FORM 2
THE PATENTS ACT 1970
{39 of 1970)
&
THE PATENTS RULES, 2003
COMPLETE SPECIFICATION
(See Section 10; rule 13) TITLE OF THE INVENTION
An improved 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
Pravin A. Tilekar
Milind Deo
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 nature of invention and the manner in which it is to be performed.

Field of the Invention
The present invention relates in general to vehicle air conditioning system and more particularly it relates to an improved air conditioning system having improved wiring harness or controls.
Background of the 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 or both cooled and heated by the HVAC unit as per passenger needs and is finally delivered to the passenger cabin.
Conventional HVAC unit comprises of the blower assembly, a heater assembly, an evaporator assembly, a duct assembly, a condenser unit and a compressor unit. Said blower assembly, the heater assembly, the evaporator assembly and the duct assembly are housed below the instrument panet/dashboard. Fresh air from the atmosphere or re-circulated air from the vehicle cabin is filtered by a filter assembly within the HVAC unit and conditioned air is delivered to cabin through duct assembly.
Reliability and durability as well as the performance of the vehicle air conditioning system are important aspects from customer point of view. Draw back associated with said conventional HVAC unit is that compressor may remain ON when blower may not be working. In order to overcome the above said drawback this invention is devised. Following are the draw backs associated with said conventional HVAC unit:
1. Compressor may remain ON when HVAC blower is OFF and hence remain unnoticed by user, which in turn may result in high power and thereby fuel consumption without achieving thermal comfort for vehicle occupants

2. Liquid refrigerant may enter compressor and damage/ reduce life of compressor which in turn may damage/ reduce life of entire HVAC system.
3. All system components including HVAC housing may get iced up and may result in condensate formation and leak inside vehicle cabin resulting into wet floor and foul smell.
4. System pressures may rise which in turn result in low durability/ breakdowns and high power consumption of HVAC system
Object of this invention
The main object of the present invention is to provide an improved air conditioning system.
Another object of the present invention is to provide an improved air conditioning system which can be used in the existing vehicle architecture with minimal changes and to satisfy the vehicle cabin cooling requirements.
Another object of the present invention is to provide an improved air conditioning system having functionally well integrated components for full proof working logic for optimized performance.
Another object of the present invention is to provide an improved air conditioning system having high durability without functional failure.
Yet another object of the present invention is to provide an improved air conditioning system which is simple in construction and cost effective.

Statement of invention
An improved air conditioning system comprises; a control means (01) for ignition; a fuse means (02) for vehicle wiring harness; a relay means (03) for ventilation blower; a HVAC control panel (04); a resistor means (05) for controlling blower speed; a blower unit (06) for ventilation; a switch interlock (07) for operating air conditioning; a thermister means (08); a sensor means (09) for sensing the refrigerant pressure; an electronic control unit (10); a first relay (11) for operating clutch of compressor; a second relay (12) for operating cooling fan; said resistor means (05) for controlling said blower speed, switch interlock (07) for operating air conditioning having indicator light, AC operator module having illumination lights are housed in said HVAC control panel (04) and are interfaced with each other with the help of wiring harness such that when engine is started said first operating relay (11) engages the compressor clutch only when the said blower unit (06) is turned ON and said second relay (12) starts the cooling fan for cooling the vehicle cabin.
The system , in accordance with this invention, wherein said thermister (08) is having a thermo-amplifier housed in said HVAC control panel (04) or electronic control unit of an engine.
The said system , in accordance with this invention, wherein said control means (01) is an ignition switch which gives signal to operate said relay means (03) for ventilation blower to connect vehicle battery supply (11) to drive ventilation blower unit (06).
The said system , in accordance with this invention, wherein said HVAC control panel (04) is electric hardware unit provided for the selection of desired settings of HVAC control unit as per requirement of user, ON/OFF signal of AC compressor is selected based on the ON/OFF supply voltage of motor for said blower unit (06).

The system, in accordance with this invention, wherein said control means (01) is interfaced with said fuse means (02) for vehicle wiring harness, said fuse means (02) is interfaced with said relay means (03) for ventilation blower, said relay means (03) for ventilation blower is interfaced with HVAC control panel (04) and said resistor means (05) for controlling blower speed is interfaced with said HVAC control Panel (04).
The said system, in accordance with this invention, wherein said blower unit (06) for ventilation and said switch interlock (07) for operating air conditioning are interfaced with said resistor means (05) for controlling blower speed, said switch interlock (07) for operating air conditioning is interfaced with thermister means
(08) which in turn interfaced with refrigerant pressure sensor (09).
The said system , in accordance with this invention, wherein said sensor means
(09) is interfaced with electronic control unit (10), said first relay means (11) for
operating compressor clutch and said second relay means (12) for operating
cooling fan are interfaced with said electronic control unit (10).
The said system , in accordance with this invention, wherein said blower unit (06) is switched ON when said ignition switch (01) is ON, said fuse means (02) is in working condition or has not failed, said relay means (03) provided on HVAC control panel (04) is switched ON and said resistors means (05) are in working condition.
The said system , in accordance with this invention, wherein said switch interlock (07) is switched ON when said ventilation blower unit (06) provided on HVAC control panel (04) is switched ON and resistors means (05) are in working condition.

The said system , in accordance with this invention, wherein said ventilation blower unit (06) is switched ON, said resistor means (05) are in working condition, switch interlock (07) is ON, thermister means (08) signal is ON and refrigerant pressure sensor (09) signal is ON to pass AC ON request signal to said electronic control unit (10) which facilitates to switch ON or OFF said first relay means (11) for operating compressor clutch and said second relay means (12) for ON or OFF operation of cooling fan.
The system , in accordance with this invention, wherein said electronic control unit (10) having a threshold limit of AC ON signal even at lowest allowable electric charge balance condition of said battery.
The system , in accordance with this invention, wherein said HVAC control panel (04) having a threshold limit of AC ON indicator illumination even at lowest allowable electric charge balance condition of said battery.
Brief Description of invention
In accordance with the present invention, an improve air conditioning system comprises; control means 01 for ignition, fuse means 02 for vehicle wiring harness, relay means 03 for ventilation blower, control means 04 for ventilation blower, resistor means 05 for controlling blower speed, blower unit 06 for ventilation, switch interlock 07 for operating air conditioning, thermister means 08, refrigerant pressure sensor 09, Electronic control unit 10, first relay 11 for operating compressor clutch, and second relay 12 for operating cooling fan, Wherein said resistor means 05 for controlling said blower speed, switch interlock 07 for operating air conditioning (AC) having indicator light, AC operator module having illumination lights are housed in said HVAC control panel and are interfaced with each other with the help of wiring harness such that when engine is started said first operating relay 11 engages the compressor clutch only when

the said blower unit 06 is turned ON and said second relay 12 starts the cooling fan for cooling the vehicle cabin. The said first operating relay 11 engages said compressor clutch only when said blower unit 07 is turned ON. The said thermister 08 having a thermo-amplifier housed in said HVAC control panel or electronic control unit of an engine.
Brief description of drawings
Figure-01A shows vehicle heating system with bypass line
Figure-01B shows vehicle heating system without bypass line
Figure-01C shows HVAC or air conditioning and heater unit or air conditioning unit, HVAC control panel or air conditioning and heater unit control panel or air conditioning unit control panel electrical hardware interface with the other components of the system
Figure-02 shows the block diagram of flow of control logic embedded in HVAC or air conditioning and heater unit or air conditioning unit, HVAC control panel or air conditioning and heater unit control panel or air conditioning unit control panel.
Figure-03 shows the block diagram showing interconnection between vehicle battery, fuse, ventilation blower relay, ventilation blower and AC ON/ OFF switch interlock relay, HVAC control panel unit or air conditioning and heater unit control panel or air conditioning unit control panel, ventilation blower speed control resistor with thermal fuse, ventilation blower motor, AC operator module, thermister with thermo-amplifier, refrigerant pressure sensor, engine electronic control unit, compressor clutch operating relay with fuse, cooling fan operating relay with fuse, compressor clutch and cooling fan

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,
Now referring to figure-01-03, In accordance with the present invention, ah improve air conditioning system comprises; control means 01 for ignition, fuse means 02 for vehicle wiring harness, relay means 03 for ventilation blower, control panel 04 Heating Ventilation and Air Conditioning (HVAC), resistor means 05 for controlling blower speed, blower unit 06 for ventilation, switch interlock 07 for operating air conditioning, thermister means 08, refrigerant pressure sensor 09, Electronic control unit 10, first relay 11 for operating compressor clutch, and second relay 12 for operating cooling fan, Wherein said resistor means 05 for controlling said blower speed, switch interlock 07 for operating air conditioning (AC) having indicator light, AC operator module having illumination lights are housed in said HVAC control panel and are interfaced with each other with the help of wiring harness such that when engine is started, said first operating relay 11 engages the compressor clutch only when the said blower unit 06 is turned ON and said second relay 12 starts the cooling fan for cooling the vehicle cabin.
The said first operating relay 11 engages the compressor clutch only when said
blower unit 06 is turned ON. The said thermister means 08 is having a thermo-
amplifier housed in said HVAC control panel 04 or electronic control unit 10 of an
engine.
The control means 01 is an ignition switch which gives signal to operate said
relay means 03 for ventilation blower to connect vehicle battery supply (11) to
said drive ventilation blower unit 06.

The HVAC control panel 04 is an electric hardware unit provided for the selection of desired settings of HVAC control unit as per requirement of user, the ON/OFF signal of AC compressor is selected based on the ON/OFF supply voltage of motor for said blower unit 06.
The control means 01 which is an ignition switch is interfaced with said fuse means 02 for vehicle wiring harness and said fuse means 02 is interfaced with said relay means 03 for ventilation blower; Said relay means 03 for ventilation blower is interfaced with HVAC control panel 04, said resistor means 05 for controlling blower speed is interfaced with said HVAC control Panel (04).
The blower unit 06 for ventilation and said switch interlock 07 for operating air conafftforrrng are fnterraced' with sard resfstor means 05 for controrVr'ng bfower speed. The switch interlock 07 for operating air conditioning is interfaced with thermister means 08 which in turn interfaced with refrigerant pressure sensor 09.
The refrigerant pressure sensor 09 is interfaced with electronic control unit 10; said first relay means 11 for operating compressor clutch and said second relay means 12 for operating cooling fan are interfaced with said electronic control unit 10.
The blower unit 06 is switched ON when said ignition switch 01 is ON, said fuse means 02 is in working condition or has not failed, said relay means 03 for ventilation blower is ON, said relay means 03 for ventilation blower on HVAC control panel 04 is switched ON and said resistors means 05 for controlling blower speed are in working condition.
The switch interlock 07 is switched ON when said ventilation blower switch 06 provided on HVAC control panel 04 is switched ON and resistors means 05 for controlling speed of ventilation blower are in working condition.

The ventilation blower unit 06 provided on HVAC control panel 04 is switched ON and resistor means 05 for controlling ventilation blower speed are in working condition, switch interlock 07 is ON, thermister means 08 signal is ON and refrigerant pressure sensor 09 signal is ON to pass AC ON request signal to engine electronic control unit 10 to take decision to switch ON/ OFF first relay means 11 for operating compressor clutch and second relay means 12 for ON/ OFF operation of cooling fan.
The electronic control unit 10 is having a threshold limit of AC ON signal even at lowest allowable electric charge balance condition of said battery. The said HVAC control panel 04 is having a threshold limit of AC ON indicator illumination even at lowest allowable electric charge balance condition of said battery.
An improved vehicle air conditioning system is having heating ventilation & air conditioning (HVAC) unit (A) or air conditioning & heater unit or heater unit, Heater hoses/ pipes (D, E), Bypass line (F) , Upper coolant line (G), Lower coolant line (H), Thermostat (I), Engine (J), Engine Coolant circuit.
Said HVAC unit (A) or air conditioning & heater unit or heater unit further comprising heat exchanger (C) to transfer engine coolant heat to air, compressor, compressor drive, condenser, receiver dryer bottle, expansion valve, evaporator, suction and discharge line pipes, flap arrangement and flap movement mechanism, blower motor and impeller to suck air in fresh or recirculation mode and blow inside vehicle cabin through heat exchanger and add on Positive temperature coefficient heater units(B), control panel,
Said heater hoses/ pipes (D, E) are provided for connecting cabin heater inlet and outlet to said engine coolant circuit. Said engine Coolant circuit comprising a coolant pump (K), Coolant reservoir (L) and engine cooling module (M).

Said engine cooling module (M) further comprising a radiator coil, radiator fan, radiator shroud.
The HVAC unit (A) or air conditioning and heater unit or heater unit houses electric heater units (B) in air flow path next to coolant based heater unit. Said coolant based heater unit inlet and outlet are connected to engine coolant circuit through said coolant hoses/ pipes (D, E).
When engine starts, the coolant is pumped by coolant pump (K) from coolant reservoir (L) and is circulated through water jacket/s of engine (J) meant for cooling of said engine and is further circulated to by pass line (F) and coolant based cabin heater (C) through heater suction hose/ pipe (D).Thermostat (I) provided in the coolant flow path allows the coolant flow only to by pass line