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


PROVISIONAL SPECIFICATION
(See Section 10; rule 13)
TITLE OF THE INVENTION
Automobile 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
Abhishek Gupta, Ram Mohan Bothuca both 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 describes the invention


FIELD OF INVENTION
This invention is related to dual condenser system for air conditioning system used in automobiles where one air conditioning unit is in front and the second unit is placed in the roof of the vehicle.
BACKGROUND OF THE INVENTION
Generally the automobile air conditioning system has engine driven compressor, a condenser which liquefy high temperature high pressure gases by rejecting heat to the ambient, an evaporator wherein the liquid refrigerant convert to gases by absorbing heat and delivers conditioned air to the passenger compartment. The adoption of this type of the system for big vehicles poses a challenge as the packaging of the air conditioner's component in the available space is very difficult. Especially to meet the requirement of the higher heat rejection to the ambient in high seating capacity vehicles in hot and humid environment like in India, condenser packaging is a challenge.
Normally for small passenger vehicles the condenser is packaged in front of the radiator as the size of the condenser is small and availability of the ram air makes it possible to work it efficiently. When the vehicle size becomes bigger the size of the condenser need to be bigger. With bigger condenser size, it is not possible to package it in front of the radiator as it hampers the performance of the radiator and other heat exchanger. For bigger capacity vehicles, people generally place condensers at the roof with higher capacity dedicated fan. Placement of the condenser at higher level require compressor to work more, at the same time the condenser fan consumes a lot of energy.
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OBJECTS OF INVENTION
Main objective: With a need to package a large condenser to fulfill the requirement of high heat rejection, the condenser is split in two where the main condenser is placed in front end of vehicle with a intention to use the available space infront of the radiator without effecting the performance of other heat exchanger of the vehicle system and utilization of available ram air, and the second condenser is placed underneath the vehicle floor
Another objective of this invention is to use of secondary/auxiliary condenser in the AC system with all precaution to protect it from the stone and mud while vehicle operating in a rough and dusty environment.
Yet another objective is to have a front AC unit which is mounted on fire wall of the automobile/vehicle and is easily serviceable and can be removed to have accesses to other serviceable part of the Vehicle system. At the same time the complete AC system should be assembled in minimum time production assembly line .
BRIEF DESCRIPTION OF INVENTION
Air conditioning system in accordance with this invention basically consists of following components AC Condensers
1. Main Condenser Core
2. Auxiliary condenser core
3. Protective shield
4. Auxiliary condenser mounting frame
5. Auxiliary condenser fan motor assembly
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6. Auxiliary condenser assembly mounting bracket
7. Refrigerant pipes Front AC unit
8. Front half of the casing
9. Rear half of the casing
10. Side cap
11. Blower motor
12. Evaporator core
13. Filter
14. Insulation
15. Refrigerant pipeline
16. Drain hose
17. Grilles at the outlet end
The AC system has two condensers; main condenser is placed in front of the radiator and the auxiliary condenser is placed underneath the floor of the vehicle. The auxiliary condenser is fixed on the channel frame. At the top of auxiliary condenser core an electric fan is mounted to assist heat transfer. The channel frame has mounting location for protective shield. This assembly of the condenser core, electric fan , protective shield and the channel frame is mounted underneath the vehicle at an angle so that it faces the ram air.
Front AC unit is mounted on the fire wall. The casing of the front unit has three parts, which are assembled together to make the evaporator and blower housing.
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BRIEF DESCRIPTION OF DRAWINGS
Fig. 1 shows a location of the main component of the AC system in the vehicle in
accordance with this invention
Fig. 2 shows a front view and top view of the auxiliary condenser in accordance
with this invention
Fig.3 shows a isometric view of the auxiliary condenser in accordance with this
invention
Fig.4 shows a front view and top view of the front AC unit in accordance with this
invention
Fig.5 shows an isometric view of the front AC unit in accordance with this
invention
DETAILED DESCRIPTION OF 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,
Details of total AC system.
Now referring to figs. 1 the main condenser (1) in placed in front of the radiator
and the auxiliary condenser (2) is placed underneath the vehicle floor (3). The
front air conditioning unit (4) is mounted on firewall and the rear airconditioning
unit (5) is mounted inside of the roof (7) of the vehicle. Compressor (6) is engine
driven.
Compressor(6) delivers high pressure and high temperature refrigerant to the
main condenser (1) where it desuperheat and condense the refrigerant, it further
pump the refrigerant to the auxiliary condenser (2) for condensation and
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subcooling of the refrigerant. Now the subcooled liquid refrigerant is passed through the receiver dryer bottle for the absorption of any moisture present. Upstream of the receiver dryer bottle the refrigerant carrying line is branched into two, one line delivers refrigerant to the front air conditioning unit (4) and the other line delivers refrigerant to the roof air conditioning unit (5), where in the refrigerant after expansion gains heat from the conditioned air and becomes gaseous. The refrigerant lines carrying low temperature, low pressure gaseous refrigerant from the front air conditioning unit and roof air conditioning unit join to deliver it to compressor. This completes one cycle of operation. Referring to Fig 2 and 3, An electric fan (8) is mounted on the auxiliary condenser core (9). The electric fan is having a strip of foam at its periphery of the fan shroud (10) sandwiched between the shroud and the condenser core. The condenser core and the fan assembly are mounted on the C channel frame (11) to provide it support. Z shaped brackets of 2 nos. each (12 and 13) of differential height are fixed on channel frame at the shorter edge of the frame to provide the necessary angle to the assembly to get the benefit of the ram air ( 17). The condenser core guard (14) is fixed on the C channel frame(ll) has scoops which faces the ram air and divert maximum air to the condenser core. The complete condenser assembly is thus mounted underneath the vehicle floor (3) with the help of brackets (12 and 13), spring washer and nut (15). Refrigerant pipes are connected to the refrigerant ports (16). Figure 3 gives the descriptive view for condenser core guard. The auxiliary condenser can also be packaged in a bumped cavity on the vehicle floor. Now referring to figs. 4 and 5
Front evaporator casing is made of mainly two parts front half (18), rear half (19). These two parts are stuck together to make a single piece which houses the front evaporator coil. The evaporator core (21) is stuffed inside the evaporator casing from the side opening, which is further closed with the side unit cap (20).
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Rear Blower scroll (22) is coupled with blower motor (23) to suck the air from the cabin and delivered on to the evaporator (21) for cooling and dehumidification. The cooled and dehumidified air from the evaporator (21) passes through the filter (24) which is placed in front of the evaporator. The other end of the said evaporator is connected to the flexible refrigerant hoses (25) and routed to the engine side of the firewall.
Said filter (24) removes the water droplets and dust from the cool and dehumidified air delivered through the front grilles(26) at the outlet end (25). Drain hoses (28) are located at the sides of the bottom casing to drain the condensed water formed over the evaporator.
Insulation (29) is provided at the outer surface of the front half of the casing (18) of the front air conditioning unit in order to prevent the transfer of heat and to prevents condensation of water droplets formation on the outer part of the said casing of the front air conditioning unit.
3 Grilles (26) are located at outlet end ( 27) have a provision to adjust in horizontal (left and right) and vertical (up and down) direction according to the requirements. The cool and dehumidified air is distributed to all grilles in such a way that the air distribution and the temperature distribution are uniform through out the vehicle / automobile. Air distribution to each grilles outlet is optimized through experiments for providing comport to the passengers inside the vehicle. The arrangement is made simple without any ducting to reduce the air side pressure drop and heat pickup while it is passing through the ducts. The complete front air conditioning unit is mounted on the engine hood (31) with the help of mounting brackets (30)which in turn mounted on the firewall (33) with the help of bracket (32) with suitable fasteners. The engine hood (31) is provided on the firewall to have accesses to the serviceable parts in the engine compartment from inside of the vehicle. With this design, as the front air conditioning unit is
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mounted on this engine hood and flexible hoses are used for the plumbing, complete air conditioning unit can be removed along with engine hood by removing the brackets (32) to accesses the engine parts for servicing. This activity is done without any recovery of the refrigerant from the air conditioning circuit as there is no need to dismantle any parts form the AC unit.
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.
Dated this 30th day of January 2009
TATA MOTORS LIMITED By their Agent & Attorney

(Karuna Goleria) of DePENNING & DePENNING