FORM 2
THE PATENTS ACT 1970
(39 of 1970)
&
THE PATENTS RULES, 2003
PROVISIONAL SPECIFICATION
(See Section 10; rule 13)
TITLE OF INVENTION
Energy Efficient Vehicle Heating System And Method Of Heating Vehicle Thereof


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. Pravin Arun Tilekar and Mr. Mangesh Maruti Khochare
Both 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 describes the invention.


FIELD OF INVENTION
The present invention relates in general to vehicle heating system and more particularly this relates to vehicle heating system which uses electric heaters/s or combination of coolant based heater/s and electric heater/s.
BACKGROUND OF INVENTION
In order to fulfill the requirement of cold countries it is necessary to have a vehicle heating system of requisite capacity to meet the stringent norms. Different Homologation authorities follow different norms but among the said norms gosudarstvennyy standard (GOST) norms followed in Russia is the most stringent norm to fulfill this requirement.
GOST standard specifies following tests for heater performance assessment:
a. Windscreen demist test
b. Windscreen defrost test
c. Cabin heater performance test
GOST standard refers to European Economic Community (EEC) norms for demist and defrost tests. Cabin heater performance test is unique test devised for Russian climatic conditions. GOST standard has classified the climatic zones in Russia as follows:
a. Cold region
b. Mildly cold region
c. Very cold region
Cabin heater performance test for cold and mildly cold region is carried out at -25 Deg C and that for very cold regions is carried out at -40 Deg C. The test is carried out with vehicle running condition on road. Vehicle need to be soaked at the defined ambient temperatures before the start of the test. Passing criteria defines average

cabin temperatures, temperatures at leg level, waist level and head level of driver, co-driver and passengers within 15 minutes of start of test.
Existing vehicles in Russia use following types of heaters for the cabin heating:
1. Engine coolant based heaters: In this type of heater, air is passed through heat exchanger and blown inside vehicle cabin by blower. Heat exchanger picks up heat from hot engine coolant and transfers to cold air.
2. Fuel fired heaters:
Conventionally two types of fuel fired heaters are used:
a. Coolant based fuel fired heaters: In this type of heater, heat is generated by
burning fuel in a combustion chamber and engine coolant is circulated through
jackets around the combustion chamber. This increases engine coolant heat-up rate
and coolant temperature. This coolant is then passed through heat exchanger. A
blower sucks the air and blows inside vehicle cabin by passing it through the heat
exchanger. Heat exchanger transfers heat from engine coolant to air and thus heats
the vehicle cabin.
b. Air heating fuel fired heaters: In this type of heater, heat is generated by
burning fuel in a combustion chamber. A blower sucks the air and blows inside
vehicle cabin by passing it over hot outside surface of combustion chamber of fuel
fired heater. Heat gets transferred from combustion chamber surface to air and thus
heats the vehicle cabin. Fins/ projections are provided on outside surface of
combustion chamber of fuel fired heater for efficient heat transfer.
Fuel fired heater has its own fuel lines, fuel pump, coolant circulation pump, electric wiring, harness, spark plug, air blower and control unit. Said fuel fired heater draws power from vehicle battery. It can work independent of vehicle engine system or work as add on heater. These types of heaters are usually used for very cold climatic

regions wherein it is mandatory that the vehicles be fitted with cabin heating system independent of engine system.
3. Electric heater:
Electric heaters draw electric power from vehicle alternator or battery. The electric power is converted into heat by means of electric resistive coils. A blower sucks the air and blows inside vehicle cabin by passing it through the coils/s. Heat exchanger transfers heat from electric resistive coil/s to air and thus heats the vehicle cabin. These type of heaters are usually used as add on heater where engine coolant based heaters fall short of its capacity to meet cabin heating requirements. This is due to high current requirement by the electric heater.
The blower in all above mentioned types of heater may work both in fresh air and recirculation mode. In fresh air mode suction air is taken from the outside of vehicle cabin. In recirculation mode cabin air itself is sucked by blower and re-circulated within vehicle cabin. Some of the blower also use mixed mode wherein both fresh air and vehicle cabin air is sucked by blower in certain proportions.
Drawbacks associated with engine coolant based heaters:
Vehicles fitted with engine coolant based heaters alone need good engine coolant heat up rates. This need major engineering changes and prolonged development time.
Drawbacks associated with fuel fired type of heater:
1. The cost of heater is very high and hence is not feasible to fit for low segment and economy class vehicles.
2. Fuel fired heater packaging location is critical due to safety aspects and may not be possible due to limitations of space and vehicle level modifications.

Drawbacks of electric heaters:
1. Higher capacity alternator and battery is required.
2. Separate battery for electric heater is required.
3. Heating requirement and battery charging is required to be balanced.
4. Higher capacity electric heater is required which necessitates high capacity or separate add on vehicle battery or high capacity alternator
5. Low air flow inside cabin as overall pressure drop of across air flow path is more due to addition of electric heater coil in air flow path
6. Requirement of high capacity blower and hence increase in power consumption of system.
7. Low cabin heat-up rate at low engine speeds as electric heaters need to be switched off due to non-availability of sufficient current.
8. High duty cycle of relays and electric heater coils which reduces life of the system.
9. Retro fitment of add on electric heater requires major changes in Heating, ventilation and air conditioning unit (HVAC) or air conditioning and heater unit or heater unit
OBJECTS OF INVENTION
The main object of the invention is to provide a vehicle heating system which can be used in the existing vehicle architecture with minimal changes and to satisfy the vehicle heating requirements of cold countries.
Another object of this invention is to provide a vehicle heating system which is energy efficient, gives more uniform cabin heating and compact in size.
Another object of this invention is to provide a add on vehicle heating system which can be independent of coolant based heating system and complement/aid primary vehicle heating system.

Another object of this invention is to provide a vehicle heating system which can act as emergency heating system in case of failure of coolant based heating system for reasonably long period for occupant thermal comfort.
Another object of this invention is to provide a add on vehicle heating system which can be retro fitted to aid primary heating system of vehicle
Yet another object of this invention is to provide a vehicle heating system which is simple in construction and cost effective.
STATEMENT OF INVENTION
Vehicle heating system comprises of at least one heating device, engine, engine coolant circuit, electric heater controller, alternator, battery, engine coolant and ambient temperature sensors, electric heater ON/OFF switch and switching circuit, wherein said heating device is provided with at least one electric heater unit and coolant based heater unit, said electric heater controller is interfaced with alternator, coolant and ambient temperature sensors, electric heater ON/OFF switch, blower unit of heating device (1 in fig.4), electric heater unit, switching circuit.
Vehicle heating system wherein said electric heater unit with blower arrangement (lin fig.4) is provided separately inside vehicle cabin. Vehicle heating system wherein said electric heating device is mounted within vehicle cabin.
Vehicle heating system wherein said electric heater controller is further interfaced with diagnostic & configuration/calibration device.
Vehicle heating system wherein said heating device is heating, ventilation and air conditioning unit (HVAC) or air conditioning and heater unit or heater unit.

Vehicle heating system wherein the said ambient temperature sensor is mounted at outside rear view mirror or behind the front grills of the vehicle or suction air duct of heating, ventilation and air conditioning unit (HVAC) or air conditioning and heater unit or heater unit and said coolant temperature sensor is mounted at inlet of coolant based heater unit or upper cooling line of engine coolant circuit. .
Vehicle heating system wherein said electric heater ON/OFF switch is integrated within temperature control unit or provided separately.
Vehicle heating system wherein said heating system is further provided with fault indication unit and is interfaced with electric heater controller.
Vehicle heating system wherein said electric heater unit is interfaced with alternator and vehicle battery or vehicle battery through switching circuits.
Vehicle heating method by using system comprises
a. Starting engine;
b. Switch ON blower motor;
c. Switch ON electric heater ON/OFF switch;
d. Estimating heating demand by using coolant temperature sensor, ambient
temperature sensor and electric heater controller;
e. Estimating incremental heating capacity to meet the demand;
f. Estimating the current capacity available with the vehicle electrical system;
g. Providing time delay between turn ON/OFF event, between two consecutive
turn ON events, between two consecutive turn OFF events;
h. Switching ON electrical heater unit based on the estimations done in said
steps d to f; i. Switching OFF electrical heater unit based on set temperature, non
availability of current with vehicle electric system, engine rpm cut off value
and electrical bus voltage cut off values.

BRIEF DESCRIPTION OF INVENTION
In accordance with the present invention, Vehicle heating system comprises; Heating, ventilation and air conditioning (HVAC) unit, electric heater units, coolant hoses/ pipes, engine , engine coolant circuit, electric heater controller, alternator, battery, engine coolant and ambient temperature sensors, fault indication unit, electric heater ON/OFF switch, switching circuits and diagnostic & configuration/calibration device. Wherein said HVAC unit houses coolant based heater unit(l in fig.4) and said electric heater unit comprises of electric heater coils, blower unit with inlet and outlet ducts(2 in fig.4) for directing airflow with vents to control airflow direction. Said coolant based heater unit having inlet and outlet are connected to engine coolant circuit through coolant hoses/ pipes. Said Alternator is driven by engine and is provided to charge the said battery. Electric heater controller is connected to said alternator, coolant and ambient temperature sensors, electric heater ON/OFF switch, blower unit of (HVAC) or air conditioning and heater unit or heater unit, electric heater unit, fault indication unit, switching circuit and diagnostic & configuration/calibration device.
When engine is started and HVAC or air conditioning and heater unit or heater unit is turned ON in heater mode along with blower unit turned ON then coolant based heater unit activates and starts heating the vehicle cabin. The electric heater will turn ON when the temperature control unit provided on control panel is set at maximum heat zone, coolant based heater is not able to meet the cabin heating requirement and alternator current capacity is sufficient enough to drive the said heater.
Electric heater and blower unit(l in fig.4) are activated irrespective of engine ON/OFF condition with an emergency switching device by taking power from battery.
BRIEF DESCRIPTION OF DRAWINGS
Fig. 1A & IB shows vehicle heating system with and without bypass line in

accordance with this invention respectively
Fig. 2 shows electric heater controller hardware interface with the other components of the system and the flow of control logic embedded in electric heater controller
Fig. 3 shows the block diagram showing interconnection between electric heater controller and diagnostic & configuration/calibration device.
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,
Referring to figlA; Vehicle heating system comprises of:
1. Heating, ventilation and air conditioning unit (A) which further comprising of heat exchanger (C) to transfer engine coolant heat to air, compressor, compressor drive, condenser with separate or integrated 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 or mixed mode and blow inside vehicle cabin through heat exchanger and add on Positive temperature coefficient heater units(B), control panel, ducts for airflow passage, vents to control airflow directivity OR
2. Air conditioning & heater unit comprising of 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 or mixed mode and blow inside vehicle cabin through heat

exchanger, ducts for airflow passage, vents to control airflow directivity, control panel OR
3. Heater unit comprising of heat exchanger (C) to transfer engine coolant heat to air, flap arrangement and flap movement mechanism, blower motor and impeller to suck air in fresh or recirculation or mixed mode and blow inside vehicle cabin through heat exchanger ducts for airflow passage, vents to control airflow directivity and
4. Electric heater unit comprising of positive temperature coefficient heater units(B) (1 in fig.4), flap arrangement and flap movement mechanism(2 in fig.4), blower motor and impeller(3 in fig.4) to suck air in recirculation mode and blow inside vehicle cabin through heat exchanger control panel, ducts for airflow passage, vents to control airflow directivity and
5. Heater hoses/ pipes (D, E) connecting cabin heater inlet and outlet to engine coolant circuit and
6. Bypass line (F) and
7. Upper coolant line (G) and
8. Lower coolant line (H) and
9. Thermostat (I) and
10. Engine (J) and
11. Engine Coolant circuit comprising of coolant pump (K), Coolant reservoir (L) and Engine cooling module (M) further comprising of radiator coil, radiator fan, radiator shroud.

Wherein said HVAC unit (A) or air conditioning and heater unit and electric heater units (B) is housed separately. Said coolant based heater unit inlet and outlet are connected to engine coolant circuit through 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 (F) and to coolant based cabin heater (C) till coolant temperatures reaches to a specified value. When the coolant temperature reaches to said specified value said thermostat blocks bypass line (F) and opens upper cooling line (G) allowing the coolant to flow through engine cooling module (M). The coolant returns back to the coolant pump through outlet line (E) of said coolant based cabin heater, outlet line (H) of said engine cooling module and bypass line (F).
Blower motor and impeller of Heating, ventilation and air conditioning unit (HVAC) or air conditioning and heater unit or heater unit (A) sucks air in fresh or recirculation or mixed mode and blows inside vehicle cabin through coolant based cabin heater (C). The coolant heat is absorbed and transferred to the air by coolant based heat exchanger (C). Air blown inside the cabin gets sucked by blower unit of positive temperature coefficient heater unit/s (B) and is heated further. This air is directed inside vehicle cabin through the flap arrangement (not shown) and ducts with vents (not shown) in different directions to heat vehicle cabin by both Heating, ventilation and air conditioning unit (HVAC) or air conditioning and heater unit or heater unit (A) and positive temperature coefficient heater unit/s (B).
Referring to Fig. IB wherein for increasing the coolant based heater capacity from the vehicle heating system as explained in fig.lA the bypass line (F) is to be removed and because which the coolant flow to the cabin based coolant heater (C) increases.

Referring to Fig. 2, Alternator , used to charge the battery, is driven by engine. Electric heater controller is connected to alternator load factor sensor, coolant temperature sensors, ambient temperature sensor, temperature control sensor, motor speed sensor of blower unit of (HVAC) or air conditioning and heater unit or heater unit, motor speed sensor of blower unit of electric heater unit, fault indication unit, electric heater switching circuit, diagnostic & configuration/calibration device (7). Electric heater controller (1) is the microprocessor based hardware unit and is responsible for the switching of electric heaters (2). The decision of switching the heater ON / OFF is taken in the software designed for this controller based on the status of electric heater ON/OFF switch (4), blower motor (5), said heaters (2), coolant and ambient temperatures as indicated by respective sensors (8, 9), alternator rpm (12) and duty cycle of the alternator load signal (DF) .
Duty cycle of the alternator load signal (DF) is used for estimating the ratio of the current which is used up by the electrical systems in the vehicle to the total current supplied by the alternator to the battery. This ratio is named as Load Factor (LF). The alternator load signal (DF) is filtered using a software filter for deriving the consistent value of alternator load. This filtered DF value is used for estimating the value of LF.
The total current supplied by the alternator (6) to the battery is a function of the alternator rpm and the alternator surrounding temperature. This is a characteristic of the alternator (6). Alternator surrounding temperature is estimated from the information of the coolant water temperature acquired using the coolant temperature sensor (8). On measuring said rpm, this charging current is estimated in the controller software using the map that relates alternator charging current with the alternator rpm and the alternator surrounding temperature.
Excess charging current is estimated from the information of said LF and total charging current. This is the part of total charging current supplied by the alternator

(6) to the battery and not used by any of the vehicle electrical loads. Thus, this part of the total charging current is responsible for the charging of the vehicle battery. One of the valid conditions for turning the next electric heater ON is that the excess charging current should be more than the amount of steady state current required by the electric heater plus the excess headroom in current value maintained for charging of the vehicle battery.
Apart from the above mentioned condition, for turning ON of a any electric heater (2) requires the electric heater ON/OFF switch (4) to be in turned ON condition, the blower motor (5) should be running and that particular heater (2) should have been in the OFF state previously for some amount of time (in order of ms). The time delay in switching ON of same heater is introduced for protecting the switching circuit (3), which is used for connecting / disconnecting the electric heater (2) from the vehicle electrical supply line, from the frequent ON-OFF action. Similar delay is maintained between the TURN ON event and TURN OFF event of the given heater.
Also, after turning ON any heater, next heater is turned ON only after certain time delay. This time delay is for taking care of the sudden rise in current consumption in the vehicle electrical system, which is a result of switching ON of previous electric heater. Thus the electrical disturbance in the system is allowed to settle before turning ON of the next electric heater.
Again, electric heaters are turned ON only if they are required, i.e. only if the temperature condition is such that the driver of the vehicle requires the air to be heated. For this, the driver is provided with a switch, which works as Heater ON command in the system. Also, the system temperature information is derived using the coolant water temperature signal and ambient temperature signal, which are derived from sensors (8) and (9) respectively. Thus the maximum number of heaters that can be turned ON is based on the coolant and ambient temperature information. Again electric heater blower is run in recirculation mode. Amount of airflow from the said blower shall not be less than 30% of the amount of airflow of Heating,

ventilation and air conditioning unit (HVAC) or air conditioning and heater unit or heater unit for good cabin heating performance.
The controller (1) gives the out put signal to fault indication device (10, 11) regarding the health status of all the system components and decides the fault code to be indicated while diagnostic mode is ON. Said controller (1) is provided with safe working limits for battery voltage and voltage generated by alternator, which acts as additional pre requisites for positive temperature co-efficient heater coils to be made ON.
The entire logic as discussed above in fig 2 and is embedded in electric heater controller (1). The flowchart routine considers the entire set of input signals as discussed above in fig.2 is available with the system. However if either or both of the two signals from the alternator is/are not available, then the switching of electric heaters is based on the vehicle supply bus voltage. This voltage is compared with two different extreme values to set the two indications - "Battery Voltage More" and "Battery Voltage Less".
Electric heater controller (1) software logic is designed for
(A) Estimation of the alternator surrounding temperature from the coolant
temperature and ambient temperature inputs.
(B) Estimation of the alternator rpm from the engine rpm and pulley ratio
information.
(C) Estimation of the charging current supplied by the alternator based on current engine rpm, mapped as a function of alternator rpm, ana; alternator temperature,
(D) Estimation of the load factor for the working condition in the real-time based on the engine rpm, mapped as a function of alternator rpm, and alternator load duty cycle input signal. This is the measure of the proportion of the current used by the electrical loads in the vehicle system.
(E) Estimation of the excess current available with the electrical system that can be
supplied to the electric heater units.

(F) Estimation of number of heaters required to be switch ON.
(G) Estimation of number of heaters actually kept ON in the run-time.
(H) ON / OFF switching of the switching circuits, and hence the heater units. (I) Fault indication routine and fall back strategies for switching process of the electric heaters.
(J) Routine for enabling communication with the diagnostic & configuration/calibration device and supporting the activities like run-time calibration of the system parameters, data-logging of the system parameters as interpreted by the electric heater controller.
Fig.3 shows the connection diagram of the diagnostic & configuration/calibration device (7) with the electric heater controller (1) and its various constituents. The above mentioned software logic for electric heater functionality has various calibration parameters like set temperature limits, time delay between switch ON and OFF of the given heater, time delay between switching ON of two consequent heaters, etc. These parameters are kept programmable during run-time. Such functionality is achieved using a diagnostic & configuration/calibration device (7). The electric heater controller (1) communicates with the diagnostic & configuration/calibration device (7) through an interfacing hardware. This interfacing hardware converts one- wire communication line supported by the electric heater controller (1) into two-wire serial communication line supported by the diagnostic & configuration/calibration device (7).
Vehicle heating method by using system comprises
a. Starting engine;
b. Switch ON blower motor of heating device is heating, ventilation and air
conditioning unit (HVAC) or air conditioning and heater unit or heater unit;
Switch ON blower motor of electric heater unit;
c. Switch ON electric heater ON/OFF switch;
d. Estimating heating demand by using coolant temperature sensor, ambient
temperature sensor and electric heater controller;

e. Estimating incremental heating capacity to meet the demand;
f. Estimating the current capacity available with the vehicle electrical system;
g. Providing time delay between turn ON/OFF event, between two consecutive
turn ON events, between two consecutive turn OFF events;
h. Switching ON electrical heater unit based on the estimations done in said
steps d to f; i. Switching OFF electrical heater unit based on set temperature, non
availability of current with vehicle electric system, engine rpm cut off value
and electrical bus voltage cut off values.
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 26th day of March 2009
TATA Motors Limited By their Agent & Attorney

(Karuna Goleria) of De PENNING & De PENNING