U.S. patent number 3,854,459 [Application Number 05/429,627] was granted by the patent office on 1974-12-17 for fan shroud for an engine cooling system.
This patent grant is currently assigned to Mack Trucks, Inc.. Invention is credited to David F. Stimeling.
United States Patent |
3,854,459 |
Stimeling |
December 17, 1974 |
FAN SHROUD FOR AN ENGINE COOLING SYSTEM
Abstract
A cooling system for an internal combustion engine includes a
radiator, a fan, and a plurality of closable shutters. The shutters
regulate the flow of air through the system and thereby control the
cooling effected by the system. A shroud encircles the fan and
defines at least a portion of a passageway between the shutters and
the fan. The shroud has a central opening that affords a free path
of flow for air exhausted from the fan after being drawn through
the radiator. At least one closable vent formed in the shroud is
normally closed when the shutters are open and the fan is operating
and normally open when the shutters are closed and the fan is
operating. The vent thus reduces the noise generated by the fan in
the passageway when the shutters are closed.
Inventors: |
Stimeling; David F. (Whitehall,
PA) |
Assignee: |
Mack Trucks, Inc. (Allentown,
PA)
|
Family
ID: |
23704061 |
Appl.
No.: |
05/429,627 |
Filed: |
December 28, 1973 |
Current U.S.
Class: |
165/98;
123/41.04; 123/41.05; 123/41.49; 123/41.59; 415/145 |
Current CPC
Class: |
F01P
11/10 (20130101); F01P 7/10 (20130101) |
Current International
Class: |
F01P
7/00 (20060101); F01P 11/10 (20060101); F01P
7/10 (20060101); F01p 007/02 () |
Field of
Search: |
;123/41.04,41.05,41.06,41.49,41.59 ;415/158,145,148,147,149
;165/39,51 ;181/35R,.5R |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Antonakas; Manuel A.
Assistant Examiner: O'Connor; Daniel J.
Attorney, Agent or Firm: Brumbaugh, Graves, Donohue &
Raymond
Claims
I claim:
1. In a cooling system for an internal combustion engine including
a fan and closable shutter means for controlling a flow of air to
the fan, the improvement comprising:
a fan shroud defining at least a portion of a passageway extending
from the shutter means to the fan, the shroud encircling the fan
and including an opening affording a free path of flow for air
moving through the passageway from the shutter means and being
exhausted from the fan, at least one vent being formed in the
shroud, and automatic means for closing the vent when the shutter
means is open and the fan is operating and for opening the vent
when the shutter means is closed and the fan is operating.
2. The improvement of claim 1, wherein at least a portion of the
shroud extends radially outwardly of the fan and lies in a plane
generally parallel to the fan, said portion of the shroud having
the vent formed therein.
3. The improvement of claim 1, wherein the cooling system further
includes a radiator located between the fan and the closable
shutter means.
4. The improvement of claim 1, wherein the closing and opening
means includes a pivotable flap for closing the vent and spring
means for biasing the flap into a closed position.
5. The improvement of claim 1, wherein the closing and opening
means includes a pivotable flap for closing the vent and linkage
means coupling the flap to the shutter means.
6. The improvement of claim 1, wherein the closing and opening
means includes a flexible diaphragm covering the vent and having a
slit therein aligned with the vent.
7. The improvement of claim 6, wherein the closing and opening
means further includes stop means disposed on one side of the
diaphragm to prevent flexing of the diaphragm in one direction
beyond the stop means.
8. The improvement of claim 7, wherein the stop means includes a
strip on the shroud and extending across the vent lengthwise of the
slit in the diaphragm and laterally across the slit.
9. The improvement of claim 7, wherein the stop means includes a
strip on the diaphragm adjacent one side of the slit, the strip
extending lengthwise of the slit and laterally across the slit to
overlap the diaphragm on the other side of the slit.
10. The improvement of claim 1, wherein the cooling system further
includes a radiator located ahead of the shutter means on a side
thereof opposite the fan.
11. In a cooling system for an internal combustion engine including
a fan and closable shutter means for controlling a flow of air
through the system, the improvement comprising:
a. a fan shroud defining at least a portion of a passageway
extending from the fan to the shutter means, the shroud encircling
the fan and including an opening affording a free path of flow for
air moving through the passageway from the fan to the shutter
means, a portion of the shroud extending radially outwardly of the
fan and lying in a plane generally parallel to the fan, at least
one vent being formed in said portion of the shroud; and
b. automatic means for closing the vent when the shutter means is
open and the fan is operating and for opening the vent when the
shutter means is closed and the fan is operating.
12. The improvement of claim 11, wherein the closing and opening
means includes a pivotable flap for closing the vent and linkage
means coupling the flap to the shutter means.
Description
BACKGROUND OF THE INVENTION
In many cooling systems for motor vehicle engines, a shroud extends
from the fan for the cooling system to a radiator placed between
the fan and an incoming flow of relatively cool air. The shroud
improves the effectiveness of the fan and increases the cooling
efficiency of the system. An engine cooling system may also include
a set of shutters for regulating the flow of cooling air through
the system, as illustrated, for example, in Tice U.S. Pat. No.
1,759,527 and Brennan U.S. Pat. No. 2,118,484. Presently
manufactured large trucks often have both a set of shutters,
mounted either in front of or behind the radiator, and a fan
shroud. When the shutters are closed, however, the noise produced
by the cooling fan is increased due to air turbulence and resonance
in the enclosed passageway defined by the closed shutters and the
shroud. Such increased cooling fan noise is a major contributor to
excessive vehicle noise, particularly in heave-duty motor
trucks.
SUMMARY OF THE INVENTION
The present invention relates to a noise reducing fan shroud for
use with engine cooling systems and similar air moving systems in
which the flow of air can not be controlled by interrupting the
operation of the fan. According to the invention, at least one
closable vent is formed in a shroud extending at least partway
between a cooling system fan and a set of closable shutters. The
vent is normally closed when the shutters for the cooling system
are open and the fan is operating, and is normally open when the
shutters are closed and the fan is operating. The vent effectively
eliminates the enclosed cavity otherwise formed by the closed
shutters and the shroud, thereby reducing the noise generated by
the fan to a level generally equivalent to the noise level of a
shroudless fan.
In one embodiment of the invention, the portion of the shroud
immediately adjacent the fan extends radially outward from the fan
and is substantially coplanar therewith. At least one vent is
formed on each side of the fan in the coplanar portion of the
shroud. The vents are closed by a pair of spring-biased, hinged
flaps that are normally biased into a closed position. The vent
flaps open inwardly into the shroud cavity, against the forces of
the biasing springs, in response to the partial vacuum created
inside the shroud between the fan and the cooling system shutters
when the fan is operated with the shutters closed. When the vent
flaps are open, the resonant cavity defined by the shroud and the
closed shutters is disrupted and the noise generated by the fan is
reduced without opening the shutters or otherwise substantially
influencing the cooling effected by the system. When additional
cooling air is required and the shutters are opened, the partial
vacuum in the shroud is relieved and the vent flaps are returned to
their closed positions by the biasing springs and by the effect of
impinging "ram air," if a vehicle on which the cooling system is
mounted is in motion.
In another embodiment of the invention, the vent flaps are coupled
by appropriate linkage to the shutters. The linkage opens the flaps
as the shutters are being closed and closes the flaps as the
shutters are being opened.
The vents, in still another embodiment of the invention, are
covered by flexible diaphragms. Each diaphragm has in it a slit and
a strip of material on the fan shroud or on the diaphragm extends
lengthwise of and laterally across the slit. The strip prevents
flexing of the diaphragm in one direction beyond the strip.
Consequently, the slit can open up to enable a flow of air through
the vent only when the diaphragm flexes in the opposite direction.
The diaphragms are arranged to open the vents in response to a
partial vacuum inside the shroud caused by operating the cooling
fan with the cooling system shutters closed.
The closable shutters for an engine cooling system utilizing one of
the embodiments of the invention described above may be located in
front of both a radiator for the cooling system and the cooling
system fan, between the radiator and the fan, or behind both the
radiator and the fan. If the shutters are located behind both the
radiator and the fan, however, and diaphragms or spring-loaded
flaps are used to close the shroud vents, the vents are opened in
response to excess air pressure, rather than a partial vacuum,
created inside the shroud between the fan and the shutters.
BRIEF DESCRIPTION OF THE DRAWINGS
For a better understanding of the invention, reference may be made
to the following description of various exemplary embodiments taken
in conjunction with the figures of the accompanying drawings, in
which:
FIG. 1 is a perspective view of a portion of a cooling system,
according to the invention, for an internal combustion engine;
FIG. 2 is a side view of the portion of the cooling system of FIG.
1;
FIG. 3 is a perspective view of a portion of a second embodiment of
a cooling system according to the invention;
FIG. 4 is a perspective view of a portion of a third embodiment of
a cooling system according to the invention;
FIG. 5a is a partial sectional view of the cooling system of FIG.
4, shown generally with the cooling system shutters open;
FIG. 5b is a partial sectional view of the cooling system of FIG.
4, shown operating with the cooling system shutters closed;
FIG. 6 is a front view of a portion of a fourth embodiment of a
cooling system according to the invention;
FIG. 7a is a partial sectional view of the cooling system of FIG.
6, shown operating with the cooling system shutters open;
FIG. 7b is a partial sectional view of the cooling system of FIG.
6, shown operating with the cooling system shutters closed;
FIG. 8 is a perspective view of a portion of a fifth embodiment of
a cooling system according to the invention; and
FIG. 9 is a perspective view of a portion of a sixth embodiment of
a cooling system according to the invention.
DESCRIPTION OF PREFERRED EMBODIMENTS
FIGS. 1 and 2 of the drawings illustrate a portion of the cooling
system for an internal combustion vehicle engine 10, according to
the present invention. The cooling system includes a radiator 12
through which is circulated a liquid coolant for the engine 10. The
liquid coolant absorbs heat from the engine 10 to maintain a proper
operating temperature and is cooled in the radiator 12 by a flow of
air passing therethrough, from left to right as viewed in FIG. 2. A
positive flow of air through the radiator 12 is ensured by a fan 14
placed behind the radiator and operated by the engine 10. A fan
shroud 16 encircling the fan 14 and extending between the fan and
the radiator 12 enhances the effectiveness of the fan.
In front of the radiator 12, a set of shutters 18 mounted in a
frame 20 controls the flow of air to the radiator and the fan. Each
of the shutters 18 is rotatable about its longitudinal axis and
carries, at its upper end, a connecting arm 22. The arms 22 are
also pivotally coupled to a control rod 24 extending across the
width of the mounting frame 20. Axial movement of the control rod
24 to the right or left, as viewed in FIG. 1, causes rotation of
the shutters 18 into their closed or open positions,
respectively.
Axial movement of the control rod 24 is effected by a pneumatically
operated piston (not shown) enclosed in a cylinder 26 mounted
adjacent one end of the control rod on a bracket 28. A plunger 30
extends from the piston through an end of the cylinder 26 and is
pivotally connected to one end of a lever 32, the opposite end of
which is rigidly joined to the upper end of the adjacent shutter
18. Axial movement of the plunger 30 pivots the lever 32, which, in
turn, rotates the adjacent shutter 18 about its longitudinal axis
and also pivots the corresponding connecting arm 22. The pivoting
connecting arm 22 moves the control rod 24 axially to the right or
left and, thereby, closes or opens all of the remaining shutters
18.
The piston in the cylinder 26, as shown, is single-acting and has a
spring return (not shown). The cylinder 26 obtains its air supply
through a line 33 from a source of pressurized air (not shown),
such as a conventional air compressor. The air source also supplies
pressurized air to the windshield wipers (not shown) and other
devices, such as air brakes, for the vehicle. A conventional
temperature sensitive control valve 34 in the air line 33 is
actuated in response to the temperature of the engine 10 so that
operation of the shutters 18 is related to the temperature of the
engine. The tubing that comprises the air line 33 is supported
between the engine 10 and the cylinder 26 by a clamp 35 attached to
a tie rod 36 for the radiator 12.
The shutters 18 may be opened and closed by any convenient
mechanism and may be operated in response to the pressure in the
engine intake manifold. Different shutter assemblies are
illustrated both in Tice U.S. Pat. No. 1,759,527 and in Brennan
U.S. Pat. No. 2,118,484. The Tice patent also discloses several
control devices for operating cooling system shutters in response
to intake manifold pressure. The shutters or louvers illustrated in
the Brennan patent are operated by a thermostat.
The metal fan shroud 16 is mounted directly behind the radiator 12
to form an enclosed passageway between the radiator and the fan 14.
The shroud 16, as shown, is rectangular, but it can be any other
convenient shape. The rear surface 38 of the shroud 16 is generally
coplanar with the fan 14 and has a circular central opening 39 for
the fan exhaust. On opposite sides of the central opening in the
shroud 16, the rear surface 38 is cut away to provide a number of
vents 40. The vents 40 are closed by a pair of flaps 42 that are
shaped so as not to project into the central opening 39 and are
fabricated of any convenient material, such as stiff, molded
plastic. Each of the flaps 42 is mounted by a hinge 44 adjacent an
outside edge of the rear surface 38 of the shroud 16. The flaps 42
swing inwardly into the shroud 16 to open the corresponding vents
40 and are normally biased into a closed position by springs 46.
One end of each spring 46 is secured to the corresponding flap 42
and the other end is anchored to a U-shaped bracket 48 that
projects rearwardly from the rear surface 38 of the shroud 16. The
bracket 48 is mounted on a pair of metal angles 50 which reinforce
the rear surface 38. Reinforcement is also provided about the
central opening 39 by an upstanding circular flange 52. The spring
arrangement is a matter of choice and other arrangements for spring
loading the vent flaps, such as combination hingesprings, may be
utilized.
In operation, when the engine 10 is relatively cold and a flow of
cooling air through the radiator 12 is not needed, for example when
the engine is first being started, the control valve 34 is opened
in response to the low engine temperature and the piston in the
cylinder 26 closes the shutters 18. With a conventional shroud,
closing the shutters would greatly increase the noise produced by
the cooling fan due to air turbulence and resonance in the enclosed
cavity formed by the closed shutters, the radiator, and the shroud.
In the illustrated embodiment of the invention, however, the
partial vacuum resulting within the shroud 16 due to closing the
shutters 18 causes the vent flaps 42 to be drawn inwardly into the
shroud 16, against the forces of the springs 46, opening the vents
40. The open vents 40 effectively open up the enclosed cavity in
the shroud 16 and reduce the noise produced by the fan 14 to
approximately the level that would be encountered with a fan not
equipped with a shroud. When the engine 10 is sufficiently warmed
up so that the control valve 34 is closed, the piston and the
control rod 24 are positioned by the spring return in the cylinder
26 to open the shutters 18. A flow of cooling air is drawn through
the radiator 12 by the fan 14 and is exhausted rearwardly through
the central opening 39 in the shroud 16. The flaps 42 are closed by
the biasing springs 46 and possibly by impinging "ram air," if the
vehicle is traveling at sufficient speed. The amount of the force
of the "ram air" flowing through the shutters and impinging on the
flaps depends upon the speed of the vehicle.
FIG. 3 of the drawings illustrates a second embodiment of the
invention in which the vent flaps 42 are operated by a direct
mechanical linkage to the shutters 18. The embodiment of FIG. 3 is
generally similar to the embodiment of FIGS. 1 and 2 except that
the biasing springs 46 and the U-shaped brackets 48 are eliminated.
Instead, the lever 32' that is pivotally connected to the piston
plunger 30 is both rigidly joined to the upper end of the adjacent
shutter 18 and pivotally coupled to one end of a linkage rod 54a.
The linkage rod 54a extends along the side of the radiator 12 and
is pivotally connected to one end of an arm 56a. The other end of
the arm 56a is carried on the upper end of a shaft 58a that is
coaxial with one of the vent flap hinges 44 and is secured to the
corresponding vent flap 42 for rotation therewith. A similar
linkage arrangement of a linkage rod 54b, an arm 56b, and a shaft
58b is used to couple the second vent flap 42 to the shutters 18. A
lever 60 rigidly joined to the upper end of the shutter farthest
from the cylinder 26 is pivotally attached to the adjacent end of
the linkage rod 54b to complete the linkage for the second vent
flap 42. As the piston plunger 30 moves axially to open or close
the shutters 18, the vent flaps 42 are simultaneously closed or
opened by their respective linkages.
In the embodiment of FIGS. 4, 5a, and 5b, which is otherwise
similar to the embodiment of FIGS. 1 and 2, the vents 40' in the
fan shroud 16' are circular in shape and are located in each corner
of the rear surface 38' of the shroud. Each vent 40' is closed by a
circular, flexible diaphragm 62 made of synthetic rubber, for
example, and having a diametral slit 64. The diaphragms 62 are
larger than the vents 40' and are cemented about their
circumferences to the inside of the shroud 16'. A reinforcing strip
66, which is also fabricated of rubber, is glued to the diaphragm
62 along one side of the slit 64. The strip 66 extends the length
of and overlaps the slit 64. As shown in FIGS. 5a and 5b, the fan
14 is not and need not be coplanar with the rear surface of the
shroud.
In operation, when the shutters 18 are open, as shown in FIG. 5a
(the radiator 12 is omitted from FIGS. 5a and 5b for simplicity),
the flow of air, indicated by the arrow 68, pushes the diaphragm 62
on both sides of the slit 64 against the reinforcing strip 66. The
stiffening effect of the strip 66 keeps the diaphragm from flexing
in response to the air flow and thereby seals the slit 64. When the
shutters 18 are closed, as shown in FIG. 5b, the rotating fan 14
produces a partial vacuum in the shroud 16'. The partial vacuum
causes the side of the diaphragm 62 to which the reinforcing strip
66 is not glued to flex inwardly into the shroud, against the
biasing force generated as that diaphragm side is flexed. The
stiffening effect of the strip 66 restrains the other diaphragm
side from flexing into the shroud. The flexing of the diaphragm
opens the slit 64 and thus the vent 40' to reduce the noise
produced by the fan 14 in the shroud 16'.
In an embodiment of the invention similar to the embodiment of
FIGS. 4, 5a, and 5b, as shown in FIGS. 6, 7a, and 7b, the vents 40"
in the shroud 16" are formed as paired semi-circles. A rubber
diaphragm 70 closes each pair of vents 40" and has a diametral slit
72. The portion 74 of the shroud 16" separating the two vents 40"
of each pair replaces the reinforcing strip 66 of the embodiment of
FIGS. 4, 5a, and 5b, and prevents the diaphragm 70 from flexing
outwardly of the shroud.
As shown in FIGS. 7a and 7b, in which the radiator 12 is omitted
for simplicity, the diaphragms 70 function in a manner similar to
the diaphragms 62 of the embodiment of FIGS. 4-5b. Since a
reinforcing strip is not glued to each diaphragm 70, however, the
diaphragm flexes inwardly on both sides of its slit 72 when the
shutters 18 are closed, against the biasing forces generated as the
diaphragm sides are flexed.
Although each of the embodiments of the invention described above
has been illustrated with the cooling system shutters located in
front of the cooling system radiator and fan, the vented fan shroud
of the invention can also be used in cooling systems having
shutters located either between the radiator and the fan or behind
both the radiator and the fan.
An embodiment of the invention used in a cooling system having a
set of shutters between a radiator and a fan is illustrated in FIG.
8, while FIG. 9 illustrates an embodiment of the invention used in
a cooling system having a set of shutters located behind a radiator
and a fan. Both embodiments are generally similar to the embodiment
of FIG. 3 and operate in a similar manner.
In the embodiment of FIG. 8, features corresponding to features of
the embodiment of FIG. 3 are designated with reference numerals
derived by adding 100 to the reference numerals of FIG. 3. The
major difference between the embodiments of FIGS. 3 and 8 is that
the fan shroud 116 of FIG. 8 is deeper than the shroud 16 of FIG. 3
so that the shutters 118 can be mounted in the shroud 116.
Accordingly, there is no mounting frame in the embodiment of FIG. 8
corresponding to the frame 20 of FIG. 3. In addition, the linkage
rods 154a and b of FIG. 8 are shorter than the rods 54a and b of
FIG. 3 because of the correspondingly reduced distance between the
shutters 118 and the vent flap hinges 144. Although the vent flaps
142 of FIG. 8 are illustrated as being moved by mechanical
linkages, spring-loaded flaps or flexible diaphragms could also be
utilized to open and close the vents 140.
The features of the embodiment of FIG. 9 corresponding to the
features of the embodiment of FIG. 3 are designated with reference
numerals derived by adding 200 to the reference numerals of FIG. 3.
Again, similar to the embodiment if FIG. 8, the fan shroud 216 of
FIG. 9 is extended to mount the shutters 218. The components 232',
254a, 254b, 256a, 256b, and 260 of the linkages for the vent flaps
242 are also arranged differently from their counterparts in FIG. 3
because the shutters 218 are located behind the vent flaps, unlike
the shutters 18 of FIG. 3.
The relative orientation of the shutters 218 and the vent flaps 242
of the embodiment of FIG. 9 requires the shutters 218' located
above the drive shaft 280 for the fan 214 to be shorter than the
remaining shutters. A lateral support 282 extends across the fan
shroud 216 above the drive shaft 280 and carries a mounting plate
284 which receives the lower ends of the short shutters 218'.
Baffle plates 286 and 288 extend between the mounting plate 284 and
the drive shaft 280 and downwardly from the drive shaft,
respectively, to block air flow in the area of the drive shaft. The
baffle plates 286 and 288 have corresponding flanges 290 and 292
and are formed with corresponding semi-circular offsets so that the
plates can be fitted around the drive shaft 280 and fastened
together. An annular gasket 294 is fitted between the offset
portions of the plates 286 and 288 and the drive shaft 280.
As in the embodiment of FIG. 8, flexible diaphragms or
spring-loaded vent flaps can be used to cover the vents 240. In the
embodiment of FIG. 9, however, the rotating fan 214 does not create
a partial vacuum in the shroud 216 between the fan and the shutters
218 when the shutters are closed, but rather an excess positive
pressure. Accordingly, if flexible diaphragms or spring-loaded vent
flaps are used in the embodiment of FIG. 9, they are opened by the
excess positive pressure created in the shroud 216 between the
vents 240 and the shutters 218. The pressure in the shroud would
also have to overcome the force of "ram air," if any, impinging on
the flaps or diaphragms in order to open the vents 240.
It will be understood that the above-described embodiments are
merely exemplary and that those skilled in the art may make many
variations and modifications without departing from the spirit and
scope of the invention. All such modifications and variations are
intended to be within the scope of the invention as defined in the
appended claims.
* * * * *