frame. The support frame structure can be a single injection-molded part with an air-carrying plenum section adjacent to a heat exchanger, a circular jacket section surrounding the fan, a motor support structure, and several support arms ("guide vanes") that connect the jacket section to the motor support structure, providing physical support and centering for the motor support structure. In some cases, the jacket section is a separate injection-molded part attached to the plenum section. The guide vanes occupy the generally annular space between the inner diameter of the casing and the outermost part of the motor support structure. Since the air expelled by the fan flows through this annular area, the guide vanes can influence the aerodynamic efficiency of the fan-guide vane system. If the guide vanes are appropriately designed for their operating environment, the aerodynamic efficiency can be improved by recovering energy from the airflow. If the guide vanes are not optimized for the operating environment, they can create an aerodynamic blockage, reducing the fan's aerodynamic efficiency. As motor vehicles evolve, the available space under the hood for equipment, including cooling fans, continues to decrease. This trend toward tighter under-hood designs has increased fan airflow obstruction, negatively impacting the fan assembly's efficiency. In cases where the vehicle installation creates significant axial obstruction of the fan's airflow field, the flow lines, following the path of least resistance, are forced to veer more radially to circumvent the axial obstruction. When the flow lines become more radial, a guide vane may no longer be aligned with the previously more axially oriented streamlines. This suboptimal guide vane alignment with the flow results in an undesirable loss of aerodynamic efficiency. There is a need for a support frame guide vane design that improves the aerodynamic performance of an automotive cooling fan assembly, especially when the exit streamlines have a large radial velocity component. Disclosure of the invention A cooling fan assembly comprises a fan, a motor, and a support frame. The support frame is an injection-molded part with an air-conducting plenum section adjacent to a heat exchanger, a circular jacket section surrounding the fan, a motor support structure, and several guide vanes connecting the jacket section to the motor support structure. Under certain conditions, the guide vanes described herein improve aerodynamic performance compared to some prior art guide vanes by reducing the undesirable aerodynamic blockage effect caused by surrounding stationary structures in the airflow path, while simultaneously providing a robust physical structure to support the motor and fan. In particular, the helix angle of at least one guide vane of the cooling fan assembly is highly inclined, resulting in a support frame guide vane design that improves the aerodynamic performance of an automotive cooling fan assembly, especially when the exit streamlines have a large radial velocity component. This can be compared to some prior art guide vanes that have a thick cross-section and generate a significant blocking effect, as well as to other prior art guide vanes that add reinforcements to increase stiffness, at the expense of increased aerodynamic blockage, for example, a circular guide vane reinforcement ring. Other prior art guide vanes, while having a streamlined cross-section, are not well aligned with the fan outflow over the at least partially annular flow area of the support frame shroud. Brief description of the characters 1 This is a perspective view of a state-of-the-art cooling fan arrangement.2 is a perspective exploded view of the cooling fan assembly from 1 .3 This is a perspective view of a state-of-the-art fan, from upstream of the fan towards downstream. The diagram illustrates the three-dimensional velocity components. The direction of the fan rotation is represented by an arrow.4 Figure 1 is a front view of a prior art cooling fan arrangement, seen from upstream of the fan towards downstream, illustrating the location of section line AA. The direction of fan rotation is indicated by an arrow.5 Figure 1 is a rear view of a prior art cooling fan arrangement, seen from downstream of the motor towards upstream, illustrating two of the three velocity components. The direction of fan rotation is indicated by an arrow.6 is a cross-sectional view of the cooling fan arrangement 4 Viewed along line AA, which illustrates two of the three velocity components. The direction of fan rotation is represented by a solid arrow, and the direction of airflow is represented by a dashed arrow.7A Figure 1 is a front view of a state-of-the-art motor