A Method and Assembly for Improving Performance and Emission Characteristics of an Internal Combustion Engine
Field of the Invention
[0001] The present invention relates, generally, to improving emission characteristics of internal combustion engines, and more particularly to an internal combustion engine assembly comprising a modified and improved piston bowl geometry and an exhaust gas recirculation conduit to provide improved emission and performance characteristics.
Background of the invention
[0002] Internal Combustion Engines (ICE) such as diesel engines are mostly preferred for its higher thermal efficiency, high-torque and outstanding longevity. In a diesel engine, the fuel is injected into an engine cylinder and. more specifically into a combustion chamber, where it mixes with air resulting in combustion. Diesel engines have limitations such as excessive exhaust emissions, especially in the form of harmful gases such as Nitrogen Oxides (NOx), Particulate Matters (PM or Soot), Carbon Monoxide (CO), Hydro Carbon (HC), Sulphur Dioxide (SO2) etc.
[0003] Emission norms for IC engines are becoming stringent with time with a view to control pollution levels. Engine manufacturers are required to take extreme care in engine design and selection of sub-systems of the engine to comply with the emission norms, and therefore have to undertake various measures to meet the ever-tightening emission regulations. In order to keep engine emissions within permissible limits, authorities in most of the countries impose stringent emission norms, which are mandatory and vehicles are required to comply with the emission levels applicable in respective countries.
[0004] Conventionally, engine emissions are controlled by reducing the emission formation of an IC engine by adding control devices (external control) such as a catalytic converter to meet the most stringent emission regulations. However, the catalytic converter is an additional component which suffers wear and tear over

time and requires regular maintenance. As such it has been observed that it would be desirable to control emissions internally within the engine.
[0005] Currently Bharat stage 4 (BS-IV) is the norm that the manufactures have to comply with in India. Yet again various techniques and technologies have been explored to control emission-formation inside the combustion chamber of the IC engine and comply with said BS-IV norms. One such approach to improve emission characteristics in IC engines from BS-III to BS-IV is to use common-rail-direct-injection assembly instead of conventional in-line or rotary-pump fuel injection assembly, particularly in diesel-engines. However, this approach increases the cost of engine by approximately 20-25 %. Moreover, in common-rail systems the general trend to meet desired emission characteristics is to use higher injection pressure. However, when evaluating research using aforesaid configuration a dramatic increase in NOx concentrations is observed. Further possible increases in Brake Specific Fuel Consumption (BSFC) at low engine speeds and part load (which is an engine operating below the maximum power that the engine can produce) is observed. These findings suggest that it takes more power to keep the common rail fuel injection assembly pressurized under low speed and part load conditions. Since the operating condition for diesel engines is not always at full load and high speed in a common rail assembly, said assembly is not advantageous for economic reasons. Accordingly, it is desirable to eliminate the aforementioned drawbacks.
[0006] In light of the aforementioned drawbacks, there is a need for an engine with increased combustion efficiency and reduced emissions. There is a need to provide internal combustion engines which satisfy BS-IV emission norms by controlling emissions effectively within the combustion chamber at a relatively lower cost and at the same time meeting user requirements without any increase in complexity. Further there is a need to provide BS-IV emission compliant engines without using high cost electronic controlling devices, and whose fuel efficiency is at par with any other engine with existing electronic systems for BS-IV emission norms.

Summary of the invention
[0007] In various embodiments of the present invention, an assembly for improving performance and emission characteristics of an internal combustion engine (300), is provided. The assembly is integrable with an in-line fuel injection pump assembly (302) including non-electronic injectors (302a) for injecting fuel at a predetermined high injection pressure. The assembly comprises an exhaust gas recirculation (EGR) conduit (104, 314) in fluid communication with an intake manifold (106, 312) of the internal combustion engine (300). The intake manifold (106, 312) opens into a combustion chamber (304) of the internal combustion engine (300) through an intake port (110, 304a) of the combustion chamber (304). An intake manifold access end (104a) of the EGR conduit (104, 314) forms a protrusion 104a' at an interface of the EGR conduit (104, 314) and the intake manifold (106, 312). The protrusion 104a' extends into the intake manifold (106, 312) and is disposed substantially perpendicular to a central axis (106a') of a circumferential wall 106a of the intake manifold (106, 312). The assembly further comprises a piston (200, 308). The piston (200, 308) comprises a bowl (202, 310) defining a portion of the combustion chamber (304). The bowl (202, 310) forms a central convex dome (210) subtending an angle of 118 degrees. The bowl (202, 310) further forms an impingement area (214) that defines an angle of about 110 degrees with respect to a top surface (218) of the piston (200, 308). Further, the bowl (202, 310) forms a lip portion (216) that extends from the impingement area (214) defining an angle of about 24 degrees with respect to the top surface (218) of the piston (200).
[0008] In an embodiment of the present invention, the bowl (202, 310) has a circumferential wall (206) and a base (204) defining an inner surface (208) to receive a fuel-air mixture. The base (204) protrudes inwardly towards a central axis (not show) of the bowl (202) to form a convex dome (210) subtending an angle of about 118 degrees. The circumferential wall (206) protrudes outwardly to form a concave surface (212) with a toroidal radius of at least 2mm. Further the circumferential wall (206) bends outwardly from an upper edge (212a) of the concave surface (212) to form the impingement area (214) that defines an angle of 110 degrees with respect to the top surface (218) of the piston (200, 308). Further, the lip portion (216) with a radius of 1mm- 2mm extends from the impingement

area (214) and forms an angle of 24 degrees with respect to the top surface (218) of the piston (200, 308). The shape of the protrusion (104a') of the EGR conduit (104, 314) and the piston bowl (202, 310) facilitates improved air movement during fuel-air mixing, with fuel injected at a high injection pressure of about 1400 bar using the non-electronic injectors (302a). Further, improved mixing pattern of recirculated exhaust gas with air forms a cooler exhaust gas-air mixture with reduced temperature resulting in increased combustion efficiency and lowering emissions of harmful gases such as PM and NOx.
[0009J In accordance with various embodiments of the present invention, the internal combustion engine (300) is compliant with BS-IV emission norms.
[0010] In accordance with various embodiments of the present invention, a method for improving performance and emission characteristics of an internal combustion engine (300) is provided. In accordance with said method, a combustion chamber (304) of the internal combustion engine (300) is integrable with an in-line fuel injection pump assembly (302) including non-electronic injectors (302a). The method comprises injecting a fuel into the combustion chamber (304) at a predetermined high injection pressure using the non-electronic injectors (302a). In accordance with this method injection pattern of the fuel is defined by a piston bowl (202, 310) having a circumferential wall (206) and a base (204) defining an inner surface (208) to receive a fuel-air mixture. The base (204) protrudes inwardly towards a central axis of the bowl (202) forming a convex dome (210) subtending an angle of 118 degrees. The circumferential wall (206) protrudes outwardly to form a concave surface (212) with a toroidal radius of at least 2mm. Further the circumferential wall (206) bends outwardly from an upper edge (212a) of the concave surface (212) to form an impingement area (214) that defines an angle of 110 degrees with respect to the top surface (218) of the piston (200, 308). A lip portion (216) with a radius of 1mm- 2mm extends from the impingement area (214) and forms an angle of 24 degrees with respect to the top surface (218) of the piston (200, 308) to improve air movement during fuel-air mixing. Further the method comprises recirculating exhaust gas by inserting a protrusion (104a') formed on an EGR conduit (104, 314) at the interface of the EGR conduit (104, 314) and an intake manifold (106, 312). The protrusion (104a') extends into the intake manifold (106, 312) and is disposed

substantially perpendicular to a central axis (106a') of a circumferential wall (106a) of the intake manifold (106, 312) to improve a mixing pattern of recirculated exhaust gas with air resulting in an exhaust gas-air mixture with reduced temperature. In accordance with said method the shape of the protrusion (104a') of the EGR conduit (104, 314) and the piston bowl (202, 310) results in increased combustion efficiency and lowering emissions of harmful gases such as PM and NOx.
[0011] In accordance with another embodiment of the present invention, a method for achieving BS-IV emission norms in an IC engine (300) integrable with an inline fuel injection pump assembly (302) including non-electronic fuel injectors (302a) is provided. The method comprises injecting fuel into a combustion chamber (304) of the IC engine (300) at a predetermined high pressure of about 1400 bar using the non-electronic fuel injectors (302a). Further the method comprises accommodating injection pattern of the non-electronic fuel injectors (302a) by modifying geometry of the piston bowl (202, 310). The piston bowl (202, 310) forms a portion of the combustion chamber (304) and thereby optimizes swirl ratio and improves fuel air mixing and combustion efficiency resulting in reduction of particulate matter. Further the method comprises reducing nitrogen oxide formation inside the combustion chamber (304) by injecting fuel at a fixed injection timing and introducing exhaust gas into said combustion chamber (304) by an optimized EGR conduit for improving exhaust gas-air mixing pattern.
Brief Description of the Drawings
[0012] The present invention is described by way of embodiments illustrated in the accompanying drawings wherein:
[0013] Fig. la shows an isometric image of a conventional EGR conduit;
[0014] Fig. lb illustrates a cross-sectional view of an EGR conduit with an improved design in accordance with an embodiment of the present invention;
[0015] Fig. lc illustrates an isometric image of the EGR conduit in accordance with various embodiments of the present invention;

[0016] Fig. 2a illustrates the progressive improvements made in the piston bowl geometry in accordance with various embodiments of the present invention;
[0017] Fig. 2b illustrates a piston bowl in accordance with various embodiment of the present invention;
[0018] Fig. 3 illustrates a block diagram of an IC engine in accordance with various embodiments of the present invention;
[0019] Figs. 4a and 4b show a graphical representation of comparison between engine performance with respect to engine power, torque and speed in accordance with various embodiments of the present invention and a common rail direct fuel injection engine; and
[0020] Figs. 5a and 5b show a graphical representation of the comparison between the emission characteristics of an engine, in accordance with various embodiments of the present invention, and the conventional common rail direct fuel injection engine.
Detailed Description of the Invention
[0021] The disclosure is provided in order to enable a person having ordinary skill in the art to practice the invention. Exemplary embodiments herein are provided only for illustrative purposes and various modifications will be readily apparent to persons skilled in the art. The general principles defined herein may be applied to other embodiments and applications without departing from the spirit and scope of the invention. The terminology and phraseology used herein is for the purpose of describing exemplary embodiments and should not be considered limiting. Thus, the present invention is to be accorded the widest scope encompassing numerous alternatives, modifications and equivalents consistent with the principles and features disclosed herein. For purposes of clarity, details relating to technical material that is known in the technical fields related to the invention have been briefly described or omitted so as not to unnecessarily obscure the present invention.
[0022] It is to be noted that, as used in the specification by the term "substantially" it is meant that the recited characteristic, parameter, or value need

not be achieved exactly, but that deviations or variations, including for example, tolerances, measurement error, measurement accuracy limitations and other factors known to those skilled in the art, may occur in amounts that do not preclude the effect the characteristic was intended to provide. The terms piston bowl and bowl have been used interchangeably throughout the specification.
[0023] The present invention would now be discussed in context of embodiments as illustrated in the accompanying drawings.
[0024] It would be appreciated that direct injection diesel engines have a single, open combustion chamber into which entire quantity of diesel fuel is injected directly with desired injection pressure. An open combustion chamber is one in which the combustion space incorporates no restrictions that are sufficiently small to cause large differences in pressure between different parts of the chamber during the combustion process.
[0025] Prior to the commencement of actual combustion, there are several key processes namely swirl, turbulence and mixing of air with fuel until any physical and chemical reaction takes place inside the cylinder during intake and compression strokes in a diesel cycle of an IC engine. It has been observed that these key processes need to be optimized for effective combustion and to meet improved performance and emission levels. Further, controlling emission levels within the engine is also highly desirable in order to meet the desired emission norms.
[0026] In an embodiment of the present invention, an improved Exhaust Gas Recirculation (EGR) conduit has been designed for achieving desired control in emission levels of NOx emissions. The design of the improved EGR conduit and its resultant advantageous effect on NOx emission reduction is explained in detail in the below mentioned paragraphs.
[0027] EGR is typically used with conventional internal combustion engines for reducing NOx formation through lowering of oxygen concentration in the combustion chamber of an IC engine as well as through heat absorption. An image of a conventional EGR conduit 102 is shown in Fig. la. Referring to this figure, an intake manifold 100 is shown which provides a path for fresh air and

exhaust gas mixture into the combustion chamber (not shown) of an IC engine (not shown).
[0028] Further, as shown in Fig. la, an EGR conduit 102 comprises an intake manifold access end 102a, an EGR cooler connecting end 102b and an exhaust gas outlet 102c. The EGR cooler connecting end 102b is operably connected to an EGR cooler (not shown). The intake manifold access end 102a of the EGR conduit 102 is a part of the EGR conduit 102 which operably connects the EGR conduit 102 to the intake manifold 100. The exhaust gas outlet 102c of the EGR conduit 102 allows recirculated exhaust gas to enter into the intake manifold 100. The exhaust gas outlet 102c is disposed on the same plane as the circumferential wall 100a of the intake manifold 100.
[0029] Fig. lb illustrates a cross-sectional view of an EGR conduit 104 with an improved design in accordance with an embodiment of the present invention. Fig. lc illustrates an isometric image of the EGR conduit 104 in accordance with Various embodiments of the present invention.
[0030] As illustrated in Figs, lb and lc the outer surface of an intake manifold access end 104a of the EGR conduit 104 is designed such that it forms a protrusion 104a' at the interface of the EGR conduit 104 and an intake manifold 106. The protrusion 104a' is an extended portion of the intake manifold access end 104a that is disposed substantially perpendicular to a central axis 106a' of a circumferential wall 106a of the intake manifold 106. The protrusion 104a' defines an exhaust gas outlet 104c disposed in an inclined position in relation to the intake manifold access end 104a such that the height of the protrusion 104a' is up to said central axis 106a' towards an entry point 108 of the intake manifold 106 for fresh air and is greater than the side of the protrusion 104a' facing an intake port (110), which is an entry point of the combustion chamber (not shown). The protrusion 104a' may optionally comprise a plurality of perforations on its outer surface.
[0031] In various embodiments of the present invention, the shape of the intake manifold access end 104a of the EGR conduit 104, as described above, aids in improving the mixing of fresh air and exhaust gas. This enhanced mixing pattern results in uniform level of dilution of fresh air in combustion chambers (not

shown) of respective cylinders (not shown) of the IC engine (not shown) during entire engine operating cycle. Further, injecting fuel at a fixed injection timing using non-electronic injectors (not shown) facilitates consistent lowering of NOx formation.
[0032] In another embodiment of the present invention, it has been observed that shape of the combustion chamber plays a key role on the motion of the fluid inside the cylinder during a piston's reciprocal movement in an IC engine as well as in emission control.
[0033] Fig. 2a illustrates the progressive improvements made in the piston bowl design 200 in accordance with various embodiments of the present invention.
[0034] As shown in the Fig. 2a, VI, V2 and V3 depict developments in the bowl geometry from a conventional piston bowl geometry to the improved piston bowl geometry. VI and V2 show the conventional bowl geometry and V3 shows the improved bowl geometry in accordance with an embodiment of the present invention. The bowl geometry V3 has a wider, less shallow design for reducing particulate emission. The bowl geometry V3, progressively developed in accordance with the present invention helps to meet effective combustion for targeted emission (BS-IV) and provides for better fuel-economy. Said redesigned bowl geometry V3 enables better air-movement in terms of optimized swirl ratio and assists in the mixing of air with injected fuel. In a conventional inline fuel injection pump assembly, the injection pressure is around 500-700 bars, and length of the injection cone formed by the injectors is relatively smaller as compared to high pressure injection assembly (with 1400 bar injection pressure). As such the bowl, in accordance with various embodiments of the present invention, is uniquely designed to accommodate maximum portion of the injection cones therewithin for achieving fixed injection timing and enhanced combustion efficiency with improved performance, rather than using dynamic injection-timing using electronic injectors as is the case with common rail fuel injection assemblies. The bowl geometry V3 of the present invention helps to accommodate injection pattern of conventional non-electronic injectors with higher injection pressure (1400 bar) for aiding improved mixing of fuel with air for better combustion and lowering emissions of harmful gases such as PM and NOx. The bowl geometry V3 is explained in more detail herein below.

[0035] Fig. 2b illustrates a piston bowl in accordance with various embodiment of the present invention. In an embodiment of the present invention, the piston 200 comprises a bowl 202. The bowl 202 forms a portion of the combustion chamber of the IC engine. The bowl 202 includes a base 204 and a circumferential wall 206 around the periphery of the base 204 defining an inner surface 208 to receive a fuel-air mixture. The base 204 protrudes inwardly towards a central axis (not shown) of the bowl 202 forming a convex dome 210. The circumferential wall 206 protrudes outwardly to form a concave surface 212 with a toroidal radius of at least 2mm around the periphery of said convex dome 210. The base 204 therefore is bounded by two radial concave surfaces 212 defined by the circumferential wall 206 and has a radius of curvature greater than 6.5 mm. The circumferential wall 206 further bends outwardly from the upper edge 212a of said concave surface 212 forming an impingement area 214. The impingement area 214 defines an angle of 110 degrees with respect to the top surface 218 of the piston 200. A lip portion 216 defining the upper edge of the bowl 202 has a radius of 1mm- 2mm and extends from said impingement area 214 to the top surface 218 of the piston 200 forming an angle of 24 degrees with said top surface 218 of the piston 200. The diameter of the bowl 202 is greater near the concave surface 212 than the diameter of the bowl near the impingement area 214. In an embodiment of the present invention, the bowl 202 has an inner volume ranging from 45cc to 55cc. The inner surface of the bowl 202 is symmetrical in shape and yet further the bowl 202 is symmetric around centre of the piston 200.
[0036] In this embodiment of the present invention, the bowl 202 has a depth of 19.2 mm from the centre of the convex dome 210 to the top surface 218 of the piston 200 and subtends an angle of 118 degrees for accommodating the injection cones formed by the non-electronic fuel injectors (not shown) and resulting in effective combustion as explained in conjunction with Fig. 2a. The shape and dimensions of the lip portion 216 and the circumferential wall 206 helps to promote the charge or air-movement (including squish, squash, swirl and turbulence) during fuel-air mixing and combustion process at a set of engine operating conditions thereby improving the combustion efficiency and reducing particulate (soot) emissions.

[0037] Fig. 3 illustrates a block diagram of an IC engine in accordance with various embodiments of the present invention. In an embodiment of the present invention, the IC engine 300 may be a diesel engine and includes a conventional fuel injection assembly 302. Examples of the fuel injection assembly 302 may include an inline fuel injection pump assembly to deliver higher injection pressure (1400 bar) unlike conventional in line fuel injection pumps used with conventional IC engines with 500-700 bar of injection pressure. The fuel injection assembly 302 comprises a plurality of non-electronic fuel injectors 302a which open into respective combustion chambers 304 of respective cylinders 306 of the IC engine 300. In an embodiment of the present invention, the fuel injection assembly 302 is an inline fuel injection assembly upgraded with e-governance and the IC engine 300 has six cylinders 304. A piston 308 comprising improved geometry of the bowl 310 (as explained in conjunction with Fig. 2b) is disposed within each cylinder 304 respectively.
[0038] The intake manifold 312 is in fluid communication with each cylinder 306, through an intake port (304a), to provide air into each cylinder 306 i.e. into respective combustion chambers 304 within each cylinder 306. The EGR conduit 314 is in fluid communication with the intake manifold 312. An EGR cooler 316 is in fluid communication with the other end of the EGR conduit 314. The EGR cooler 316 is optimized based on the quantity and temperature requirements of re-circulated exhaust gas at various engine operating conditions. In an exemplary embodiment of the present invention, the operation of the EGR cooler 316 is optimized on the basis of level of nitrogen oxide formation and specific powers based on European Stationary Cycle (ESC) and European Transient Cycle emission certifications. An exhaust gas manifold 318 has an inlet in fluid communication with the cylinder 306 and an outlet in partial fluid communication with the EGR cooler 316. The quantity of exhaust gas being discharged into the EGR cooler 316 is controlled by an EGR valve 316a, which is operable based on a feedback system. Outlet of exhaust manifold 318 is also in fluid communication with a turbocharger 320 from where the exhaust gas is discharged into the environment through an exhaust gas assembly (not shown). In particular, the exhaust gas partially discharged into a turbine housing (not shown) of the turbocharger 320 is further discharged into the environment through the exhaust gas assembly (not shown). The turbine housing (not shown) is further connected

via rotating shafts to a compressor (not shown) within the turbocharger 320. The compressor (not shown) compresses fresh air taken in through a filtered air inlet 320' of the turbocharger 320 and the compressed fresh air flows into the intake manifold 312 via an intercooler 320a. It would be apparent to a person skilled in the art that the turbocharger 320 is an air-boosting device optimized to boost the intake-air at desired quantity in order to meet engine power and torque requirements at various engine-speed. The turbocharger 320 uses the exhaust-gas energy and improves the over-all engine efficiency.
[0039] It would be further apparent to a person skilled in the art that an Engine Control Unit (ECU) 322 controls various engine conditions based on driver's demand by receiving and sending signals to and from various sensors and actuators respectively along with other key inputs. The ECU 322 controls the precise amount of fuel to be injected by the in-line fuel injection pump assembly 302 and aids in controlling the emission and performance of the IC engine 300 more reliably. The ECU 322 may include microprocessors, multiprocessors, microcontrollers or any other computing device capable of executing instructions.
[0040] In operation, in an embodiment of the present invention, the air enters into the cylinder 306 through the intake manifold 312 and a typical diesel engine cycle including the strokes of intake, compression, power and exhaust takes place. The piston 308 including the improved geometry of the bowl 310 (as explained in conjunction with Fig. 2b) provides for improved air-movement and injection pattern which assists in optimized mixing of air and fuel when the fuel is injected at a desired pressure by the fuel injection assembly 302. In particular, the optimized swirl ratio for effective mixing of air with fuel injected with a high pressure (e.g. up to 1400 bar) results in reduced production of particulate matter e.g. soot within the combustion chamber 304.
[0041] Further, the exhaust gas comprising reduced particulate matter flows out from the cylinders 306 into the exhaust gas manifold 318. From the exhaust gas manifold 318, the exhaust gas, partially, enters into the turbocharger 320 and partially into the EGR cooler 316. The turbocharger 320 performs its function of boosting air intake into the intake manifold 312 by utilizing exhaust gas energy, and further the EGR cooler 316 cools down the exhaust gas. Said cooled exhaust

gas enters into the improved EGR conduit 314. As described in conjunction with Fig. lb and lc, the intake manifold access end (104a) provides for an effective mixing pattern of the fresh air from the turbocharger 320 further cooled by intercooler 320a and exhaust gas, which further leads to reduction in the temperature of the fresh air-exhaust gas mix. The fresh air-exhaust gas mix enters into the combustion chamber 304, wherein the diesel engine cycle continues. The reduced temperature inside the combustion chamber 304 due to the improved EGR conduit 314 facilitates better mixing pattern of fresh air and exhaust gas and in conjunction with an optimized injection timing of the fuel from the non-electronic fuel injectors 302a further reduces the nitrogen oxide formation inside the combustion chamber 304.
[0042] As demonstrated above, overall emissions from the IC engine 300 are reduced by significantly lowering particulate matter formation (soot formation) by the modified and improved geometry of piston bowl 310 along with inline fuel injection pump assembly 302 comprising non-electronic fuel injectors 302a injecting fuel at a high injection pressure ofl400 bar, and by reducing the nitrogen oxide formation by the modified and improved structure of the EGR conduit 314.
[0043] Advantageously, the IC engine 300 of the present invention achieves the BS-IV emission norms without using high cost electronically controlled fuel injectors and other subsystems such as a catalytic converter, thereby reducing manufacture cost. The use of conventional fuel injection assembly 302 along with non-electronic fuel injectors 302 enables the upgradation of a BS-III engine to BS-IV with only 5-7 % cost impact.
[0044] Referring to Figs. 4a and 4b a graphical representation of comparison between engine performance with respect to engine power, torque and speed in accordance with various embodiments of the present invention and a common rail direct fuel injection engine is shown. In Fig. 4a Full Throttle Performance (FTP) has been plotted for power with engine speed; and in Fig. 4b torque with engine speed has been plotted. It has been observed that performance of the IC engine (300 - Fig. 3) in accordance with various embodiments of the present invention is at par with the IC engines using common rail assembly for BS-IV. It may further be observed from Fig. 4b that the low-end-torque (1800-2600 rpm) which is a key

requirement for diesel engine or vehicle is better (improved by 10 %) in the IC engine (300-Fig. 3) in accordance with various embodiments of the present invention. The improved geometry of the bowl (202- Fig. 2b and 310-Fig. 3) in accordance with the present invention aids in improving the low-end-torque.
[0045] Referring to Figs. 5a and 5b a graphical representation of the comparison between the emission characteristics of an engine of the present invention and a common rail direct fuel injection engine is shown. A plot of particulate matter with nitrogen oxide formation has been shown in Fig. 5 a. A plot of hydrocarbon and carbon monoxide is shown in Fig. 5b during European Stationary Cycle (ESC) as per the application of the engine of the present invention on vehicle category. It is observed that the results are at par with common rail engines, especially on Particulate Matter (PM or Soot), NOx. Said results were achieved with the improved bowl geometry (202- Fig. 2b and 3 3-Fig. 3) and the EGR conduit (104-Fig. lb, lc and 314-Fig. 3) in accordance with the present invention providing optimized swirl motion and by maintaining the fuel (injection) spray with desired level of penetration and number of sprays accommodated in combustion chamber. Further, the Nitrogen Oxides (NOx) reduction is also achieved with less trade-off, which is challenging for diesel engines.
[0046] While the exemplary embodiments of the present invention are described and illustrated herein, it will be appreciated that they are merely illustrative. It will be understood by those skilled in the art that various modifications in form and detail may be made therein without departing from or offending the spirit and scope of the invention except as it may be described by the following claims.

We claim:
1. An assembly for improving performance and emission characteristics .of
an internal combustion engine (300), wherein the assembly is integrable with an
in-line fuel injection pump assembly (302) including non-electronic injectors
(302a) for injecting fuel at a predetermined high injection pressure, comprising:
an exhaust gas recirculation (EGR) conduit (104, 314) in fluid communication with an intake manifold (106, 312) of the internal combustion engine (300), the intake manifold (106, 312) opens into a combustion chamber (304) of the internal combustion engine (300), characterised in that an intake manifold access end (104a) of the EGR conduit (104, 314) forming a protrusion 104a' at an interface of the EGR conduit (104, 314) and the intake manifold (106, 312), said protrusion 104a' extending into the intake manifold (106, 312) and disposed substantially perpendicular to a central axis (106a') of a circumferential wall 106a of the intake manifold (106, 312); and
a piston (200, 308) comprising a bowl (202, 310) defining a portion of the combustion chamber (304), said bowl (202, 310) forms a central convex dome (210) subtending an angle of 118 degrees, an impingement area (214) that defines an angle of about 110 degrees with respect to a top surface (218) of the piston (200, 308), and a lip portion (216) that extends from the impingement area (214) defining an angle of about 24 degrees with respect to the top surface (218) of the piston (200).
2. The assembly as claimed in claim 1, wherein the bowl (202, 310) has a
circumferential wall (206) and a base (204) defining an inner surface (208) to
receive a fuel-air mixture, said base (204) protrudes inwardly towards a central
axis (not shown) of the bowl (202) forming the convex dome (210) subtending an
angle of about 118 degrees, the circumferential wall (206) protrudes outwardly to
form a concave surface (212) with a toroidal radius of at least 2mm, said
circumferential wall (206) bends outwardly from an upper edge (212a) of the
concave surface (212) thereby forming the impingement area (214) that defines an
angle of 110 degrees with respect to the top surface (218) of the piston (200, 308),
the lip portion (216) with a radius of 1mm- 2mm extends from said impingement

area (214) and forms an angle of 24 degrees with respect to the top surface (218) of the piston (200, 308), wherein
the shape of the protrusion (104a') of the EGR conduit (104, 314) and the piston bowl (202, 308) facilitates improved air movement during fuel-air mixing, with fuel injected at a high injection pressure of about 1400 bar using the non-electronic injectors (302a), and improved mixing pattern of recirculated exhaust gas with fresh air forming a cooler exhaust gas-air mixture with reduced temperature resulting in increased combustion efficiency and lowering emissions of harmful gases such as PM and NOx.
3. The assembly as claimed in claim 1, wherein the protrusion (104a') defines an exhaust gas outlet (104c) disposed in an inclined position in relation to the intake manifold access end (104a) such that the height of the extended portion of the protrusion (104a') towards an entry point (108) of the intake manifold (106, 312) is greater than the side of the protrusion (104a') towards an intake port (110, 304a) of the combustion chamber (304).
4. The assembly as claimed in claim 1, wherein the protrusion (104a') comprises a plurality of perforations on its outer surface.
5. The assembly as claimed in claim 1, wherein the radius of curvature of the bowl (202, 310) defined by the concave surface (212) is greater than 6.5 mm.
6. The assembly as claimed in claim 1, wherein the bowl (202, 310) has an inner volume ranging from about 45cc to about 55cc.
7. The assembly as claimed in claim 1, wherein the bowl (202, 310) has a depth of 19.2 mm from the centre of the convex dome (210) to the top surface (218) of the piston (200, 308).
8. The assembly as claimed in claim 1, wherein the inner surface (208) of the bowl (202, 310) is symmetrical in shape.
9. The assembly as claimed in claim 1, wherein the internal combustion engine (300) is compliant with BS-IV emission norms.

10. The assembly as claimed in claim 1, wherein a diameter of the bowl (202,
310) is greater near the concave surface (212) than the diameter of the bowl (202,
310) near the impingement area (214).
11. A method for improving performance and emission characteristics of an
internal combustion engine (300), wherein a combustion chamber (304) of the
internal combustion engine (300) is integrable with an in-line fuel injection pump
assembly (302) including non-electronic injectors (302a), said method
comprising:
injecting a fuel into the combustion chamber (304) at a predetermined high injection pressure using the non-electronic injectors (302a), wherein injection pattern of the fuel is defined by a piston bowl (202, 310) having a circumferential wall (206) and a base (204) defining an inner surface (208) to receive a fuel-air mixture, wherein said base (204) protrudes inwardly towards a central axis of the bowl (202) forming a convex dome (210) subtending an angle of 118 degrees, the circumferential wall (206) protrudes outwardly to form a concave surface (212) with a toroidal radius of at least 2mm, said circumferential wall (206) bends outwardly from an upper edge (212a) of the concave surface (212) thereby forming an impingement area (214) that defines an angle of 110 degrees with respect to a top surface (218) of the piston (200, 308), a lip portion (216) with a radius of 1mm- 2mm extends from said impingement area (214) and forms an angle of 24 degrees with respect to the top surface (218) of the piston (200, 310) thereby improving air movement during fuel-air mixing,
recirculating exhaust gas by inserting a protrusion (104a') formed on an EGR conduit (104, 314) at the interface of the EGR conduit (104, 314) and an intake manifold (106, 312), said protrusion (104a') extending into the intake manifold (106, 312) and disposed substantially perpendicular to a central axis (106a') of a circumferential wall (106a) of the intake manifold (106, 312) thereby improving a mixing pattern of recirculated exhaust gas with air resulting in an exhaust gas-air mixture with reduced temperature, wherein
the shape of the protrusion (104a') of the EGR conduit (104, 314) and the piston bowl (202, 310) results in increased combustion efficiency and lowering emissions of harmful gases such as PM and NOx.

12. The method as claimed in claim 11, wherein the fuel is injected at a high injection pressure of 1400 bar using the non-electronic injectors (302a).
13. The method as claimed in claim 11, wherein the shape of the piston bowl (202, 310) results in an optimized swirl ratio leading to improved air movement during air-fuel mixing.
14. The method as claimed in claim 11, wherein the fuel is injected using the non-electronic injectors (302a) at a fixed injection timing for an injection cycle.
15. A method for achieving BS-IV emission norms in an IC engine (300)
integrable with an inline fuel injection pump assembly (302) including non¬
electronic fuel injectors (302a), said method comprising the steps of:
injecting fuel into a combustion chamber (304) of the IC engine (300) at a predetermined high pressure of about 1400 bar using the non-electronic fuel injectors (302a);
accommodating injection pattern of the non-electronic fuel injectors (302a) by modifying geometry of the piston bowl (202, 310), the piston bowl (202, 310) forming a portion of the combustion chamber (304), thereby optimizing swirl ratio and improving fuel air mixing and combustion efficiency resulting in reduction of PM; and
reducing nitrogen oxide formation inside the combustion chamber (304) by injecting fuel at a fixed injection timing and introducing exhaust gas into said combustion chamber (304) by an optimized EGR conduit (104, 312) for improving exhaust gas-air mixing pattern.