U.S. patent application number 11/389849 was filed with the patent office on 2007-09-27 for vehicle cooling fan.
This patent application is currently assigned to VALEO, INC.. Invention is credited to Tao Hong, John R. Savage.
Application Number | 20070221147 11/389849 |
Document ID | / |
Family ID | 38532012 |
Filed Date | 2007-09-27 |
United States Patent
Application |
20070221147 |
Kind Code |
A1 |
Hong; Tao ; et al. |
September 27, 2007 |
Vehicle cooling fan
Abstract
A cooling fan for a vehicle. Many engine compartments of motor
vehicles are small in size, and contain numerous components.
Electric cooling fans are used to draw air through a radiator.
Given the cramped conditions within the engine compartment, the
exhaust of the fan cannot be directed into open air, but must
impinge on one or more of the components within the compartment.
This situation reduces velocity in the exhaust, and also reduces
efficiency of the fan. The invention provides a collection of
generally co-axial stators which divert the exhaust around the
components, while retaining much of the velocity of the
exhaust.
Inventors: |
Hong; Tao; (Farmington
Hills, MI) ; Savage; John R.; (Rochester Hills,
MI) |
Correspondence
Address: |
MATTHEW R. JENKINS, ESQ.
2310 FAR HILLS BUILDING
DAYTON
OH
45419
US
|
Assignee: |
VALEO, INC.
AUBURN HILLS
MI
|
Family ID: |
38532012 |
Appl. No.: |
11/389849 |
Filed: |
March 27, 2006 |
Current U.S.
Class: |
123/41.49 ;
123/41.7; 416/179 |
Current CPC
Class: |
F01P 5/06 20130101; F04D
29/541 20130101; F04D 29/582 20130101 |
Class at
Publication: |
123/041.49 ;
123/041.7; 416/179 |
International
Class: |
F01P 7/10 20060101
F01P007/10; F01P 1/02 20060101 F01P001/02; B63H 1/16 20060101
B63H001/16 |
Claims
1. An apparatus comprising: a) a fan which produces an exit flow
toward an obstacle in the exit flow; and b) vanes upstream of said
obstacle which divert a portion of the exit flow into a radial
direction.
2. The apparatus according to claim 1, wherein said fan, obstacle,
and vanes are located in the engine compartment of a vehicle.
3. The apparatus according to claim 2, wherein said fan draws
cooling air through a heat exchanger which cools engine coolant
and/or a condenser that cools refrigerant for the vehicle air
conditioning system.
4. The apparatus according to claim 1, wherein said fan is
generally an axial flow type.
5. The apparatus according to claim 1, wherein said vanes mitigate
reduction in fan efficiency caused by the obstacle.
6. The apparatus according to claim 4, wherein at least three vanes
are present, and radial spacing between one pair of neighboring
vanes is different from radial spacing between a second pair of
neighboring vanes.
7. The apparatus according to claim 1, wherein a plurality of said
vanes have different chord lengths.
8. The apparatus according to claim 1, wherein said fan is of the
axial flow type and i) vanes which are relatively near the axis are
relatively far from said fan, and ii) vanes which are relatively
far from the axis are relatively near to said fan.
9. The apparatus according to claim 1, wherein said vanes are
generally ring-shaped, and larger diameter vanes are closer to said
fan than smaller diameter vanes.
10. The apparatus according to claim 1, wherein at least one of
said vanes has an inlet angle IA-1 and another of said vanes has an
inlet angle IA-2, different from IA-1.
11. The apparatus according to claim 1, wherein at least one of
said vanes has an inlet angle IA-1 and another of said vanes has an
inlet angle IA-2, is equal to IA-1.
12. The apparatus according to claim 1, wherein at least one vane
has an exit angle EA-1 and another of said vanes has an exit angle
EA-2, different from EA-1.
13. The apparatus according to claim 10, wherein all inlet angles
of said vanes at similar angular positions are similar.
14. The apparatus according to claim 12, wherein all exit angles of
vanes having similar angular positions are similar.
15. The apparatus according to claim 1, wherein the fan is
generally an axial-flow type and at least some vanes span an arc of
less than 360 degrees.
16. The apparatus according to claim 14, wherein vanes at different
radii span different arcs.
17. The apparatus according to claim 1, wherein radial struts
support the vanes, and the radial struts do not significantly
re-direct tangential exhaust from the fan into axial flow.
18. The apparatus according to claim 1, wherein radial struts
support the vanes, and re-direction of tangential exhaust from the
fan into axial flow by the radial struts is minimal.
19. An apparatus, comprising: a) a vehicle; b) within the vehicle,
a cooling fan which generates a generally cylindrical airflow
toward an obstruction downstream of said fan; and c) one or more
stators between said fan and said obstruction, which turn generally
axially flowing air into generally radially flowing air.
20. The apparatus according to claim 19, wherein said fan,
obstruction, and stators are located in the engine compartment of a
vehicle.
21. The apparatus according to claim 19, wherein said fan draws
cooling air through a heat exchanger which cools engine coolant
and/or a condenser that cools refrigerant for the vehicle air
conditioning system.
22. The apparatus according to claim 19, wherein said fan is an
axial flow fan.
23. The apparatus according to claim 19, wherein the said vanes
mitigate reduction in fan efficiency caused by the obstacle.
24. The apparatus according to claim 23, wherein at least three
stators are present, and radial spacing between one pair of
neighboring vanes is different from radial spacing between a second
pair of neighboring vanes.
25. The apparatus according to claim 19, wherein different ones of
said stators have different chord lengths.
26. The apparatus according to claim 19, wherein said fan has a
central axis defined therein and i) stators which are relatively
near the axis are relatively far from the fan, and ii) stators
which are relatively far from the axis are relatively near to the
fan,
27. The apparatus according to claim 19, wherein said stators are
generally ring-shaped, and larger diameter stators are closer to
the fan than smaller diameter vanes.
28. The apparatus according to claim 19, wherein one of said
stators has an inlet angle IA-1 and another stator has an inlet
angle IA-2, different from IA-1.
29. The apparatus according to claim 19, wherein one stator has an
exit angle EA-1 and another stator has an exit angle EA-2,
different from EA-1.
30. The apparatus according to claim 28, wherein all inlet angles
of stators at similar angular positions are similar.
31. The apparatus according to claim 29, wherein all exit angles of
stators having similar angular positions are similar.
32. The apparatus according to claim 19, wherein said fan is
generally an axial-flow type and at least some stators span an arc
of less than 360 degrees.
33. The apparatus according to claim 32, wherein stators at
different radii span different arcs.
34. The apparatus according to claim 19, wherein radial struts
support the stators, and the radial struts do not significantly
re-direct tangential exhaust from the fan into axial flow.
35. The apparatus according to claim 19, wherein radial struts
support the stators, and re-direction of tangential exhaust from
said fan into axial flow by the radial struts is minimal.
36. An apparatus, comprising: a) a generally axial-flow fan which
produces exhaust having polar coordinates (r, theta, z) defineable
therein; b) vanes present in the exhaust, which increase radial
component of the exhaust; and wherein vanes at different
coordinates (r, theta, z) have different geometries.
37. The apparatus according to claim 36 and further comprising a
vehicle having an engine compartment, wherein the fan and the vanes
are located in the engine compartment.
38. The apparatus according to claim 36, wherein an obstacle is
present in the exhaust, and the vanes divert exhaust around the
obstacle.
39. The apparatus according to claim 36, wherein inlet angles of
vanes at a common angle theta are similar.
40. The apparatus according to claim 36, wherein exit angles of
vanes at a common angle theta are similar.
41. The apparatus according to claim 36, wherein, at a given
z-coordinate, vane geometry is non-uniform for all theta.
42. The apparatus according to claim 36, wherein vanes at different
r-coordinates span different angles theta.
43. The apparatus according to claim 19, wherein adjacent vane
pairs define a channel therebetween, and different channels have
different widths.
44. The apparatus according to claim 36, wherein a first vane of a
first radius spans an arc A1, and a second vane of a second radius
spans an arc A2, different from A1.
45. An apparatus, comprising: a) a generally axial-flow fan which
produces an exhaust, b) means present in the exhaust for reducing a
change in angle-of-attack of blades in the fan, which change is
caused by an obstacle in the exhaust.
46. The apparatus according to claim 45, and further comprising a
motor vehicle which carries said fan and the means in an engine
compartment.
47. An apparatus, comprising: a) a cooling system; b) a generally
axial-flow cooling fan for use in a vehicle having an obstruction
in said vehicle downstream of the cooling fan which, if exhaust of
the fan is allowed to reach the obstruction unimpeded, diverts the
exhaust into radial directions with an average speed V1, and c) a
set of stators between the fan and the obstruction, which divert
the exhaust into radial directions with an average speed V2, higher
than V1.
48. A method for improving cooling of an engine in a vehicle, said
method comprising the steps of: situating a set of stators or vanes
in an airflow path between a fan and an obstruction to divert
exhaust in a generally radial direction at a speed that exceeds the
speed at which airflow is diverted by said obstruction.
Description
BACKGROUND OF THE INVENTION
[0001] In modern motor vehicles, the engine compartment is becoming
increasingly crowded, primarily because of (1) the placement of
additional components into the engine compartment, (2) the
reduction in volume of the engine compartment, primarily to reduce
overall aerodynamic drag of the vehicle, and many other
factors.
[0002] The crowded nature of the compartment can cause problems in
the operation of a cooling fan, such as that illustrated in FIG. 1.
Fan 3 draws air 4 through a heat exchanger 6, commonly termed a
radiator, thereby cooling the liquid coolant within the radiator 6.
However, if, as on the right side of FIG. 1, an obstruction 9 is
positioned within the exhaust of the fan 3A, the obstruction 9 can
reduce flow through the radiator, thereby reducing cooling.
[0003] The invention presents a stratagem for reducing the negative
effects of the obstruction 9.
SUMMARY OF THE INVENTION
[0004] An object of the invention is to provide an improved cooling
fan for a vehicle.
[0005] A further object of the invention is to provide a cooling
fan for a vehicle which operates efficiently in a confined
environment.
[0006] In one form of the invention, stators are positioned in the
exhaust stream of a cooling fan in a motor vehicle. The stators
divert air into the radial direction, while increasing total
airflow over the situation wherein the exhaust stream impinges on
an obstacle it its path.
[0007] In one aspect, one embodiment comprises an apparatus,
comprising: a fan which produces an exit flow; and vanes upstream
of the obstacle which divert a portion of the exit flow into a
radial direction.
[0008] In another aspect, one embodiment comprises an apparatus;
comprising: a vehicle; within the vehicle, a cooling fan which
generates a generally cylindrical airflow toward an obstruction
downstream of said fan; and one or more stators between said fan
and said obstruction, which turn generally axially flowing air into
generally radially flowing air.
[0009] In still another aspect, one embodiment comprises an
apparatus comprising: a generally axial-flow fan which produces
exhaust having polar coordinates (r, z, theta) definable therein;
vanes present in the exhaust, which increase radial component of
the exhaust; and wherein vanes at different coordinates (r, theta,
z) have different geometries.
[0010] In yet another aspect, one embodiment comprises an
apparatus; comprising: a generally axial-flow fan which produces an
exhaust, and means present in the exhaust for reducing a change in
angle-of-attack of blades in the fan, which change is caused by an
obstacle in the exhaust.
[0011] In another aspect, one embodiment comprises an apparatus;
comprising: a cooling system; a generally axial-flow cooling fan
for use in a vehicle having an obstruction in said vehicle
downstream of the cooling fan which, if exhaust of the fan is
allowed to reach the obstruction unimpeded, diverts the exhaust
into radial directions with an average speed V1, and a set of
stators between the fan and the obstruction, which divert the
exhaust into radial directions with an average speed V2, higher
than V1.
[0012] In yet another aspect, one embodiment comprises a method for
improving cooling of an engine in a vehicle, said method comprises
the steps of: situating a set of stators or vanes in an airflow
path between a fan and an obstruction to diver exhaust into a
generally reclined direction at a speed that exceeds the speed at
which airflow is diverted by said obstruction.
[0013] These and other objects and advantages of the invention will
be apparent from the following description, the accompanying
drawings and the appended claims.
BRIEF DESCRIPTION OF THE DRAWINGS
[0014] FIG. 1 illustrates a prior-art fan used to cool a component
in a vehicle;
[0015] FIG. 2 illustrates the general location of the invention
within the vehicle environment;
[0016] FIG. 3 illustrates a fan used in FIG. 2;
[0017] FIGS. 4 and 5 illustrate one form of the invention;
[0018] FIG. 6 is a cross-sectional view of part of FIG. 4 or 5;
[0019] FIG. 7 is a three-dimensional view of turning of air, which
occurs in FIG. 6;
[0020] FIG. 8 illustrates one of the stators of FIGS. 4 and 5, in
perspective view;
[0021] FIGS. 9-12 are plots of velocities and pressure contours
that illustrate effectiveness of the stator vanes of FIGS. 4 and
5;
[0022] FIGS. 13-15 illustrate flow vs pressure, flow vs input
torque, and efficiency of the invention;
[0023] FIG. 16 is a schematic of a blade B of a fan 200;
[0024] FIG. 17 is a vector diagram illustrating two airstreams 210
and 220 seen by blade B of FIG. 16;
[0025] FIG. 18 illustrates the vector sum 225 of the vectors in
FIG. 17;
[0026] FIG. 19 illustrates how the vector sum 225 changes if the
vector 220 changes;
[0027] FIG. 20 illustrates a velocity profile of air which
encounters a blockage, in the absence of turning vanes;
[0028] FIG. 21 illustrates a velocity profile of air which
encounters a blockage, with turning vanes V present;
[0029] FIG. 22 illustrates a standard cylindrical coordinate
system;
[0030] FIGS. 23, 24, and 26 illustrate different forms of the
invention;
[0031] FIG. 25 illustrates two locations P3 and P6, at the 3
o'clock and 6 o'clock positions, respectively;
[0032] FIG. 27 illustrates two sectors S1 and S2 in a fan; and
[0033] FIG. 28 illustrates vanes occupying part of sector S1.
DETAILED DESCRIPTION OF THE INVENTION
[0034] FIG. 2 illustrates a generalized motor vehicle 15, which
contains an element 18, such as a gasoline engine, which requires
cooling. Block 21 represents a cooling system, which is shown in
greater detail in FIG. 3.
[0035] In FIG. 3, a fan 24, which is preferably, but not limited,
to being driven by an electric motor (not shown), and preferably
runs at a relatively constant speed, draws airstreams 22 through a
radiator 30. An obstruction 33 can be present in the exhaust of the
fan 24. The invention utilizes stators 35 to divert air around the
obstruction 33.
[0036] FIGS. 4 and 5 illustrate one type of fan 24 that can be
used. Stators 36 are present in the exhaust of the fan 24 and
function to turn the axial component and increase the radial
component of the fan exhaust, as indicated in FIG. 6. It is
emphasized that FIG. 6 is a fragmentary cross-sectional view; FIG.
7 illustrates the turning accomplished by the stators 36 in
perspective view.
[0037] FIG. 8 illustrates a perspective view showing a cutaway
drawn in wire frame illustration which is contained to show a cut
away of one of the stators 36, but in exaggerated scale: the solid
metal/plastic cross section is enlarged with respect to the
diameter, to more clearly show the shape of the cross section.
[0038] As FIG. 6 indicates, the stators 36 can take the form of
circular arcs, spanning 90 degrees, for example.
[0039] FIGS. 9-15 set forth test results and simulation results
which illustrate selected properties of an embodiment of the
invention. FIGS. 9-12 are tracings of digital computer maps
produced by simulation software, and are thus approximate
illustrations.
[0040] FIGS. 9 and 10 illustrate a cross section of the annular
operating region of the fan blade 45, showing the exit plane of the
fan blades themselves and an obstruction 48 which is downstream of
the annular fan blade region. Wall section 51 of the obstruction 48
can be viewed as cooperating with wall section 54, to thereby form
a radial exit flow path for the fan exhaust flow.
[0041] FIG. 9 illustrates profiles of total pressure within the
system in relative units. Total pressure includes a static
component and a dynamic component. A scale of relative pressures is
shown as the column of numbers, with 79.00 at the top.
[0042] To aid in showing overall patterns, the arrows leading from
the scale of relative pressures are labeled with round numbers,
such as 1, 15, 35, and so on. These round numbers represent
convenient approximate values. For example, the arrow labeled 60
originates at a point between 52.14 and 65.57 on the scale. The
number 60 is a convenient intermediate value between those two
numbers.
[0043] Two significant features of FIG. 9 are that (1) the highest
pressure region (labeled 70) abuts the obstruction, and (2) the
pressures diminish in the radial direction, as the sequence 60, 50,
35, and 15 indicates.
[0044] FIG. 10 is a plot similar to FIG. 9, but with the stator
vanes V present. The highest pressure regions (labeled 70) lie on
the concave sides of the vanes V.
[0045] Significantly, in FIG. 10, the region of next-highest
pressure, that labeled 55, extends significantly farther outward in
the radial direction than the corresponding region in FIG. 9, and
the third pressure region, that labeled 40, extends virtually to
the outer boundary 100.
[0046] Stated more precisely, FIG. 9 indicates that at the radially
outermost point from the flow regime, pressure has dropped from
about 70 to about 15 in positive units, or to about 20 percent of
the maximal value of 70. In contrast, FIG. 10 indicates that the
analogous pressure drop is to only about 40 units, which is about
60 percent of the maximal value.
[0047] Thus, under the invention, high total pressure is sustained
for a longer radial distance from the fan tip diameter, compared
with the case of FIG. 9.
[0048] FIGS. 11 and 12 are similar to FIGS. 9 and 10, but
illustrate velocity maps. In FIG. 11, the highest velocity is just
above 11.07 units, and drops to just above 5.34 units at the
radially farthest point from the fan tip diameter region N.
[0049] In FIG. 12, in which the stator vanes V are present, the
highest velocity is higher, at above 12.12 units, compared with
FIG. 11. Further, the triangular region in FIG. 12 labeled with a
value of about 11.02, and extending to the radially outermost flow
region 105, has a value about equal to the highest velocity in FIG.
11.
[0050] That is, the highest velocity in FIG. 11 has a certain
value, but which drops to about half that value at the radially
outermost flow region 105. In contrast, the vanes in FIG. 12
produce a higher velocity, at roughly the same location, and at
least 80 percent of that velocity (about 11.02/12.12) is sustained
at the region 105.
[0051] The invention of FIG. 12 delivers a higher velocity air
stream, such as that indicated as about 11.02 relative units in
FIG. 12, for a longer radial distance than does the apparatus of
FIG. 11, as a comparison of the region labeled 9.97 in FIG. 11 with
that labeled 11.02 in FIG. 12 indicates.
[0052] FIGS. 13-15 provide additional test results. Three cases
were considered in each plot, namely (1) a physical situation
similar to that of FIGS. 9-12, but with no stators present, and no
obstruction present (that is, with both stators and downstream
blockage absent), (2) a similar physical situation, but with no
stators present, but with the obstruction present (that is, with
the ring stator absent), and (3) a similar physical situation, but
with stators present and the obstruction present (that is, with the
ring stators present).
[0053] FIG. 13 is a plot of non-dimensional pressure rise
coefficient against non dimensional flow coefficient. The pressure
coefficient is the ratio of fan static pressure rise divided by
both fan RPM and Tip diameter squared. The Flow coefficient is the
ratio of the airflow divided by both the speed and fan tip
diameter. These coefficients convenient non-dimensional groupings
that relate directly to measured static pressure rise and airflow
performance.
[0054] These convenient non-dimensional groupings allow plots of
different experimental setups to be compared directly. For example,
if a different fan speed were used or a fan of a different
diameter, the plots of those two situations could be compared
directly with that of FIG. 13.
[0055] FIG. 13 shows that in all cases for a flow rate exceeding
about 0.16, the invention provides a higher pressure rise. This
pressure rise is a figure-of-merit for the type of fan in question,
and the increase in pressure rise indicates better performance,
particularly in view of the reduction in torque required to obtain
that increase in pressure rise comparing the without vs with ring
stator condition for operation above 0.225 flow coefficient.
[0056] The pressure rise drops as flow increases because, as flow
increases, the dynamic component of the total pressure becomes
larger. Because the Fig. reports static pressure, static pressure
drops as flow increases.
[0057] FIG. 14 is a plot of torque drawn by or applied to the fan
24 by the motor driving the fan 24. Plot 120 indicates that, with
no stators nor obstruction present, the torque behavior drops as
flow increases.
[0058] Plot 125 indicates that, with the obstruction present, but
no stators present, torque remains somewhat constant, with a slight
rise at about 0.22 units of flow coefficient.
[0059] Plot 130 indicates that, with the obstruction present and
the stators installed, torque drawn form the motor is about the
same as for plot 125, up to about 0.21 units of flow coefficient.
Then, torque behavior drops.
[0060] FIG. 15 is a plot of efficiency against flow coefficient.
FIG. 15 can be derived from FIGS. 13 and 14. From a broad view,
FIG. 13 indicates the power produced by the fan. FIG. 14 indicates
the power required by the fan. Thus, a comparison of power produced
with power required provides a measure of efficiency.
[0061] More precisely, efficiency is computed as (P*F)/T [0062]
wherein [0063] P is the pressure coefficient in FIG. 13, [0064] F
is the flow coefficient in FIGS. 13, 14, and 15, and [0065] T is
the torque coefficient in FIG. 14.
[0066] For example, for a flow coefficient F of 0.2, the pressure
coefficient P in FIG. 13 is about 0.075, for the case without both
obstruction and stators. The torque coefficient T in FIG. 14 is
about 0.029. (P*F)/T equals about (0.075* 0.2)/(0.029). Since the
quotient 0.075/0.029 is just under 3.0, the answer is under 0.6,
consistent with FIG. 15.
[0067] FIG. 15 indicates that efficiency of the configuration with
both blockage and ring stators increases for all flow coefficients
exceeding 0.16. Further, the amount of the increase is obtained
from plots 150 and 155. The increase at point P1 is from about 0.1
to 0.3, or by about 300 percent. The increase at point P2 is from
about 0.25 to 0.4, or by about 160 percent. The increase at point
P3 is from about 0.42 to about 0.52, or about 125 percent.
[0068] A significant comparison can be made between curves 155 and
150. The condition without both stators and blockage is a curve of
interest, but does not relate to an installed vehicle condition.
Curve 150 shows higher efficiency than curve 155 for flow
coefficient levels above 0.16. Typical on vehicle operating range
for cooling fans of this type ranges from 0.16 at an idle condition
to above 0.30 at higher vehicle speed operation. The combination of
stators with the downstream blockage provides benefit throughout
the entire on vehicle operating range
[0069] In one mode of operation, it is contemplated that the fan 24
operate above a flow coefficient of 0.25 at least 90 percent of the
time.
Additional Considerations
[0070] 1. The invention improves efficiency of the cooling system.
FIG. 16 illustrates a generalized fan 200 which produces an exhaust
stream 201. A single blade B is shown, which rotates in direction
205.
[0071] FIG. 17 is a cross section of blade B. Arrow 210 represents
the incoming air velocity seen by the blade B, due to rotation
alone. The action of the fan 200 itself induces an axial component
of inlet flow velocity represented by arrow 220. The magnitude of
arrow 220 with respect to arrow 210 will increase with increasing
vehicle speed which by the action of higher levels of ram flow
admitted by the fan 200.
[0072] The net incoming air seen by the blade B is the vector sum
of the two components 210 and 220, indicated in FIG. 18. In
general, for (1) a given rotational speed, which determines vector
210, and (2) a given vehicle speed, which determines vector 220,
one (or more) specific blade shapes provide optimal efficiency of
the fan 200.
[0073] However, the presence of the obstacle disrupts this optimal
efficiency. While the particular mechanism of the disruption is
complex, a simplified view is that the obstacle reduces the
velocity of the air flowing through the fan 200. The disruption can
be viewed as reducing the size of vector 220, as indicated in FIG.
19. The vector sum 225 is now different. The changes to the vector
sum 225 can vary greatly depending on the location along the blade
hub to tip span and the location and nature of the downstream
obstacle.
[0074] In general, the fan 200 was not designed for this different
vector 225, and efficiency is reduced.
[0075] FIGS. 20 and 21 are simulations illustrating how the
invention mitigates the loss in efficiency caused by the obstacle.
In FIG. 20, with no vanes present, the 5.5 meter-per-second profile
line 230 is indicated. Arrow 235 points to a region where this
velocity has been lost.
[0076] In contrast, in FIG. 21, with vanes V present, the velocity
in that region is not reduced so greatly. Flow through the fan is
maintained more closely to the optimal value.
[0077] 2. The vanes in cross section can assume airfoil shapes.
These shapes can be different at different circumferential
locations around the fan.
[0078] FIG. 22 illustrates the fan 200, together with a polar
coordinate system superimposed thereon. A z-axis is shown. The
radial coordinate, r, is the distance from the z-axis. The angle
theta is measured from a reference line 250. Point P, for example,
has the coordinates (r, theta, z) of (4, 0, 10).
[0079] In general, the shapes of the vanes can be different at
different coordinates. For example, in FIG. 23, vane V1 has a chord
length C1, while vane V2 has a chord length C2. Different vanes can
also have different axial lengths AX or different radial depths
RD.
[0080] In FIG. 24, vane V5 has an inlet angle A. Vane V6 has a
different inlet angle of zero. Vane V7 has an exit angle of ninety
degrees. Vane V8 has a different exit angle A2.
[0081] In one embodiment, the inlet angles, or exit angles, or
both, can be similar at similar angles theta, but at different
angles theta, they can differ. For example, in FIG. 25, the angles
in question can be similar at the 3 o'clock position P3. The angles
in question can also be similar at the 6 o'clock position P6, but
the former can be different from the latter.
[0082] In addition, the similar angles can span a range of
positions. For example, the angles in question can be similar from
3 o'clock to 6 o'clock.
[0083] In FIG. 26, three vanes V are shown. The radial distance R1
between adjacent vanes V10 and V11 is different from the radial
distance R2 between adjacent vanes V11 and V12.
[0084] In a related type of difference, the channel width W between
different pairs of vanes is different: different pairs define
different channel widths. The channel width W need not be constant.
Thus, an average width can be considered, or the minimum or maximum
width.
[0085] Similarly, an annulus can be defined in the exhaust of the
fan. An annulus is a band between two circles of different
diameter. For example, the rings of Saturn form an annulus. In one
form of the invention, vanes can be present in all or part of an
annulus of given inner diameter, but vanes may be absent from other
annuli.
[0086] In FIG. 27, vanes can be present in one sector S1, but
absent from another sector S2. In FIG. 28, vanes can be partially
present in sector S1, as indicated by the hatching, which indicates
the presence of vanes.
[0087] Therefore, in general, the airfoil shape of the vanes can be
different, at different coordinates (r, theta, z). The difference
includes the absence of vanes entirely at certain coordinates. The
parameters of airfoil shape, such as chord length, thickness, inlet
angle, and exit angle, are defined in the art of aerodynamics. As
stated, these parameters can vary over the (r, theta, z) space.
[0088] Also, the vanes in the sector which covers the obstacle can
be designed differently from vanes in other sectors. For example,
in FIG. 28, the obstacle O is represented. Sector S1 covers the
obstacle.
[0089] 3. The vanes can be ring-shaped, with the larger-diameter
rings closer to the fan, and the smaller-diameter rings farther
from the fan.
[0090] 4. In one embodiment, radial struts generically indicated by
dashed block 300 in FIG. 24 support the vanes.
[0091] In many types of fans, such radial struts are shaped to
re-direct exhaust air generated by the fan. For example, in FIG.
22, because of the rotation indicated by arrow 205, the airstream
generated by the fan will have a velocity component in the
tangential direction. The radial struts are shaped to re-direct
this tangential air into the axial direction, that is, parallel
with the z-axis.
[0092] In one form of the invention, this re-direction does not
occur, is not desired, and the radial struts are not designed to
perform this re-direction.
[0093] It is recognized that any time an object is placed in a flow
stream, some re-direction will occur. For example, if a flow stream
is moving East, and encounters an object, part of the flow stream
will flow North, part South, and part upward.
[0094] Similarly, if a flow stream generated by a fan encounters a
radial strut, part of the flow stream will flow slightly
tangentially, to avoid the strut.
[0095] Nevertheless, under the form of the invention in question,
the struts are not designed to enhance or decrease this minimal
amount of tangential flow. Stated another way, the impact on
tangential flow is sought to be minimal, and the radial struts
designed accordingly.
[0096] 5. The fan-vane system is designed to be mounted within an
engine compartment of a vehicle. Block 350 in FIG. 22 represents a
mounting means. For example, the mounting means can take the form
of three flanges, each having a bolt hole, the bolt holes defining
a triangle. With such three-point mounting, flexing of the vehicle
does not impart torsion to the fan.
[0097] That is, with four-point mounting, the four points define a
quadrilateral, such as a rectangle. Assume that the rectangle is
vertical, facing south, and the two lower corners are anchored. If
the left upper corner moves north, and the right upper corner moves
south, then torsion is applied to the rectangle.
[0098] Such torsion does not occur in three-point mounting.
[0099] Numerous substitutions and modifications can be undertaken
without departing from the true spirit and scope of the invention.
What is desired to be secured by Letters Patent is the invention as
defined in the following claims.
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