This invention relates to an aerodynamic drag improvement structure for a vehicle. The invention in particular comprises air dam assembled onto the front suspension frame of the vehicle underbody.
BACKGROUND/PRIOR ART
In dynamic condition of the vehicle, air partially enters to the vehicle underbody through the front bumper bottom and from engine room. This air flows through the underbody structures of the vehicle like suspension systems, exhaust system, fuel tank, front and rear floor etc. When the air passes over uneven surfaces of said structures, the streamlined flow of air is disturbed and as a result the turbulence increases. This increase in turbulence leads to increase in the overall drag coefficient (Co) of the vehicle. Fig. 1 shows the airflow movement (A) and turbulence (T) generated in vehicle underbody without any aerodynamic improvement parts.
An aerodynamic improvement structure is available in the market according to which car front bumper is provided with air dam thereunder, which resists the air flow from the front so as to make the air to flow over the engine under cover, front floor and rear floor etc. However, when the air passes over the uneven surfaces like suspension systems, exhaust system, fuel tank, front and rear floor etc. the streamlined flow of air gets disturbed and it may cause recirculation under the floor by directly hitting the under floor forwardly of aii" dam. This leads to increase in coefficient of drag(CD) and rusting of under floor. Therefore, under floor cover is required to be provided. Thus the under floor covers and/or front bumper air dam is normally employed to reduce the turbulence of the air flow over the underbody.
The disadvantage with the above is that provision of under floor cover leads to increase in weight owing to its huge size which in turn results in high cost and less fuel efficiency.

Now, some prior Patents/Publications may be discussed hereinbelow:
A Known art discloses an air deflecting cover mountable on a suspension device of a vehicle for straightening out air flowing underneath the vehicle. The air deflector cover comprises an inside cover section mounted on a suspension member of the suspension device. The inside cover section is liaving a vertical flow straightening surface extending in a longitudinal direction of the vehicle and facing towards a widthwise central portion of the vehicle. The inside cover section is integrated to a bottom cover section. The bottom cover section is mountable on a bottom part of the suspension member and having a flow straightening surface facing downward of the vehicle.
In accordance with another prior art, there is disclosure of an air dam for attachment to the underside of a vehicle comprising a flexible sheet including first and second edges with an air deflecting surface therebetween. An attaching means is provided at or proximate the first edge for attaching the flexible sheet to the underside of a vehicle such that in use the flexible sheet lies in a non-deployed position at relatively low vehicle speeds, with the air deflecting surface disposed in the oncoming air stream. At relatively higher vehicle speeds the flexible sheet is adapted to flex downwardly of the attaching means progressively to a deployed position in response to increasing air pressure impinging on the air deflecting surface.
The flexible sheet is substantially rectangular in shape. The flexible sheet is formed with a fold therein. The air deflecting surface lies between the first edge and the fold. A secondary air deflecting surface is provided between the fold and the second edge which extends at an angle to the first air deflecting surface.

'I'he air dam also comprising a second rectangular flexible sheet including a support surface smaller in size than the back surface of the first mentioned flexible sheet. The air dam can be attached to the underside of the vehicle for directing air to a radiator of the vehicle in which there is provision of an air guide at the underside of the vehicle to the top of the radiator for providing an upper path for the aii Lo the radiator.
US2007096420t It teaches regarding an air deflector for a vehicle underbody. The air fieflector includes a fairing having a convex shape in width direction of the fairing and extending in longitudinal direction of the fairing. The fairing is affixed to an open end of a generally U-shaped vehicle underbody component to reduce aerodynamic drag during motion of the vehicle. The fairing further comprises a plurality of integrated clips positioned on opposite ends of the width of the fairing.
There is also provision of an air guiding device on a wheel suspension
clement of a rear axle of a motor vehicle, comprising: an air guiding element
extending horizontally in an installed position. The air guiding element is
divided into a section in front of the rear axle and a section behind the rear
axle.
The section in front of the rear axle extends at an angle greater than that in
the section behind the rear axle with respect to a horizontal plane.
A fuel tank is situated in front of the rear axle such that air flow resulting from a drive of the motor vehicle flows around the fuel tank. Thus, the structure of invention guides the airflow past the rear wheel suspension.
None of the above can satisfy the design criteria of present invention, therefore the instant invention introduces an aerodynamic drag improvement structure for a vehicle which can address issues of prior art(s).

OBJECTS OF THE INVENTION
Primary object of the present invention is to provide an aerodynamic drag improvement structure for a vehicle which overcomes disadvantages associated with the prior art.
Another object of invention is to eliminate underfloor cover thereby reducing weight, which inturn leads to reduction in cost and improvement in. fuel efficiency.
l<'urther object of the present invention is to provide an aerodynamic drag improvement structure for a vehicle which is efficient.
Yet another object of the present invention is to provide an aerodynamic drag improvement structure for a vehicle which reduces turbulence of vehicle underbody airflow, thereby reducing drag.
SUMMARY OF THE INVENTION
According to this invention, there is provided an aerodynamic drag improvement structure for a vehicle comprising a longitudinal curved structure to be mounted on front suspension frame wherein the longitudinal structure comprises a center part undergoing angular transition at each end thereof to be extended further on both sides.
1^'urther according to this invention, there is provided an aerodynamic drag improvement structure for a vehicle comprising a plurality of parts including a center part between side parts maintaining a gap therefrom, which is situated rearward of the side parts on vehicle un4erbody in a direction from front towards rear of vehicle.
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. 1 shows:
Fig. 2 shows:
Fig. 3 shows:
Fig. 4 shows: Fig. 5 shows: Fig. 6 shows: Fig. 7 shows:
Fig. 8 shows: Fig. 8A shows:
Fig. 9 shows: Fig. 9ashows: Fig. 9b shows: Fig. 10 shows:
Fig. 10a shows: Fig. 10b shows:

Air flow in underbody in normal condition without aerodynamic improvement structure.
Suspension frame air dam in vehicle underbody of present invention.
An aerodynamic drag improvement structure for a vehicle according to invention.
Mounting details of the structure of present invention. Second embodiment of present invention. Angular variation of center part of the structure. Third embodiment of present invention. Fourth embodiment of present invention. ' Airflow movement in vehicle underbody by using front suspension air dam.
Velocity contours in a section Z=200mm, in which Without suspension frame air dam. With suspension frame air dam.
Turbulent kinetic energy plot in rear side of vehicle, wherein
Without suspension frame air dam. With suspension frame air dam.

DETAIL DESCRIPTION OF THE INVENTION WITH REFERENCE TO THE ACCOMPANYING DRAWINGS
The invention makes a disclosure in respect of aerodynamic drag improvement structure for motor vehicle. The structure constitutes an air dam like structure which is assembled to the front suspension frame of vehicle underbody called suspension frame air dam in width direction of vehicle for controlling vehicle

under body airflow movement. Thus, the present invention involves assembly of an aerodynamic drag (Co) improvement structure in the front suspension frame of the vehicle underbody which diverts the underbody air flow towards the ground and vehicle side body thereby reducing the overall vehicle aerodynamic drag coefficient. Referring to Fig. 2 in which the suspension frame air dam is detachably attached in the bottom side of front suspension frame in vehicle underbody directing towards ground.
The invention focuses on suspension frame air dam which is a rigid part with a plurality of mountings (M2', Mi', Mi, M2) as best seen in fig. 3. The central mountings (Mi', Mi) are used for mounting on the front suspension frame and the extreme end mountings (M2', M2) are employed for fitting on the floor side sill area.
The mountings (M2', M2) are fitted on the side sill by means of nut and the intermediate mountings (Mi', Mi) are clip fitted to the front suspension frame, which can be taken as an example.Regarding connecting means like nut, clip reference may be made to fig. 4.
The drag improvement structure of invention forms a longitudinal curved member with uniform thickness throughout. The structure constituting a single piece and is symmetrical about its central axis. It can be divided into three parts for understandability, namely a central part (Ai) with a side arm (A2', A2) on each side. The central part is uniform in height thus having a constant height. However, the arm (A2', A2) is having varying height from one end to other end. According to one embodiment, height of the arm progressively increases from central part end towards the edge (Ei', Ei) to be in contact with the sill.
The height of the suspension air dam is governed by factors, namely vehicle ground clearance, styling and requirements of aerodynamic drag improvement.

The profile of the air dam specifically the curvature in various locations are according to the vehicle under body airflow requirement. The profile of the structure has a smooth curve for required flow of air along the outer surface thereof.
Variation in height is such that, it avoids interference with the parts in the underbody adjacent to the suspension frame.
According to second embodiment, height of the arm (A2', A2) reduces gradually from the center part (Ai) end towards both the ends (Ei', Ei) as shown in fig. 5. The height (slope) is based on the vehicle underbody airflow movement.
The above design improves the vehicle underbody styling aesthetics and also reduces the part weight and cost.
In both the above embodiments, the approximately curved arm subtends an angle of 10 to 60 degrees with substantially straight center part as shown in fig. 6. This contributes to improvement in the vehicle underbody styling.
In accordance with third embodiment of present invention, for which reference rnay be made to fig. 7.The arm, a portion of which can be disposed at angle of 10 to 60° with respect to the center part. This also enhances acstheticness of the vehicle underbody.
According to fourth embodiment of invention as in fig. 8, air dam structure includes a plurality of parts (1, 2, 3) which are placed in the desired position in the underbody of vehicle. The plurality of parts include a center part (1) between side parts (2,3) maintaining a gap therefrom.The center part is situated rear ward of the side parts on vehicle underbody in a direction from front to\yards rear of vehicle. The substantially straight center part (1) with curvature at both ends thereof is placed on front suspension frame by being

mounted at both ends. The nearly straight side parts (2,3) are disposed.on the underbody at an angle with respect to the center part. One end of side part in proximity to the center part is in connection with vehicle underbody and extreme end of which is connected to under floor side sill area as shown. The side parts are symmetrical with respect to each other. The air flow follows the profile of outer surface of the parts of structure.
The center part and side parts are having uniform and same thickness.Further boLh the side parts and center part maintain constant height. However, height of the center part is smaller than that of side parts.
The center part is bent at an angle of 10-60° towards the side parts. The side parts are also situated at an inclination of 10-60°. So that curvature of center part can be in alignment with the respective side part for airflow as required.
The above provision also improves the vehicle underbody styling aesthetics and weight. The air flow movement is diverted in the similar way as shown in fig. 8.
The air dam is preferably made of any polymer of plastic by the method of injection molding without restricting scope of the invention to the same.
Results
This suspension frame air dam helps to reduce the turbulence created at the underbody regions in specific exhaust system, fuel tank, rear suspension system etc. The air dam mounted front suspension frame of the vehicle underbody diverts the underbody air flow towards the ground and vehicle side body thereby direct hitting of air behind the suspension air dam underbody parts is prevented. This reduces the underbody turbulence and the overall drag coefficient (Co). Fig.SA shows the details of airflow movement (F) in vehicle underbody by implementing front suspension air dam.

CFD Evaluation Results
Fig.9 and 10 shows the Computational fluid dynamic (CFD) analysis results in a typical passenger car with the proposed inventive part (suspension air dami) and without this part (Fig. 9b and 9a) wherein fig.9b indicates comparatively low airflow rate (Ci) and airflow diverted to the vehicle side body (C2). Fig 9 shows the velocity contours in an underbody section. It was observed that, when the suspension airdam is added, the ainuunL of air striking in the underbody components like exhaust pipes, front and rear floor is reduced as the portion of air is diverted to the vehicle sidebody. This reduces the underbody turbulence and simultaneously improves the rear wake region which is shown in Fig. 10, in which fig. 10(a) and 10(b) shows high wake region (Dr) and comparatively low wake region (D2) respectively.
In CFD evaluation an improvement in drag coefficient (Co) was observed with the help of the suspension airdam in the underbody of a typical passenger car. This is likely to improve the overall fuel economy of the vehicle.
Ad'vantageous Features
- Elimination of under floor cover thereby reducing weight, which in turn leads to reduction in cost and improvement in fuel efficiency. Reduction in turbulence of vehicle underbody airflow thereby reducing drag.
- Improvement in the vehicle aerodynamic drag coefficient (Co) which results in increase of the overall fuel economy.
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 aerodynamic drag improvement structure for a vehicle comprising a longitudinal curved structure to be mounted on front suspension frame wherein the longitudinal structure comprises a center part undergoing angular transition at each end thereof to be extended further on both sides.
2. An aerodynamic. drag improvement structure for a vehicle as claimed in claim 1 wherein the structure is having uniform thickness forming a single structure.
3. An aerodynamic drag improvement structure for a vehicle as claimed in claim 1 or 2 wherein the center part has a constant height, which is extended on both sides constituting arm on each side thereof which is approximately curved.
4. An aerodynamic drag improvement structure for a vehicle as claimed in any of the preceding claims wherein the arm, height of which increases gradually from the center part end towards edge.
5. An aerodynamic drag improvement structure for a vehicleas claimed in any of the preceding claims wherein the arm, height of which decreases progressively from the center part end towards edge.
6. An aerodynamic drag improvement structure for a vehicle as claimed in any of the preceding claims wherein the center part, which is substantially, straight undergoes an angular variation in the range of 10-60°.

7. An aerodynamic drag improvement structure for a vehicle as claimed in any of the preceding claims wherein the arm, a portion of which may be disposed at an inclination of 10 to 60° with respect to the center part.
8. An aerodynamic drag improvement structure for a vehicle as claimed in any of the preceding claims wherein the structure is mounted on bottom side of the suspension frame directing towards ground, wherein the centre part is assembled to the frame and each of the arms is fitted to the front under floor side sill area at edge.
9. An aerodynamic drag improvement structure for a vehicle comprising a plurality of parts including a center part between side parts maintaining a gap therefrom, which is situated rearward of the side parts on vehicle underbody in a direction from front towards rear of vehicle.

10. An aerodynamic drag improvement structure for a vehicle as claimed in claim 9 wherein the center part is substantially straight with curvature at both ends thereof placed on front suspension frame.
11. An aerodynamic drag improvement structure for a vehicle as claimed in claim 9 or 10 wherein the side parts are substantially straight and symmetrical with respect to each other, each of which is located at an inclination with respect to the center part and one end of the side part in proximity to the center part is in connection with vehicle underbody and extreme end of which is connected to under floor side sill area.

12. An aerodynamic drag improvement structure for a vehicle as claimed in any of the preceding claims 9 to 11 wherein the center part and side parts are having uniform and same thickness with constant height, in which height of the center part is smaller than that of said side parts.
13. An aerodynamic drag improvement structure for a vehicle as claimed in any of the preceding claims 9 to 12 wherein the center part is bent at an angle of 10-60° towards the side parts and the side parts are located at 10-60° to be in alignment with the respective curvature of center part.
14. An aerodynamic drag improvement structure for a vehicle as claimed in any of the preceding claims is associated with the advantageous features such as herein described.