FORM 2
THE PATENTS ACT 1970
(39 of 1970)
&
THE PATENTS RULES, 2003


COMPLETE SPECIFICATION
(See Section 10; rule 13)
TITLE OF THE INVENTION A Roof mounted Air Duct for Vehicles
APPLICANT
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
Ram Bothuca, Ambadas Kandekar and S H Kapoor
All 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 cabin climate control system for an automobile and more particularly relates to a roof mounted Heating Ventilation and Air Conditioning (HVAC) ducting system.
BACKGROUND OF INVENTION
An HVAC unit is commonly used in automobiles to provide comfort to passengers in different climatic conditions. Air is drawn into the HVAC unit either from inside the cabin of the automobile or from the outside atmosphere. The drawn air is cooled or heated by the HVAC unit as per passenger needs and is finally delivered to the passenger cabin.
In vehicle with large cabin size than car, the comfort to the rear passenger is a challenge. In high temperature and high humidity territory, the cooling needs of rear rows of passenger are high, which is not possible by front fitted HVAC unit. Conditioned air handling ducts will meet this requirement but the ducting is challenging because of packaging constrain. Rear unit with duct will result into huge energy loss in ducts. It is required to have cooling unit fitted inside cabin with minimum ducting size and with effective vent developed to meet cooling requirement.
In Passenger carrying bus like vehicle, there is a need to provide cold air to rear passengers also. Front vent openings are used to provide comfort for driver and co-driver. It is common practice to provide separate ducting for rear passengers, it is needed to provide separate HVAC unit with ducting. HVAC unit is mounted at rear of at top of the vehicle.

OBJECTS OF THIS INVENTION
In this invention, efficient air distribution ducts are used which starts from front side and run towards back passengers with inventive vents for better air flow over passengers.
> The main object of this invention is to provide effective air distribution of cold air coming out from evaporator
> Yet another object of this invention is to have minimum energy loss of air during it flows through ducts.
> Yet another object of this invention is to direct air on passengers with bi¬directional air vent for better comfort.
BRIEF DESCRIPTION OF THE DRAWINGS
Figure 1 shows the vehicle showing the total refrigerant circuit and air distribution units as per the first embodiment of the invention.
Figure 2 shows the isometric view of the roof mounted cooling unit and duct assembly as per the first embodiment of the invention.
Figure 3 shows the top and sectional view of the duct assembly as per the first embodiment.
Figure 4 shows the vehicle showing the total refrigerant circuit and air distribution units as per the second embodiment of the invention.
Figure 5 shows the isometric view of the roof mounted cooling unit and duct assembly as per the second embodiment of the invention.
Figure 6 shows the top and sectional view of the duct assembly as per the second embodiment.
Figure 7 shows the exploded view of integrated arrangement of duct with headliner.

Figure 8 shows the dual barrel arrangement for air vents.
DETAIL DESCRIPTION OF INVENTION
Referring now to the drawings wherein the showings are for the purpose of illustrating preferred embodiments of the invention only, and not for the purpose of limiting the same
Referring to Fig 1. HVAC unit with air distribution ducts in this invention comprises of a roof mounted cooling unit assembly (2) consisting of blower assembly, evaporator with expansion device, adapter and air ducts, vent or grill assembly. Roof evaporator is connected to main air conditioning circuit through pipe (3). Main air conditioning circuit includes a compressor (4) running on engine (not shown), main condenser (5), an auxiliary condenser located at bottom (7) of the vehicle (1), front cooling unit (6). All components are connected with pipes through which refrigerant travels. In high temperature and pressure refrigerant coming out from compressor (4) is converted into liquid phase by rejecting heat to atmosphere by condenser (5, 7) and this high pressure liquid refrigerant is allowed to pass through expansion and evaporators for front cooling unit (6) and for roof mounted cooling unit (2). The roof unit with air distribution system is mounted in the top side of vehicle along with ducting integrated with headliner.
Referring to figure 2, and figure 3 the roof mounted cooling unit (2) having a blowers (8), evaporator (9) arranged in front of the blowers and a duct (10) to distribute the air coming through the evaporator (9) to the passenger compartment. The duct (10) is connected to the evaporator assembly (9) through an adaptor (11). The underside of adaptor (11) provided with air vents to distribute air in front row of passenger compartment. The first end of the duct (10) is connected to the adaptor and second end is formed in a branched configuration. The branched configuration of duct (10) having three passages (10a, 10b & 10c) to divide the flow equally and end of passages provided with vents located in rear side of the passenger compartment. The first and third passages are located either side of the second passages which is aligned

with the center of the vehicle. The blower and evaporator assembly is located above the driver and co-driver and the duct (10) starting from the front side of the vehicle and running to the rear side of the vehicle to distribute the air to the rear of the passenger compartment. The adaptor is provided with air vent located between evaporator and duct assembly is distributing air to the front side of the passenger compartment i.e first row the passenger compartment. Where as the duct (10) is supplying air to the remaining rows of the passenger compartment as per vehicle configuration. A recess (15) is provided on the duct (10) to accommodate control switches and roof lamp. The shape of the recess is such that it creates minimum resistance to the flow of air through the duct (10). The recess is located before branching of the duct (10) and in front of the central passage (10b).
Figure 4, 5 & 6 shows an alternative embodiment for the duct arrangement which is suitable for a vehicle (1') is having extended length with different variant of wheel base. The duct (10) has an extended portion (10') at one end connecting to the adaptor (11). The extended portion (10') increases the length of the duct so that conditioned air can be distributed to the rear of the vehicle more efficiently. The duct is further provided with air out lets (14) at end near to the extended portion to distribute air in the middle of the passenger compartment.
Figure 7 shows the manufacturing scheme for the air conditioning duct arrangement as per present invention. The duct arrangement is formed as integral to the headliner (17) of the vehicle. The duct (10) is divided into the upper and lower part. Where the headliner liner upper portion is act as the lower part of the duct and an upper part (18) positioned on the top of the headliner create a closed passage for air flow to form as duct (10). The head liner is provided opening for accommodating blower - evaporator assembly (8, 9) and the adaptor (11). During assembly the headliner fitted with upper part of the duct (18) is attached to the roof of the vehicle. Then the blower-evaporator assembly and the adaptor is attached to the roof of the vehicle, by accommodating into the opening provided in the headliner thereby a continuous passage for air flow formed by the blower-evaporator, adaptor and
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headliner with the upper part of the duct. Openings are provided on the headliner to provide air vents (12 &14). Two different embodiments with same blower-evaporator, adaptor and duct make the arrangement suitable for two different variants of wheel bases. The blower-evaporator assembly is used with adaptor for different variants of wheel bases with commonization of headliner and duct in a single component die using die technology.
Figure 8 shows the air vents for distributing the air. Each air vent provided with two barrels/grilles (19, 19') having series of flap (20) for directing air. The barrels/grilles are supported on bazzle (grill housing, 18), where the flaps can be adjusted in lateral direction and each barrel can be swing in longitudinal direction of the vehicle. This arrangement makes it easy for adjusting the air distribution in all four directions. Each air vents provided with two barrels so that air can be directed to two different direction at same time from a single air vent. This arrangement gives benefit of arranging air distribution for each passenger even if the no. of passengers are more than the no. of air vents provided for air distribution.
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.
2 1 MG m9

We Claim
1. A roof mounted air duct for an air conditioned vehicle comprising; a main duct having a first end for receiving inlet air and a second end with branched configuration for distributing air from said air duct toward respective rear seats of the vehicle; an adaptor for connecting said first end to a blower-evaporator assembly; and an extended duct portion at said first end for optionally increasing the length of said duct.
2. A roof mounted air duct as claimed in claim 1 wherein said blower-evaporator assembly located front end of the passenger compartment of said vehicle.
3. A roof mounted air duct as claimed in claim 1 wherein Plurality of air vents provided underside of said adaptor for emitting air from said duct toward front row of passenger compartment.
4. A roof mounted air duct as claimed in claim 1 wherein said branched configuration consists of three passages with air vents provided at the end of said passages.
5. A roof mounted air duct as claimed in claim 1 wherein the head liner of said vehicle acting as a lower part of the main duct and an upper part attached to the head liner to form a closed passage for said main duct.
6. A roof mounted air duct as claimed in claim 5 wherein said duct integrated headliner is manufactured from a single component die for different variants of wheel bases and same blower-evaporator, adaptor is used for said variants of wheel bases.
7. A roof mounted air duct as claimed in claim 1 wherein plurality of air vents provided under side of said main duct at first end for distributing air to the middle row of the passenger compartment of said vehicle when said extended duct portion provided to said first end.
8. A roof mounted air duct as claimed in claim 1 wherein said main duct provided with recess to accommodate control switches and/or roof lamp.
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9. A roof mounted air duct as claimed in any one of the claims 2, 3 and 5 wherein said air vent provided with two barrels (grilles) supported on a bazzle (grille housing); and each grille capable of swing in particular axis and provided with series of adjustable flaps.
10. A roof mounted air duct for an air conditioned vehicle comprising; a main duct having a first and second end, said first end located at front side of the passenger compartment of said vehicle for receiving inlet air and said second end with branched configuration for distributing air from said air duct toward rear side of the passenger compartment of said vehicle; an adaptor for connecting said first end to a blower-evaporator assembly; and the underside of said adaptor and main duct provided with air vents to emit air toward front and middle row of the passenger compartment respectively.
11. A roof mounted air duct substantially as herein described with reference to accompanying drawings.
Dated this 21st day of August 2009
TATA MOTORS LIMITED By their Agent & Attorney
Karuna Goleria of DePENNING & DePENNfNG
2 1 AUG Z009