FORM 2
THE PATENTS ACT 1970
(39 of 1970)
&
THE PATENTS RULES, 2003
COMPLETE SPECIFICATION
(See Section 10; rule 13)
TITLE OF THE INVENTION Fresh Air Duct For Vehicle Air Conditioning System
APPLICANTS
TATA MOTORS LIMITED, an Indian company
having its registered office at Bombay House,
24 Homi Mody Street, Hutatma Chowk,
Mumbai 400 001 Maharashtra, India
INVENTORS
Mr. Kavindra Rawat, Mr. Milind M Deo
and Mr, Ambadas Kandekar
All are Indian Nationals
of TATA MOTORS LIMITED,
an Indian company having its registered office
at Bombay House, 24 Homi Mody Street, Hutatma Chowk,
Mumbai 400 001 Maharashtra, India
PREAMBLE TO THE DESCRIPTION
The following specification particularly describes the invention and the manner
in which it is to be performed

FIELD OF INVENTION
This invention relates to fresh air duct for air conditioning system in an automobile and more particularly relates to fresh air ducting of HVAC (Heating, Ventilation and Air Conditioning) system for a vehicle.
BACKGROUND OF INVENTION
HVAC systems in vehicles consist of a duct which connects the blower of the HVAC unit to ambient. When the passenger operates the system in fresh air mode the fresh air is sucked by the blower through the fresh air duct. The fresh air duct has to be provided in such a way that rain water, hot air from engine/condenser compartment should not enter through it.
Conventionally the fresh air duct is generally connected to an opening in an interior panel/cowl or rain panel of BIW (Body In White) of the vehicle, and in most of the cases said interior panel is the wall of the vehicle. Said panel is not directly open to the ambient in order to prevent rainwater entry through it to the HVAC unit. Air is sucked through another panel which has the cutout open to atmosphere but is significantly offset from opening provided on the said fire wall.
Conventionally fresh air ducts are also connected from fire wall to leaf screen panel of a vehicle, the end of said duct towards leaf screen panel is covered with a grill. The leaf screen panel is located between the wind screen and bonnet of the vehicle.
The drawbacks associated with said conventional ducts are that it is necessary to provide a cutout or grill on exterior BIW which becomes visible from outside, therefore some time it is not desirable from exterior styling point of view.
OBJECTS OF INVENTION
The main object of this invention is to provide a fresh air duct in a vehicle which does not require any cutout or grill on exterior BIW and at the same time prevents entry of

rainwater and/or hot air from engine/condenser compartment.
Yet another object of this invention is to provide a fresh air duct in a vehicle which is simple in construction and cost effective.
BRIEF DESCRIPTION OF THE INVENTION
Fresh air duct of a vehicle in accordance with this invention basically comprises of a duct with two ends, wherein one of its end is having a thin opening while other end is having larger opening. The thin opening end is connected to the gap between leaf screen and bonnet of a vehicle and other end is connected to fire wall of a vehicle. The gap provided between the leaf screen and bonnet is provided in such a way that it should not be easily visible. Because of the thin gap, the provision of an exterior panel with cutout to suck the air from atmosphere or the grill is not required.
This duct isolates the HVAC (heating, ventilation and Air conditioning) unit from hot air of condenser compartment. Said duct is also provided with opening at its lowermost portion for drainage of rainwater from the bottom. Said duct is also further provided with net preferably Nylon net at the exit of the duct to restrict the insects and other foreign particles to come inside.
SUMMARY OF THE INVENTION
This invention relates to a fresh air duct for air conditioning system in an automobile comprising a duct having inlet and outlet ends, said inlet end is smaller in diameter than the opposing outlet end which is larger in diameter. Said inlet being connected in between the leaf screen and the bonnet of said automobile; said outlet being connected to the blower of the heating, ventilating and air conditioning system of said automobile through an opening provided on the fire wall of said automobile, filter means for removing suspended impurities from the incoming airflow provided near the exit end of the duct and drainage means for draining rain water and other impurities provided on said duct before the filter means.

BRIEF DESCRIPTION OF DRAWINGS
Fig. 1 shows the sectional view of front end of vehicle showing details of fresh air duct in accordance with this invention.
Fig 2. Shows fresh air duct used in this invention.
Fig 3. shows the exploded view of the fresh air duct.
DETAILED DESCRIPTION OF THE INVENTION
Referring now to the drawings wherein the showings are for the purpose of illustrating a preferred embodiment of the invention only, and not for the purpose of limiting the same.
Referring to Figs 1, 2 & 3: Fresh air duct (1) of a vehicle in accordance with this invention basically comprises of a duct with two ends (2,3), wherein inlet end (2) is having smaller opening area compared to the outlet end (1). The width (w) of the doct is restricted to opening provided at the firewall for HVAC unit. The inlet (2) and outlet (3) openings are extended in the entire width (w) of the duct (refer figure 3). Said thin opening end (2) is connected to the gap (4) between leaf screen (5) and bonnet (6) of a vehicle and other end (3) is connected to fire wall (7) of a vehicle. Said gap (4) provided between the leaf screen (5) and bonnet (6) is provided in such a way that it should not be easily visible. Because of very thin gap the provision of an exterior panel with cutout to suck the air from atmosphere or the grill is not required.
This duct isolates the HVAC unit from hot air of condenser compartment (8). Said duct is also provided with opening (9) at its lowermost portion for drainage of rainwater from the bottom. Said duct is also further provided with net (10) preferably Nylon net at the exit of the duct to restrict the insects and other foreign particles to come inside.
The blower of HVAC unit (11) is connected to firewall (7), the cutout at the firewall (12) is connected to the gap between leaf screen (5) and bonnet (6) by the fresh air duct (1). This way it connects the blower to the atmosphere (13) and isolates it from engine/condenser compartment (8). The nylon net (10) is placed at firewall cutout

which avoids the insects, dust or foreign particles to come inside. The blower is connected to the outside atmosphere through the duct.
Referring to figures 2 &3, figures 2 & 3 shows a preferred embodiment of duct as described above. The duct assembly further provided with a baffle (16) for improving the water proof-ness of the duct. A drainage hole (9) provided at bottom portion said duct to drain the water entering into the duct. The water entering into the duct strikes against the baffle and lead to the drainage hole (9) provided at the bottom. The area of opening of drainage hole is much lesser than the area of opening of inlet (2). An air dam (17) is provided to restrict entry of the water/ water droplets in HVAC system under full blower suction. The baffle (16) and air dam (17) are overlapping in the flow path to effectively restrict entry of the water into the HVAC system. The geometry of the duct has been designed to reduce pressure drop and to make more production friendly. The duct is designed in two-part (14, 15) and combined together by snap fitting arrangement. The part (15) is connected to the firewall (7) of the vehicle. The total duct assembly can be removed from the firewall and serviced independently. The air dam (17) and baffle (16) are integrated and removably connected with the part (15) respectively. Form (18,18a) are provided at the inlet portion (la) of the duct to sealingly locate with the leaf screen and the bonnet of the vehicle. The forms are made ofpolyurethane.
Advantages
The duct connects the blower to ambient with out an exterior panel cutout. This way it avoids an exterior panel with cutout.
Duct is having provision for avoiding rainwater entry.
Duct eliminates the need for firewall integrated rain or cowl panel.
Duct isolates the blower from hot air of condenser compartment
Duct is having provision to stop insects and foreign particles to enter the blower and passenger compartment.
The duct assembly can be removed and serviced easily.

The foregoing description is a specific embodiment of the present invention. It should be appreciated that this embodiment is described for purpose of illustration only, and that numerous alterations and modifications may be practiced by those skilled in the art without departing from the spirit and scope of the invention. It is intended that all such modifications and alterations be included insofar as they come within the scope of the invention as claimed or the equivalents thereof.

WE CLAIM
1. A fresh air duct for air conditioning system in an automobile comprising a duct having inlet and outlet ends, said inlet end is smaller than the opposing outlet end, said inlet being located between the leaf screen and the bonnet of said automobile, said outlet being connected to the blower of a HVAC system of said automobile through an opening provided on the fire wall of the automobile, and a drainage means provided between said inlet and outlet ends..
2. The fresh air duct as claimed in claim 1, wherein the inlet of the duct is sealingly connected to a narrow gap provided between the leaf screen and the bonnet.
3. The fresh air duct as claimed in claim 1 wherein said duct is of two-part
design.
4. The fresh air duct as claimed in claim 1 wherein said duct having a baffle for deflecting water to the drainage provided therein.
5. The fresh air duct as claimed in claim 1 wherein said duct is having an air dam for preventing entry of water into said blower.
6. The fresh air duct as claimed in claims 1, wherein said air duct isolating the air entering through the inlet of said duct from the engine/condenser compartment.
7. The fresh air duct as claimed in claims 1 to 3, wherein the filter means provided at said outlet end.
8. The fresh air duct as claimed in claims 1 to 4, wherein said drainage means is located at the lowest part of said duct
9. A fresh air duct as claimed in any one of the previous claims wherein said duct can be removed and serviced.

10. A fresh air duct for air conditioning system in an automobile substantially as herein described and illustrated with particular reference to the figures in the accompanying drawings.