FORM 2
THE PATENTS ACT 1970
(39 of 1970)
&
THE PATENTS RULES, 2003
PROVISIONAL SPECIFICATION
(See Section 10; rule 13)
TITLE OF THE INVENTION METHOD OF FUELING AN INTERNAL COMBUSTING ENGINE


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
Arunendra Mishra, Jayagopal S and Rajasekhar M V
all Indian nationals of TATA MOTORS LIMITED,
an Indian company having its registered office
at Bombay House, 24 Ho mi Mody Street, Hutatma Chowk,
Mumbai 400 001 Maharashtra, India
PREAMBLE TO THE DESCRIPTION The following specification describes the invention.


Area of invention: The present invention relates to a system and method for controlling fuel injections of multipoint fuel injection system in multi-cylinder hydrogen fueled internal combustion engine.
Background of the Art:
Recently, the importance has been placed on the cleanliness of exhaust gas by reducing the pollutants like C02. CO; NOx & HC. Past decades have seen an increased demand for use of gaseous fuel as a fuel source in both compression and spark ignition engines. Gaseous fuel combustion engines that burn natural gas, petroleum gas, and hydrogen gas produces less emission from tail pipe.
Hydrogen is the promising fuel to meet energy sustainability and no Green House Gas emissions. Day-by-day the fossil fuel price is increasing and the day is going to come when the cost of hydrogen will be comparable with conventional (Gasoline / Diesel) fuels along with development of hydrogen technologies.
To meet the IC engine requirement for Hydrogen Fueling system, a technological need has arisen for safe & precise fuelling system.
Few attempts were done in the area of use of hydrogen fuel in internal combustion engine. In the patent 3,799,124, invention is mentioned in which an internal combustion engine is fueled by hydrogen with the ratio of hydrogen to air within the combustion chamber or cylinder being varied to change the speed and power output of engine and flow of air to engine substantially un-throttled in contrast to the usual throttle engine. Drawback of this invention is that, controlling of engine at low speed will be difficult as lean mixture at lower speed of engine can lead to misfire. Power
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generation at lower speed will be low if A/F is low and if inventor increases A/F it may lead to back ftre.
Summary and Advantages of Invention:
The present invention is about the fueling method and fueling strategy, which are
being recommended for Multi Point gas Injection system in a dedicated (100 %)
hydrogen IC engine. The invention has the capability to provide the accurate fuel
control for all load condition. Further, the objective of this invention is to ensure safe
running of multi-cylinder engine without back-fire.
Unlike any other conventional engine (gasoline or diesel), hydrogen internal
combustion engine uses both quantity and quality type of fueling method. Further said
invention provides precise control of fuel injection timing & the duration with better
drivability and safe vehicle running.
Another object of this invention is to provide a fuel control apparatus and fuel
injection control method for an internal combustion engine, which is capable of
adequately setting the start, and termination timings of fuel injection, thereby to
prevent occurrences of ignition failure, discharge of bare fuel and stains of the interior
of fuel injection valves.
As hydrogen can ignite at higher equivalence ratio, by reducing the throttling losses
the amount of power generation can be managed by controlling the fuel only. Based
on the principle mentioned a method has been formulated where the power output of
the engine is controlled using combination of partial charge control and partial fuel
control as the case in spark ignited and compressed ignited engines.
In this invention by pressing the driver pedal from zero to half, the throttle position
changes from partial opening to full open condition. Above 50 % of accelerator pedal
position, the throttle will be fully open irrespective of the driver pedal position. The
control for power output of the engine will be done using charge control till driver
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pedal demand exists below fifty percentage and above fifty percentage the control will be on fueling only as the amount of air flowing into the system remains the same.
Brief Description of the Drawings:
Fig.l: Schematic diagram of arrangement of hydrogen internal combustion engine.
Fig 2: Cross-sectional view of engine with injection system
Fig 3: ECU sensor and actuator overview
Fig 4: ECU fueling overview.
Fig 5: ECU fueling method
Fig 6: Graph exhibiting relation between Engine Load, Throttle Opening, Equivalence
ratio and Accelerator Pedal Position
Detailed Description of the preferred Embodiment(s):
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 figure 1, the Internal Combustion Engine comprise a multi-cylinder inline arrangement, Pistons, 2 valves per cylinder, Ignition Coils, Cylinder block, Cylinder Head, Cam shaft, Push-Rod, Plenum chamber, Fuel Rail, Gas (fuel) Injectors, Crankshaft, Accessories Drives and etc. Gas (fuel) is stored in Composite cylinders (10). These cylinders have in-built High-Pressure Regulator (11). High pressure line (13) carries gases to electronic Low-Pressure Regulator (14), which converts high pressure to working level pressure. Low-pressure line (15) carries gases to common rail (16). The other end of common rail consists of a low pressure sensor (31) to monitor the rail-pressure. Injectors (42) are connected to the common rail.
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Intake manifold (19) consists of plenum chamber (30), TMAP Sensor (24) and Electronically Controlled Throttle body (23). In the intake port (22), the air is delivered to the cylinders through intake valves. The valve Opening & closing is controlled by a cam shaft. Slot (25) is provided on intake runner pipe (22) to accommodate injectors and ensuring the optimized angle of injection with respect to the air flow direction. The exhaust port (21) is provided with exhaust valve with the valve Opening & Closing controlled by a cam. An engine control unit controls various aspects of the engine's operation. The numeric (18) represent ECU which gates inputs from various sensor and actuated the actuators as per requirement. The simplest ECU's control only the quantity of fuel injected into each cylinder each engine cycle. More advanced ECU's found on most modern cars also control the ignition timing. ECU's determine the quantity of fuel, ignition timing and other parameters by monitoring the engine through sensors. These can include MAP sensor, throttle position sensor, air temperature sensor, oxygen sensor and many others. Often this is done using a control loop control.
Figure 2 shows the cross-section view of arrangement of present invention with the related components fitted on Multi Cylinder Inline Engine. In preferred embodiment of present invention, in-line cylinders are formed in cylinder-block (36). The cylinder head (37) is secured to upper side of cylinder block (36) by set of cylinder-head bolts. Rocker cover and intake manifold unit surrounds and protect the engine valve assemblies and rocker arm mechanism. This is fastened to cylinder head (37) by thin & longer bolts. A piston (41) is reciprocally supported in each cylinder (36). Each piston is connected by a connecting rod (not shown in figure) to a crankshaft (44) in a conventional manner in lower portion of cylinder blocks (36). Fuel is combusted within the cylinders, which reciprocates the pistons. This reciprocating force acts on crankshaft (44), from which power is transferred to the vehicle. A single integrated intake manifold and cylinder-head cover, generally indicated at (19) is mounted to
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cylinder head (37). Intake port (38) connects intake runner (22) and cylinder (36). Intake valve (35) is placed in between cylinder and intake port to control the fluid flow and the valve Opening & Closing controlled by camshaft (43). Camshaft (43) driven by crankshaft (44) through timing gears (not shown in figure).
Referring to figure 3, we have shown the interaction of ECU with the real world engine through sensors. Here only few sensors are shown as the inputs to the ECU for sensing the condition of engine and generating the required output through actuators. The sensors provide the ECU the status of engine manifold, driver demand, Throttle position, exhaust conditions, engine temperature and so on. Based on these inputs the ECU calculates and does fueling and sparking. Strategy used in any ECU for controlling the output functions of the system plays significant role in achieving the desired results.
In a petrol internal combustion engine, the throttle is used to regulate the amount of air entering the engine, indirectly controlling the fuel burned on each cycle due to the fuel-injector or carburetor maintaining a relatively constant fuel/air ratio. In a motor vehicle, the control used by the driver to regulate power is sometimes called the throttle pedal or accelerator. In our case Electronic Throttle body is not hard-wired with accelerator Pedal. Here the signals from accelerator pedal are received by the ECU and based on driver demand, ECU then send signals to throttle body. Throttle position sensor signals from the throttle body are sent to the ECU as a feedback for confirming the achievement of the required move.
Figure 4, provides an overview of the control base used by the ECU for generating the fuel pulse that needs to be given to the injector for fueling. The control strategy used in fueling the engine is based on speed density method where in manifold pressure is used as primary load input. As shown in Figure 4 the ECU receives the input from the temperature sensor, manifold pressure sensor and soon for
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fuel calculations. Once the inputs are being received by the ECU, it does further processing for necessary action.
Here, the airflow into the cylinder is derived using a combination of a mapped volumetric efficiencies and standard gas equations to determine the actual air mass. The air mass is used to determine the mass of fuel required to achieve the desired air fuel ratio. Finally the injector pulse width required to deliver the desired mass of fuel is calculated. After calculation of the air mass, the desired fuel mass is being calculated taking in account the lambda sensor values for emission purpose. The base fuel value is then modified using fuel modifiers for further fine-tuning of the actual required quantity for combustion. Once the fuel mass to be injected is calculated, pulse width value is computed based on injector characteristics.
Figure 5, depicts the control method used in controlling the fueling from the ECU side based on number of parameters. Hydrogen has a wide range of flammability which makes hydrogen engines to run on A/F ratios anywhere from 34:1 (stoichiometric) to 180:1. The A/F ratio can also be expressed in terms of equivalence ratio, denoted by phi (<£). Phi is equal to the stoichiometric A/F ratio divided by the actual A/F ratio. For a stoichiometric mixture, the actual A/F ratio is equal to the stoichiometric A/F ratio and thus the phi equals unity (one). For lean A/F ratios, phi will be a value less than one. For example, a phi value of 0.5 means that there is only enough fuel available in the mixture to oxidize with half the air available. Another way of saying this is that there is twice as much air available for combustion than is theoretically required. Hydrogen engines should be operated at WOT whenever possible, but throttling is needed at very low loads to maintain combustion stability and to limit unburned hydrogen emissions. At medium to high loads, throttling might-be necessary to limit NOx emissions.
To achieve the said objective of fuel control at different conditions, ECU uses the fiieling method as base to control the amount of fueling in the cylinders for generating
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the necessary power output. Demand from the driver is the primary input which followed by further steps results in achieving the said goal. The driver demand in terms of accelerator pedal position is being sent to the ECU and accordingly provides signals to the throttle body for required movement. Throttle position sensor signals are being sent back to the ECU as a feedback. The throttle movement results in pressure variation in the manifold. The change in manifold pressure is taken as an input from manifold pressure sensor for calculating the load percentage at that instant. The load percentage value plays a significant role in deciding what type of fueling to be done, whether the fueling control should be quantitative or of qualitative.
Figure 6 Shows the graphical relation between the load on the engine and throttle position. As the load on the engine increases, the throttle increases. When the load is 50 % of the total load of the engine, butter fly valve opens fully. Rest of operating points of engine i.e above 50% of engine load conditions, butter fly valve will be fully open implying no throttling after and above 50% load condition. Figure 6 also shows the graphical relationship between engine load and Equivalence ratio. At idle and low load condition, equivalence ratio is constant to have good control on engine and avoid back fire. In this graph, this value is 0.4 but this is depending on the engine condition and power generated by at that particular equivalence ratio by the engine. At high load, power required by driver will be high. As hydrogen displaces air, this particular phenomenon reduces the volumetric efficiency of engine. Throttling of the engine also results in volumetric efficiency reduction. To generate desired power at high load, throttling loss was reduced by fully open valve. The control of engine takes place by the amount of fuel injected inside combustion chamber. For an engine with fuel injection, an ECU will determine the quantity of fuel to inject based on a number of parameters. If the throttle pedal is pressed further down, this will open the throttle body and allow more air to be pulled into the engine. The ECU will inject more fuel according to how much air is passing into the engine. If the engine has not warmed up
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yet, more fuel will be injected (causing the engine to run slightly 'rich' until the engine warms up). Electronic throttle body changes its position as per load and pedal position and based on amount of fuel required, ECU will decide the duration of injection of the fuel. Initially to have a good control on and for ease equivalence ratio will be kept constant i.e. 0.4.As load increases we need to generate more power, the amount of air goes will be constant, but by increasing the air to fuel ratio a high power can be achieved.
Dated this 18th day of March 2009

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