DESC:FIELD OF INVENTION
The present invention relates to a system for sequentially injecting LNG in a modified compression ignition internal combustion engine. More specifically, the present invention relates to the field of generation of power in using combustion of cryo-fuel such as LNG, wherein composition and rate of burning of air and LNG is electronically governed.

BACKGROUND OF INVENTION:
For more than a century, internal combustion engines 1 have been relied upon as a principal source of power in a variety of applications. Of those engines, the most widely used are the reciprocating piston engines which are found in automobiles or other forms of transportation, as well as a variety of industrial and consumer applications. Such engines can be built in a variety of sizes, types and configurations depending on the power requirements of a particular application.

Of those variations, Diesel engines have a number of important advantages over gasoline engines. They provide reliability, long life, and good fuel economy, and are expected to remain the dominant heavy-duty transport power plants for several years. Diesel engines typically inject diesel fuel into the engine's combustion chamber when that chamber's piston is near the end of the compression stroke. The high pressure present in the chamber ignites the diesel fuel.

Due to the uncontrolled nature of the mixing of diesel and air during combustion, a large fraction of the fuel exists at a very fuel-rich equivalence ratio. That is, the fuel and air in the combustion chamber are not necessarily a homogenous mixture. This typically results in incomplete combustion of the diesel fuel, which tends to result in high particulate emissions. Furthermore, the fuel-rich equivalence ratio can also lead to high flame temperatures in the combustion process, which results in increased NOx emissions. As tougher environmental standards are being enacted for diesel sources, users of diesel engines are looking for ways to lower emissions. These fuels provide a dense exhaust fume as a by-product of combustion like CO, CO2, NOx, etc. Gasoline compounds contain petroleum, octane, diesel, LPG, butane, etc. By using diesel or gasoline in the vehicles cannot run longer kilometres with one time refuel the storage tank. It is not possible to increase the storage volume as it leads to increase the weight of the vehicle.

One solution is to partially or completely convert the engine for use with alternative fuels such as, compressed natural gas (CNG), liquid natural fuels (LNF) such as ethanol, and liquid or liquefied petroleum gas (LPG) such as propane. Utilization of such alternative fuels with diesel engines not only provides for more complete combustion and thereby enhanced fuel economy, but also typically results in lower engine emissions.

However, alternative fuels, and more particularly gaseous fuels, typically do not have the centane value required to allow for their ignition through compression. Accordingly, diesel engines must be modified to use such fuels. Methods for converting a diesel engine to consume alternative fuels typically fall into three categories. The first is to convert the engine to a spark-ignited engine; a second is to convert the engine to allow for the direct injection of gaseous-fuels into the combustion chamber; and a third is "fogging" or "fumigation" of the gaseous-fuel with all or a portion of the intake air charge entering the engine.

As will be appreciated, the second and third methods utilize injected diesel (i.e., pilot diesel) to ignite the gaseous-fuel. In this regard, the combustion of the gaseous-fuel results in more complete combustion of the diesel. Furthermore, the combination of gaseous-fuel and diesel allows the engine to produce additional power while less diesel fuel is injected into the cylinders.

Another shortcoming of diesel engines that results in inefficiency and increased emissions relates to supercharging, where an intake air compressor is mechanically driven or driven with exhaust gases from the engine being expanded through a high speed rotary expander to drive a rotary, centrifugal compressor to compress the incoming air charge to the combustion cylinders, e.g. turbocharging. The supercharging or turbocharging of the intake air raises the temperature of the incoming air charge. This heated air adversely affects the performance of the engine by decreasing the density of the intake air charge, and therefore limits the available mass of intake air for a given engine displacement. In addition, a hot intake air charge increases the likelihood of premature detonation of the fuel charge in the cylinders which may damage engine components.

The present invention overcomes the above mentioned problem by delivering cryogenic fuel to the internal combustion engine. Cryogenic fuels are environmentally cleaner than gasoline or fossil fuels. Among other things, the greenhouse gas rate could potentially be reduced by 11–20% using LNG as opposed to gasoline when transporting goods.

The invention uses LNG as a cryogenic fuel in I.C engine of vehicles. The lower carbon deposits associated with the combustion of LNG provide for reduced maintenance cost in vehicles. LNG (Liquefied Natural Gas) basically is a liquid methane which contain approximately 90 percent to 93 percent methane, mixed with nitrogen, ethane, carbon dioxide and less than 1 percent of propane.

LNG is a clean burning fuel and it is extremely safe. Economically price of the LNG fuel is less (nearly 40% or more) than other fossil fuels. LNG when mixed with air provides a combustible mixture that is ideal as a source of energy for IC engine. LNG increases mileage of the IC engine than diesel engine and also increases the life of the IC engine by almost 50% or more.

The present invention overcomes the above mentioned problems by adopting a method of conversion of diesel fuelled engines to LNG multipoint sequential mono-fuel conversion. In this method of conversion, CNG is taken as backup fuel.

SUMMARY OF INVENTION
It is therefore the principal object of the present invention to convert, a diesel engine to LNG internal combustion engine; wherein a multi-port injection sequential control is employed for controlling air-fuel ratio and an control unit is connected to the engine system in order to control operation of the said diesel engine converted to LNG internal combustion engine.
According to another aspect of the present invention, an electronic control unit 21 is provided for a diesel engine converted to LNG internal combustion engine; wherein, said control unit 21 is capable of inputting operating characteristics of the engine system and controlling amounts of a fuel for delivery to the engine system based on at least one of the operating characteristics; whilst operating characteristics includes gas pressure and gas temperature.

Another aspect of the present invention may provide a method for initializing an electronic control unit 21 for a diesel engine converted to LNG internal combustion engine, wherein the method of comprising: connecting the electronic control unit 21 to one or more sensors configured to monitor a condition of a gaseous fuel containing device; connecting the electronic control unit 21 with one or more initialization device having a display showing a user interface; entering, via the user interface, specifications for the one or more sensor.

A further aspect of the present invention relates to a vehicle control system for a diesel engine converted to LNG internal combustion engine comprising: a cryogenic fuel or a gaseous fuel containing device of the vehicle; an electronic control unit 21 capable of communicating one or more data with one or more entities on the vehicle and/or remote from the vehicle, wherein the entities include a sensor, a gauge and at least one of the following: a control, another electronic control unit 21, a device, or an information system hosted on a device, wherein the electronic control unit 21 is configured to enable logging and acquisition of the communicated data, and wherein the communicated data express a condition, a state or an instruction regarding a condition or a state of the a cryogenic fuel or gaseous fuel containing device.

Aspects of the present invention may be directed to safety of the vehicle a diesel engine converted to LNG internal combustion engine during fueling. One, two, three or more switches may be provided to check that the fuel dispenser is disconnected from a receptacle by preventing engine cranking. Such switches may optionally not use relays. Such switches may be spark proof.

A further aspect of the present invention relates to a diesel engine converted to LNG internal combustion engine comprises a block having a cylindrical block 3; a cylinder head 4 having an spark plug 20; an intake manifold 5 structured to receive a fuel gas and guide the fuel to the combustion chamber; a piston 3 with piston rings structured to move axially within the cylindrical block 3 toward the cylinder head 4 in a compression cycle of the combustion engine, the piston 3, the cylindrical block 3, and the cylinder head 4 forming a combustion chamber; a multi-port fuel injector 14 structured to discharge the fuel in a gaseous state; individually supplies air to the engine, using inlet manifold and gas is injected to the specific cylinder of the engine; wherein an Inlet 7 and exhaust valves 10 used for sealing the combustion chamber and controlling the gas exchange process in internal combustion engines and a control unit 21 connected to the engine system in order to control operation of the diesel engine converted to LNG internal combustion engine.

Another object of the present invention is to provide a diesel engine converted to LNG internal combustion engine comprising the modification of the cylinder head 4 of the LNG internal combustion engine.

A further object of the present invention is to convert the diesel engine to LNG internal combustion engine involves the installation of spark plugs 20 by removing the fuel injectors 17 and further precise machining is carried out in fuel injector hole to get it surfaced and to make threads in the hole.

A further object of the present invention is to provide a diesel engine converted to LNG internal combustion engine involves the replacement of the inlet 7 and exhaust valve 10 bodies and oil seals which are used at times cryogenically treated to withstand more heat while combustion of the natural gas.

A further object of the present invention is to provide a diesel engine converted to LNG internal combustion engine involves the new valves which are grinded by using the grinding paste and valve grinding tool and after the creation of the valve seat, the valve is installed.

A further object of the present invention is to provide a diesel engine converted to LNG internal combustion engine is to change the valves to withstand the more heat which is generated during the process of the LNG combustion.

Other object of the present invention is to provide a diesel engine converted to LNG internal combustion engine is to provide the intake 7 and exhaust valves 10 which can be hardened by the cryogenic treatment and frozen down below sub-zero temperature.

Other object of the present invention is to provide a diesel engine converted to LNG internal combustion engine wherein the diesel engine piston are replaced with natural gas piston to increase compression ratio.

Other object of the present invention is to provide a diesel engine converted to LNG internal combustion engine wherein the diesel engine piston are replaced with natural gas piston by the replacement of the standard sized engine sleeves.

Other object of the present invention is to provide a diesel engine converted to LNG internal combustion engine is to provide the engine piston having the three piston rings wherein the first two piston rings are plain faced rings and the third piston ring is oil controlled ring which comprises one inner ring, one helical spring ring and outer ring.

Further object of the present invention is to provide a diesel engine converted to LNG internal combustion engine are to provide the piston with a deep hole on the top of the cylinder 3a to improve the compression ratio.

Further object of the present invention is to provide a diesel engine converted to LNG internal combustion engine is to provide the engine head which is assembled with new aluminium gasket, so that the cylinders 3 are sealed and further water and oil conduits are also sealed.

Further object of the present invention is to provide a diesel engine converted to LNG internal combustion engine is to provide the Control Unit 21 to read the values from the multiple sensors from the engine bay and controls the actuators to operate the engine to run efficiently and to obtain better emissions.

Further object of the present invention is to provide a diesel engine converted to LNG internal combustion engine is to provide the CNG which as a backup fuel in the process of conversion of the diesel to LNG multipoint sequence.

Further object of present invention is the convert LNG into the natural gas in dual phase convective heat exchanger 40 using heat of coolant circulating in the radiator and heated by the heat of the engine/cylinder bock.

Another object of the present invention is to provide a by-pass line for bleeding of the natural gas converted in the dual phase convective heat exchanger 40, in order to replenish the tank 16b of natural gas.

Another object of the present invention to provide a three-piece pipe connector 42 for combining the flow lines of natural gas converted from LNG tank 16a and natural gas coming from the natural gas tank 16b.

Another object of the present invention is to provide a buffer storage tank 41 for the natural gas converted from the LNG in the heat exchanger 40, so as to receive stable/non-interrupted flow of natural gas to the 3-piece pipe connector 42.

Another object of the present invention is to provide a first regulator 22 attached at one of the inlets of the 3-piece pipe connector 42, and secondary pressure regulator 22a connected to outlet of the 3-piece pipe connector 42.
BRIEF DESCRIPTION OF DRAWINGS
The drawings constitute a part of this invention and include exemplary embodiments of the present invention illustrating various objects and features thereof.
Figure 1: Illustrates components of ignition cycle of the present inventio;
Figure 2: Illustrates functioning of the camshaft trigger wheel 24;
Figure 3: Illustrates functioning of the camshaft shaped wheel 12;
Figure 4: Illustrates connectivity between ignition system, control unit, camshaft trigger wheel 24, and camshaft shaped wheel 12;
Figure 5: Illustrates modifications in the piston 3;
Figure 6: Illustrates elements of ignition system 19;
Figure 7: Illustrates arrangement of LNG tank, natural gas tank, three-piece pipe connector 42, first pressure regulator 22, and second pressure regulator 22a.

DETAILED DESCRIPTION OF INVENTION
For the purposes of promoting an understanding of the principles of the invention, reference will now be made to the embodiments illustrated in the drawings and specific language will be used to describe the same. It will nevertheless be understood that no limitation of the scope of the invention is thereby intended, such alterations and further modifications in the illustrated device, and such further applications of the principles of the invention as illustrated therein being contemplated as would normally occur to one skilled in the art to which the invention relates.

In one of the embodiment, the internal-combustion engine 1 comprises (includes, but is not limited to) an engine block 2 in which there are a number of combustion chambers in the form of cylinders 3 and a cylinder head 4 in which inlet tracts (not shown), inlet ports (not shown), a valve assembly (not shown), exhaust pipes (not shown) and exhaust ports (not shown) are formed. The conventional diesel engine cylinder head is modified to cylinder head 4 wherein fuel injectors are removed and ignition system 19 is installed. An intake manifold 5 is coupled to the inlet ports of the cylinder head 4 and an exhaust manifold 6 is coupled to the cylinder head’s exhaust port. The inlet manifold 5 is connected to an inlet tract 7 in which a throttle 8 is mounted. The exhaust manifold 6 is in turn coupled to an exhaust system 10 in which optionally an catalyser is mounted.

The cylinders 3 are fed fuel in the form of natural gas via a multi-port fuel injection system 14. The multi-port fuel injection system 14 includes a fuel reserve for supply of natural gas through injectors 17, which are usually mounted upstream of the inlet manifold 5. In an alternative embodiment, the injection can take place outside the cylinders 3 and in proximity to the cylinders inlet ports, that is frequently referred to as port injection. According to a further embodiment, the injection devices 17 are mounted and open directly in the combustion chambers of the cylinder 3 in what is commonly referred to as direct injection. In an alternative embodiment, a camshaft shaped wheel 12 is installed by removing the diesel fuel pump using a housing on which camshaft trigger wheel 24 is mounted, on that camshaft trigger wheel 24 a camshaft position sensor is attached which is calibrated in a way such that when pistons inhales air, gas is also injected at a pressure higher than atmospheric pressure, using the values of the sensors control unit 21 gives the signals to the injector 17 to inject gas. The gas supplied to the injector 17 is regulated at a constant pressure with a given amount of flow rate using second pressure regulator 22. Second pressure regulator 22a regulates and reduces the high/unregulated pressure.

Furthermore, there is an ignition system 19 installed to the diesel engine converted to LNG internal combustion engine. The ignition system 19 is installed by removal of fuel injectors 17 from conventional type diesel engine and precise machining is carried out in fuel injector 17 hole to get it surfaced, further injector holes are threaded and spark plugs 20 are installed. As illustrated first fuel injectors 17 are removed, and then the holes are machined by surfacing tool to get it surfaced. Secondly the holes are to be threaded by threading tool so that spark plug 20 can be installed. LNG internal combustion engine includes a voltage source (not shown) and a high voltage part with spark plugs 20 that are mounted in the cylinder head 4.

The diesel engine converted to LNG internal combustion engine is controlled by a Control Unit 21 that is arranged to control: the throttle 8 to obtain the correct throttle angle for the current operation state of the internal-combustion engine, injection devices 17 for achieving the correct supply of fuel for the current operation state of the internal-combustion engine and an ignition system 19 to achieve the correct ignition time for the current operation state of the internal-combustion engine. For this purpose, the control device control unit 21 communicates with an actuator (not shown) arranged to set the throttle angle, with the injection device 17 to set the injection times and with the ignition system for ignition control.

The diesel engine converted to LNG internal combustion engine wherein engine operation is controlled by a LNG or CNG gaseous fuel controller. The controllers are connected to multipoint injector in which an individual gas fuel injector was assigned to each cylinder, those injectors 17 would be controlled by the gaseous fuel controller. The controllers receive data from an accelerator pedal position sensor, an engine position sensor, an intake manifold pressure sensor, an intake manifold temperature sensor, a mass air flow (MAF) sensor, and an intake O2 sensor.

Other sensors, such as an EGR temperature sensor, an ambient pressure sensor, an ambient temperature sensor, a humidity sensor, and a vehicle speed sensor may be provided as well. These sensors are collectively denoted “other sensors” and are connected to the gaseous fuel controller by appropriate signal line(s). The gaseous fuel controller also is connected to the gas metering device, and to other controlled equipment, such as high-pressure and/or low pressure gas shut off valves, denoted by reference numeral. If the engine were a multipoint engine in which an individual gas fuel injector was assigned to each cylinder 3, those injectors would be controlled by the gaseous fuel controller in lieu of the controlling metering device.

In one of the embodiment of the invention the control device control unit 21 in accordance with the invention enables an economic, fuel-efficient method and apparatus for a spark ignition engine to operate on a gaseous fuel such as natural gas. Further embodiment control device control unit 21 controls injection of gaseous fuel by generates a pulse width modulated fuel injection signal to control a high-speed, two-way normally closed injection solenoid valve 43 to inject the gaseous fuel into an area of the intake tract of the engine determined to be the most advantageous location for proper distribution of the gaseous fuel to the respective cylinders of the engine. More than one injector 17 may be used for an engine, depending on the fuel requirements of the engine. The pulse width modulated fuel injection control signal generated by the electronic controller is dependent upon various engine condition sensor inputs which include at least manifold absolute pressure, engine coolant temperature or intake air temperature, the speed of revolution of the engine and battery voltage. Additional sensor inputs may further improve engine performance and lessen exhaust emissions. Additional sensor inputs optionally include fuel gas temperature, throttle position and exhaust gas recirculation. In addition, when a modern closed-loop engine is converted using a system in accordance with the invention, the controller also accepts signals from at least one sensor which measures the oxygen content of exhaust gases generated by the spark ignition engine in order to ensure that stoichiometric mixtures of fuel gas and intake air are supplied to the engine when exhaust gas recirculation is enabled. In this instance, the controller utilizes a dual-array block learn scheme in which a first block learn array is utilized when an exhaust gas recirculation valve is opened and a second block learn array is used when the exhaust gas recirculation valve is closed. This enables the controller to rapidly adapt to changing engine conditions and automatically compensate for changing environmental factors, engine wear, etc.

A control unit 21 in accordance with the invention also assumes complete control of ignition and ignition timing when the engine is operating in gaseous fuel mode. The controller preferably uses manifold absolute pressure and revolution of the engine in conjunction with intake air temperature and engine coolant temperature to compute a timing signal which controls ignition spark timing. Battery voltage, manifold absolute pressure and revolution of the engine are also used to compute a coil dwell period. The ignition spark timing and coil dwell period are combined to generate the complete fuel ignition sequence to ensure that an ignition spark of a required intensity is initiated at an optimal time for igniting the gaseous fuel. The system includes a solid state switch which permits direct control of the spark timing and ignition coil current period (dwell angle). Control of the coil dwell permits spark energy to be increased to compensate for the high ionization voltage required to ignite gaseous fuels such as natural gas. In addition, the solid state switch simulates the presence/operation of the original equipment ignition module so that the original equipment controller is kept “happy”. A second solid state switch controlled by the original equipment ignition bypass signal applies a simulated load to the original equipment ignition signal when the original equipment controller enters ignition bypass control. This ensures that the original equipment ignition bypass diagnostics operate properly while the engine is in gaseous fuel mode.

The diesel engine converted to LNG internal combustion engine a spark ignition engine equipped with a system that includes an electronic control unit. The a diesel engine converted to LNG internal combustion engine is equipped with natural gas fuel injectors 17 which are supplied with geouesous fuel from a LNG tank 16a or natural gas tank 16b. The diesel engine converted to LNG internal combustion engine equipped with an intake manifold 5 and ignition system 19 which controls ignition spark generation by a spark plug 20 in each engine cylinder. The diesel engine converted to LNG internal combustion engine is also equipped with an exhaust system 10.

The control unit 21 accepts inputs from a plurality of sensors and outputs control signals to a two-way normally closed gaseous fuel injection and to the spark ignition module 18.

Figure 1 of the present invention illustrates the components and working of the ignition system. An ignition system generates a spark or heats an electrode to a high temperature to ignite a fuel-air mixture in spark ignition internal combustion engines, oil-fired and gas-fired boilers etc. It comprises of 60-2 trigger wheel, crankshaft trigger wheel 24, crankshaft position sensor 25, coil on plug and spark plugs 20. A 60-2 trigger wheel which is a gear toothed metal wheel is installed with the crankshaft to sense the position of the piston 3 during the operation of the engine. The information about the position is communicated to the control unit 21, when the piston comes to TDC control unit 21 supplies the signal to the ignition coil 19 where the ignition coil 19 will generate high voltage spark using spark plugs 20. This process mainly depends on the firing order of the engine.

Figure 2 of the present invention illustrates the work which is controlled by the throttle 8. An engine's power can be increased or decreased by the restriction of inlet gases by the use of a throttle 8, but usually decreased. The throttle 8 has come to refer, informally, to any mechanism by which the power or speed of an engine is regulated, such as a car's accelerator pedal. What is often termed a throttle 8 is also called a thrust lever, particularly for jet engine powered aircraft. For a steam locomotive, the valve which controls the steam is known as the regulator. Here, a throttle pedal 8a is installed under the steering, so that the driver can accelerate or decelerate according to the situations. There is a position sensor which is installed with the pedal which can able to sense the degree of the rotation and sends the information to the control unit 21. This information helps to calibrate the amount of the throttle 8 to be applied where the control unit 21 governs the stepper motor which is already inbuilt in the throttle 8.

Figure 3 of the present invention illustrates the working of the fuel supply. The main function of the fuel system is to store and supply fuel to the engine. It consists of the camshaft trigger wheel 24, camshaft position sensor 26, timing wheel housing, gas injectors and pressure regulator 22a. Although, fuel systems vary from engine to engine, all systems are the same, where they must supply fuel to the combustion chamber and control the amount of the fuel supplied in relation to the amount of the air. Initially, a camshaft shaped wheel 12 is installed by removing the diesel fuel pump using a housing on which camshaft trigger wheel 24 is mounted. Here, on the camshaft trigger wheel 24, a camshaft position sensor 26 is installed which can able to calibrated when pistons inhales air, gas is also injected at a pressure higher than atmospheric pressure, using the values of the sensors control unit 21 gives the signals to the injector 17 to inject gas. The gas supplied to the injector 17 is regulated at a constant pressure with a given amount of flow rate using second pressure regulator 22a. Second pressure regulator 22a is incorporated to regulate and reduce the unregulated pressure from the fuel tank.

Figure 4 of the present invention illustrates the injection of the gas using multi-port injection system 14. It injects fuel into the intake ports just upstream of each cylinder’s intake valve, rather than at a central point within an intake manifold. It is a method of injecting fuel into internal combustion engine through multi-ports situated on intake valve of each cylinder 3a. In the simultaneous system, fuel is inserted to all cylinders 3a at the same time, while the sequential system injection is timed to overlap with intake stroke of each cylinder 3a. On the head of the engine, a runner is provided which will supply air to the engine individually. Using this runner on the inlet, manifold gas is injected to the specific cylinder of the each engine. A common rail for the gas is developed on the top of the nozzles.

Figure 5 of the present invention illustrates arrangement of piston 3 entailing a crank 28 attached with for facilitating flywheel effect for the completion of two-stroke or four-stroke combustion cycle, and further involves plurality piston rings 27 affixed with the peripheral groves of the piston 3. Wherein, preferably three piston rings 27 conferred with the piston 3, two of which serves to limit the effect of sliding friction between the moving piston and cylinder wall and remainder one arrests leakage of engine of contained in the crank case. Further, the cavity provided at the top surface of the piston 3 provides a crown contour for efficient agitation of natural gas in to the bore of the cylinder. Moreover, the said recess/cavity present at the top of piston 3 enables smooth path as suitable for non-viscous flow of natural gas; the said recess improves circulation of the natural gas and improves burning efficiency.

Figure 6 of the present inventio illustrates arrangement wherein an injector 17 is shown being placed in the vicinity of spark plug 20, in which injector 17 functions to inject flow of natural gas into the bore of the cylinder and spark plug 20 provides spark as necessitated for igniting the fuel; which collectively constituents ignition system 19.

Figure 7 of the present invention illustrates about the LNG and natural gas tank which is used as a backup. It consists of a LNG fuel tank 16a and a heat exchanger 40 which will supplies gas to the second pressure regulator 22a in the range of 5 bars to 25 bars. At the other end, there are natural gas cylinders which are attached and can be used as backup. As natural gas converted from the LNG is a clean fuel and environment friendly, it is also used as a backup source to reduce the pollution. To supply natural gas the required pressure range the cylinders are cascaded and connected with the filling receptacle from one end and at the other end a first pressure regulator 22 is installed which reduces the pressure from 200 bars to the excess of 6.5 bar. After the first pressure regulator 22 a solenoid valve 43 is attached which is used to open and close the connection when required that line connects with the LNG pressure regulator with the help of three-piece pipe connector 42.

Further, the said 3-piece pipe connector 42 entails at least two inlet flow passage and at least one outlet flow passage, wherein one of the inlet is connected towards the LNG tank 16a, another inlet is connected towards the natural gas tank 16b, and the outlet is connected to the solenoid valve 43.

The inlet connected towards the LNG tank involves a dual-phase convective heat exchanger 40 and buffer tank 41 placed there between so as to receive the supply of natural gas converted from the LNG which is stored in the LNG storage tank 16a; the another inlet connected towards the natural gas tank involves the first pressure regulator 22 placed therebetween for regulating/reducing the pressure of already compressed natural gas from the gauge pressure value of 200 bar to the reduced value of gauge pressure in the range of 5.5 bar to 25 bar.

The outlet of 3-piece pipe connector 42 has a solenoid valve 43 being further connected to the second pressure regulator 22a, wherein said solenoid valve 43 connects either of the inlet passage with the second pressure regulator 22a based on the control signal received from the control unit, whereas the second pressure regulator 22a functions to regulate/reduce the pressure of natural gas to the gauge pressure value of 3.5 bar which is getting fed to the injector for the burning in the bore of the cylinder 3a.

In one of the embodiments of the present invention control unit takes input from sensors which includes an ambient temperature sensor, pressure and humidity sensor, exhaust gas temperature sensor, intake air mass sensor, coolant temperature sensor, vehicle speed, engine life, camshaft position sensor, pedal position sensor, throttle position sensor, natural gas level sensor, piston position sensor, intake and exhaust manifold pressure and temperature sensor, engine condition sensor, pressure sensors at inlet and outlet of 3-point connector pipe, solid state switches, Manifold Absolute Pressure [MAP] sensor, LNG temperature sensor, LNG flow rate sensor, and lambda sensor.

In one of the embodiment cryogenic treatment is the process of treating work pieces to cryogenic temperatures (i.e. below -190 °C (-310 °F)) in order to remove residual stresses and improve wear resistance on steels and even composites. In addition to seeking enhanced stress relief and stabilization, or wear resistance, cryogenic treatment is also sought for its ability to improve corrosion resistance by precipitating micro-fine eta carbides, which can be measured before and after in a part using a quantimet.

The process has a wide range of applications from industrial tooling to the improvement of musical signal transmission. Some of the benefits of cryogenic treatment include longer part life, less failure due to cracking, improved thermal properties, better electrical properties including less electrical resistance, reduced coefficient of friction, less creep and walk, improved flatness, and easier machining

The present invention overcomes environment pollution related problem by conversion of diesel fuelled engine vehicle into LNG fuelled engine vehicles effectively and economically by providing the CNG as a backup fuel. The invention relates to major equipment’s that are LNG fuel tank 16a, natural gas tank/cylinders 16b, natural gas filling receptacle, pressure regulators 22 & 22a, three-piece pipe connector 42, injector 17, engine 7 and buffer tank 41 and dual phase convective heat exchanger 40.

The present invention introduces the modified diesel engine in which the conversion of diesel engine is done to LNG engine which is used as the fuel by the method of multi-point sequential process. The method uses the CNG which acts as the backup fuel.

In one of the embodiments of the present invention is to invention to convert diesel-fuelled engine vehicles into LNG fuelled engine vehicles by multi-point sequential mono-fuel conversion.

Another embodiment of this invention is to provide a modified diesel engine comprising the modification of the cylinder head 4 of the LNG engine.

In one of the embodiments of the present invention camshaft positioning system involves the use of camshaft positioning sensor 26 for determining position of camshaft.

In one of the embodiments of the present invention crankshaft positioning system involves the use of crankshaft positioning sensor 25 for determining position of crankshaft.

Another embodiment of the present invention involves the installation of spark plugs 20 by removing the fuel injectors 17 and further precise machining is carried out in fuel injector hole to get it surfaced and to make threads in the hole.

Another embodiment of the present invention involves the replacement of the intake and exhaust valve bodies and oil seals which are used at times cryogenically treated to withstand more heat while combustion of the natural gas.

Further embodiment of the present invention involves the new valves which are grinded by using the grinding paste and valve grinding tool and after the creation of the valve seat, the valve is installed.

One of the embodiments of the present invention is to convert the diesel engines that are currently used in vehicles. To convert a diesel engine into LNG engine by multi-point sequence, the cylinder head 4 is to be modified, in which first step is to remove fuel injectors 17 and precise machining is carried out in fuel injector hole to get it surfaced. The second step is to make threads in the hole to install spark plugs 20. As illustrated fuel injectors 17 are removed, and then the holes are machined by special proprietary surfacing tool to get it surfaced and then the holes are to be threaded by threading tool so that spark plug 20 are installed appropriately. Then the intake 7 and exhaust valve 10 bodies and oil seals. Then replace the intake 7 and exhaust valve 10 bodies and oil seal. New valves are grinded by using grinding paste and valve gridding tool, valve seat is created and then the valve is installed. These valves are changed so that valves can withstand more heat which is generated during the process of the LNG combustion. Valves can also be hardened by cryogenic treatment and frozen down below sub-zero temperature.

The further step involves the changing of the Diesel piston to natural gas piston. For that standard sized engine, sleeves are replaced and engine pistons are changed. The natural gas piston has three piston rings wherein two rings are plain faced rings and the third piston ring is oil control ring that comprises one inner ring, helical spring ring and outer ring. The natural gas piston has a deep hole or a combustion bowl on top of the piston head to improve the compression ratio. When the engine head is assembled on the engine new aluminium gasket is installed so that cylinders 3a are sealed and further water and oil conduits are also sealed.

One of the embodiments of the present invention is to provide a device called Control Unit 21, also known as Engine management system reads the values from the multiple sensors from the engine bay and controls the actuators to operate the engine to run efficiently and to obtain better emissions. Control unit 21 performs four types of operations at a time which includes Controls ignition system, Controls throttling of the engine, Controls the fuel supply and Controls speed governing.

One of the embodiments of the present invention involves the working of the ignition control. The ignition system consists of 60-2 Trigger wheel, 60-2 Trigger wheel, Crankshaft position sensor, Coil on plug and spark plugs 20. On the crankshaft of the engine a 60-2 trigger wheel (gear toothed metal wheel) is installed with crankshaft position sensor which senses the position of the piston during the operation using the firing order of the engine. This sensor detects the position of the pistons and informs the control unit 21, when the piston comes to TDC control unit 21 supplies the signal to the ignition coil and the ignition coil will generate high voltage spark using spark plugs 20, this process depends on the firing order of the engine.

One of the embodiments of the present invention involves the working of the throttle control wherein a throttle pedal 8a is installed under the steering so that driver can accelerate/decelerate according to the situations, there is a position sensor in the pedal which senses the degree of the rotation and gives the signal to the control unit 21 the amount of throttle 8 to be applied, according to the pedal the control unit 21 governs the stepper motor which is inbuilt in the throttle body.

One of the embodiments of the present invention involves the working of the fuel supply and it consists of camshaft trigger wheel 24, camshaft position sensor, timing wheel housing, gas injectors and second pressure regulators 22a. A camshaft shaped wheel 12 is installed by removing the diesel fuel pump using a housing on which camshaft trigger wheel 24 is mounted, on that camshaft trigger wheel 24 a camshaft position sensor is attached which is calibrated in a way such that when pistons inhales air, gas is also injected at a pressure higher than atmospheric pressure, using the values of the sensors control unit 21 gives the signals to the injector 17 to inject gas. The gas supplied to the injector 17 is regulated at a constant pressure with a given amount of flow rate using second pressure regulator 22a. Second pressure regulator 22a regulates and reduces the high/unregulated pressure from the fuel tank.

One of the embodiments of the present invention involves control unit which governs operations such as spark timing of spark plug, pressure value in pressure regulators, rate of flow of air-fuel, ratio/composition of air-fuel mixture, activation of bypass line, activation of ignition coil, flow rate of coolant, conversion of LNG into natural gas, rotation of camshaft wheel, and ignition of natural gas.

In some of the embodiments of the present invention, the control unit for receiving input from the sensors and controlling burning of the natural gas through positive ignition, can be related to Engine Control Unit [ECU] of the conventional engine having added advantage for facilitating use of cryo-fuel such as LNG for a compression ignition portable engine of a two-wheeler or four-wheeler vehicle, in general.

One of the embodiments of the present invention involves use of a by-pass line for bleeding of the natural gas converted from the LNG in the dual-phase convective heat exchanger 40 for the replenishment of the natural gas in the natural gas tank; wherein, activation of the by-pass line is governed by the control unit.

In one of the embodiments of the present invention wherein means replenishment of the natural gas into the natural gas tank is alternatively selected from using by-pass line for bleeding-in the natural gas converted from the LNG, or inserting fresh natural gas into the natural gas tank through inlet receptacle using make-up natural gas means. wherein, one-way valve is employed for assuring single directional flow of natural gas.

In some of the embodiments of the present invention natural gas tank is utilized for storing of the Compressed Natural Gas (CNG).

In one of the embodiment of the present invention said dual-phase convective heat exchanger 40 receives flow of LNG from the LNG tank and supplies flow of natural gas into the buffer tank 41, whereas the cooling effect liberated by the LNG is soaked by the coolant of radiator, for reducing heat content of coolant communicating with the engine in expense of cooling effect of LNG.

In one of the embodiment of the present invention indirect cooling of the engine with the excessive cooling effect reserved with the LNG through the coolant of the radiator improves overall performance of the engine, and recuses the capacity of radiator.

In one of the embodiment of the present invention the LNG tank 16a is wholly enclosed using cryo-grade insulation.

In some of the embodiment of the present invention the LNG tank 16a along with the whole assemblage of the present invention is positioned at the part of the two-wheeler or four wheeler or multi-wheeler vehicle, to serve as a source of mechanical power to run the said assortment of vehicle.

In one of the embodiment of the present invention replenishment rate of natural gas into the natural gas tanker is kept in the range of 13.5% to 20% of the overall flow rate of natural gas which is converted from the LNG in the dual-phase convective heat exchanger 40; so as to avoid disturbance in the overall flow of natural gas reaching towards the throttle body and maintain process variables within the comfortable control range of control unit.

In one of the embodiment of the present invention the cam profile of the camshaft employed in the camshaft positioning system involves use of contour wherein positive difference of 10% to 24% is preferred in the base diameter and cam diameter for effective injection of natural gas into the bore at optimum mechanical effort.

Consistent with the precedent embodiment of the present invention, use of positive difference in the range of 10% to 24% implies the use of diametric difference between smaller-most diameter [i.e. referred as base circle diameter in cam geometry] and largest-most diameter [i.e. referred as the cam diameter in the cam geometry], which in turn leads to reduction of mechanical effort for actuating valve and other accessories associated in valve mechanism. For instance, in a given case, if the base circle diameter of specific cam profile is 100 mm, than the largest=most diameter is to eb selected in the range of 110 mm to 124 mm, for the optimum loading the mechanical valve operating mechanism.

Wherein, in term ‘bore’ is defined as internal cavity of the cylinder, in which piston 3 reciprocates; moreover bore is an inherent feature in the conventional piston-cylinder assembly.

The term ‘incineration’ is defined as ‘complete combustion’ or ‘perfect combustion’ of the air-fuel mixture supplied and burned in the bore of the cylinder.

Wherein, having existence of said of phenomenon of incineration in the compression ignition engine [i.e. diesel engine] is hard to attain when fuel such as diesel or combination of diesel with other fuel is used, as the said fuel diesel and its family variants inherently possess characteristics of incomplete burning, as the result of inability to ignite diesel located at each of the corners of the bore in the cylinder.

The term ‘spark ignition’ is used for indicating presence of petrol engine, or part of the petrol engine, or one of the element of the petrol engine; further, the term ‘compression ignition’ is used to indicate presence of diesel engine, or part of the diesel engine, or one of the element of the diesel engine.

The term ‘LNG’ describes presence or use of ‘Liquified Natural Gas’; term ‘CNG’ describes presence of use of ‘Compressed Natural Gas’; and term ‘NG’ describes presence or use of ‘Natural Gas’; in the several aspects of the present invention, without deviating scope of the present invention.

Whereby, the amount of diesel left unburnt is exhausted into the atmosphere, which causes adverse implications in the atmosphere in general. Which is eliminated by the present invention, by virtue of using natural gas converted from the LNG for the combustion.

Notably, the natural gas converted from LNG and used directly at the point of application such as engine and the natural gas converted from the source of Compressed Natural Gas [CNG] involves significant difference in the attributes of the natural gas, due to the detrimental influence of presence of compressor oil, enthalpy drop into expanders, and heating cycle of natural gas in the case of natural gas converted from the source of CNG. Wherein, by means of using natural gas converted from the LNG afore stated adverse effects can be nullified.

One of the embodiments of the present invention includes the injection of the gas using multi-port injection 14. On the engine head a runner is provided which individually supplies air to the engine, using this runner on inlet manifold gas is injected to the specific cylinder 3a of the engine. A common rail for the gas is developed on the top of the nozzles.

One of the embodiments of the present invention includes how CNG is adopted as the backup. There is a LNG fuel tank 16a and a heat exchanger 40 which supplies gas to the second pressure regulator 22a at the pressure between the range of 5 bar to 25 bar, and from the other end there are CNG cylinders are attached which can be used as backup. To supply CNG in the required pressure range the cylinders are cascaded and connected with the filling receptacle from one end and at the other end a pressure regulator is installed which reduces the pressure from 200 bar to the range of 8 bar to 10 bar. After the second pressure regulator 22a a solenoid valve 43 is attached which is used to open and close the connection when required that line connects with the LNG pressure regulator with the help of three-piece connector 42.

One of the embodiments of the present invention involves the emission achievement. To achieve better emissions the flow of the gas injection, the amount of gas to be supplied is to be calibrated. During the calibration few sensors are involved as follows:
a) Uego wideband lambda sensor
b) Oxygen lambda sensor
c) Exhaust temperature sensor
d) Engine temperature sensor

Uego wideband lambda sensor and oxygen lamda sensor senses the oxygen and informs the control unit 21 about the type of combustion (rich/lean/stoichiometric), and the temperature sensors provide temperature information, Using this values the control unit 21 will calculate and controls the pressure and flow of the gas to be provided to the engine.

One of the embodiments of the present invention involves the cooling system for the engine.Diesel engine when used for LNG, heats up more than while running on diesel. Cryo-energy from low temperature LNG (-150°C to -162°C) is utilized with precise cryo-thermal heat exchange engineering. LNG cryogenic tube heat-exchanger utilizes cryo-energy of LNG (-150°C to -162°C) to effectively & positively cool the coolant coming from the engine to ensure that additional heat generated by the engine while running on LNG is effectively, efficiently, economically, & positively syphoned away. Precise & positive heat-exchanger ensures confirmed LNG re-gasification before supply to the engine.

One of the embodiments of the present invention is to diagnostics of OBD 23. For this type of conversions, an OBD 23 socket is provided which has the ability to detect any type of faults and the driver is intimated about the faults.
,CLAIMS:CLAIMS
We claim,

1. A method and apparatus for controlling air-fuel ratio for a diesel engine converted to LNG internal combustion engine is characterised by:
a) an insulated LNG receiving tank 16a located at part of vehicle for supplying LNG to the dual-phase convective heat exchanger 40;
b) a dual-phase convective heat exchanger 40 converting phase of the LNG;
c) a natural gas tank 16b connected to the LNG tank 16a through bypass line;
d) a three-piece pipe connector 42 connecting flow line of natural gas and LNG to the inlet manifold 5;
e) a throttle 8 receiving supply of air-fuel for multipoint injection 14 of air-fuel through inlet manifold 5;
f) a control unit 21 for receiving input from the sensors and controlling burning of the natural gas through positive ignition;
g) a compression ignition cylinder receiving supply of natural gas;
h) a natural gas piston 3 for reducing volume of natural gas;
i) an ignition system 19 for incinerating the natural gas;
j) a camshaft positioning system having camshaft trigger wheel 24 for determining position of piston 3;
k) a crankshaft positioning system for determining position of crank 28;
l) an exhaust system 10 for exhaust of burnt fuel.

2. The method and apparatus for controlling air-fuel ratio for a diesel engine converted to LNG internal combustion engine as claimed in claim-1, wherein method of controlling air-fuel ratio and sequentially injecting natural gas into the bore comprises the steps of:
a) operating solenoid valve 43 based on the reserve of LNG in the LNG storage tank 16a and natural gas storage tank 16b;
b) altering pressure reduction value of the second pressure regulator 22a based on the input received from manifold absolute pressor sensor;
c) altering composition of air-fuel in the throttle 8 based on the input received from manifold absolute pressor sensor and intake air mass sensor through control unit 21;
d) injecting natura gas into the bore through common rail and inlet manifold 5, based on the input received from cam shaft positioning system and crankshaft positioning system, using pre-determined firing order defined by the control unit 21.

3. The method and apparatus for controlling air-fuel ratio for a diesel engine converted to LNG internal combustion engine as claimed in claim-1, wherein the three-piece pipe connector 42 comprises:
a) an input flow line connected to buffer tank 41 receiving flow of LNG;
b) another input flow line connected to first pressure regulator 22 for receiving regulated flow of natural gas;
c) on output flow line connected to the second pressure regulator 22a for receiving flow of flow of natural gas from first pressure regulator 22 or buffer tank 41 based on the mode of actuation of solenoid valve 43 located prior to the second pressure regulator 22a.

4. The method and apparatus for controlling air-fuel ratio for a diesel engine converted to LNG internal combustion engine as claimed in claim-1, wherein a camshaft shaped wheel 12 located at the place of diesel fuel pump has a camshaft trigger wheel 24 and a camshaft position sensor 26 attached to regulate the supply of natural gas supply to the injector 17.

5. The method and apparatus for controlling air-fuel ratio for a diesel engine converted to LNG internal combustion engine as claimed in claim-1, wherein natural gas received from the dual-phase convective heat exchanger 40 is stored into the buffer tank 41 at constant gauge pressure in the range of 6.5 bar to 25 bar for supplying non-fluctuated flow of natural gas to the three-piece pipe connector 42.

6. The method and apparatus for controlling air-fuel ratio for a diesel engine converted to LNG internal combustion engine as claimed in claim-1, wherein first pressure regulator 22 connected to one of the inlet of three-piece pipe connector 42 regulates the pressure of natural gas at the final pressure in the range of 5.5 bar to 25 bar, and second pressure regulator 22a connected to outlet of the three-piece pipe connector 42 regulates the pressure of natural gas at the final pressure of 3.5 bar for injection through injector 17.

7. The method and apparatus for controlling air-fuel ratio for a diesel engine converted to LNG internal combustion engine as claimed in claim-1, wherein control unit 21 comprises:
a) means for accepting signals from set of sensors for determining engine conditions;
b) means for generating an ignition timing signal independent of an original equipment ignition timing signal;
c) means for generating a pulse width modulated fuel injection signal independent of the original equipment fuel injection signal in response;
d) means for enabling the spark ignition engine to be operated using the original equipment ignition timing signal and the original equipment fuel injection signal.

8. The method and apparatus for controlling air-fuel ratio for a diesel engine converted to LNG internal combustion engine as claimed in claim-1, wherein control unit 21 takes input from sensors which includes an ambient temperature sensor, intake air pressure and humidity sensor, exhaust gas temperature sensor, intake air mass sensor, coolant temperature sensor, vehicle speed, engine life, camshaft position sensor, pedal position sensor, throttle position sensor, natural gas level sensor, piston position sensor, intake and exhaust manifold pressure and temperature sensor, engine condition sensor, pressure sensors at inlet and outlet of 3-point connector pipe, solid state switches, MAP sensor, LNG temperature sensor, LNG flow rate sensor, and lambda sensor.

9. The method and apparatus for controlling air-fuel ratio for a diesel engine converted to LNG internal combustion engine as claimed in claim-1, wherein control unit 21 governs operations which includes spark timing of spark plug 20, pressure value in first pressure regulator 22 and second pressure regulator 22a, rate of flow of air and-fuel, ratio of air-fuel mixture, activation of bypass line, activation of ignition coil, flow rate of coolant, conversion of LNG into natural gas, rotation of camshaft wheel, and ignition of natural gas.

10. The method and apparatus for controlling air-fuel ratio for a diesel engine converted to LNG internal combustion engine as claimed in claim-1, wherein camshaft position sensor 8 determines position of piston 3 for injecting natural gas converted from the LNG into the bore.

11. The method and apparatus for controlling air-fuel ratio for a diesel engine converted to LNG internal combustion engine as claimed in claim-1, wherein multi-port injector system 14 individually supplies air and natural gas converted from the LNG to the inlet manifold for incinerating the natural gas in the bore.

12. The method and apparatus for controlling air-fuel ratio for a diesel engine converted to LNG internal combustion engine as claimed in claim-1, wherein LNG stored in the LNG tank 16a and engine coolant of the radiator unit are placed in heat communication with the transition fluid in the dual-phase convective heat exchanger 40 for converting phase of LNG.

13. The method and apparatus for controlling air-fuel ratio for a diesel engine converted to LNG internal combustion engine as claimed in claim-1, wherein means for replenishing the natural gas into the natural gas tank 16b at gauge pressure of 200 bar is selected from fresh filing through make-up source and bleeding natural gas from the dual-phase convective heat exchanger 40 through one-way valve.

14. The method and apparatus for controlling air-fuel ratio for a diesel engine converted to LNG internal combustion engine as claimed in claim-1, wherein cam profile of camshaft shaped wheel 12 has positive difference in the base diameter and cam diameter in the range of 10% to 24% for effective injection of natural gas into the bore at optimum mechanical effort.

15. The method and apparatus for controlling air-fuel ratio for a diesel engine converted to LNG internal combustion engine as claimed in claim-1, wherein replenishment rate of natural gas into the natural gas tank 16b is selected in the range of 13.5% to 20% of the flow rate of LNG through the dual-phase convective heat exchanger 40.

Dated this 8th Day of July, 2021.

To Controller of Patents,
The Patent Office,
At Mumbai.