FIELD OF INVENTION
This invention is directed to aerodynamic drag 'reducing structure for rear
bumper of a vehicle. The invention relates to external aerodynamics of
passenger car.
BACKGROUND/PRIOR ART OF INVENTION
The rear-end shape of a car plays prominent role in aerodynamics of a vehicle.
The rear shape is governed by shape of the rear bbmper, rear glass and rear
combination lamp. It directs the .aerodynamic characteristics of the car i.e.
drag, lift and the wake structure of the car.To improve the performance
significant shape changes by the automotive aerodynamicist is limited' by
variety of factors such as styling, ergonomics and loading capacity.
In the existing model,the geometry of commhn passenger car's rear bumper 'is
bent .upwards as' shown in Figl. The upward bend tends to spoil the styling
aspect but for the sake of aerodynamic advantage, aesthetic look is
sacrificed:~lthou~thh e upward bend helps the flow toconverge nearer to the I car body but still there is not enough pressure restoration. The abrupt uneven
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flow at the back of car .creates a. larger low, pressure envelope. This ,in turn i . .
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leads to higher drag and lesser fuei efficiency., .
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In view of the above, there is neekl to design a novel aerodynamic drag reducing
apparatus for rear bumper of a vehicle,' which can facilitate reducing the
coefficient of drag (CD) and improving the fuel economy.
Some known Patents/Publications may be discussed herein below:
A prior art is related to a bumper ,structure for a vehicle having a flowing hole t
for making air flow under the vehicle body to ,transmit air from front to rear. In
the rear bumper beam in a rear part of the
vehicle, there is an outflow hole for making the air flowing out of a rear side
opening to the vehicle rear by making air pass through in the rear bumper face 1
facing the rear side opening of the flowing hole, and an introducing passageis
connected to a front side opening having the front end opening at a rear
surface of a wheel house and having the rear end opening at the front side of c
the flowing hole. It does not add to styling of vehicle. Another known art discloses an apparatus for reducing aerodynamic forces and
in particular the aerodynamic drag and lift of an automotive vehicle comprising
a body formed from multiple body components creating vortex areas.It
comprises, at least one of said vortex zones, at least one ventilating duct
extending substantially parallel .to the longitudinal axis of the vehicle and
provided at each of its ends, respectively an. inlet opening of air and an outlet
opening of air fonned in. the body components.Said inlet openingis ,provided
with an adjusting member. The adjusting member comprises a pivoting
flaplslide valve. There is no enhancement in styling with the requirement of
special motor and rollers.
Another prior art is having provision for reduction system of aerodynamicy ,
forces and in particular the aerodynamic drag and lift of an automotive vehicle.
comprising a body whose rear part includes a plurality of bodywork
componentseach of which creating a vortex zones. It comprises, upstream of at
least one of said vortex zones, means of air into the vehicle longitudinal axis
and, downstream of said at least vortex region, means blowing in the vehicle
longitudinal axis of the' air sucked to control the flow of air at the rear part of
the motor vehicle. The suction means and blowing means are interconnected
by at least one conduit. The suction and blowing means
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comprises at least one slot or orifices formed in - the body member F
r\, corresponding .respectively to form an air curtain or jets of air. The system is
used to create swirling zones. However, it degrades the aestheticness of vehicle.
Another prior art is provided in the front bumper in front of tires with N shaped
guide unit. It does not contribute to styling enhancement.
: Another technology in existence reduces tire turbuleslce, which is provided on
the 'rear side of wheel housing/ tire., being integral part of bumper. 1.
According to still another prior art closed grill. is provided for aestheticness.
None of the above can fulfill the requirements, for which the present invention
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has been designed. b
OBJECTS OF THE INVENTION
The principal object of the present invention is to provide aerodynamic drag
reducing structure for rear bumper of a vehicle which overcomes disadvantages
associated with the prior art.
Another object of the present invention is to provide aerodynamic drag
reducing structure for rear bumper of a vehii:'le which leads to reduction in the
coefficient of drag (CD)an d improvement in the fuel economy.
Still another object of the presen't invention is to provide aerodynamic drag,
reducing structure for rear bumper of a vehicle which is simple in construction
and can be retrofitted to vehicle.
Yet another object of the present invention is to provide aerodynamic drag
reducing structure for rear bumper of a vehicle which is efficient
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Further object of the present invention is to Grovide aerodynamic drag reducing
structure for rear bumper of a vehicle to maintain aesfheticness of vehicle 4
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Yet further object: of the present invention is to provide aerodynamic drag
reducing structure for rear bumper of a vehicle to restore back door pressure
leading to reduction in wake (low pressure) region.
SUMMARY OF THE INVENTION
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b.
According to this invention, there: is provided an aerodynamic drag reducing
I structure for rear bumper of a vehicle, whichcomprises a bumper extension'
assembly having a bumper extension member with grill wherein a duct is
interface fitted to the grill on one side and to the rear bumper/extension P
I member on other side. \1
BRIEF DESCRIPTION OF THE ACCOMPANTfING 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:
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Fig. 1 shows: Conventional vehicle rear bumper; t
Fig. 2 shows: " Exploded view df bumper extension 'assembly according to
present invention;
Fig. 3 shows: Retrofitting of bumper ,extension assembly of present
P invention with rear bumpe; of vehicle;
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Fig. 4 shows: Exploded view of bumper extension assembly of invention
integrated to rear bumper;'
Fig. 5 shows: Aerodynamic drag reducing apparatus for rear bumper of a
vehicle in accordance with present invention;
Fig. 6 shows: Velocity distribution in prior art;
Fig. 7 shows: Velocity distribution in present invention;
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Fig. 8 shows: Drag contour in2prior art, wherein the bar indicates mean of
drag total;
Fig. 9 shows: Drag contour in present invention, wherein the bar indicates
mean of drag toml;
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Fig. 10 shows: Normalized drag'between known art and instant invention.
DETAIL DESCRIPTION OF THE INVENTIQN WITH REFERENCE TQ 'THE .
ACCOMPANYING DRAWINGS ?
The instant invention makes a disclosure in respect of novel aerodynamic drag t
reducing structure for rear bumper of a vehicle. The apparatus comprises a
bumper extension assembly (A) as shown in fig. 2.
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The extension assembly comprises a bumper extension member (1) with two
grills (2), wherein a ducts (3) is interface fitted to the respective grill opening.on
one side and to the bumper extension member with cushioned rubber (4) on
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other side.
The rear grills are mounted into the bumper extension member. The ducts are
' interface fitted on the grill side and on the other'side, are connected to the c
bumper extension member with the help of cushioned rubber.
The above is regarding an exemplary embodiment of invention. The grill and
! a duct is atleast one in number.
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The assembly (A) thus obtained can be retrofitted to the existing rear bumper
(B) by drilling holes under the existing bumper to obtain rear bumper of
invention (R) as in fig. 3.
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According to another embodiment, the bumper extension assembly can' be
integrated to the rear bumper (I) as shown in fig. 4, in which rear bumper is
integrated to bumper extension' niember to constitute a single piece (1) with F
. . k
opening for fitment of rear grill (2). The rear grills (2) are mounted into the rear
bumper and the ducts (3) are interface fitted:on the grill side and on the other
side, are in connection with the bumper with the help. of cushioned rubber (4)
as best seen in the figure 4.
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b
The grill (s) is snap fitted or integral to the extension. memberlrear bumper of
vehicle. The duct (s) is positioned in front of'the grill in the rear is interface or
snap fitted in the rear side and fastened~~lueind t he front side.
Further, the duct that takes the flow to the back door can be converging or
diverging to the opening of the grill.
The novel designed rear bumper of the invention is illustrated in fig. 5.
The apparatus can be an integral part of rear bumper or retrofitted to existing
rear bumper by fastening, clip fitting or gluing to the rear bumper. The
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ductsinlet openings are near the rear axle and receivethe air from the vehicle
underbody, wherein the air passes via grill opening in bumper towards the
back door. Directionalization of air enhances the flow at the back door that
leads to better pressure recovery, which diminishes the wake size. Also this
directionalized flow merges with the vehicle upper and side body air streams
nearer to the back door which further enhances the back door pressure. This
flow phenomenon reduces the overall vehicle' aerodynamic drag and results in ,
?. an impi-ovement in vehicle fuel economy. :,.
With the present invention not only the aerodynamic performance is improved
but also styling appeal can be refurbished. The current invention allows the F
flow from the underbody to be in contact with the surface and glide through I\:
the ducts and pass towards the back door via grill openings.The apparatus
leads to directionalisation of the flow on the back door and therefore there is
substantial increase in flow on the back door. This diminishes the size of low
pressure envelope behind the vehicle and hetrce the wake size is reduced.Better
pressure restorationleads to smaller low prebsure envelope and which in turn '
decreases the drag. . !I
. s 1. Results
1.1 Air Flow at the back door
1.1.1 Existing model
In the existing model, the flow from the underbody moves upwards by
the bend at the bumper, but it converges with the flow from over the car
at the farther end as shown in Fig 6 indicating:
I Bigger wake size-A
Flow converges at the farther end from 'back door-B
1.1.2 Resent invention
In the present invention, the flow from the underbody is directed towards
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the back door with the help of ducts towards the back door via grills. The
directionalisation of flow reduced the wake size behind the vehicle and
led to nearer convergence of flow as' shown in fig. 7 indicating:
Smaller wake size-A . ,
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I Flow converges nearer to ~ back door-B ~~ 1.2 Drag Performance
I 1.2.1 Existing model
In the existing model the lesser pressure restoration at the back door
creates a larger wake envelope and causes higher drag as shown, in
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Fig. 8 indicating:
Higher drag-A
1.2.2Resent invention
ti In the existing model the directionalisation of flow helps in better
pressure restoration at the back door which leads to smaller wake
envelope and lesser drag as shown in Fig.9 indicating:
Lesser drag-B
1.2.3 Drag
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Advantageous' Features
- Reduction in the. co-efficient of drag (CD) and improvement in the fuel
Models
Existing model Drag (E)
Inventive design model drag (I)
economy. 7
- Maintains styling by bearing sportier look and refurbishes astheticness. '\i
Normalised Drag (Fig. 10)
1.000
0.99 1
- Simple in construction and efficient in design. :
- Flexible as the apparatus can be retrofitted to the existing vehicle. I
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' - Flexible as the apparatus can be integral part of bumper.
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 0
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 CLAIMS:-
1. Aerodynamic drag reducing structure for rear bumper of a vehicle
comprises a bumper extension assembly having a bumper extension
member with grill wherein a duct is interface fitted to the grill on one side
and to the rear bumper/extension member on other side.
2. Aerodynamic drag ,reducing structure for rear bumper of a vehicle as
claimed in claim 1 wherein the extension member is provided with
atleastone grill for fitment with the respective duct, other side of which is
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connected to said extension member bj; means of cushioned rubber.
3. Aerodynamic drag reducing structure for rear bumper of- a vehicle as
' claimed in, any of the. preceding 'claims wherein the apparatus is
retrofitted to the existing vehicle, which is placed adjacent to the vehicle
rear bumper.
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4. Aerodynamic drag reducing: structuret: ( . for rear bumper of a vehicle as
claimed in any of the preceding claims wherein the bumper extension
member is integrated to said rear bumper having atleastone grill for
fitment with the respective duct, other side of which is connected to said .
rear bumper by means of cushioned rubber. 1
5. Aerodynamic drag reducing structure for rear bumper of a vehicle as
. claimed in any of the preceding claims which can be an integral part of
the rear bumper, alternatively which ,can be retrofitted being fastened,
clip fitted, glued to the rear bumper. i '
6. Aerodynamic drag reducing structure for rear bumper of a vehicle as
claimed in any of the preceding claims wherein the grill (s) is snap fitted
or integral to the extension member./rear bumper of vehicle.
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7. Aerodynamic drag reducing: structure for rear bumper of a vehicle as
claimed in any of the preceding claims wherein theduct (s) is positioned,
in front of the grill in the rep is interface or snap fitted in the rear side
and fastenedfglued in the front side.
8. Aerodynamic drag reducing structure for rear bumper of a vehicle as
claimed in any of the preceding claim$ wherein the duct that takes the
flow to the back door can be converging or diverging to the opening of the
grill.
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9. Aerodynamic drag reducing structure for rear bumper of a vehicle as +
claimed in any of the preceding claims is associated with the .
advantageous features such as herein described.
10. Aerodynamic drag reducing struqture for rear bumper of a vehicle P
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substantially as herein 'described with reference to the accompanying
drawings.