Axial fan arrangement with free blade tips

Abstract

Axial fan assembly (1) with free blade tips (46), comprising: a blower (4) comprising several radially extending blades (40) rotatable about a blower axis (6), each of the several blades (40) having a blade tip (46), a leading edge (LE) and a trailing edge (TE), the blower (4) having a diameter (D) which is twice a radial dimension (R) TE) of the blade tips (46) at the exit edge (TE); and a jacket (2) comprising a tube (22), wherein the tube (22) includes an inlet (242), wherein a radial dimension (R1) of the inlet (242) at its upstream end is larger than a radial dimension (R2) of the inlet (242) at its downstream end, wherein an angle (θ) in a meridional plane between a surface of the inlet (242) and a direction of the blower axis (6) with respect to a surface coordinate (s) that increases with the distance along the surface of the inlet (242) from its upstream end to its downstream end varies non-monotically over a region of the inlet surface, wherein the angle (θ) first decreases and then increases again with increasing surface coordinate (s), and several successive such sequences are provided in which the angle (θ) first decreases and then increases again with increasing surface coordinate (s).where a radial dimension of the inlet area decreases or remains constant with increasing area coordinate (s).

Description

[0001] The present invention relates generally to axial blowers with free blade tips, which can be used, among other uses, as cooling blowers for motor vehicles.

[0002] Engine cooling fans are used in motor vehicles to move air through a set of heat exchangers, which typically includes a radiator for cooling an internal combustion engine, an air conditioning condenser, and perhaps additional heat exchangers. These fans are generally installed in a mantle that directs air between the heat exchangers and the fan and controls recirculation. Typically, these fans are driven by an electric motor supported by the mantle.

[0003] The blowers are typically injection-molded from plastic, a material with limited mechanical properties. Plastic blowers exhibit deflection due to creep when subjected to torsional and aerodynamic loads at high temperatures. This deflection must be taken into account during the design process.

[0004] Although some power engine cooling fans have rotating shrouds connecting the tips of all blades, many have free tips—that is, the tips of the blades are not connected to each other. Free-tip fans offer several advantages over shrouded fans. They can have lower costs, reduced weight, better balancing, and other benefits due to their reduced inertia, such as lower coupling imbalance, lower precession torque, and faster shutdown.

[0005] Often, free-tip blowers are designed with a tip shape of constant radius and operate within a jacket tube that is cylindrical in the region closest to the blower blades. In other cases, the tip radius is not constant. For example, US Patent 6,595,744 B2 describes a free-tip engine cooling blower in which the blade tips are shaped to conform to a flared jacket tube. This configuration reduces flow separation at the tube inlet while allowing the blade tip to operate in close proximity to the jacket.

[0006] Blowers with free blade tips are designed to have a tip gap or clearance between the blade tips and the casing. This tip gap must be sufficient to accommodate both manufacturing tolerances and the maximum deflection that may occur over the blower assembly's service life. In practice, this gap is generally at least 0.5 percent, but less than 2 percent of the blower diameter, and more commonly around 1 percent.

[0007] The presence of a tip gap is associated with numerous adverse performance effects. One effect is that, as the gap increases, the blower must operate at higher speeds to reach a given operating point. This is because the blade loading—the pressure differential between the pressure and suction sides of the blower blade—is reduced near the gap. Other effects include reduced blower efficiency and increased blower noise, particularly when system resistance is high. These adverse effects can limit the applicability of free-tip blowers to applications where system resistance is relatively low. To broaden the applicability of free-tip blowers, numerous attempts have been made to overcome the adverse performance effects caused by the tip gap.

[0008] One approach is to design the blower in such a way as to counteract the effect of the peak gap on the blower load. US Patent 9,004,860 B2 describes a blower with improved peak load capacity in the presence of a peak gap. This blower can improve blower performance, but the efficiency and noise level of the blower are still affected by the gap.

[0009] Other efforts sought to reduce blade tip deflection so that the tip gap could be made smaller without the risk of obstruction. US Patent 6,595,744 B2 describes a slope distribution that can reduce the axial deflection of a curved blower with free blade tips, and US Patent 8,137,070 B2 describes an inlet and outlet edge curvature distribution that minimizes radial deflection.

[0010] Another approach is to design the tip of the blower in such a way as to minimize the airflow through a gap of a given size. US Publication 2014 / 0271172A1 describes a blower with a locally thickened tip that exhibits improved efficiency and lower noise levels compared to a blower with a non-thickened tip section.

[0011] Although past efforts have improved the efficiency and reduced the noise level of free-tip blowers, quieter free-tip blower configurations are still needed, particularly at high-pressure operating points. At these operating points, the tip vortex generated by each blade can interact with the blade, the casing, and / or the following blade. This interaction can cause a significant increase in noise compared to the noise level at a low-pressure operating point.

[0012] The publication DE 10 2012 224 485 A1 describes a fan device.

[0013] Publication US 2010 / 0 068 028 A1 describes axial fans with reduced tip penetration.

[0014] The printed document JP 2015 - 038 338 A describes a blower.

[0015] In one aspect, the present invention provides an axial fan arrangement with free blade tips, comprising a fan and a casing, wherein the fan includes several radially extending blades rotatable about a fan axis, each of the several blades having a blade tip, a leading edge, and an exit edge, wherein the fan has a diameter D corresponding to twice a radial dimension of the blade tips at the exit edge. The casing includes a tube, and the tube comprises an inlet, wherein a radial dimension of the inlet at its upstream end is larger than a radial dimension of the inlet at its downstream end.The blower arrangement is characterized in that the angle in a meridional plane between the surface of the inlet and the direction of the blower axis with respect to a surface coordinate that increases with the distance along the surface of the inlet from its upstream end to its downstream end does not vary monotonically. The angle initially decreases with increasing surface coordinate and then increases again, and several successive such sequences are provided in which the angle initially decreases with increasing surface coordinate and then increases again.

[0016] In one aspect of the invention, the axial blower with free blade tips is further characterized in that a radial dimension of the inlet area decreases or remains constant with an increase in the area coordinate.

[0017] In another aspect of the invention, the axial blower arrangement with free blade tips is further characterized in that the axial dimension of the inlet area increases with increasing area coordinate or remains approximately constant.

[0018] In another aspect of the invention, the axial blower arrangement with free blade tips is further characterized in that the inlet comprises steps, each step having an approximately axial surface extending radially in the meridional plane and an approximately radial surface extending axially in the meridional plane.

[0019] In another aspect of the invention, the axial blower arrangement with free blade tips is further characterized in that an imaginary straight line lying in the meridional plane touches the inlet surface at two points positioned along the region of a non-monotically varying angle, without intersecting the area between the points, and a distance between the imaginary straight line and a point on the inlet surface located between the two points, measured normal to the imaginary straight line, is greater than or equal to 0.2 percent of the blower diameter.

[0020] In another aspect of the invention, the distance is greater than or equal to 0.4 percent of the blower diameter.

[0021] In another aspect of the invention, the axial fan arrangement with free blade tips is further characterized in that a first part of the blade tip lies in the axial extent of the inlet, and a radial dimension of the inlet at the axial location of the upstream end of the first part is larger than a radial dimension of the inlet at the axial location of the downstream end of the first part, and a radial dimension of the blade tip at the upstream end of the part is larger than a radial dimension of the blade tip at the downstream end of the first part, and the first part of the inlet positioned at the axial location of the first part of the blade tip contains at least a part of the region with a non-monotically varying angle, wherein the axial location of the part of the region with a non-monotically varying angle defines a second part of the blade tip.which lies in the axial extension of the area with a non-monotonically varying angle.

[0022] In another aspect of the invention, the axial blower arrangement with free blade tips is further characterized in that an imaginary straight line lying in the meridional plane touches the inlet surface at two points, both of which lie in the region with a non-monotically varying angle and within the axial extent of the blade tip, without intersecting the area between the points, and a distance between the imaginary straight line and a point on the inlet surface, which, measured normal to the imaginary straight line, lies between the two points, is greater than or equal to 0.2 percent of the blower diameter.

[0023] In another aspect of the invention, the axial blower arrangement with free blade tips is further characterized in that the distance is greater than or equal to 0.4 percent of the blower diameter.

[0024] In another aspect of the invention, the axial blower arrangement with free blade tips is further characterized in that the first part is equal to the entire axial extent of the blade tip between the leading edge and the exit edge.

[0025] In another aspect of the invention, the axial blower arrangement with free blade tips is further characterized in that the area with a non-monotically varying angle extends at least over the most upstream 50 percent of an axial extension of a first part.

[0026] In another aspect of the invention, the axial blower arrangement with free blade tips is further characterized in that the area with a non-monotically varying angle extends at least over the most downstream 50 percent of the axial extent of a second part of the inlet, which is located upstream of the blade tip.

[0027] In another aspect of the invention, the axial blower arrangement with free blade tips is further characterized in that the radial dimension of the inlet at the upstream end of the first part is at least 2 percent larger than the radial dimension of the inlet at the downstream end of the first part.

[0028] In another aspect of the invention, the axial blower arrangement with free blade tips is further characterized in that the radial dimension of the blade tip at the upstream end of the first part is at least 2 percent larger than the radial dimension of the blade tip at the downstream end of the first part.

[0029] In another aspect of the invention, the axial blower arrangement with free blade tips is further characterized in that a sweeping extent of the blade tip portion, extending from the leading edge to the trailing edge, corresponds to the shape of the corresponding part of the inlet.

[0030] In another aspect of the invention, the axial blower arrangement with free blade tips is further characterized in that a minimum distance between the first part of the blade tip and the part of the inlet, measured perpendicular to a sweep extent of the blade tip, is greater than 0.005 times the blower diameter D and less than 0.02 times the blower diameter D, wherein the sweep extent extends from the leading edge to the trailing edge.

[0031] In another aspect of the invention, the axial blower arrangement with free blade tips is further characterized in that the angle in the meridional plane between a sweep extent of the second part of the blade tip and the direction of the blower axis with respect to a tip coordinate, which increases with a distance along the sweep extent of the blade tip from the leading edge of the blade tip to the trailing edge of the blade tip, decreases monotonically, wherein the sweep extent extends from the leading edge to the trailing edge.

[0032] In another aspect of the invention, the axial blower arrangement with free blade tips is further characterized in that a distance between the sweep extent of the second part of the blade tip and the locally nearest points on the corresponding part of the inlet, measured perpendicular to the second part of the blade tip which lies in the axial extent of the region of the non-monotically varying angle, varies by no more than plus or minus 30 percent or no more than plus or minus 20 percent along the second part of the blade tip, wherein the sweep extent extends from the leading edge to the trailing edge.

[0033] In another aspect of the invention, the axial blower arrangement with free blade tips is further characterized in that the distance, measured perpendicular to the sweep extent of the blade tip, between the second part of the blade tip and the inlet surface between two of the nearest points on the corresponding part of the inlet is at least 20 percent greater than the average distance between the second part of the blade tip and the two nearest points on the corresponding part of the inlet, wherein the sweep extent extends from the leading edge to the trailing edge.

[0034] In another aspect of the invention, the axial blower arrangement with free blade tips is further characterized in that the distance, measured perpendicular to the sweep extent of the blade tip, between the second part of the blade tip and the inlet surface between two of the nearest points on the corresponding part of the inlet is at least 40 percent greater than the average distance between the second part of the blade tip and the two nearest points, wherein the sweep extent extends from the leading edge to the trailing edge.

[0035] In another aspect of the invention, the axial blower arrangement with free blade tips is further characterized in that the minimum distance between the second part of the blade tip and the nearest points on the corresponding part of the inlet, measured perpendicular to the sweep extent of the blade tip, is greater than 0.005 times the blower diameter D and less than 0.02 times the blower diameter D, wherein the sweep extent extends from the leading edge to the trailing edge.

[0036] In another aspect of the invention, the axial blower arrangement with free blade tips is further characterized in that a sweep extent of the second part of the blade tip corresponds to an envelope in a meridional plane that traverses the points that are locally closest to the blade tip at the corresponding part of the inlet, wherein the sweep extent extends from the inlet edge to the outlet edge.

[0037] In another aspect of the invention, the axial blower arrangement with free blade tips is further characterized by the fact that the envelope curve is smooth.

[0038] In another aspect of the invention, the axial blower arrangement with free blade tips is further characterized in that the axial and radial coordinates of the envelope are each given approximately as values ​​of a spline curve, wherein the spline curve is determined in the following way: 1) Creating a belt coordinate that follows a piecewise linear curve whose vertices are the points that are locally closest to the blade tip on the corresponding part of the inlet, 2) Generating cubic splines of the axial and radial coordinates with respect to the belt coordinate, with nodes positioned at the vertices, 3) Evaluate the splines on belt coordinate values ​​that lie between the vertices.

[0039] In another aspect of the invention, the axial blower arrangement with free blade tips is further characterized in that a distance between the sweep extent of the second part of the blade tip and the envelope, measured perpendicular to the envelope, varies by no more than plus or minus 30 percent or no more than plus or minus 20 percent over the extent of the second part of the blade tip.

[0040] In another aspect of the invention, the axial blower arrangement with free blade tips is further characterized in that the distance, measured perpendicular to the sweep extent of the blade tip, between the second part of the blade tip and the inlet surface at a point between two of the nearest points on the corresponding part of the inlet is at least 20 percent greater than the local distance between the second part of the blade tip and the envelope.

[0041] In another aspect of the invention, the axial blower arrangement with free blade tips is further characterized in that a distance, measured perpendicular to the sweep extent of the blade tip, between the second part of the blade tip and the inlet surface at a point between two of the nearest points on the corresponding part of the inlet is at least 40 percent greater than a local distance between the second part of the blade tip and the envelope.

[0042] In another aspect of the invention, the axial blower arrangement with free blade tips is further characterized in that a minimum distance between the sweep extent of the second part of the blade tip and the envelope, measured perpendicular to the envelope, is greater than 0.005 times the blower diameter D and less than 0.02 times the blower diameter D.

[0043] In another aspect of the invention, the axial blower arrangement with free blade tips is further characterized in that the envelope in the area where the blade tip corresponds to it passes through at least 3 points at the inlet, which are locally the closest to the blade tip.

[0044] In another aspect of the invention, the axial blower arrangement with free blade tips is further characterized in that the surface of the inlet is axially symmetrical.

[0045] In another aspect of the invention, the axial blower arrangement with free blade tips is further characterized in that the casing is an injection-molded plastic part.

[0046] In another aspect of the invention, the axial blower arrangement with free blade tips is further characterized in that the casing has supports which engage with mounting features of a heat exchanger positioned upstream of the blower arrangement, and wherein the casing has an arrangement of motor supports.

[0047] In another aspect of the invention, the axial blower arrangement with free blade tips is further characterized in that the jacket comprises a chamber upstream of the pipe, which is located downstream of an upstream heat exchanger, wherein the area of ​​the heat exchanger surface encompassed by the chamber corresponds to at least 1.5 times the blower disc surface.

[0048] In another aspect of the invention, the axial blower arrangement with free blade tips is further characterized in that the angle in several meridional planes, which are positioned over one or more regions of the azimuthal angle, which in total amounts to more than 180 degrees, does not vary monotonically.

[0049] Other aspects of the invention will become apparent from the detailed description and accompanying drawings. Fig. Figure 1a is a schematic view of a prior art axial fan assembly with free blade tips, showing a blade tip that corresponds to the shape of a flared casing tube. The axial fan assembly with free blade tips is configured as a power engine cooling fan assembly. Fig. Figure 1b is a detailed schematic view in the meridional plane of the casing tube of Fig. 1a and the sweep area of ​​the outermost part of each shovel. Fig. 1c is a view from upstream of the blower, showing the inlet and outlet edges and the blade tip. Fig. 2a is a schematic view of an axial blower arrangement with free blade tips according to an embodiment of the present application, wherein a jacket tube comprises an inlet with several steps and a blower blade tip corresponding to the stepped tube. Fig. 2b is a detailed schematic view in the meridional plane of the casing tube of Fig. 2a. Fig. 2c is a detailed schematic view in the meridional plane of the casing tube of Fig. 2a and the area swept by the outer part of each shovel. Fig. 3a is a schematic view of an axial blower arrangement with free blade tips according to an embodiment of the present application, wherein a jacket tube includes an inlet with several steps and a blower blade tip corresponds to a smooth envelope that traverses the local nearest points on the tube. Fig. 3b is a detailed schematic view in the meridional plane of the casing tube of Fig. 3a and the area swept by the outermost part of each shovel. Fig. Figure 3c shows a top view (looking from upstream to downstream) of the axial fan arrangement with free blade tips of Fig. 3a, which shows a rectangular mantle chamber. Fig. 4a is a detailed schematic view in the meridional plane of the mantle tube and the sweep area of ​​the outer part of a blade, where the axial extent of the blade tip is smaller than the axial semi-axis of the ellipse defining the envelope of the nearest points at the inlet. Fig. 4b is a detailed schematic view in the meridional plane of a mantle tube and of the sweep area of ​​the outer part of a blade, wherein the axial extent of the blade tip is smaller than the axial semi-axis of the ellipse defining the envelope of the nearest points at the inlet and terminating the tube near the trailing edge of the blade. Fig. 4c is a detailed schematic view in the meridional plane of a casing tube and of the sweep area of ​​the outer part of a blade, wherein the axial extent of the blade tip is smaller than the axial semi-axis of the ellipse defining the envelope of the nearest points at the inlet, and the blower is positioned such that the tip exit edge is on the radial semi-axis of the ellipse. Fig. Figure 5a is a meridional view of a stepped mantle tube showing the points at the inlet that are closest to the blade tips not shown. Fig. 5b is a meridional view of a stepped mantle tube showing a piecewise linear envelope and defining a belt parameter. Fig. 5c is a meridional view of a stepped mantle tube showing a smooth envelope whose coordinates are defined by cubic spline functions. Fig. 5d is a meridional view of a stepped mantle tube showing a curve that differs from the smooth envelope of Fig. It is offset by 5c. Fig. Figure 5e is a meridional view of a stepped mantle tube and the area swept by a blade, wherein the sweep extent of the blade tip is the offset curve of Fig. 5d follows. Fig. Figure 6a is a meridional view of a stepped mantle tube and the sweep area of ​​a blade, with a conic angle located at the approximately axial surfaces of the steps. Fig. Figure 6b is a meridional view of a stepped mantle tube and the sweep area of ​​a blade, with the outer corners of the steps rounded. Fig. Figure 6c is a meridional view of a stepped mantle tube and the sweep area of ​​a blade, with the inner corners of the steps rounded. Fig. Figure 6d is a meridional view of a casing tube and the sweep extent of a blade, wherein the inlet to the tube has axial grooves. Fig. Figure 6e is a meridional view of a casing tube and the sweep extent of a blade, wherein the inlet to the tube has non-continuous steps. Fig. Figure 6f is a meridional view of a jacket tube and the sweep area of ​​a blade, wherein the inlet to the tube has steps with axial surfaces and surfaces angled with respect to the radial direction. Fig. Figure 7a shows both sides of a stepped casing pipe, where the depth of the steps is comparable to the thickness of the pipe and the outside of the pipe is also stepped. Fig. Figure 7b shows both sides of a stepped casing tube, with the outer steps being rounded. Fig. Figure 7c shows both sides of a stepped casing pipe, where the depth of the steps is small compared to the thickness of the pipe and the outer surface of the pipe is smooth. Fig. Figure 8a is an axial view of the suction side of a blower according to US patent application md publication number 2014 / 0271172 and of a stepped pipe inlet according to an embodiment of the present application. Fig. 8b is a meridional section through the blade and the pipe inlet at an angle corresponding to the point of maximum thickness at the blade tip, as shown in Fig. 8a shown. Fig. 8c is a detailed view of the peak area of Fig. 8b. Fig. Figure 9a is a perspective view of the blower with free blade tips and the stepped pipe inlet of Fig. 8, where the paragraphs are axially symmetrical. Fig. 9b is a perspective view of the blower with free blade tips according to Fig. 8 and a stepped pipe inlet, wherein the steps are not axially symmetrical and are helically shaped. Fig. Figure 10 is a diagram of the performance of a blower arrangement according to an embodiment of the present application, compared with that of a blower arrangement according to the prior art which has a uniformly expanded casing tube. Fig. 11 shows the same data as that of Fig. 10, but uses dimensionless variables. Fig. Figure 12a is an axial view of the suction side of a blower according to US patent application md publication number 2014 / 0271172 and a stepped pipe inlet, wherein the steps are discontinuous azimuthal. Fig. 12b is a meridional section, in Fig. 12a shown, through the blade and the pipe inlet at an angle corresponding to the point of maximum thickness at the blade tip, the cut traversing the mantle at an angle where the cut is stepped. Fig. 12c is a perspective view of part of the in Fig. 12a shown jacket pipe inlet. Fig. Figure 13a is an axial view of the suction side of a blower according to US patent application md publication number 2014 / 0271172 and a pipe inlet with staggered rows of circular pockets. Fig. 13b is a meridional section, in Fig. 13a shown, through the blade and the pipe inlet at an angle corresponding to the point of maximum thickness at the blade tip, with this cut passing through two inlet pockets. Fig. 13c is a meridional section through the blade and the pipe inlet at such an angle that the section passes through an inlet pocket. Fig. 13d is a perspective view of a part of the in Fig. 13a shown jacket pipe inlet.

[0050] Before a detailed explanation of any embodiments of the invention, it should be noted that the invention is not limited in its application to the details of the design and arrangement of components listed in the following description and illustrated in the following drawings. The invention may have other embodiments and may be implemented or carried out in various ways.

[0051] Fig. Figure 1a shows a prior art axial fan assembly 1 with free blade tips. In the illustrated design, the axial fan assembly 1 with free blade tips is an engine cooling fan assembly installed alongside at least one heat exchanger 5. In this design, the heat exchanger 5 contains a radiator 51, which cools an internal combustion engine (not shown). In alternatively powered vehicles, the fan assembly 1 could be used together with one or more heat exchangers to cool batteries, electric motors, etc. A jacket 2 guides cooling air from the radiator 51 to a fan 4, surrounds the fan to control leakage, and provides supports 28 for the engine 3.

[0052] The casing 2 comprises a chamber wall 21 and side walls 23, which together enclose a chamber 20. In the illustration, the chamber wall 21 has a small conical angle, but in other cases, it may lie in a plane approximately perpendicular to the blower axis 6. The side walls 23 are shown parallel to the blower axis 6, but often have a conical angle to improve manufacturability. The casing 2 also comprises a tube 22 that surrounds the blower 4. The tube 22 includes a uniformly flared inlet 24 and a cylindrical section 26 downstream of the flared inlet 24. The radial coordinate R1 (measured from axis 6) of the inlet to the casing inlet is larger than the radial coordinate R2 of the outlet, where it meets the cylindrical section 26.Although part 26 is described as cylindrical, for manufacturability it can also be formed with a taper angle, so that it does not actually run parallel to axis 6. In both cases, part 26 is distinguishable from the part with the shape defining the widened inlet 24.

[0053] The blower 4 rotates about an axis 6 and comprises a hub 41 and several generally radially extending blades 40. Fig. Figure 1a shows the area in a meridional plane (a plane containing the blower axis) swept by these blades when the blower rotates. The end of each blade 40 adjacent to the hub 41 is a blade root 43, and the outermost end of each blade 40 is a blade tip 46. The blade tips 46 correspond to the casing tube 22. In other words, the blade tips 46 are offset from the casing tube 22 but have a shape that follows or corresponds to a contour defined by the casing tube 22. The radial coordinate of the blade tip leading edge R LE is greater than the radial coordinate of the blade tip exit edge R TE The blower nominal radius R corresponds to R TE , and the blower diameter D is 2 x R. A tip gap 7 provides a minimum running clearance between the blade tips 46 and the jacket tube 22, which is between 0.005 D and 0.02 D.

[0054] Fig. Figure 1b is a detailed schematic view in the meridional plane of the casing tube 22 of Fig. 1a and the area swept by the outermost part of each blade 40. The widened inlet has an approximately elliptical shape, and the sweep extent of the blade tip 46 is a smooth curve offset at an approximately constant distance “g” from the tube 22. This distance represents the width of the spacer gap 7 between the blade tip 46 and the casing tube 22.

[0055] Fig. Figure 1b further shows an inlet surface coordinate “s”, which is zero where the inlet meets the chamber wall 21, and increases linearly with the distance along the inlet profile. Although the in Fig. While the flared inlet shown in Figure 1b is elliptical, other flared mantles may differ slightly in shape according to the prior art. In all cases, the angle “Θ” in a meridional plane between the surface of the flared inlet 24 and the direction of the blower axis 6 decreases monotonically with increasing “s”.

[0056] Although Fig. While in Figure 1b the gap width is approximately constant, in other cases the gap is not constant from the leading edge to the trailing edge. In particular, it is sometimes designed such that the minimum axial clearance between the blade tip and the mantle is greater than it would be in the case of a constant gap width. This is especially advantageous when the predicted axial deflection of the blade tip is greater than the predicted radial deflection.

[0057] Although the Fig. 1a and Fig. 1b The tube 22, which extends at a certain distance downstream of the trailing edge TE of the blade tip 46, sometimes terminates very close to the trailing edge TE of the blade tip 46. This is often the case at points along the tube circumference where there is no motor support structure 28 downstream. At these points, there is often little or no aerodynamic advantage to extending the tube 22 further than necessary to limit backflow around the blade tip 46. In some cases, good performance can even be achieved if the tube 22 terminates somewhat upstream of the blade tip trailing edge TE.

[0058] Although the Fig. 1a and Fig. While Figure 1b shows the axial extent of the blade tip 46, which is approximately equal to the axial extent of the expanded inlet, this is sometimes not the case. In some cases, the blade tip extends beyond the end of the inlet and into the approximately cylindrical part of the tube 22. In other cases, the exit edge TE of the blade tip 46 is located at an axial position where the angle of the expanded inlet with respect to the blower axis 6 is not yet zero. In the case of an elliptical mantle shape, this corresponds to a position upstream of the radial semi-axis “b”.

[0059] In some cases, the leading edge of the shovel tip lies in front of the entrance to the inlet, and in other cases, it is clearly inside the entrance to the inlet.

[0060] Fig. 1c is an axial projection of the blower 4 with free blade tips according to the prior art with a blade tip corresponding to a flared mantle, as in the Fig. 1a and Fig. Figure 1b shows the rotation clockwise, and the blower inlet edge LE and outlet edge TE are as shown. The radius of the blade tip at the inlet edge R LE is larger than at the exit edge R TE .

[0061] Fig. 2a represents an axial blower arrangement with free blade tips according to an embodiment of the present application. As the blower arrangement according to the prior art of Fig. 1a The pipe 22 includes an inlet 242, which is characterized in that the radial coordinate at the inlet surface with respect to the blower axis 6 is larger at the inlet entrance than at the outlet. Thus, the inlet defines a region with decreasing cross-sectional area in the axial flow direction F. In this example, the radial coordinate R1 of the inlet at the axial location of the blade tip leading edge is approximately 6.8 percent larger than the radial coordinate R2 of the inlet at the axial location of the blade tip trailing edge. In contrast to the engine cooling blower arrangement of Fig. 1a the inlet 242 is not uniformly widened, but is instead stepped, with each step in the meridional plane comprising an approximately radial (axially pointing) surface and an approximately axial (radially pointing) surface.

[0062] Fig. Figure 2a shows a blower 4 having blade tips 46 corresponding to the shoulders. The radial extent (measured from axis 6) of the blade tip leading edge R LE is greater than the radial extent of the blade tip exit edge R TE In this example, R surpasses R. LE R TE by approximately 6.9 percent of R TE . A tip gap 7 provides a running clearance between the blade tips and the casing tube, which in this example is approximately constant and equal to 1.0 percent of the blower diameter D.

[0063] Fig. 2b is a detailed schematic view in the meridional plane of the casing tube 22 of Fig. 2a. The tube 22 comprises a stepped inlet 242 and an approximately cylindrical part 26. Upstream of the inlet 242 is the chamber wall 21. The surface coordinate “s” is zero at the point where the inlet meets the chamber wall 21 and decreases linearly with distance along the stepped inlet surface until it meets the cylindrical part 26.

[0064] In the case of the in Fig. In the inlet shown in Figure 2b, the radial coordinate of the surface decreases monotonically with an increase in "s"—that is, it either decreases or remains constant. This property allows the inlet to be manufactured from injection-molded plastic using a simple injection mold.

[0065] The in Fig. The stepped inlet shown in Figure 2b has the additional property that the axial coordinate (positive downstream) of the inlet surface increases monotonically with increasing surface coordinate "s"—that is, it either increases or remains approximately constant. This property is particularly advantageous in the design of injection molds.

[0066] The angle between the inlet surface and the blower axis, which is in Fig. 2b, shown as “Θ”, is approximately 90 degrees at the inlet and approximately 0 degrees at the outlet from the inlet where it meets the cylindrical part of the tube, although by providing a cone angle (of, for example, 5 degrees), as with the chamber wall 21 of Fig. As shown in 2a, a deviation can occur. In contrast to the uniformly widened inlet of Fig. 1. As "s" increases, the value of the angle "Θ" at the inlet decreases non-monotonic to its value at the outlet, changing from approximately 90 degrees along the approximately radial surfaces of the steps to approximately 0 degrees along the approximately axial surfaces of the steps. Viewed in cross-section along a meridional plane, the inclination of the inlet surface between a point "A" and a point "B" (see Fig. 2b) discontinuous and is defined between these points as a region in which the angle “Θ” does not change monotonically. In the region of non-monotonic change of the angle “Θ”, several steps are defined in the inlet surface, with each step connecting two inlet surface segments at different radial coordinates.

[0067] Fig. Figure 2b shows a straight line 28 that touches two points on the inlet surface (for example, two consecutive protruding points) without intersecting the inlet surface, so that the straight line 28 represents a straightedge placed on the inlet surface. The distance "d" between the straight line 28 and the pipe surface at a point lying between the two points where the straight line 28 touches the inlet surface, measured perpendicular to the straight line 28, is in the illustration at least 1.0 percent of the blower diameter D (for example, 1.5 percent of the blower diameter D).

[0068] Fig. 2c is a detailed schematic view in the meridional plane of the casing tube 22 of Fig. 2a and the area swept by the outermost part of each blade 40. The part P1 of the blade tip that lies in the axial extent of the pipe inlet is equal to the total axial extent of the blade tip between the leading edge LE and the trailing edge TE. The region of the non-monotonic varying angle “Θ” extends at least over the most upstream 50 percent of the axial extent of the portion of the inlet that overlaps with part P1. The portion of the blade tip that lies in the axial extent of the region of the non-monotonic varying angle is referred to as a second part P2 of the blade tip.

[0069] The sweep area of ​​the shovel tip 46 in Fig. 2c is stepped to match the stepped inlet and is set off by radial gap “g”. r “ and axial column “g a“, which, as shown, can be the same or different, offset. In particular, it is sometimes advantageous to g a to set larger than g r This is particularly advantageous when the predicted axial deflection of the blade tip is greater than the predicted radial deflection. A typical minimum distance between the blade tip and the inlet is between 0.005 and 0.02 times the blower diameter D.

[0070] Fig. 3a represents an axial blower arrangement with free blade tips similar to that of Fig. 2a, but with certain differences discussed below. The above description is used to disclose similar features. Instead of corresponding to the stepped inlet 242, the blade tips 46 correspond to an envelope that traverses the points on the casing tube that are locally closest to the blower blade tip. As in Fig. 2a is the radial extent (measured from axis 6) of the blade tip leading edge R LE greater than the radial extent of the blade tip exit edge R TE The inlet area of ​​pipe 22 is, in comparison to the inlet area of ​​the blower arrangement, Fig. 2a to 2c are designed with an increased number of paragraphs.

[0071] Fig. 3b is a detailed schematic view in the meridional plane of the casing tube 22 and the outermost part of each blade 40 of Fig. 3a swept area. In this example, the envelope traversing the points on the pipe that are locally closest to the blower blade tip forms part of an ellipse with an axial semi-radius “a” and a radial semi-axis “b”. The sweep of the blade tip is a curve offset from the envelope by an approximately constant distance “g”. In this example, “g” is approximately 1.0 percent of the blower diameter D. A tip coordinate “t” increases linearly along the sweep of the blade tip from the leading edge to the trailing edge. The angle “ψ” in a meridional plane between the sweep of the blade tip and the direction of the blower axis 6 decreases monotonically with increasing “t”. In the Fig. In the embodiment shown in 3b, the sweepout of the blade tip is a smooth curve insofar as the angle “ψ” is a continuous function of “t”. In other embodiments, the sweepout of the blade tip is not smooth insofar as the angle “ψ” is not a continuous function of “t”, but such embodiments may still exhibit an angle “ψ” that decreases monotonically with increasing “t”.

[0072] Viewed in cross-section along a meridional plane, the inclination of the inlet surface between a point “A” and a point “B” (see Fig. 3b) discontinuous, and between these points a region is defined in which the angle “Θ” between the inlet face and the direction of the fan axis, as defined above, does not vary monotonically. The part P1 of the blade tip that lies within the axial extent of the inlet is the entire axial extent of the blade tip. The region with the non-monotonically varying angle “Θ”, which lies between points A and B, extends over at least the most upstream 50 percent of the axial extent of the portion of the inlet that overlaps the axial extent of the blade tip. The portion of the blade tip that lies within the axial extent of the region with the non-monotonically varying angle is called the second part P2 of the blade tip.

[0073] Fig. Figure 3b shows a straight line 28 that touches the inlet surface at two points, both of which lie within the axial extent of the blade tip, without intersecting the inlet surface. This represents a straightedge placed against the inlet surface. The distance 'd' between the straight line and the pipe surface at a point between the two points where the straight line touches the inlet surface, measured perpendicular to the straight line 28, is approximately 0.5 percent of the blower diameter D in the diagram. In this particular example, this measurement represents a maximum value for the offset depth—if a similar measurement is taken closer to the trailing edge TE of the blade tip 46, the distance will be less. This maximum offset depth d can be used as a metric for comparing different inlet designs.The maximum step depth d within the axial extent of the blade tip 46 can be 0.2 percent of the blower diameter D or more, and in some designs the maximum step depth d is greater than 0.3 percent or even greater than 0.4 percent of the blower diameter D. Although this limits the amount of steps that can be provided along the inlet surface, the maximum step depth d within the axial extent of the blade tip 46 can even exceed 0.5 percent of the blower diameter D.

[0074] In Fig. 3b the distance “g” represents the width of the gap 7 only at the points where it is locally at a minimum.

[0075] Although Fig. Figure 3b shows an example in which the distance “g” from the blade leading edge to the blade trailing edge is constant; however, in other embodiments, it can vary over this distance. In particular, it is sometimes designed such that the minimum axial distance between the blade tip and the shell is greater than it would be if “g” were constant. This is especially advantageous when the predicted axial deflection of the blade tip is greater than the predicted radial deflection. Across the blade tip 46, the extent of variation of the distance “g” to the locally nearest points is less than ±30 percent of its average value and can be less than ±20 percent of its average value. A minimum value of the distance “g” can be between 0.005 and 0.02 times the blower diameter D.

[0076] Although the distance “g” represents the width of the gap 7 between the blade tip and the locally nearest points on the mantle, the gap 7 can be significantly larger than the dimension “g” at other points. In the example of Fig. 3b The width of the clearance gap 7, measured normal to the sweep extent of the blade tip, is 50 percent greater than the local value of the dimension “g” at a point between two locally nearest points. This locally maximum width of the clearance gap 7 between points that are locally closest to the blade tip 46 can be at least 20 percent greater than the local value of the dimension “g” and, in some embodiments, is at least 30 percent, at least 40 percent, or even at least 50 percent greater than the local value of the dimension “g”.

[0077] The in Fig. The blade tip 46 shown in Figure 3b extends over the entire extent of the ellipse defining the envelope, and the depth of the steps in the region of the blade tip exit edge TE is shallow. However, the inlet may be smooth (i.e., not stepped) over a portion of the inlet with an axial extent to the exit edge TE of the blade tip 46. In some aspects, the steps extend over at least the most upstream 50 percent and, in particular, a large proportion of the axial extent of the portion of the inlet that overlaps with the axial extent of the blade tip 46.

[0078] Fig. Figure 3c shows a top view (looking from upstream to downstream) of the axial fan arrangement with free blade tips of Fig. 3a. The jacket 2 has an approximately rectangular chamber 20 enclosed by an approximately rectangular chamber wall 21 and side walls 23 extending axially from the outer edges of the chamber wall to an upstream heat exchanger (not shown). The area of ​​the heat exchanger enclosed by the chamber is approximately 2.14 times the area of ​​the fan disc, which is defined as the area of ​​a circle with a diameter equal to the fan diameter D. The jacket has supports 29 that engage with mounting features on the heat exchanger. The jacket has a stepped pipe inlet 242 and an arrangement of motor supports 28. Although Fig. Figure 3c shows a blower arrangement with a single blower; other designs feature multiple blowers in a single casing. In these designs, the relevant metric for the heat exchanger surface area is the ratio of the surface area to the total disk area of ​​all blowers.

[0079] The axial projection of the in Fig. The blower 4 shown in 3c corresponds to that of the one in Fig. The blower shown in 1c has free blade tips according to the prior art. Although this blower has a forward sweep near the blade root and a backward sweep at the blade tip, other embodiments may have different sweep distributions. Likewise, although the blowers of the Fig. 2 and Fig. 3 a similar slope distribution to that of the in Fig. 1a shown blower according to the prior art, other embodiments have different inclination distributions.

[0080] The Fig. 2 and Fig. Figure 3 shows both blower arrangements in which all inlet steps have axial surfaces with the same axial extent and radial surfaces with varying radial extent. In other embodiments, all steps have radial surfaces with the same radial extent and axial surfaces with varying axial extent. A further possibility is to make the depth, normal to an envelope, constant for all steps. Other configurations are also possible.

[0081] Fig. 4a is a detailed schematic view in the meridional plane of a casing tube 22 and the sweep area of ​​the outer part of a blade 40, wherein, as in Fig. 3a, the smooth envelope that traverses the points on the pipe that are locally closest to the blower blade tip, forms part of the ellipse 23 with an axial semi-radius “a” and a radial semi-axis “b”. In this case, the axial extent of the blade tip 46 is smaller than the axial semi-axis of the ellipse 23, and the blade tip exit edge TE is a distance “X” upstream of the radial ellipse axis. This allows the steps near the blade tip exit edge TE to be deeper and more effective than the steps near the blade tip exit edge TE of the blower of Fig. 3b. The portion of the inlet downstream of the blade tip exit edge TE is smooth and has no steps. Extending the steps downstream of the blade tip exit edge does not significantly improve the performance of the fan assembly.

[0082] Fig. 4b is similar to 4a, but in this example, pipe 22 terminates near the outlet edge TE of the blower. This configuration is often used at circumferential points between the in Fig. 3a shows engine support structures 28 used.

[0083] Fig. Figure 4c further shows a case in which the axial extent of the blade tip 46 is smaller than the axial semi-axis “a” of the ellipse 23, which defines the envelope through the nearest points at the inlet. Here, the blower is positioned with its tip exit edge TE located on the radial semi-axis “b” of the ellipse 23, and the blade tip leading edge LE is located at a distance “Y” downstream of the inlet to the casing duct 22. The steps extend forward of the blade tip leading edge LE and encompass at least the most downstream 50 percent of the axial extent of a second part of the inlet, which lies upstream of the leading edge LE of the blade tip 46. The noise performance of this blower arrangement is significantly better than that of a similar arrangement in which the steps do not extend forward of the blade tip leading edge LE.

[0084] Although the envelope in the Fig. 3b and Fig. While 4a-c form part of an ellipse, other shapes can also yield good results. In some embodiments, the coordinates of the envelope are formed as spline curves by nodes corresponding to the points on the mantle that are locally the nearest points to the blade tip 46. These “locally nearest” points are in Fig. 5a marked.

[0085] Fig. Figure 5b shows an envelope that runs linearly between the nearest points. It also defines a belt coordinate “s”. g “, which increases linearly along the length of this envelope. Such an envelope has the property that the angle in a meridional plane between the envelope and the direction of the fan axis 6 increases with increasing “s g “decreases monotonically.”

[0086] Fig. Figure 5c shows a smooth envelope with axial and radial coordinates following a cubic spline whose nodes are the axial and radial coordinates of the nearest points of the inlet and whose independent variable is the coordinate “s g “ is. The final states of these splines are such that the smooth envelope transitions into the surface outside the region with non-monotonic angular variation.

[0087] Fig. Figure 5d shows a curve that deviates by a constant distance from the smooth envelope of Fig. 5c is offset, and Fig. Figure 5e shows the sweep area of ​​a blower blade, where the blade tip sweep extent follows the offset curve.

[0088] Although the Fig. 2, Fig. 3, Fig. 4 and Fig. Five stepped pipe inlets with steps that have axial and radial surfaces show that other geometries are also effective. Fig. Figure 6a shows a stepped pipe inlet 242, which has a conical angle on the parts of the inlet that are in the Fig. 2-5 are axial. The taper angle is 5 degrees. Taper can improve the formability of a plastic part and does not significantly affect the performance of the blower assembly.

[0089] Fig. Figure 6b shows a stepped pipe inlet 242 in which the outer corners of the steps—the corners closest to the blade tips—are rounded. Although rounding the corners causes a slight power loss compared to a stepped pipe with sharp corners, the loss is minimized if the envelope is redefined to incorporate the effect of the corner rounding and the offset between the blade tip 46 and the envelope is maintained.

[0090] Fig. Figure 6c shows a stepped pipe inlet 242 in which the inner corners of the steps are rounded. In the case of a molded plastic part, the advantage of such rounding is that the molten plastic can fill the mold more easily during manufacturing. Although such rounding can cause a loss of performance compared to a stepped pipe without rounded corners, this loss is generally less than in the case of a stepped inlet where the rounding is applied to the outer corners, as in Figure 6c. Fig. 6b shown.

[0091] The Fig. Figures 6a-6c show modifications to a stepped pipe inlet that can improve the manufacturability of a formed part. They are not mutually exclusive, as any combination of them or similar modifications can be used on the same outer casing pipe.

[0092] Fig. Figure 6d shows a pipe inlet 242 that includes axial grooves. The expanded view shows the inlet surface coordinate “s”, which is zero where the inlet meets the chamber wall 21, and increases linearly with distance along the inlet profile. As with the stepped inlet of the Fig. In 2-5, the radial dimension decreases with increasing "s" or remains constant. In contrast to the case of a stepped inlet, however, the axial dimension (positive downstream) does not necessarily increase with increasing "s" or necessarily remain constant; instead, it can also decrease. The inclusion of axial grooves, as in Fig. As shown in Figure 6d, the performance of an axial fan assembly with free blade tips can be improved compared to a fan assembly with a uniformly flared jacket inlet.

[0093] Fig. Figure 6e shows a stepped pipe inlet 242 where the steps are not continuous but are separated by portions of a uniformly flared jacket. In general, such a configuration is less effective than one where the steps are continuous. This may explain some of the performance loss of an inlet with axial grooves compared to a continuously stepped inlet.

[0094] Fig. Figure 6f shows a configuration in which the non-axial surfaces of the stepped inlet are not radial, but form an acute angle (for example, an angle of 30 degrees) with the radial direction in the meridional plane. The radial extent of the angled portions of the four steps is constant in this example. This configuration offers the added depth of a grooved inlet and the continuous nature of a stepped inlet. Although such a configuration is superior to a uniformly flared inlet, it may be less effective than one in which the step surfaces are approximately perpendicular to each other.

[0095] The Fig. 4, Fig. 5 and Fig. Figure 6 shows only the inner surface of the casing pipe. The outer surface of the pipe may, in some cases, follow the shape of the inner surface, as shown in the Fig. 2a and Fig. 3a shown. Fig. 7a is a meridional section through the casing pipe, the inner surface of which is in Fig. As shown in 4b. In this example, the outer surface is offset from the inner surface by an approximately constant amount. Fig. Figure 7b shows a meridional section through a casing tube where the outer corners are rounded. This reduces the amount of material used and, in the case of an injection-molded casing, can improve the flow of plastic during manufacturing. To further improve formability, the inner corners on the outer and inner surfaces can also be rounded, and the taper angle can be applied to both the outer and inner surfaces.

[0096] In cases where the steps in the casing are relatively shallow, an alternative approach is to provide the outside of the pipe with a smooth surface. This is done in Fig. Figure 7c shows that in this example, the steps perpendicular to the elliptical envelope all have the same depth. The inner corners are rounded to improve the flow of plastic material into the tool.

[0097] Fig. Figure 8a is an axial view of the suction side of a blower according to US patent application md publication number 2014 / 0271172 and a stepped pipe inlet according to an embodiment of the present application. In this view, the blower rotates counterclockwise. Fig. 8b is a meridional section through the blade and the pipe inlet at an angle corresponding to the point of maximum thickness at the blade tip, as in Fig. 8a shown. The pipe inlet corresponds to the one in Fig. 7a shown. Fig. 8c is a detailed view of the peak area of Fig. Figure 8b shows a schematic diagram of the flow leaking past the blade tip and the vortex motion generated in flow separation zones. In addition to the separated zone where the pressure side of the blade meets the inlet to the spacer gap, there is further flow separation at the radial surfaces of each shoulder of the mantle inlet. These separated zones can reduce the flow through the tip gap and can also break up the tip vortex into several smaller vortices that dissipate more readily than a single vortex, resulting in less interaction with the downstream blade. After passing the blade, the tip vortex can continue to induce flow upstream along the mantle, allowing the illustrated separation zones to persist over a large circumferential extent.The presence of these separated zones can reduce the noise radiated through the mantle due to the fluctuating pressure field. In areas between the blades where the tip vortex has moved downstream, the flow moves downstream along the stepped surface, and the separation zones shift towards the axial surfaces, generating vortex motion with the opposite sign.

[0098] Fig. Figure 9a is a perspective view of the blower with free blade tips and the stepped pipe inlet of the Fig. 8a-8c, where the paragraphs are axially symmetric. Fig. 9b is the same view of the blower with free blade tips of the Fig. 8a-8c and the stepped pipe inlet, wherein the steps are not axially symmetrical and are helically shaped. A meridional section through this jacket pipe 22 has a matched profile that corresponds to that of Fig. 9a is very similar, but the axial position of the steps changes with the circumferential position around the fan axis. Although the helically shaped steps shown have an orientation opposite to the blade pitch helix, other helically shaped pipe steps may have an orientation similar to the blade pitch helix. Although a non-axially symmetrically stepped pipe inlet can result in a significant reduction in noise compared to a uniformly flared inlet, it is not necessarily superior to an inlet with axially symmetrically stepped steps.

[0099] It should be noted that any of the inlet geometries according to any of the embodiments disclosed herein can be provided over the entire circumferential extent of the mantle (that is, the entire 360-degree azimuthal angle range). In some cases, however, the described inlet geometries may be provided over less than the entire circumferential extent. In such cases, the described inlet geometry may be present over a substantial part of the circumferential extent (that is, at least 33 percent). In some embodiments, the described geometry may be present over at least a large part (that is, more than 180 degrees of azimuthal angle range) of the circumferential extent, and in some cases, significantly more (for example, 67 percent, 80 percent, 90 percent, 95 percent, or 99 percent).

[0100] Fig. Figure 10 shows the performance of a blower arrangement according to an embodiment of the present application (solid lines) compared to that of the blower arrangement according to the prior art, which differs only in that the inlet to the casing pipe is uniformly expanded (dashed lines). The blower diameter is 375 mm. The operating speed of both blowers is set to achieve a design flow rate of 0.7 m³ / h. 3 / s at a pressure of 200 Pa, representing the vehicle's "idle" state, with the car stationary. The fan speed in the prior art arrangement is 2760 RPM, and that of the fan arrangement according to the present application is 2736 RPM. At the design point indicated by a small circle on the pressure curves, the fan arrangement according to the present application is 2.0 dB quieter than the prior art fan. Its efficiency is 1.2 points higher. At higher pressure operating points, the noise reduction is significantly greater.

[0101] Fig. 11 shows the same data as that of Fig. 10, but in the form of different variables. Here, the abscissa is the system resistance coefficient, which is proportional to the static pressure divided by the dynamic pressure. The right ordinate represents specific noise, which normalizes the measured noise, taking into account the supplied air power and the fan blade area. The noise level of the basic fan configuration increases dramatically between a system coefficient of 2.5 and 4.5. This can be referred to as the "noise wall." If the position of the noise wall is defined as the system coefficient at which the specific noise exceeds 70 dB, the effect of the stepped inlet is to shift the noise wall by 28.6 percent. This is a very significant increase. The stepped mantle allows the use of a free-blade fan with a significantly higher system resistance than is the case with a uniformly flared inlet.

[0102] Fig. Figure 12a is an axial view of the suction side of a blower according to US Patent 2014 / 0271172A1 and a stepped tube inlet, wherein the steps are discontinuously azimuthal. Although the stepped inlet shape is applied only over selected azimuthal portions of the tube inlet, similar advantages remain as in embodiments where the entire circumference of the jacket tube inlet has the stepped shape. If the tube inlet is only partially stepped, the stepped portion may be a single azimuthal angle range or, as in the case of Fig. 12a several small azimuthal regions. In total, the parts exhibiting the stepped shape can form a majority of the azimuthal part or region (that is, more than 180 degrees of azimuthal angle) of the inlet. Fig. 12b is a meridional section through the blade and the pipe inlet at an angle corresponding to the point of maximum thickness at the blade tip, as shown in Fig. As shown in Figure 12a, the section intersects the jacket pipe inlet at a point where the section is shaped to include several steps. Each individual stepped part is formed with a shape as shown in the illustration. Fig. Figures 8a to 8c are shown, and thus reference is made to the description above. In other versions, however, the individual stepped parts may be shaped according to any other construction as defined herein. Fig. Figure 12c is a perspective view of part of the jacket pipe inlet.

[0103] Fig. Figure 13a is an axial view of the suction side of a blower according to US patent application md publication number 2014 / 0271172 and a pipe inlet with staggered rows of pockets (for example, circular pockets). Each of the pockets defines an axis parallel to the blower axis or has a component forming the majority of the pocket that is parallel to the blower axis. During the in Fig. Since the jacket pipe inlet shown in Figure 12a has azimuthally discontinuous steps, the pipe inlet can be... Fig. 13a are considered to have discontinuous axial grooves. This is in the Fig. 13b and Fig. See 13c. Fig. 13b is a meridional section through the blade and the pipe inlet at an angle corresponding to the point of maximum thickness at the blade tip, as in Fig. Figure 13a shows that this section passes through two pockets such that the inlet surface defines a region with a non-monotonically varying angle “Θ”, as described with reference to the earlier embodiments. This section is similar to that shown in Fig. Axial grooves shown in Figure 6d, although Fig. 6d contains an increased number of shaped features. Fig. Figure 13c is a meridional section through the blade and the pipe inlet at such an angle that the section traverses a single pocket. Although not required in all embodiments, the portions in which multiple pockets (in the meridional cross-section) are defined can, taken together, constitute a major azimuthal portion or region (i.e., over a 180-degree azimuthal angle) of the pipe inlet.

[0104] The contents of US Publication 6,595,744 B2, US Publication 8,137,070 B2, US Publication 9,004,860 B2, and US Publication 2014 / 0271,172 A1 are all incorporated herein by reference. Publication US 6,595,744 B2 describes a tilt distribution that can reduce the axial deflection of a curved, free-blade fan, and Publication US 8,137,070 B2 discloses a curvature distribution that reduces the radial deflection of a free-blade fan. These two features can reduce the required design tip gap of a free-blade fan assembly. Document US 9 004 860 B2 discloses a modification of the blade curvature and blade angle that counteracts the effect of the tip gap on the blade tip load.Publication US 2014 / 0271172A1 discloses a blower with an increased blade thickness at the blade tip, which reduces the adverse effect of the tip gap on noise and efficiency. Since many aspects of the present application do not involve changes to the blade geometry, a blower arrangement may advantageously include, in addition to the features of the present application, any combination of features disclosed in any of these publications incorporated by reference. Furthermore, it is understood that features of the present application may be used with additional geometries of blower blades with free blade tips of other known types.

[0105] Blower assemblies with characteristics according to one or more aspects of the present application can be forward-curved, backward-curved, radial, or mixed-curve. Likewise, blower assemblies according to one or more aspects of the present application can have any number of blades, any distribution of blade angle, camber, chord, or inclination, and can be either a pusher or a puller configuration.

Claims

[1] Axial fan assembly (1) with free blade tips (46), comprising: a blower (4) comprising several radially extending blades (40) rotatable about a blower axis (6), each of the several blades (40) having a blade tip (46), a leading edge (LE) and a trailing edge (TE), the blower (4) having a diameter (D) which is twice a radial dimension (R) TE) of the blade tips (46) at the exit edge (TE); and a jacket (2) comprising a tube (22), wherein the tube (22) includes an inlet (242), wherein a radial dimension (R1) of the inlet (242) at its upstream end is larger than a radial dimension (R2) of the inlet (242) at its downstream end, wherein an angle (θ) in a meridional plane between a surface of the inlet (242) and a direction of the blower axis (6) with respect to a surface coordinate (s) that increases with the distance along the surface of the inlet (242) from its upstream end to its downstream end varies non-monotically over a region of the inlet surface, wherein the angle (θ) first decreases and then increases again with increasing surface coordinate (s), and several successive such sequences are provided in which the angle (θ) first decreases and then increases again with increasing surface coordinate (s).where a radial dimension of the inlet area decreases or remains constant with increasing area coordinate (s). [2] Axial blower arrangement (1) with free blade tips (46) according to claim 1, wherein an axial coordinate of the inlet area increases with increasing area coordinate (s) or remains approximately constant. [3] Axial blower arrangement (1) with free blade tips (46) according to claim 1, wherein the inlet (242) comprises steps, each step having an approximately axial surface extending radially in the meridional plane and an approximately radial surface extending axially in the meridional plane. [4] Axial blower arrangement (1) with free blade tips (46) according to claim 1, wherein an imaginary straight line (28) lying in the meridional plane touches the inlet surface at two points positioned along the region of a non-monotically varying angle (θ) without intersecting the surface between the two points, and a distance (d) between the imaginary straight line (28) and a point on the inlet surface located between the two points, measured normal to the imaginary straight line (28), is greater than or equal to 0.2 percent of the blower diameter (D). [5] Axial blower arrangement (1) with free blade tips (46) according to claim 4, wherein the distance (d) is greater than or equal to 0.4 percent of the blower diameter (D). [6] Axial blower arrangement (1) with free blade tips (46) according to claim 1, wherein: a first part (P1) of the blade tip (46) lies in the axial extension of the inlet (242); a radial dimension of the inlet (242) at the axial location of the upstream end of the first part (P1) is larger than a radial dimension of the inlet (242) at the axial location of the downstream end of the first part (P1); a radial dimension of the blade tip (46) at the upstream end of part (P1) is larger than a radial dimension of the blade tip (46) at the downstream end of the first part (P1); and the first part of the inlet (242) positioned at the axial location of the first part (P1) of the blade tip (46) contains at least a part of the region with a non-monotically varying angle (θ), wherein the axial location of the part of the region with a non-monotically varying angle (θ) defines a second part (P2) of the blade tip (46) which lies in the axial extent of the region with a non-monotically varying angle (θ). [7] Axial blower arrangement (1) with free blade tips (46) according to claim 6, wherein an imaginary straight line (28) lying in the meridional plane touches the inlet surface at two points, both of which lie in the region with non-monotonically varying angle (θ) and within the axial extent of the blade tip (46), without intersecting the area between the two points, and a distance (d) between the imaginary straight line (28) and a point on the inlet surface, which, measured normal to the imaginary straight line (28), lies between the two points, is greater than or equal to 0.2 percent of the blower diameter (D). [8] Axial blower arrangement (1) with free blade tips (46) according to claim 7, wherein the distance (d) is greater than or equal to 0.4 percent of the blower diameter (D). [9] Axial blower arrangement (1) with free blade tips (46) according to claim 6, wherein the first part (P1) is equal to the total axial extent of the blade tip (46) between the leading edge (LE) and the exit edge (TE). [10] Axial blower arrangement (1) with free blade tips (46) according to claim 6, wherein the region with non-monotically varying angle (θ) extends at least over the most upstream 50 percent of an axial extent of the first part (P1). [11] Axial blower arrangement (1) with free blade tips (46) according to claim 6, wherein the region with non-monotically varying angle (θ) extends at least over the most downstream 50 percent of the axial extent of a second part of the inlet (242) located upstream of the blade tip (46). [12] Axial blower arrangement (1) with free blade tips (46) according to claim 6, wherein a radial dimension of the inlet (242) at the upstream end of the first part (P1) is at least 2 percent larger than the radial dimension of the inlet (242) at the downstream end of the first part (P1). [13] Axial fan assembly (1) with free blade tips (46) according to claim 6, wherein a radial dimension of the blade tip (46) at the upstream end of the first part (P1) is at least 2 percent larger than the radial dimension of the blade tip (46) at the downstream end of the first part (P1). [14] Axial blower arrangement (1) with free blade tips (46) according to claim 6, wherein a sweep extent of the blade tip part (46) extending from the leading edge (LE) to the exit edge (TE) corresponds to the shape of the corresponding part of the inlet (242). [15] Axial blower arrangement (1) with free blade tips (46) according to claim 6, wherein a minimum distance between the first part (P1) of the blade tip (46) and the part of the inlet (242), measured perpendicular to a sweep extent of the blade tip (46), is greater than 0.005 times the blower diameter (D) and less than 0.02 times the blower diameter (D), wherein the sweep extent extends from the leading edge (LE) to the trailing edge (TE). [16] Axial blower arrangement (1) with free blade tips (46) according to claim 6, wherein the angle (ψ) in the meridional plane between a sweep extent of the second part (P2) of the blade tip (46) and the direction of the blower axis (6) with respect to a tip coordinate, which increases with a distance along the sweep extent of the blade tip (46) from the leading edge (LE) of the blade tip (46) to the exit edge (TE) of the blade tip (46), the sweep extent extending from the leading edge (LE) to the exit edge (TE). [17] Axial blower arrangement (1) with free blade tips (46) according to claim 16, wherein a distance between the sweep extent of the second part (P2) of the blade tip (46) and the locally nearest points on the corresponding part of the inlet (242), measured perpendicular to the second part (P2) of the blade tip (46) which lies in the axial extent of the region of the non-monotically varying angle (θ), varies by no more than plus or minus 30 percent along the second part (P2) of the blade tip (46), wherein the sweep extent extends from the leading edge (LE) to the trailing edge (TE). [18] Axial blower arrangement (1) with free blade tips (46) according to claim 16, wherein the distance between the sweep extent of the second part (P2) of the blade tip (46) and the locally nearest points on the corresponding part of the inlet (242), measured perpendicular to the second part (P2) of the blade tip (46) which lies in the axial extent of the region of the non-monotically varying angle (θ), varies by no more than plus or minus 20 percent along the second part (P2) of the blade tip (46), wherein the sweep extent extends from the leading edge (LE) to the trailing edge (TE). [19] Axial blower arrangement (1) with free blade tips (46) according to claim 16, wherein the distance, measured perpendicular to the sweep extent of the blade tip (46), between the second part (P2) of the blade tip (46) and the inlet surface between two of the nearest points on the corresponding part of the inlet (242) is at least 20 percent greater than the average distance between the second part (P2) of the blade tip (46) and the two nearest points on the corresponding part of the inlet (242), wherein the sweep extent extends from the leading edge (LE) to the trailing edge (TE). [20] Axial blower arrangement (1) with free blade tips (46) according to claim 16, wherein the distance, measured perpendicular to the sweep extent of the blade tip (46), between the second part (P2) of the blade tip (46) and the inlet surface between two of the nearest points on the corresponding part of the inlet (242) is at least 40 percent greater than the average distance between the second part (P2) of the blade tip (46) and the two nearest points, wherein the sweep extent extends from the leading edge (LE) to the trailing edge (TE). [21] Axial fan assembly (1) with free blade tips (46) according to claim 16, wherein the minimum distance between the second part (P2) of the blade tip (46) and the nearest points on the corresponding part of the inlet (242), measured perpendicular to the sweep extent of the blade tip (46), is greater than 0.005 times the fan diameter (D) and less than 0.02 times the fan diameter (D), wherein the sweep extent extends from the leading edge (LE) to the trailing edge (TE). [22] Axial blower arrangement (1) with free blade tips (46) according to claim 6, wherein a sweep extent of the second part (P2) of the blade tip (46) corresponds to an envelope in a meridional plane that traverses the points that are locally closest to the blade tip (46) at the corresponding part of the inlet (242), wherein the sweep extent extends from the leading edge (LE) to the trailing edge (TE). [23] Axial blower arrangement (1) with free blade tips (46) according to claim 22, wherein the envelope is smooth. [24] Axial blower arrangement (1) with free blade tips (46) according to claim 22, wherein axial and radial coordinates of the envelope are each given approximately as values ​​of a spline curve, the spline curve being determined in the following manner: 1) Creating a belt coordinate that follows a piecewise linear curve whose vertices are the points that are locally closest to the blade tip (46) on the corresponding part of the inlet (242), 2) Generating cubic splines of the axial and radial coordinates with respect to the belt coordinate, with nodes positioned at the vertices, 3) Evaluate the splines on belt coordinate values ​​that lie between the vertices. [25] Axial blower arrangement (1) with free blade tips (46) according to claim 22, wherein a distance between the sweep extent of the second part (P2) of the blade tip (46) and the envelope, measured perpendicular to the envelope, varies by no more than plus or minus 30 percent over the extent of the second part (P2) of the blade tip (46). [26] Axial blower arrangement (1) with free blade tips (46) according to claim 22, wherein a distance between the sweep extent of the second part (P2) of the blade tip (46) and the envelope, measured perpendicular to the envelope, varies by no more than plus or minus 20 percent over the extent of the second part (P2) of the blade tip (46). [27] Axial blower arrangement (1) with free blade tips (46) according to claim 22, wherein the distance, measured perpendicular to the sweep extent of the blade tip (46), between the second part (P2) of the blade tip (46) and the inlet surface at a point between two of the nearest points on the corresponding part of the inlet (242) is at least 20 percent greater than the local distance between the second part (P2) of the blade tip (46) and the envelope. [28] Axial blower arrangement (1) with free blade tips (46) according to claim 22, wherein a distance, measured perpendicular to the sweep extent of the blade tip (46), between the second part (P2) of the blade tip (46) and the inlet surface at a point between two of the nearest points on the corresponding part of the inlet (242) is at least 40 percent greater than a local distance between the second part (P2) of the blade tip (46) and the envelope. [29] Axial blower arrangement (1) with free blade tips (46) according to claim 22, wherein a minimum distance between the sweep extent of the second part (P2) of the blade tip (46) and the envelope, measured perpendicular to the envelope, is greater than 0.005 times the blower diameter (D) and less than 0.02 times the blower diameter (D). [30] Axial blower arrangement (1) with free blade tips (46) according to claim 22, wherein the envelope in the region where the blade tip (46) corresponds to it passes through at least three points at the inlet (242) which are locally the closest to the blade tip (46). [31] Axial blower arrangement (1) with free blade tips (46) according to claim 6, wherein the area of ​​the inlet (242) is axially symmetric. [32] Axial blower arrangement with free blade tips (46) according to claim 1, wherein the casing (2) is an injection-molded plastic part. [33] Axial blower assembly (1) with free blade tips (46) according to claim 1, wherein the jacket (2) has supports (29) which engage with mounting features of a heat exchanger (5) positioned upstream of the blower assembly, and wherein the jacket (2) has an arrangement of motor supports (28). [34] Axial blower arrangement (1) with free blade tips (46) according to claim 33, wherein the jacket (2) comprises a chamber (20) upstream of the tube (22), and wherein the area of ​​a heat exchanger surface encompassed by the chamber (20) is at least 1.5 times the blower disc area. [35] Axial blower arrangement (1) with free blade tips (46) according to claim 1, wherein the angle (θ) varies non-monotically in several meridional planes positioned over one or more regions of the azimuthal angle, which in total amounts to more than 180 degrees.

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