Patent Application
20210317842
Embodiments of the present invention relate generally to vehicle cooling fans, vehicles utilizing such fans, and associated methods.
Heavy duty trucks spend long periods of time driving at steady states and relatively high vehicle speeds. An example of this is typical interstate driving on a freeway. When such a vehicle is being driven at relatively high speeds, motion of the vehicle is generally enough to cool the internal combustion (e.g., diesel) engine. As the vehicle travels forward, air is forced through one or more heat exchangers, cooling the engine. This air flow from vehicle motion is often referred to as ram air. Under conditions providing sufficient ram air, a fan does not need to be driven for engine cooling purposes. A typical truck or similar vehicle will employ a clutching mechanism that selectively disconnects the fan from the engine drivetrain in order to minimize parasitic power losses, which is typically referred to as the “off” condition. A clutch and associated fan can be placed in the “off” condition when sufficient ram air cooling is available.
However, the fan can still have an influence on engine cooling even in the “off” condition due to added restriction of flow from the fan. Fan solidity can be defined by the ratio of closed area of the fan's blades to the total annular area between circles defined by an outer diameter of the fan and a hub diameter. In other words, as used herein with respect to substantially axial flow fans, “solidity” is an areal measure of how much of the annular flow area measured perpendicular to an axis of rotation is occupied by fan blades and how much is open—this calculation of solidity differs from one based on chord divided by circumferential blade spacing. A high solidity fan has relatively little opening between the fan blades, if any, and a low solidity fan has relatively large openings. The greater the solidity of the fan, the more likely it is to restrict ram air flow when placed in the air stream in the un-driven state or “off” condition. Higher restriction reduces flow and the ability of the ram air flow to cool the engine, which can increase the need for the fan to be turned on occasionally to cool the engine when the fan might otherwise be off.
Running the fan can require a substantial amount of power, especially at higher fan speeds. Operation of the fan (i.e., an “on” condition) is required to cool the engine under worst case scenarios, which can include conditions where ambient temperature is high, engine load is high, and/or vehicle speed (and therefore ram air speed) is low. An example would be a fully loaded truck ascending a hill in a hot desert. Under conditions where ram air is unavailable or insufficient, the fan must develop enough pressure to draw the required cooling air flow through the vehicle's heat exchanger.
Fan solidity and the ability of the fan to build fluid pressure are related. In the same way a higher solidity fan creates more ram air resistance, in general, it also has the ability to provide more pressure, and thus more cooling flow. In this sense, while optimization of fan characteristics in isolation may suggest relatively high solidity fan designs, in order to build pressure more efficiently, such isolated fan design considerations fail to take into account the unique operating characteristics in which vehicle fans operate, because ram air cooling can avoid the need for fan operation under some circumstances. In this regard, fan design considerations used for cooling tower, air conditioner, and similar applications do not account for the unique range of conditions faced by vehicular engine cooling fans.
The current state of the art low solidity vehicular fan is typically a 6-bladed fan. For example, the BorgWarner PS6 fan (available from BorgWarner Inc., Auburn Hills, Mich., USA) shown in
It is desired to provide a fan with an alternative configuration.
In one aspect, an axial flow fan for use with a vehicle cooling system includes a hub defining an axis of rotation, and a plurality of blades supported on the hub, the plurality of blades including at least five blades. Each blade includes a leading edge, a trailing edge opposite the leading edge, a pressure side extending between the leading edge and the trailing edge, a suction side opposite the pressure side, a tip, and a root opposite the tip along a blade length. A solidity of the axial flow fan, measured as a percentage of an annular flow area between an outer diameter of the hub and an outer diameter of the tips of the plurality of blades projected onto a plane perpendicular to the axis of rotation that is occupied by the plurality of blades, is less than 40%, less than 33%, or less than 25%. In some further aspects, a maximum total turning angle along the blade length of each of the plurality of blades is greater than 50°, greater than or equal to 80°, greater than or equal to approximately 89°, or approaches 90°. In some still further aspects, the total turning angle can vary along the blade length of each of the plurality of blades, and a minimum total turning angle along the blade length of each of the plurality of blades can be greater than or equal to 30°, or greater than or equal to 35°.
In another aspect, a vehicle includes an internal combustion engine, a heat exchanger for cooling the internal combustion engine, an axial flow fan with a solidity less than 40% (or less than 33% or less than 25%), and a clutch configured to selectively rotate the axial flow fan. The heat exchanger is exposed or is at least exposable to ram air when the vehicle is moving in at least one direction. The axial flow fan is positioned proximate to the heat exchanger, and rotation of the axial flow fan moves cooling air relative to the heat exchanger.
In yet another aspect, an axial flow fan includes a hub defining an axis of rotation, and exactly five blades integrally and monolithically formed with at least a portion of the hub. Each of the five blades is free-tipped and includes a leading edge, a trailing edge opposite the leading edge, a pressure side extending between the leading edge and the trailing edge, a suction side opposite the pressure side, a tip, a root opposite the tip along a blade length, and a hub ramp on the pressure side. A solidity of the axial flow fan, measured as a percentage of an annular flow area between an outer diameter of the hub and an outer diameter of the tips of the five blades projected onto a plane perpendicular to the axis of rotation that is occupied by the five blades, is less than 25% (or is approximately 22.7%). A maximum total turning angle along the blade length of each of the five blades is greater than or equal to 80° (or approaches 90°, or is approximately 89.2°).
The present summary is provided only by way of example, and not limitation. Other aspects of the present invention will be appreciated in view of the entirety of the present disclosure, including the entire text, claims and accompanying figures.
While the above-identified figures set forth one or more embodiments of the present invention, other embodiments are also contemplated, as noted in the discussion. In all cases, this disclosure presents the invention by way of representation and not limitation. It should be understood that numerous other modifications and embodiments can be devised by those skilled in the art, which fall within the scope and spirit of the principles of the invention. The figures may not be drawn to scale, and applications and embodiments of the present invention may include features, steps and/or components not specifically shown in the drawings.
In vehicular cooling applications, it has been discovered that the expected effects of ram air flows can alter design considerations for engine cooling fans. There is a substantial desire to minimize the ram air flow resistance caused by the fan in order to allow free air flow (i.e., ram air) to cool the engine for a greater amount of time, saving power and fuel that would be require to power the fan in an “on” condition. However, because ram air will be unavailable or insufficient under some vehicular operating conditions, fan operation will still be required, and it is therefore desired to provide a relatively low solidity fan that still provides sufficient static pressure. For instance, a static pressure that is the same or greater than that of a higher solidity fan at most operating conditions, especially at higher speed and airflow conditions, is beneficial in some applications and embodiments. Embodiments of the present invention further accomplish those flow resistance and static pressure benefits without adding depth to the blades of the fan. The blade depth is the width or thickness of the fan when measured parallel to an axis of rotation, that is, the blade depth is the axial chord or pitch width. Thus, the present disclosure provides a relatively low solidity fan, such as a five-blade fan, with a solidity less than 40% (e.g., less than approximately 33%, or less than approximately 25%). Moreover, the fan of the present invention provides a unique blade shape with the ability to develop relatively high pressures in conjunction with only a small number of blades (e.g., five blades, or less than five blades) and a relatively low solidity (e.g., less than 40%, less than 33%, or less than 25%). A fan according to the present invention can be an axial flow fan, which generates a fluid flow in generally the axial direction. The fan can include free-tipped (e.g., unshrouded) blades, though in alternate embodiments one or more blades can be connected to a shroud ring or partial shroud segment. Numerous features and benefits of the present invention will be recognized by those of ordinary skill in the art in view of the entirety of the present disclosure, including the accompanying figures.
The present application is based on and claims the benefit of U.S. provisional patent application Ser. No. 62/713,668, filed Aug. 2, 2018, the content of which is hereby incorporated by reference in its entirety.
In one embodiment, shown in
An annular flow area of the fan 20 is established between a circle at an outer diameter (OD) of the fan 20 at the blade tips 24-5 and a circle an OD of the hub 22 projected onto a plane perpendicular to the axis of rotation A. Solidity of the fan 20 is measured based on the percentage of the annular flow area (as projected onto a plane perpendicular to the axis of rotation A) occupied by the blades 24, which indicates how much of the annular flow area perpendicular to an axis of rotation A is occupied by all of the blades 24 and how much is open (that is, having lines of sight parallel to the axis of rotation A being unobstructed by the blades 24). In the illustrated embodiment, the hub ramps 24-7 do not extend beyond the areas of the blades 24 as projected onto the plane perpendicular to the axis of rotation A, and therefore have no effect on the solidity measurement. But in alternate embodiments, hub ramps 24-7, flow modification features, or other structures that reside in the annular flow area of the fan 20 and that limit how much of that annular flow area is open are counted toward the solidity measurement.
In one embodiment, the OD of the five-blade fan 20 at the blade tips 24-5 can be 813 mm and the OD of the hub 22 can be 350 mm, though larger or smaller values of the outer or hub diameters can be larger or smaller in further embodiments, such as by scaling the indicated dimensions to larger or smaller values. A total area of an 813 mm OD circle in this embodiment is 519,124 mm2 and an area of a 350 mm hub circle is 96,211 mm2. An area of an annulus between the hub 22 and the fan OD at the tips 24-5 in this embodiment is 519,124-96,211=422,913 mm2 The projected area of the five blades 24 is 96,211 mm2, in the illustrated embodiment. Thus, the solidity within the annulus of the illustrated embodiment is 96,211/422,913=0.227 or 22.7%.
In the illustrated embodiment (see, e.g.,
Furthermore, in some embodiments (see, e.g.,
In some embodiments (see, e.g.,
In some embodiments (see, e.g.,
In some embodiments (see. e.g.,
Additionally, some embodiments of the fan 20 can have blades 24 with relatively high stagger angles, measured as the angle between a ling parallel to the axis of rotation and a projected line that intersects the LE 24-3 and the TE 24-4 (see, e.g.,
The present five-blade fan is capable of delivering more flow and pressure at most operating conditions, while having approximately half the solidity of typical six-blade vehicular engine cooling fans. For instance, the plot in the graph of
Numerous other features and benefits of the present invention will be recognized by those of ordinary skill in the art in view of the entirety of the present disclosure, including the accompanying figures.
Discussion of Possible Embodiments
An axial flow fan for use with a vehicle cooling system can include a hub defining an axis of rotation, and a plurality of blades supported on the hub, the plurality of blades including at least five blades. Each blade can include a leading edge, a trailing edge opposite the leading edge, a pressure side extending between the leading edge and the trailing edge, a suction side opposite the pressure side, a tip, and a root opposite the tip along a blade length. A solidity of the axial flow fan, measured as a percentage of an annular flow area between an outer diameter of the hub and an outer diameter of the tips of the plurality of blades projected onto a plane perpendicular to the axis of rotation that is occupied by the plurality of blades, can be less than 40%.
The axial flow fan of the preceding paragraph can optionally include, additionally and/or alternatively, any one or more of the following features, configurations and/or additional components:
the solidity can be less than 33%, less than 25%, or approximately 22.7%;
the plurality of blades can consist of five blades;
each of the plurality of blades can further include a hub ramp on the pressure side;
a maximum total turning angle along the blade length of each of the plurality of blades can be greater than 50°, greater than or equal to 80°, greater than or equal to approximately 89°, or approach 90°;
a total turning angle can vary along the blade length of each of the plurality of blades;
a minimum total turning angle along the blade length of each of the plurality of blades can be greater than or equal to 30° or greater than or equal to 35°;
a total turning angle along the blade length of each of the plurality of blades can decrease from 0% to approximately 20% of the blade length, then increase to approximately 90% of the blade length, then decrease to 100% of the blade length;
each of the plurality of blades can have rearward then forward tangential sweep from 0% to 100% of the blade length along both the leading edge and the trailing edge;
each of the plurality of blades can have a radially inner section having dihedral curvature that is concave at the pressure side and a radially outward straight section having essentially no dihedral curvature at the trailing edge;
each of the plurality of blades can have a dimple along the suction side at a mid-chord location, where chord is measured between the leading edge and the trailing edge;
each of the plurality of blades has a bulge formed by a local thickness increase at a mid-chord location that decreases from 0% to a location at 40% to 50% of the blade length, where chord is measured between the leading edge and the trailing edge;
the local thickness increase at the mid-chord location that forms the bulge can be at least twice a thickness of either or both of the leading edge and the trailing edge at 0% of the blade length; and/or
the local thickness increase at the mid-chord location can decrease according to a hyperbolic curve.
A vehicle can include an internal combustion engine, a heat exchanger for cooling the internal combustion engine, an axial flow fan, and a clutch for selectively rotating the axial flow fan. The heat exchanger can be exposed or be at least exposable to ram air when the vehicle is moving in at least one direction. The axial flow fan can be positioned proximate to the heat exchanger. Rotation of the axial flow fan can move cooling air relative to the heat exchanger. The axial flow fan can be configured as described in any of the preceding paragraphs of these possible embodiments.
An axial flow fan includes a hub defining an axis of rotation, and exactly five blades integrally and monolithically formed with at least a portion of the hub. Each of the five blades can be free-tipped and can include a leading edge, a trailing edge opposite the leading edge, a pressure side extending between the leading edge and the trailing edge, a suction side opposite the pressure side, a tip, a root opposite the tip along a blade length, and a hub ramp on the pressure side. A solidity of the axial flow fan, measured as a percentage of an annular flow area between an outer diameter of the hub and an outer diameter of the tips of the five blades projected onto a plane perpendicular to the axis of rotation that is occupied by the five blades, can be less than 25%. A maximum total turning angle along the blade length of each of the five blades can be greater than or equal to 80°.
The axial flow fan of the preceding paragraph can optionally include, additionally and/or alternatively, any one or more of the following features, configurations and/or additional components:
the solidity can be approximately 22.7%;
the maximum total turning angle can be approximately 89.2°; and/or
each of the five blades can have a pocket shape defined by a radially inner section having dihedral curvature that is concave at the pressure side and a radially outward section that is essentially straight in the dihedral direction at the trailing edge and at the leading edge.
Summation
Any relative terms or terms of degree used herein, such as “substantially”, “essentially”, “generally”, “approximately” and the like, should be interpreted in accordance with and subject to any applicable definitions or limits expressly stated herein. In all instances, any relative terms or terms of degree used herein should be interpreted to broadly encompass any relevant disclosed embodiments as well as such ranges or variations as would be understood by a person of ordinary skill in the art in view of the entirety of the present disclosure, such as to encompass ordinary manufacturing tolerance variations, incidental alignment variations, transient alignment or shape variations induced by thermal, rotational or vibrational operational conditions, and the like. Moreover, any relative terms or terms of degree used herein should be interpreted to encompass a range that expressly includes the designated quality, characteristic, parameter or value, without variation, as if no qualifying relative term or term of degree were utilized in the given disclosure or recitation.
Although the present invention has been described with reference to preferred embodiments, workers skilled in the art will recognize that changes may be made in form and detail without departing from the spirit and scope of the invention. For instance, stated dimensions can be scaled to provide a fan of nearly any desired size. Moreover, features described with respect to any embodiment can be combined with features of any other disclosed embodiment, though it is not necessary that every disclosed feature appear together in a single embodiment. Additionally, embodiments of a fan can include free-tipped blades, as shown in the accompanying figures, or can optionally include a shroud, such as in a ring fan configuration.
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/US2019/041545 | 7/12/2019 | WO | 00 |
| Number | Date | Country | |
|---|---|---|---|
| 62713668 | Aug 2018 | US |
