FORM 2
THE PATENT ACT 1970
(39 of 1970)
&
The Patents Rules, 2003
COMPLETE SPECIFICATION
(See section 10 and rule 13)
1. TITLE OF THE INVENTION
APPARATUS FOR CONTROLLING FUEL TEMPERATURE
2. APPLICANT
MAHINDRA & MAHINDRA LTD.
1, GATEWAY BUILDING, APOLLO BUNDER, MUMBAI - 400001. AN INDIAN COMPANY.
The following specification particularly describes the invention and the manner in which it is to be performed.

FIELD OF INVENTION
The present invention generally relates to an apparatus and method for maintaining temperature of a liquid at intended predetermined set value, and more particularly, to maintain temperature of fuel being supplied from fuel tank to engine at intended predetermined set value in order to measure / predict engine performance parameters in engine testing process.
BACKGROUND OF THE INVENTION
In testing of Internal Combustion (IC) Engine, it is always desirable that fuel is supplied at constant temperature, as engine fuels are highly volatile, and density, viscosity etc. are prohibitively sensitive / responsive to the changes in fuel temperature. During performance testing of engine, changes in fuel temperature may lead to misleading performance conclusions.
Temperature of feed-fuel that is being fed to engine / engine manifold mainly depends upon mixture temperature of fresh fuel from fuel tank and re-circulated fuel returning (overflow) from the running engine.
Hence, there is need to provide an appropriate fuel conditioning device such that temperature of fuel that is being fed to the engine, during testing process, is always maintained at intended predetermined set temperature, also, the fuel conditioning device should be easy in

operation and comprising lesser number of parts thereby lesser frequency of maintenance needs and lesser associated costs.
Though proposed system is unique considering its mechanism configuration, some of the patent documents related to temperature control of fluid are discussed hereunder as prior art.
US patent 4,984,628 titled APPARATUS FOR MAINTAINING LIQUID TEMPERATURE AT A CONSTANT LEVEL discloses an apparatus for maintaining liquid temperature in a vessel at a constant level. An apparatus for maintaining liquid temperature at a constant level according to that invention, comprises a reaction vessel for containing liquid, cooling means for cooling the liquid and connected with the reaction vessel, heating means connected with the cooling means for heating the liquid cooled by the cooling means, circulating means for circulating the liquid through and among the reaction vessel, the cooling means and the heating means, temperature detecting means for detecting temperature of the liquid heated by the heating means, heat exchange rate control means for controlling heat exchange rate between the cooling means and the liquid, and control means for controlling the heating means and the heat exchange rate control means based on control state of the apparatus and on the temperature difference between detected temperature and desired temperature.
US patent5,211,713 titled TEMPERATURE CONTROL METHOD WITH SIMULTANEOUS HEATING AND COOLING NEAR THE SET-POINT discloses a temperature control method (first method) for controlling a temperature in a chamber to an intended constant set value, comprising the steps of: providing heating means which can select large and small heating powers for heating the chamber and

refrigerating means for cooling the chamber; detecting current temperature In the chamber; operating the heating means with low heating power for attaining the set value when a detected temperature is equal to or higher than a lower tolerable deviation value predetermined with respect to the set value of the chamber temperature, and operating the heating means with a large heating power when the detected temperature is lower than the lower tolerable deviation value; and operating the refrigerating means when the detected temperature is higher than the upper tolerable deviation value predetermined with respect to the set value of the chamber temperature.
PCT patent application WO2001032007 titled TEMPERATURE CONTROL SYSTEM discloses an invention related to heating means comprising a source of heating fluid comprising a fluid reservoir and a thermostatically controlled heater for heating said heating fluid to a first predetermined temperature, and flow and return piping connecting said reservoir to said first heat exchange means and cooling means comprises a source of coolant fluid comprising a fluid reservoir and a thermostatically controlled cooler for cooling said coolant fluid to a second predetermined temperature, and flow and return piping connecting said reservoir to said second heat exchange means.
The study of the related aforementioned prior art reveals shortcomings
such as:
Essential use / Necessity of refrigeration circuit which further requires compressor etc. and essentially requires power source to operate the same.


Invariable use of gauges and valves that adversely affects system reliability.
Frequent maintenance and related higher costs owing to more number of moving parts.
Invariable use of number of control units which are electronic devices such as switches etc.; failure of even one of them may hamper performance and reliability of the complete system. Fuel inconsistency, Air trapping, frequent breakdown of system etc. are common intermittent problems with existing fuel conditioners.
Existing conditioners are bulky, occupy larger floor space and hence require to be located at a place considerably away from engine to be tested thereby necessitating fuel pumping and carrying media like fuel piping.

Necessity has constantly been felt to develop a simple, cost effective, easy to use system to control temperature; density etc. of fuel being fed to engine, which effectively operates without use of refrigeration cycle / device, which is optionally free of valves.
SUMMARY OF THE INVENTION
The main object of the invention is to provide an apparatus and a method to control temperature of fuel being supplied to an engine, especially being performance-tested, at intended predetermined set value.

Another object of the invention is to provide a means for mixing (overflow) fuel returning from the engine with fresh fuel supply from the fuel supply tank so that an average temperature and viscosity range of fuel going to the engine / injectors in maintained at intended (desirable) predetermined value(s).
Yet another object of the invention is to provide apparatus to control temperature of fuel, accurately and safely, being supplied to engine at intended predetermined set value.
Yet another object of the invention is to provide an apparatus which controls temperature accurately and safely and ensures that temperature of fuel being fed to engine is maintained within intended range (maximum and minimum values).
Yet another object of the invention is to provide an apparatus, to control temperature of fuel being supplied to engine at intended predetermined set value, which is effectively operational without need of use of refrigeration cycle / device.
Yet another object of the invention is to provide an apparatus, to control temperature of fuel being supplied to engine at intended predetermined set value, which is compact in size, has small foot-print / floor-space requirement which can be conveniently located at / considerably near the engine so that there is no need of fuel pumping and carrying media like piping.
Afore mentioned objectives and benefits are achieved in accordance with one aspect of present invention comprising;
a mixing/conditioning chamber to receive, fresh fuel from fuel supply tank/source and relatively hot overflowing fuel from fuel injector(s) provided in cylinder head of the engine that is running;

a heat exchanger to extract heat from the fuel mixture, which is entering into said mixing/conditioning chamber, by receiving coolant form cooling tower and also provided with a manually adjustable control valve in inlet coolant line to control the flow rate;
an air heater pad to heat the said fuel mixture after passing through the heat exchanger according to the signal received from control unit based on need to heat the fuel mixture;
a temperature sensing device disposed in the mixing/conditioning chamber to sense temperature of fuel mixture after passing the air heater pad;
and a control unit to receive signal from said temperature sensing device thereupon to send the feed back signal accordingly, based on need to heat the fuel mixture, to air heater pad to activate/deactivate the same (air heater pad).
BRIEF DESCRIPTION OF THE DRAWINGS
The invention and further advantageous developments and arrangements of the invention will now be described and explained in more details by way of example(s) and with reference to the accompanying drawings in which:
FIG. 1 illustrates temperature control apparatus and method according to the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
The apparatus and method for maintaining fuel temperature at constant level is depicted in FIG.1. referring to FIG. 1, said apparatus mainly comprises a mixing / conditioning chamber, which is provided with a inlet port at the top in lateral side for receiving fuel coming from the fuel supply tank / source 2, preferably under gravity, and return / overflowing fuel from the fuel injector (not shown) provided in cylinder head of engine. 5 Said inlet port 15 is connected with a fuel line, at one end, having two branches of fuel line at another end. The first fuel line branch 3 is connected to fuel supply tank/source 2 for carrying the fuel from fuel supply tank 2 to the mixing /conditioning chamber 1 and the second fuel line branch 4 is connected to return fuel port of the injector for carrying the overflowing fuel from the fuel injector to the mixing / conditioning chamber. Said mixing/conditioning chamber is also provided with an outlet port 16 functionally below the inlet port 15 connected with a fuel line 06 for carrying the intended predetermined set temperature form the mixing / conditioning chamber to the inlet port of the fuel injector provided in cylinder head of engine 5.
Provided there is an air heater pad 7 adapted externally along the center portion of mixing/conditioning chamber, to heat the mixture of fuel coming from fuel supply tank / source 2 and overflowing fuel from engine 5 by receiving heat from the source of electrical energy. A heat exchanger 14 is kept inside the mixing/conditioning chamber, immediately at the top of the air heater 7, for extracting the heat from the fuel mixture entering through the inlet port 15. Heat exchange

process is facilitated by providing plurality of pipe lines and receives cooling water from a cooling tower 13 through water inlet line 8 generally at atmospheric/ambient temperature and thereafter extracts heat from the fuel mixture and then comes out of heat exchanger 14 and goes back to cooling tower 13 through water outlet line 9. Water inlet line 8 is optionally provided with flow control valve 11.
Temperature sensing device 10 is provided to sense fuel mixture temperature, after passing through the air heater pad 7 and generally located internally with mixing / conditioning chamber 1. In preferred embodiment, temperature sensing device 10 is located centrally inside the mixing / conditioning chamber 1, however, those skilled in the art will appreciate that, location of temperature sensing device 10 is subject matter of mixing / conditioning chamber 1 geometry and design. It is generally recommended that temperature sensing device 10 be located where fuel mixture temperature is uniform as well as near to the outlet port of the mixing/conditioning chamber.
A control unit 12 provided here to receives signal from temperature sensing device 10 and sends feedback to air heater pad 7 to function accordingly so as to maintain its temperature at intended predetermined set value. According to present invention, said control unit works on ON/OFF basis to activate/deactivate the air heater pad 7.
In accordance with the present invention, a continually replenishing fuel mixing / conditioning chamber 1 forms a reservoir for fuel in the fuel line between engine 5 and its fuel supply tank/source 2 thereby form a closed fuel recirculation loop through which fuel is circulated from the fuel supply tank/source 2 to the mixing/conditioning chamber 1 thereupon the intended predetermined set temperature fuel is

circulated to fuel injector provided in cylinder head of engine 5 and the overflowing fuel from fuel injectors is returned to the mixing/conditioning chamber 1 by converging the first fuel line 3 and second fuel line 4 in such a way to balance/average the temperature of fuel mixture consisting of fresh fuel coming from the fuel supply tank/source 2 through first fuel line 3 and hot overflowing fuel coming from the fuel injectors of engine 5 before entering the mixing/conditioning chamber to avoid any cause of thermal instability within the chamber 1. The said fuel mixture entering into the mixing /conditioning chamber is thermally exposed to heat exchanger 14, in which the water received through water inlet line 8 from the cooling tower 13, preferably at such a temperature lower than the fuel mixture, extract heat from the fuel mixture thereby to ensure that the temperature of fuel mixture after passing through the heat exchanger 14 should be within allowable lower deviation temperature range according to present invention. It will be appreciated that a person skilled in the art can decide upper and lower deviation temperature range as per requirement, accordingly changes in the parts and control unit function can be modified.
Temperature sensing device 10 continuously senses the temperature of fuel mixture, after passing through the air heater pad 7 and sends signal to control unit 12 which in turn sends signal to heater, accordingly, to switch on / switch off in order to maintain the constant intended predetermined set temperature of fuel mixture. It is generally desirable to locate temperature sensing device 10 closer to outlet port 16 of chamber 1 so that intended predetermined set temperature of fuel mixture to be supplied to the engine 5 can be maintained at constant level and thereby the engine performance test can be predicted accurately.

Generally, efficiency of heat exchange process is determined by different parameters such as flow rate, temperature gradient and surface area of the medium through which the heat to be transferred. According to the present invention, a manually adjustable control valve is provided in water inlet line 8 to change the flow rate of water in the heat exchanger 14. Generally at start of performance test on engine, opening of control valve 11 is set according to the horse power of the engine so that for any category of engine, fuel mixture passing through the heat exchanger will be having a temperature within the lower deviation temperature range according to present invention. Water required to extract heat from the fuel mixture through heat exchanger is processed through cooling tower so there is no need of refrigeration cycle / device to decrease temperature of water, further additional power source to operate compressor and related accessories to run refrigerator.
Fuel tank 2 of the present invention is preferred tobe located such that fuel flows from fuel tank 2 to mixing / conditioning tank 1 under gravity. Also, in particular, the preferred fuel supply tank 2 has fuel capacity grater than what engine can consume in unit time of full load operation.
It will be readily appreciated by those skilled in the art that modifications may be made to the invention without departing from the concepts disclosed in the foregoing description. Accordingly, the particular embodiments described in detail herein are illustrative only and are not limiting to the scope of the invention, which is to be given the full breadth of the appended claims and any all equivalents thereof.

We claim,
1) An apparatus and method for maintaining liquid temperature at constant predetermined value range comprising:
a mixing/conditioning chamber to receive liquid from supply source thereupon to process the liquid to maintain within constant temperature range thereof,
a heat exchanging means within said mixing/conditioning chamber to transfer heat between coolant and the liquid;
a control valve provided in inlet line of said heat exchanger to control flow rate of said coolant to said heat exchanger;
a heating means such as heater pad to heat said liquid in said mixing/conditioning chamber;
a temperature sensing device disposed within said mixing/conditioning chamber to sense temperature of said liquid;
a control unit to receive signal from said temperature sensing device thereupon to send signal, accordingly, to said heating means to actuate or otherwise;
a heat exchanging means such as a cooling tower to process said coolant sufficiently to enable transfer of heat as desired between said liquid and coolant.

2) An apparatus and method for maintaining liquid temperature at
constant predetermined value range according to claim 1,
wherein said mixing/conditioning chamber having at least one inlet port to receive liquid such as fuel from liquid / fuel supply tank/source and liquid from other source with relatively different temperature such as relatively hotter overflowing fuel from running engine, and at least one outlet port to deliver mixed liquid / fuel at or within predetermined set temperature value/ range,
3) An apparatus and method for maintaining liquid temperature at
constant predetermined value range according to claim 1,
wherein said heat exchanging means having plurality of coolant lines to extract heat from liquid / fuel entering into said mixing/conditioning chamber, sufficiently cooling the liquid / fuel mixture to bring it within lower deviation/ band of set temperature range.
4) An apparatus and method for maintaining liquid temperature at
constant predetermined value range according to claim 1,
wherein said control valve of coolant inlet is manually adjusted as per heat exchange/cooling rate desired such as during engine testing set up process as per requirement(s) for different type(s) and range(s) of engine and engine horse power.
5) An apparatus and method for maintaining liquid temperature at
constant predetermined value range according to claim 1,

Wherein said control unit generates signal(s) to perform ON/OFF function to activate / deactivate said heating means according to the signal received from said temperature sensing device based on need to heat the liquid.