FIELD OF INVENTION
This invention relates to an air cooling system for underhood components of
vehicle. The system attends to the cooling requirements of catalytic converter
and required engine modules and at the same time improves aerodynamic
performance of vehicle by minimizing aerodynamic drag coefficient of the
vehicle (Cd).
BACKGROUND /PRIOR ART
Air cooling system is installed in a vehicle for cooling engine compartment.
Vehicle air cooling system typically has a fixed grille (1) opening area in the
front bumper (2) which caters to the coding needs of the engine room
components as shown in fig. 1 wherein one side grille opening (3) is meant for
cooling of engine room components and another side grille opening (4) is for
cooling the radiator. Air flow from these grilles is free to flow inside engine
room; it follows a very intricate path around various engine room components
for driving away-the heat through convection which adds substantially to the
aerodynamic drag as well. If the airflow is more than the cooling requirement it
increases the drag adversely, so a tradeoff between cooling and aerodynamic
drag should be maintained during vehicle front end design. The greater the
drag the more engine power is required to overcome it and thus more fuel is
consumed which affects the overall vehicle fuel economy.
In an existing front bumper, front bumper grille is provided with
horizontal/vertical fixed type grills (G) as shown in fig. 2. These grills provide a
passage for the ram air to flow inside engine room compartment to cool the
engine room components. The ram air is continuously passing into the engine
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compartment without considering critical component temperature and heat
rejection requirements thus resulting in increased drag on the vehicle (Cd).
Hence, there is a requirement to introduce air cooling system to control and
divert required ram air flow into the engine room for satisfying cooling
requirements of engine room and improving aerodynamic performance of
vehicle as well.
Some publications may be mentioned hereinunder one by one though not
relevant to the present invention.
A device for moving a radiator grille in automobiles is disclosed. In the device, a
plurality of temperature sensors are placed in back of a radiator. The radiator
grille has a plurality of directional control fins which are rotatable within a
predetermined rotating angle by a fin moving means. The fin moving means is
operated under the control of a control unit. The control unit outputs a control
signal to the fin moving means in response to temperature signals from the
sensors. The fin moving means rapidly moves the directional control fins under
the control of the control unit.
The invention relates to a radiator grille arrangement for a motor vehicle front
end of a motor vehicle, which comprises a plurality of air passage openings,
which can be closed at least substantially by at least one flap element. In the
embodiment according to the invention, the at least one flap element is thereby
supported so as to be able to swivel about an associated flap axis. In driving
states of the motor vehicle in which little cooling air is needed for the engine or
engine compartment, the entire flap arrangement or a. part of the flaps can
thus be closed.
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The duct structure, of the vehicle front is configured so that a front grille is
installed on a.bumper face at the front extremity of the vehicle and a radiator is
installed inside the engine room behind the front grille and a duct device is
installed between the front grille and the radiator, and the air intruding from
the front grille is fed to the radiator through a plurality of ducts of duct device.
An integrated assembly includes a vehicle bumper system, and upper and
lower air shutter sections with subassembled shutter vanes movable between
closed and open positions, an actuator mechanism for moving the shutter
members between positions.
OBJECTS OF THE INVENTION
The principal object of the present invention is to provide an air cooling system
for underhood components of vehicle which overcomes disadvantages
associated with the prior art.
Another object of the present invention is to provide an air cooling system for
underhood components of vehicle which cools down catalytic converter' and
engine cooling modules so as to decrease engine room temperature.
Still another object of the present invention is to provide an air cooling system
for underhood components of vehicle which is having provision to control and
divert ram air flow into the engine room for improved aerodynamic performance
of vehicle.
Yet another object of the present invention is to provide an air cooling system
for underhood components of vehicle which results in enhanced aesthetic value
of front bumper.
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SUMMARY OF THE INVENTION
According to this invention, there is provided an air cooling system for
underhood components of vehicle comprising of a cooling duct connected to
front grille of bumper to direct ram air flow to specified location of catalytic
converter.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS
Further objects and advantages of this invention will be more apparent from
the ensuing description when read in conjunction with the accompanying
drawings of exemplary embodiments of invention and wherein:
Fig.
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iug.
Fig.
1 shows:
2 shows:
3 shows:
4 shows:
5a shows:
5b shows:
6a shows:
6b shows:
7a shows:
7b shows:
8a shows:
8b shows:
9a shows:
9b shows:
9C shows:
10 shows:
11 shows:
Bumper grille having fixed opening;
Bumper grille having horizontal type grille design;
Cooling system with grille shutter;
Cooling system with grille shutter and cooling duct;
Catalyst converter grille shutters in open position;
Radiator grille shutters in open position;
Catalyst converter grille shutters in closed position;
Radiator grille shutters in closed position;
With cooling duct;
Without cooling duct;
Top view showing cooling duct;
Front view showing cooling duct;
Grille shutter fins;
Grille shutter fins in Open position;
Grille shutter fins in Closed position;
Radiator grille shutters control chart;
Catalytic converter grille shutters control chart;
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Fig. 12 shows: Air flow streamlines with grille shutters open;
Fig. 13 shows: Temperature profile at 40 kmph (with cooling duct);
Fig. 14 shows: Air velocity across radiator at 40 kmph;
Fig. 15 shows: Air flow streamlines with grille shutter closed;
Fig. 16 (a), (b)
shows: Temperature profile at 100 kmph (Grille closed);
Fig. 17 (a), (b)
shows: Air velocity across radiator at 100 kmph (Grille closed);
Fig. 18 shows: Air flow through the bumper grille without any cooling duct;
Fig. 19 shows: Air flow through the bumper grille having cooling duct;
Fig. 20 shows: Air flow streamlines with grille shutters open;
Fig. 21 shows: Air flow streamlines with grille shutters closed.
DETAIL DESCRIPTION OF THE INVENTION WITH REFERENCE TO THE
ACCOMPANYING DRAWINGS
This invention provides a system to control and divert the ram air flow into the
engine room. In engine room only few components are critical which requires
special attention for cooling and • also the requirement varies according to
vehicle driving condition and speeds. Therefore it is better to divert the ram air
only to the critical components based on the requirement and cut off the air
supply whenever the critical components have attained cooling which will
improve vehicle aerodynamic drag.
The top front grille of front bumper as shown in fig.3 is divided into two
portions namely left and right and provided with individual grille shutters. One
side grille shutter (1) is provided, for controlling air flow to the catalyst
converter through a cooling duct and other side grill shutter (2) is provided for
controlling air flow to the radiator. A cooling duct (3) as shown in fig.4 is
connected to the shutter (1) that directs ram air to the catalytic converter (4).
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Thus, the system includes a cooling duct to receive ram air from vehicle front
end and exit to the catalytic converter outer surface that reduces the catalytic
converter surface temperature and also reduces the engine room temperature
thereby increasing the overall engine efficiency.
The cooling duct inlet covers the front bumper grille openings for converter to
supply the cooled ram air around the catalytic converter to effectively remove
the heat from the catalyst so as to maintain the converter in the required
temperature range and also to reduce emission from the engine which
otherwise may have affected engine performance and also increased
environmental temperature.
The engine room is subjected to following conditions:
Condition 1: Additional Cooling required
When vehicle running condition is such that the critical engine room
component temperature is above the acceptable limit and cooling module heat
rejection performance is less, more ram air flow is needed to enhance the
cooling performance. During this time the shutters (1) are kept in open
condition to admit portion of ram air through the cooling duct. (3) to cool the
catalytic converter (4) and another portion to the radiator (5) to improve the
radiator thermal performance as illustrated in fig. 5a and 5b respectively.
Condition 2: No additional Cooling required
When vehicle running condition is such that the engine room components are
well within the critical temperature/ performance limit, the grille shutters are
closed and the ram air is deflected around the front bumper that helps in
reducing the aerodynamic drag on the vehicle as shown in fig 6. As the
quantity of ram air entering into the engine room and engine cooling module
reduces, the turbulence generated by the airflow also reduces and
simultaneously the aerodynamic drag (Cd) reduces.
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The catalytic converter grille shutter (1) (as shown in fig. 3) is installed for
controlling air flow to the catalyst converter through the cooling duct. Cooling
duct (3) has a suitable design and dimensions (as shown in fig. 8) that allows
the duct to carry the cooled ram air around the catalytic converter top surface,
which flows from top towards bottom. It is attached to the front bumper grille
by snap fit. The design (shape) and dimension of the duct varies from model to
model of motor vehicle. Therefore it is designed as per requirement. During
forward motion of vehicle, cold ram air enters the inlet (3A) and exit through
the outlet (3B) of duct to the specified location of the catalytic convertor for
cooling. The cooled air flow from the duct receives heat from the catalytic
converter and the heated air exits to the ground as shown in fig 7a indicating
the following:-
Cooling duct-3
Cold ram air-C
Engine room temperature less-E2
Ram air takes away the heat from catalytic converter-R
Heated air exits to the bottom ground-A
As the hot air is discharged away from the engine room, the temperature inside
the engine room will be lesser than the existing techniques. But without the
cooling duct the hot air keeps recirculating inside the engine room cabin which
raises the engine room temperature as shown in fig 7b illustrating the
following:-
Engine room temperature high-Ei
Hot air re-circulation-H
Cold ram air-C
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Now, reference may be made to fig. 9 in which Grille shutters comprise of
multiple fins (F) which are connected to each other by means of a linkage arm
(L)that is connected to a linear actuator (T) which is controlled by ECU. When
the vehicle speed is above a certain speed (X), ECU sends the control signal to
the linear actuator which actuates the linkage arm in forward direction which
in turn rotates the catalytic convertor shutter fins (as described in the control
chart in fig. 11).
Similarly the radiator grille shutters are also controlled by ECU based on
radiator top tank temperature. As soon as vehicle speed goes beyond the speed
(X), the ECU checks for the radiator top tank temperature and if the radiator
top tank temperature is above the threshold value the grille shutters are kept
open fig. 9b otherwise the grilles are closed fig. 9C (as described in the control
chart in fig. 10).
Thus the shutters are controlled by actuators to variably control the grill
opening area thus controlling the air flow to the engine room thereby improving
the exhaust emissions, engine room cooling and aerodynamic drag coefficient.
The closure of fins enhances the appearance/aesthetic of the vehicle front end.
Both the grill openings are controlled by means of respective linkage
mechanism. The linkage mechanism for catalytic converter and radiator is
actuated by respective actuator.
Results
Condition 1: Additional cooling required
At low speed and high loads, temperature of engine room components may rise
and thus proper cooling of the more critical components is necessary. Thus in
these conditions of high engine room temperature grille shutters are kept open
which direct the ram air through the cooling duct to the catalyst converter and
the radiator as well as shown in fig 12.
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The addition of cooling ducts has resulted in more flow being directed directly
on to the catalyst converter surface which has brought the temperature down
as shown in fig. 13 indicating engine room temperature (overall) ~80°C (P).
The radiator top tank temperature is also within the acceptable limit as there is
sufficient air flow to the radiator through the grille openings as in fig. 14a.
Fig. 14b shows the following:-
Mass flow across radiator when grille shutter is closed: 0.37 kg/s- A
Radiator top tank temperature: 101°C- B
Radiator top tank temperature threshold: 105°C- C
Condition 2: No additional cooling required
When vehicle running condition is such that the critical engine room
components are well within the critical temperature limit, the grille shutters
are closed and the ram air is deflected around the bumper that also helps in
reducing the drag on the vehicle as shown in fig 15.
At high speed, vehicle receives more ram air than is needed thus the extra ram
air only increases the drag on the vehicle and doesn't improve the cooling
much. Thus to reduce the vehicle drag at higher speeds it is advantageous to
close the bumper grille openings (fig. 16a and 17a) as it doesn't affect the
catalyst converter and radiator top tank temperatures as shown in fig 16 and
17, wherein fig. 16 (b) indicates engine room temperature (overall)= 70°C (Pi)
and fig. 17 (b) shows the following:-
Mass flow across radiator when grille shutter is closed: 0.63 kg/s- A
Radiator top tank temperature: 77°C- B
Radiator top tank temperature threshold: 105°C- C.
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S.Air flow distribution through the cooling duct
In the Base model without the cooling duct, the air ( R) entering into the engine
compartment through the grille openings (1) in upper grill is free to flow inside
the whole engine compartment thus it is not targeting any particular region (ref
Fig 18). The catalytic converter (2) being a high temperature source contributes
more to the engine room temperature, since there is no direct air flow to the
catalytic converter the heat dissipation is not proper which increased engine
room temperature.
In the modified vehicle with cooling duct (D), the ram air (R) is directed on to
the top surface of the catalytic converter (2) through cooling duct. All the ram
air entering from the upper grill opening (1) is directed to the catalytic
converter and the heated ram air is discharged to the ground thus enhancing
the heat dissipation and lowering the engine room temperature as shown in
Fig. 19.
4. Cooling performance at various vehicle running condition:
At high load and low speed condition (e.g. At vehicle speed 40 kmph, 10%
gradient condition), the bumper grille is kept open and the addition of cooling
duct improves the cooling of catalyst converter. The overall engine room
temperature is also reduced owing to more effective cooling of critical
components. The engine cooling module performance (i.e. radiator top tank
temperature) is not affected due to the provision of cooling duct.
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At low load and high speed condition (e.g. At vehicle speed 100 kmph, 0%
gradient condition), the bumper grille is kept closed and the catalyst converter,
engine room and radiator top tank temperature is well within the acceptable
limit.
5. Aerodynamic improvement
Engine room cooling requirements vary depending upon the engine load and
the ambient conditions, often vehicle receives more ram air than what is
needed for the optimum cooling of the engine room components thus this extra
ram air entering into the engine room adversely affects the vehicle aerodynamic
drag in particular cooling drag. Air flow through the bumper grille opening (R)
is free to flow inside engine room; it follows a very intricate path around
various engine room components for driving away the heat through convection
which adds substantially to the aerodynamic drag as well. Thus it is
advantageous to close the grille openings when it is not required as it would
help in improving the streamlined flow over the vehicle by deflection of ram air
around bumper (N) which improves the aerodynamic performance of the vehicle
as illustrated in fig. 20 and 21.
Table 3: Aerodynamic Drag, Cd at 100 kmph
This improvement of drag coefficient by 0.004 in aerodynamic drag will result
in an improvement of 0.04 kmpl based on ARAI) Modified Indian driving test
cycle.
)
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Advantageous Features
- Cooling down the catalytic converter to decrease engine room
temperature, which in turn increases the overall engine efficiency.
- Improvement in the aerodynamic performance of the vehicle i.e. improved
aerodynamic drag co-efficient (Cd).
- Enhancement in the aesthetic value of front bumper.
- Operation of the catalytic converter and radiator in the required
temperature range, thereby reducing emission from the engine.
It is to be noted that the present invention is susceptible to modifications,
adaptations and changes by those skilled in the art. Such variant embodiments
employing the concepts and features of this invention are intended to be within
the scope of the present invention, which is further set forth under the
following claims:-

WE CLAIM:
1. An air cooling system for underhood components of vehicle comprising of
a cooling duct connected to front grille of bumper to direct ram air flow to
specified location of catalytic converter.
2. An air cooling system for underhood components of vehicle as claimed in
claim 1 wherein the duct constitutes a tubular longitudinal member,
inlet of which covers the front bumper grill opening for catalytic
converter and outlet supplies ram air flow to top outer surface of
catalytic converter to control the efficient operating temperature range of
the catalytic converter and reduce the engine room temperature.
3. An air cooling system for underhood components of vehicle as claimed in
claim 1 or 2 wherein a pair of grille shutter assembly is provided in the
front bumper to control and direct the ram air flow to catalytic converter
and also to engine cooling modules for removal of heat from radiator
coolant and condenser refrigerant.
4. An air cooling system for underhood components of vehicle as claimed in
any of the preceding claims wherein the grille shutter assembly
comprising of multiple fins which are connected to each other by means
of a linkage arm in connection with an actuator controlled by ECU so as
to open/close the fins as per requirement.
5. An air cooling system for underhood components of vehicle as claimed in
any of the preceding claims wherein the linkage arm for catalytic
converter grille shutter assembly is actuated by means of an actuator,
which operates according to vehicle speed such as herein described.
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6. An air cooling system for underhood components of vehicle as claimed in
any of the preceding claims wherein the linkage arm for radiator grille
shutter assembly is actuated by another actuator, which operates relying
on vehicle speed and radiator top tank temperature such as herein
described.
7. An air cooling system for underhood components of vehicle as claimed in
any of the preceding claims wherein the fins of grille shutter assembly
remain closed at particular high speed of vehicle, which improves
streamlined flow arid the aerodynamic performance as well.
8. An air cooling system for underhood components of vehicle as claimed in
any of the preceding claims is associated with the advantageous features
such as herein described.
9. An air cooling system for underhood components of vehicle substantially
as herein described with reference to the accompanying drawings.