FORM 2
THE PATENTS ACT 1970
(39 of 1970)
&
THE PATENTS RULES, 2003
COMPLETE SPECIFICATION
(See Section 10; rule 13)
TITLE OF THE INVENTION A Twin-Injector arrangement for MPSGI 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
Jayagopal S and Arunendra Mishra 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 particularly describes the invention and the manner in
which it is to be performed.

FIELD OF INVENTION
The present invention relates to automotive engine technology and more particularly to multi point electronic fuel injection system. Gaseous fuels such as Hydrogen or Compressed Natural Gas (CNG) are injected in individual intake ports of internal combustion engine by metering the fuel amount.
BACKGROUND OF INVENTION
Recently, the importance has been placed on the cleanliness of exhaust gas by reducing the pollutants like CO2; CO , NOx & HC. There are limitations to meet these requirements using Fossil Fuels in conventional IC engines. So, past decades have seen an increased demand for use of gaseous fuel as a fuel source in both compression and spark ignition engines. Gaseous fuels 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. As the Hydrogen fuel needs to be handled through Electronically Controlled Unit, the fuelling system is to be a dedicated Multipoint Hydrogen Injection system.
The existing fueling system for gaseous fuel like CNG has one mixture unit, which is mixing CNG & Air at desired A/F ratio. This mixture unit works like carburetion system. The amount of fuel (CNG) depends upon the vacuum generated at intake manifold during suction. This closed-loop system can work only for Stoichiomatric (l
= 1) operation. This system is not suitable for hydrogen application as it needs Lean-
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Burn & Leak-Proof and better control on fuelling. Throttle Body Injection system can be a better option than Air-Valve Mixture type for Hydrogen application, but TBI will result into back-fire in Multi-Cylinder engines. So, to overcome these problems the better option will be Multi-point Sequential Hydrogen Gas Injection.
In Patent No. US 5,713,336, single injector per cylinder is used for gas fuel injection technique in IC engine. But this single injector may not be suitable for higher capacity engine cylinders, to meet fuel required per cylinder per cycle, particularly fuel like hydrogen. Because, hydrogen has got very low density(energy density as well) & higher diffusivity. Hence this invention is very much suitable even for higher capacity multi-cylinder IC Engines to meet the required flow-rate and precise timing. So, the prime objective of this invention is to provide sufficient amount of fuel delivered per cylinder to get desired engine power out put.
Most of the researchers studied & published the hydrogen fuel induction methods for Single Cylinder IC engine. Among them L M Das (Int. J hydrogen energy 1990), has conducted different experiments on fuel induction technique for hydrogen operated engine to recommend an optimum fuelling technique. His attempts were made to run the engine with four different methods such as Carburetion, Continuous Manifold Injection (CMI), Timed Manifold Injection (TMI) and Direct In-cylinder Injection.
Chasten et al (Patent No. US005,343,847A) has filed a patent for electronic gaseous fuel injection system where a gaseous fuel delivery system for an internal combustion engine having at least one cylinder with fuel intake and exhaust gas port. A fuel flow control device connected between the source of gaseous fuel and fuel plenum which contains an electronic control unit having a plurality of optimum Fuel/Air mixture variable as inputs and a modulated pulse width output connected to DC motor, the stroke of which controls the operation of a fuel valve for regulating the of fuel from the gaseous source to the fuel plenum. This control system seams to be an Electronically Controlled Fuel metering device and may not be suitable for sequential injection (Hydrogen Fuel).
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A multi-point fuel injection (liquid / gasoline fuel) system is extensively employed for gasoline automotive engine application to improve fuel economy and reduced emission with higher power. Multipoint fuel injection of gaseous fuel is highly attractive method of metering fuel. Multipoint fuel injection permits much more precise control of fuel flow than single point or carburetion type fueling system.
SUMMARY AND ADVANTAGES OF INVENTION
This invention is about the design of components, which are being recommended for Multi Point Hydrogen 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 leak-proof design of fueling system and safe running of multi-cylinder engine without back-fire.
Unlike conventional multi point fuel injection system, the design of this invention system utilizes two injectors per cylinder & connected to a common fuel plenum / rail for multi-cylinder engine. These injectors are connected through flexible pipe to Common Rail, and the rail receives fuel from electronically controlled low-pressure regulator.
This invention needs very minimal hardware modification to convert conventional Diesel engine to Hydrogen IC engine.
Further this Multipoint Hydrogen Injection system provides precise control of fuel injection timing & the duration with better drivability and safe vehicle running.
There are other needs existing for a multipoint gaseous fuel injection system that may be used to provide fuel to virtually any type of internal combustion engine and it should be compatible with all types of gaseous fuels. Hence this system will be suitable.
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According to this invention a multipoint gas injection system comprising, a common gas plenum assembly having a gas rail with outlets and a low pressure sensor, plurality of injectors, said injectors connected to the outlets of said gas rail, at least one cylinder, an air intake plenum, a runner pipe connected between said intake plenum and said cylinder, and two said injectors located in said runner pipe to inject gas into runner pipe.
BRIEF DESCRIPTION OF DRAWING
FIG . 1 shows schematic diagram of IC Engine, Hydrogen Storage & Supply System.
FIG. 2 shows common Rail and Injectors arrangement
Fig. 3 shows the arrangement of twin injectors according to present invention.
Fig. 4 Shows the cross sectional top view of the arrangement of twin injectors.
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.
An embodiment of this invention is described in FIGURE 1. The Internal Combustion Engine comprising Six cylinders, Pistons, 2 valves per cylinder, Ignition Coils, Cylinder block, Cylinder Head, Cam shaft, Push-Rod, Plenum chamber, Fuel Rail, Hydrogen Injectors(2 per cylinder), Crankshaft, Accessories Drives and etc. Hydrogen gas is stored in Composite cylinders (10). These cylinders consist inbuilt High-Pressure Regulator (11). High pressure line (13) carries hydrogen gases to electronics Low-Pressure Regulator (14), which converts high pressure to working level pressure. Electronically controlled low-pressure line (15) carries hydrogen gases to common rail (16). Electronically controlled low pressure regulator which in turn connected to fuel storage through higher pressure regulator and a solenoid gas shutoff valve. The other end of common rail consist a low pressure sensor (31) to monitor the rail-pressure.
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Flexible metal pipes (26, 17) carry Hydrogen gas to hydrogen injector (44). 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 cylinder through intake valves, the valve Opening & Closing controlled by a cam shaft. Upper slot (25) and side slot (27) are provided on intake runner pipe (22). The exhaust port (21) is provided with exhaust valve, the valve Opening & Closing controlled by a cam.
FIGURE 2 shows the Multi-Point Hydrogen Injection system. The Hydrogen gas flows from Common rail plenum (16) to hydrogen injectors (44) through flexible pipes (17,26). These injectors (44, 49) are controlled by ECU for safe opening & closing in sequential with reference to firing order. The intake runner pipe (length is tuned for Ram Effect) (22) is in fluid communication with plenum (30), it delivers air to individual cylinder inline with intake valve timing. Air-flow rate to the plenum has been controlled by an Electronically Controlled Throttle-body (23) as shown in figure 1, which is assembled at upper stream of intake (plenum). In conventional fuel injection system, single fuel injector is positioned at intake port, however in this invention twin electronically control hydrogen gas injectors are placed in intake runner pipe close to intake port. Axes of the injectors are placed perpendicular to each other so that the gas is injected inside the runner pipe substantially perpendicular to each other. Two slots are provided on the runner pipe. Injectors are located in slots provided on the runner pipe. The axes of the slots are substantially perpendicular to each other. The injectors are disposed in the slots provided on the runner pipe in a leak proof manner. Basic concern for twin type injectors is to meet the required amount of hydrogen flow-rate per cylinder within available time during intake stroke. To withstand vibration and to accommodate injectors on runner pipe, the new assembly (45) has been designed and adopted in the system. This assembly (45) provides leak proof arrangement for Multi-Point Sequential Gas Injection system. The twin injector assembly unit (45) comprises a housing, which horizontally divided in upper and lower plate. These two injectors are assembled in single unit and inject the fuel in the adjacent cylinder ports. The complete assembly (Fuel Rail, Injector
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Assembly, Flexible pipe) has been assembled on intake system through two brackets (48)
As shown in figure 3 and 4, this system embodiment is used in an internal combustion engine. The engine cylinder (36) is communicated with intake runner (22) and exhaust port (not shown in figure) for Air& Fuel in-flow and Burned Gas out-flow respectively. An intake valve (35) is provided between intake port and in cylinder space (36) of internal combustion engine. Common rail (16) is mounted on top of plenum chamber (30).
Twin injectors (49, 44) are located at the intake runner pipe (22). The injectors are arranged in such way that the injectors are positioned at angle of b with respect to each other. The angle b is preferably 90°. Referring to figure 3, in a preferred embodiment one of the injectors (49) is injecting fuel vertically and other injector (44) injecting fuel horizontally into the runner pipe. Further both the injectors (49, 44) are positioned at an angle of a degrees with respect to intake runner pipe (air-flow direction) but they are not in the same vertical and horizontal planes. The injectors are located in the runner pipe preferably opposite to each other with an offset in the vertical plane of axis. The planes of axis of these two injectors are placed at "x" mm offset. This is mainly to avoid any excessive over-lapping of Fuel injection cones, as the excessive overlapping will restrict the air-flow in Naturally Aspirated engine. To avoid excessive overlapping of fuel injection, the planes of axis of two injectors (44, 49) are preferably separated by 1mm. This position is unique and finalized after many iterative processes through Computational Fluid Dynamics. The positions of injectors relative to intake runner pipe helps to achieve better mixing of gaseous fuel and air to form homogenous Air-Fuel mixture to meet the complete combustion. This relative position improves engine performance and fuel economy. Injecting fuel into the intake runner pipe make it possible to introduce a uniform concentrated mixture into the cylinder. Further it avoids the back-fire issues by optimizing the injection timings in the latter period of intake stroke. This is ensured by initial entry of pure air into the cylinder through intake port, cools the engine cylinder, combustion chamber, the
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exhaust & inlet valves and crevice volume. Hence there is no hot spot to initiate any unwanted combustion. By providing two injectors per cylinder, Fuel (low density hydrogen) required per cycle per cylinder (high cubic capacity) can be met at higher engine power output.
The volume of Common Rail pipe is decided by considering rail as fuel plenum chamber. The constant rail pressure is maintained through out the engine operation and the low-pressure sensor is used to ensure the leak-proof hydrogen flow for safer usage. Low-pressure electronically controlled pressure-regulator (14) keeps the rail pressure constant. One end of the rail (30) is connected to hydrogen inlet from storage and the other part is connected with a low-pressure (31) sensor. In this assembly the Flexible metal pipes (42) connected between fuel rail and injector, such a way that to meet the vibration test & leak-proof joints (special joints) (41) with higher reliability. The common rail plenum assembly and fluid lines are made of stainless steel.
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.
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WE CLAIM
1. A twin injector assembly for multipoint sequential gas injection system, the arrangement comprising, two injectors located in a runner pipe of said injection system and said injectors are injecting gas into said runner pipe in perpendicular to each other.
2. A twin injector assembly as claimed in claim 1 wherein said runner pipe connected between an air intake plenum and a cylinder of said injection system.
3. A twin injector assembly as claimed in claim 1 wherein said injector is connected to a gas plenum of said injection system.
4. A twin injector assembly as claimed in claim l wherein the axis of said injectors located in said runner pipe are perpendicular to each other.
5. A multipoint gas injection system as claimed in claim l wherein said injectors are electronically controlled.
6. A multipoint gas injection system as claimed in claim l wherein said runner pipe having two slots with axis perpendicular to each other to accommodate said injectors.
7. A multipoint gas injection system as claimed in calim 8 wherein said injectors are disposed in said slots in a leak proof manner to inject gas inside said runner pipe.
8. A twin injector assembly as claimed in claim l wherein said injectors preferably making an angle of 45° with air flow direction in said runner pipe.
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9. A twin injector assembly as claimed in claim 1 wherein said injectors are located opposite to each other with an offset of axes preferably 1mm.
10. A multipoint gas injection system substantially as herein described with reference to accompanying drawings
Dated this 4th day of March 2008
TATA MOTORS LIMITED
By their Agent & Attorney
(Karuna Goleria) of DePENNING & DePENNING
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ABSTRACT
A Twin-Injector arrangement for MPSGI system
Alternate fuel with less carbon content (high H/C ratio) is present demand of automotive industry to meet Carbon-free (Without Green House Gases) tail-pipe emissions. In general, less-carbon content fuels are in gaseous form and the fuel without carbon is Hydrogen. Conversion of conventional diesel Internal Combustion Engine to run on hydrogen or gaseous fuel, require some fundamental modification at component level. The main components of IC engines are Cylinder-Head, Intake-System (cylinder head cover), Fuel-Induction system, Combustion Chamber (Piston), Engine Valves, Exhaust-System & etc. To achieve minimal modification of above components, A Multipoint Hydrogen Gas injection system needs to be introduced / adopted to have higher control on Fuelling & Safe handling of hydrogen to avoid back-fire in-case of Multi-Cylinder Bus engine. This invention is related to the design of components and hydrogen fuelling systems to meet the above requirement. The invented Multipoint Hydrogen Injection system for an IC engine consist fuel-metering devices such as Hydrogen injector, Fuel rail, Rail Pressure sensor, Electronic Pressure Regulator, Flexible pipes & fittings and Injector arrangement unit. This fuelling system ensures the optimized & safe injection timing & duration through Electronically Controlled system and further ensures the leak-proof design. According to objective of the present invention two injectors are connected to the runner pipe connecting between the air intake plenum and cylinder to achieve required flow rate in all running condition. The injectors are positioned inside the runner pipe perpendicular to each with an offset in the plane of axis. The axis of the injectors are making an 45° with wall of the runner pipe (axis of air flow). Further the injectors are located opposite to each other with an offset of plane of axis preferably 1mm. Fig.3