U.S. patent number 3,799,699 [Application Number 05/259,700] was granted by the patent office on 1974-03-26 for reversible fan assemblies and integral blade and trunnion units.
This patent grant is currently assigned to Caterpillar Tractor Co.. Invention is credited to Ralph E. Master, Richard D. Philipsen, Kenneth E. Starr, Herbert C. Unkrich.
United States Patent |
3,799,699 |
Master , et al. |
March 26, 1974 |
REVERSIBLE FAN ASSEMBLIES AND INTEGRAL BLADE AND TRUNNION UNITS
Abstract
For a reversible fan, a blade is manufactured from a tubular
member of a proper gage and diameter by spreading or flattening one
end into a blade shape and swaging the other end of the tubular
member to a reduced diameter to form an integral trunnion. The
tubular member may be first slotted to aid in spreading the blade
portion into the proper blade configuration. At the distal end of
the trunnion of the integral blade and trunnion unit, a portion of
the trunnion can be upset to provide a shoulder for retaining and
positioning the integral blade and trunnion in a fan bub in one of
two positions for reversing air flow. Springs can be employed to
bias each integral blade and trunnion radially outwardly so that
the position of these units will be maintained by engagement with
complementary indexing structure in the associated hub. As an
alternative to upsetting the end of the trunnion, a washer member
may be secured on its distal end and a blade indexing mechanism
provided by the washer member and cooperating hub assembly.
Inventors: |
Master; Ralph E. (Washington,
IL), Philipsen; Richard D. (Peoria, IL), Starr; Kenneth
E. (Manito, IL), Unkrich; Herbert C. (Peoria, IL) |
Assignee: |
Caterpillar Tractor Co.
(Peoria, IL)
|
Family
ID: |
22985998 |
Appl.
No.: |
05/259,700 |
Filed: |
June 5, 1972 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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813081 |
Apr 3, 1969 |
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70328 |
Sep 8, 1970 |
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Current U.S.
Class: |
416/206;
416/245R; 416/223R |
Current CPC
Class: |
F04D
29/36 (20130101) |
Current International
Class: |
F04D
29/32 (20060101); F04D 29/36 (20060101); F04d
029/36 () |
Field of
Search: |
;416/206,205,204,223 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
Primary Examiner: Powell, Jr.; Everette A.
Attorney, Agent or Firm: Fryer, Tjensvold, Phillips &
Lempio
Parent Case Text
This application is a continuation-in-part of applicant's prior
copending application, Ser. No. 813,081, filed Apr. 3, 1969, and
entitled "Reversible Fan Assembly," now abandoned.
This is a division of Ser. No. 70,328, filed Sept. 8, 1970.
Claims
In the claims:
1. A fan blade unit for use in reversible fan blade assemblies
comprising a swaged trunnion portion, said swaged trunnion portion
being of generally cylindrical configuration having an opening in
the distal end thereof so as to define thickened sidewalls, said
trunnion portion being formed by swaging one end of a metallic
tubular member to increase its wall thickness, said swaged trunnion
portion also having a shoulder on the distal end thereof, and a
blade portion which forms at least a part of the fan blade formed
by flattening its opposite end into a blade shape so that the
trunnion portion and the blade portion are of integral, one-piece
construction, said blade portion defining a single wall thickness
at its distal end and a double wall thickness as its proximal end
which is twice the wall thickness of said single wall thickness,
said thickened sidewalls of said trunnion portion being of greater
thickness than said single wall thickness whereby adequate strength
is obtained in the resulting transition area between said trunnion
and blade portions.
2. The fan blade unit as defined in claim 1 wherein the shoulder is
of integral, one-piece construction with the trunnion portion and
is formed on the distal end of the trunnion portion by upsetting
said distal end.
3. The fan blade unit as defined in claim 1 wherein the shoulder is
a separate member, and further including attaching bolt means
passing through the opening in said trunnion portion, attaching
said shoulder to said trunnion portion.
4. The fan blade unit as defined in claim 1 wherein the shoulder
includes indexing means formed therewith to maintain the blade unit
in selected positions when cooperating with structures in a hub
assembly.
5. The fan blade unit as defined in claim 1 wherein the opening
extends through the trunnion portion, and further including a
formed depression in the double wall thickness transition area
between the trunnion portion and the blade portion opposite the
base of said blade portion so that the wall portions in the
transition area are in contact thereby closing off the opening
through said trunnion portion and strengthen the transition area
and reduce noise resulting when the unit is revolved in a hub.
6. A reversible fan assembly comprising a disc-like hub assembly
attachable to a rotating shaft having a plurality of equally spaced
inwardly directed radial bores in its periphery; a plurality of
blade units mounted in said radial bores, each blade unit having an
integral blade portion that forms at least a part of the fan blade
and a swaged trunnion portion, said swaged trunnion portion being
of generally cylindrical configuration having an opening in the
distal end thereof so as to define thickened sidewalls, said
trunnion portion being formed from a tubular member by swaging one
end to form said trunnion portion and flattening the other end to a
blade shape to form said blade portion so that the trunnion portion
and the blade portion are of integral, one-piece construction; said
trunnion portion also having a shoulder on the distal end thereof
for securing said distal end within its associated radial bore in
said hub assembly in one of several selected positions and against
outward radial movement, said blade portion defining a single wall
thickness at its distal end and a double wall thickness at its
proximal end which is twice the thickness of said single wall
thickness, said thickened sidewalls of said trunnion portion being
of greater thickness than said single wall thickness whereby
adequate strength is obtained in the resulting transition area
between said trunnion and blade portions.
7. The reversible fan assembly as defined in claim 6 wherein the
shoulder is of integral, one-piece construction with the trunnion
portion and is formed on the distal end thereof by upsetting said
distal end.
8. The reversible fan assembly as defined in claim 6 wherein the
shoulder is attached to the distal end of the trunnion portion with
attaching bolt means passing through the opening in said trunnion
portion.
9. The fan blade unit of claim 1 wherein said blade portion is of
generally arcuate configuration.
10. The reversible fan assembly as defined in claim 6 further
including counterbores associated with each bore and spring means
biasing each of said plurality of blade units whereby each shoulder
is seated within a respective counterbore.
11. The invention of claim 10 wherein said spring means comprises a
spring within the opening in the trunnion end portion and a pin
biased by said spring into abutment with said hub assembly thereby
urging each of said blades radially outwardly.
12. The invention of claim 10 wherein said spring means comprises a
spring on each blade unit intermediate said hub assembly and a
respective blade portion.
Description
BACKGROUND AND SUMMARY OF THE INVENTION
This invention relates to a fan in which the individual blades are
reversed or repositioned to change the direction of air flow
through the fan assembly. More particularly, the invention relates
to the fabrication of the individual blades which produces
increased flexibility in mounting, simplified manufacturing and
reduced balancing requirements along with a reduction in total
costs.
The invention described herein relates to reversible fans such as
disclosed in assignee's copending U. S. application entitled
"Reversible Cooling Fan," Ser. No. 733,133, filed May 29, 1968, now
U. S. Pat. No. 3,452,820.
Reversible fans may be used to select several directions of air
circulation through a radiator of a vehicle engine. Such reversible
fans usually include mechanism for independently rotating each of
the blades about its longitudinal axis to one of two positions so
the direction of air circulation can be conveniently changed.
Thus, the individual blade assemblies in a reversible fan may
rotate between two indexed positions in the fan hub and are
retained in either position by pins or grooves for the selected
angular position to obtain the desired direction of air flow
through the fan. Such pins are generally located in a transverse
passage in the blade supporting member (trunnion) which is normally
a casting to which the blade is fixedly secured. These trunnion
assemblies usually include some means to keep the individual blades
from rotating a full 360.degree. about their respective
longitudinal axis. Such pin restrained blades place large shear
stress concentration on blade-pin connection and on the pin. The
pin diameter can be enlarged in cross-section to prevent it from
shearing due to the high shear forces, but this reduces the
cross-section of the pin supporting trunnion structure which often
leads to fracture of this structure under high centrifugal
loadings. To avoid this problem, the trunnion support structure is
often increased in size, which in turn increases the shear loading
on the pin due to added weight. Sometimes a shoulder is employed on
the inner end of the trunnion which is disposed in a counterbore of
the hub member to alleviate some of the above pin shear problems.
However, such shoulder configurations also add weight. Balancing
problems are further complicated due to the fact that the trunnion
support member with the shoulder is usually made from a relatively
heavy forging on which the thin blade is fixedly secured. Thus,
prior art configurations utilizing shoulders often resulted in
heavy blade and trunnion assemblies to provide the necessary
mechanical strength for retaining and indexing the conventional
blade and trunnion structures in the fan hub assembly.
By contrast, this invention provides a strong, light-weight blade
having an integral trunnion for use in reversible fan applications.
The balde is formed by swaging one end of the tube of the proper
gage and diameter to produce an increase in wall thickness for an
integral trunnion where the maximum strength is needed, and shaping
its other end into a blade. The decrease in weight in suce integral
or unitary blade and trunnion units results in a reduction in
centrifugal forces acting upon these units during normal operation
leading to a lighter, lower-cost, reversible fan assembly. Due to
the light-weight blade units, this invention also offers
versatility in mounting such units in a fan hub which can be a
single piece hub or a split hub.
It is therefore an object of this invention to provide a
lightweight integral blade and trunnion unit for reversible fan
assemblies which obviates many of the above described problems of
the heavier prior art reversible fan assemblies.
It is also an object hereof to provide a method of manufacturing a
new lightweight integral blade and trunnion unit for reversible fan
assemblies having a light strength-to-weight ratio.
It is a further object of this invention to provide a cooperating
indexing means for the integral blade and trunnion units for
positioning them in either of two positions when mounted in a fan
hub.
Other objects and advantages of the present invention will become
apparent from the following description in conjunction with
embodiments illustrated in the accompanying drawings which show one
embodiment of the present invention and its principles. It is
recognized that other embodiments of the invention utilizing the
same or equivalent principles may be used, and structural changes
may be made as desired by those skilled in the art, without
departing from the present invention and purview of the appended
claims.
SUMMARY OF INVENTION
An integral blade and trunnion unit for reversible fan assemblies
can be formed from metallic tubular member by swaging one end of
the member and flattening the other end into a blade shape. By
slotting the tubular member from one end to its central portion
prior to flattening this end into a blade shape, it can be
simultaneously spread as it is flattened to increase the blade
area-to-weight ratio as the individual blade units are formed.
Also, the distal end of the trunnion portion can be upset to
provide a means for indexing and retaining these units in a fan
assembly.
A reversible fan assembly can be formed by incorporating a
plurality of the above-described blade units into a hub assembly
having a plurality of inwardly directed radial holes since the
transition area between the resulting blade and trunnion portions
provides sufficient strength for these mounting arrangements. A
depression formed in this transition area may be employed to
increase its strength and decrease noise of the units in a fan
assembly.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a perspective of a tubular metal member of a suitable
gage and diameter from which the integral blade and trunnion units
can be fabricated;
FIG. 1A is an isometric of the tubular member which has been swaged
on one end and slotted at the other prior to shaping the integral
blade portion on the resulting trunnion unit;
FIG. 2 is an isometric of the tubular member shown in FIG. 1A after
the slotted end has been shaped into an integral blade
configuration;
FIG. 3, is a section of a blade taken along a line III--III of FIG.
2;
FIG. 4 is an isometric of the blade shown in FIG. 2 with the distal
end of the swaged end upset to form a shoulder for use in
restraining and indexing the unit in a hub assembly;
FIG. 5 illustrates a partial isometric view of the blade showing an
alternate embodiment wherein a trunnion extension member friction
welded to the swaged end of the unit;
FIG. 6 illustrates an elevation with parts broken away of a fan
blade assembly having indexing mechanisms cooperating with surfaces
on the upset end of the new integral blade and trunnion units;
FIG. 7 is a section of the indexing mechanisms of the fan blade
assembly shown in FIG. 6, taken along a line VII--VII thereof;
FIG. 8 is an isometric of the indexing surfaces on the units
utilized with the fan assemblies shown in FIGS. 6 and 7;
FIG. 9 shows an isometric of an upset end portion of an integral
blade and trunnion unit employing notches to form indexing
surfaces;
FIG. 10 illustrates how springs may be utilized to maintain the
indexed position in a fan hub assembly of the upset shoulder
illustrated in the embodiment of FIG. 9;
FIGS. 11 and 12 illustrate cross-sectional views of alternative
embodiments of the integral blade and trunnion unit wherein a
washer member is secured to the distal end of the trunnion and
employed to hold the blade in its indexed position in a hub
structure;
FIG. 13 is an elevation of a tubular member with opposite ends
swaged and sectioned to form two of the novel units thereby saving
material;
FIGS. 14 and 15 are an edge elevation and end view of an integral
blade and trunnion unit formed from the tubular member shown in
FIG. 13; and
FIG. 16 is a perspective of fan assembly employing the integral
blade and trunnion units in a hub.
DETAILED DESCRIPTION
Referring now to the drawings in greater detail, FIG. 1 shows a
metal tubular member 11 from which an integral blade and trunnion
unit is fabricated. In FIG. 1A, the tubular member 11 is
illustrated with its end 13 swaged to a smaller diameter increasing
wall thickness to form a trunnion and with its other end 15 having
machined therein a blind longitudinal slot 17 for a predetermined
distance toward the swaged end of the tubular member.
End 15 of the tubular member is spread in the area of the slot 17
and is then shaped to the blade contour generally indicated at 25
in FIGS. 2 and 3. As the shaping is accomplished, the transition
area between the blade and the swaged portion 13 (that forms the
integral trunnion) is shaped into a transition connecting portion
between the blade and trunnion thereby eliminating conventional
riveting of the blade portion to the trunnion portion.
The dimensions of the blade may dictate that a slot be employed so
that the tubular member can be opened during blade fabrication
which will reduce the weight of the blade portion eliminating a
double wall thickness in the blade. Alternatively, the tubular
member could be flattened to form the blade portion. However, the
slotting technique represents the most preferred technique since it
forms the best compromise between a compatible swaging operation to
form the trunnion and fabricated blade area by opening the tubular
member to form the blade portion. Slotting also provides a single
wall thickness at the distal end of the blade which is less than
the thickness of the trunnion portion wall as well as a double wall
thickness at the proximal end of the blade which is in the
transition area.
FIG. 13 illustrates how two integral blade and trunnion units are
formed from a single tubular member without wasting material.
As shown in FIG. 4, the swaged end 13 of the blade structure may
also be upset so as to form an integral shoulder or collar 21 which
may be utilized both to index the blade and hold it in the hub.
In the alternate embodiment shown in FIG. 5, an extension trunnion
member 23 may be attached to the swaged end 13, such as by inertia
welding, to increase its length since the wall thickness has been
increased by swaging sufficiently to accomplish such a weld. Of
course, the extension member may be either solid or hollow, as
desired.
With reference to FIGS. 6 and 7, a fan hub has been illustrated
having two cooperating split hub sections 31 and 33 which are
joined with bolts 35. These split halves or sections are
manufactured to be complementary, and when joined, form radial
bores 37 extending through the hub and terminating in an internal
recess 39 having faces 41 and 43. An integral blade and trunnion
unit with a blade 111 and trunnion 113 is secured in each bore 37
and the upset shoulder 121 of each seats in the recess preventing
outward radial movement.
The shoulder 121 can be formed by upsetting the swaged end of the
blade after which it is machined to fashion two chords to form
faces 123 and 125. As shown in FIG. 7, face 125 cooperates with the
face 41 of the recess and face 124 operates similarly with face 41.
A spring 127 acting against a pin 129 which abuts an inner hub
member 131 urges each blade radially outwardly as shown in FIG. 6
to maintain the indexing when the fan is not rotating.
When reversing the blade, it is pushed radially inward, toward the
hub member 131 until shoulder 121 clears slot 39. Then the blade
may be rotated about its longitudinal axis so face 123 abuts on
face 41 or face 125 abuts the face 41 of the slot. Since face 43 is
further away from the axis of the bore, the larger, curved end of
the shoulder 121 will clear the face 43 when the blade is properly
positioned, but will not clear the edge of the slot at face 41 when
improperly positioned. Proper positioning can occur only when face
123 or face 125 abuts on face 41.
A cover 141 may be secured over the face of the hub by bolts 143 to
keep dirt or foreign matter out of the blade reversing
mechanisms.
Referring now to the embodiment shown in FIG. 9, it can be seen
that a swaged end 213 of a blade has been upset to form a shoulder
221 having notches 223 and 225 therein which can be used for
indexing in place of the machined surfaces previously discussed.
When the trunnion section 213 is situated within a bore 237 between
two hub sections, one of which is illustrated as 231, shoulder 221
formed thereon will be seated within a counterbore 239. An indexing
structure, such as a pin 241 may be employed adjacent the periphery
of the counterbore 239 so as to cooperate with alternately notch
223 or 225 to index the integral blade and trunnion units.
Shoulder 221 is urged against its seat within counterbore 239 by an
external spring 227 acting between a hub at 229 and a collar 231
which abuts against the transition portion of the blade and
trunnion unit.
Reversal of the blade from one position to another may be
accomplished by manually depressing the blade until shoulder 221
completely clears the counterbore, and rotating the blade until the
other notch is positioned to receive pin 241 when the blade is
released and moved radially outwardly by the spring 227.
Referring now to the embodiment of FIG. 11, a fan blade 311 has
been illustrated as situated within a unitary hub structure 231. An
external spring 337 acting between a collar 331 on the blade and a
counterbore 329 in the hub serves to bias the blade radially
outwardly. The trunnion section 313 of the blade is secured to a
washer member 321 which is received within a counterbore 339 in the
hub. A slot 323 is machined a small distance into the end of
trunnion 313 to admit a raised key 325 which projects from the
washer member 321. The key member 325 also cooperates with a groove
or notch 341 in the hub for indexing the integral blade and
trunnion unit in its forward or reverse positions.
A bolt 351 extends through the washer member 321 and axially into
the trunnion 313 so that its threaded end screws into a nut 353
that is fitted within the flattened section of the blade assembly
to hold the washer member on the trunnion.
When it is desired to reverse the blade, it is manually depressed
into the hub so that the key 325 clears the bottom of the
counterbore 339. The blade is then rotated until the key mates with
another groove (not shown) similar to notch 341.
In the embodiment of FIG. 12, a blade 411 has been illustrated
which is similar in all respects to the blade 311 illustrated in
FIG. 11. However, in fastening a washer member 421 on the trunnion
member 413, a bolt 451 having a formed head 453 is passed into the
flattened section from the blade side so it extends axially through
the trunnion section 413 and washer 421. A nut 455 is employed on
the threaded end of the bolt to secure the washer member. The blade
of this embodiment may be reversed in a manner similar to those
previously described.
FIGS. 13, 14, 15 and 16 illustrate one of the preferred embodiments
of the novel blade construction since its fabrication minimizes
waste in the tubular starting material. Also, as can be seen in
FIGS. 14, 15, and 16, the integral blade and trunnion can be
modified by forming a depression or dimple 18 in the transition
zone between these structures. By closing the opening through the
trunnion by flattening the opposite wall against the blade portion
to be in contacting relation at its root or base as shown, the
noise (whistle) in the resulting fan assembly is appreciable
reduced. In addition, the resulting ridges formed in the transition
area between the trunnion portion and the blade portion strengthen
this area against bending on opposite sides of the depression
18.
In FIG. 16 a plurality of the integral blade and trunnion units are
shown assembled on a hub 20 to form a reversible fan assembly. The
individual trunnion 13 can be adjustably secured in the hub in any
of the manners previously described.
* * * * *