DESC:FIELD

The present disclosure relates to an internal combustion engines. More particularly, the present disclosure relates to a combustion chamber for a diesel engine.

DEFINITION(S):

piston crown – is defined as the topmost part of the piston that enters the combustion chamber and is so configured so as to effect the combustion process;

BACKGROUND

An internal combustion engine includes a combustion chamber, at least one intake port directing fresh air into the combustion chamber without any swirling. A piston is received inside the combustion chamber. A multi-hole injector is arranged to inject fuel under high injection pressure inside the combustion chamber. The multi hole injector forms spray plumes and each spray is having central axis oriented at a positive spray angle sufficient to facilitate impinging of the fuel on the piston received inside the combustion chamber. The reflection angle of the impingement of the central axis is positive during at least start of injection in order to increase balance between vertical upwardly directed and tangential movements of the spray/flume and to preserve mixing energy rate in the combustion cycle. The interaction of spray flume with in-cylinder air is mainly the function of combustion chamber design. The various parameters associated with the combustion chamber including dimensions, shapes are considered and modified for trying to achieve better mixing characteristics and better mixing between the air and the fuel.
However, the conventionally known combustion chamber for a diesel engine has such configuration that fail to provide conditions required for proper mixing between the air and fuel introduced inside the combustion chamber or cylinder. More specifically, in the regions inside the combustion chamber that are away from the cylinder head there are unfavourable conditions for mixing of the air and fuel and there is no provisions for achieving mixing of the air and fuel introduced inside the engine.

Due to improper mixing of the air and fuel inside the combustion chamber, the efficiency of the diesel engine is reduced. The incomplete combustion of the fuel inside the combustion chamber also have various drawbacks associated therewith, for example, incomplete combustion of the fuel inside the combustion chamber of the diesel engine may lead to higher NOx and soot emissions and reduced efficiency of the diesel engine. Further, incomplete combustion of the fuel inside the combustion chamber has detrimental effect on the fuel economy and the performance and the service life of the engine.

With more stringent environment protection laws there has been a focus on achieving cleaner environment by reducing engine out emissions particularly NOx and soot emissions. Further, there has been increased focus on reducing emissions of Global House Warming Gases (GHG). The internal combustion engines designers are facing challenge of improving fuel economy as well as reducing NOx and soot emission. To meet future stringent emissions, use of Diesel Particulate Filter (DPF) for reducing soot emissions and use of Selective Catalyst Reduction (SCR) for reducing NOx emissions have been suggested. However, the need to regenerate the DPF and consumption of Ad-blue solution mainly limit the use of Diesel Particulate Filter (DPF) and the use of Selective Catalyst Reduction (SCR) for reducing soot and NOx emissions respectively.

Accordingly, combustion chamber modification for improving NOx and soot emissions trade has been considered a potential option for achieving mixing between fuel and air and improving the fuel efficiency of the engine.
A variety of modification had been suggested in the profile, dimension and shape of the engine chamber for trying to achieve better mixing between the fuel and the air.

For example, EP Published Patent Application EP2063081A1 (hereinafter referred to as ‘081 EP Published Patent Application) discloses piston crown with double re-entrant piston bow. More specifically, the disclosure relates to a piston crown comprising a face and a piston bowl recessed within the face. The piston bowl comprises an entry side a bottom side opposite the entry side, a restriction between the entry side and the bottom side, a re-entrant portion at the bottom side and an annular side surface extending between the entry side and the restriction. The annular side surface at least partly defines a space widening in the direction of the restriction.

However, the above mentioned piston crown receiving bowl configuration of the combustion chamber disclosed in the ‘081 EP Published Patent Application has a confined bowl throat opening as such the access required for machining the intricate interior portions of the bowl portion of the combustion chamber is limited. Accordingly, the piston crown receiving bowl of the combustion chamber is difficult to manufacture. Further, the piston crown receiving bowl of the combustion chamber disclosed in the ‘081 EP Published Patent Application can configure cylinder bore having diameter in the range of 90 to 150mm and as such with such configuration, configuring cylinder bores with other cylinder bore diameters is difficult.

Accordingly, there is a need for a need for combustion chamber for a diesel engine that provides conditions for proper mixing of the air and fuel introduced inside the engine. Further, there is a need for a combustion chamber for a diesel engine that improves engine efficiency. Furthermore, there is a need for combustion chamber for a diesel engine that promotes mixing between the air and the fuel even in regions inside the combustion chamber that are away from the cylinder head. There is a need for a combustion chamber for a diesel engine incomplete combustion of the fuel inside the combustion chamber. Further, there is a need for a piston crown receiving bowl configuration of the combustion chamber that is easy to manufacture, simple in construction and efficient in operation.

OBJECTS

Some of the objects of the present disclosure are described herein below:

It is an object of the present disclosure to ameliorate one or more problems of the prior art or to at least provide a useful alternative.

An object of the present disclosure is to provide a combustion chamber having a piston crown receiving bowl configuration that is easy to manufacture.

Another object of the present disclosure is to provide a combustion chamber having a piston crown receiving bowl configuration that is simple in construction.
Still another object of the present disclosure is to provide a combustion chamber that improves mixing characteristics and facilitate proper mixing of the air and fuel introduced inside the engine.
Yet another object of the present disclosure is to a combustion chamber for a diesel engine that improves performance of the engine and enhances service life of the engine.

Another object of the present disclosure is to provide a combustion chamber for a diesel engine that eliminates incomplete combustion by ensuring proper mixing of the air and fuel introduced inside the combustion chamber.

Still another object of the present disclosure is to provide a combustion chamber that eliminates drawbacks associated with incomplete combustion such as higher NOx and soot emissions, reduced efficiency, in-efficient performance of the engine and reduced service life of the engine.

SUMMARY

A combustion chamber for an engine is disclosed in accordance with an embodiment of the present disclosure. The combustion chamber receives air from an intake port and fuel to be combusted in the form of droplets from an injector. The combustion chamber is defined by a cylinder and a piston. The cylinder includes a cylinder head a cylinder wall extending from the cylinder head. The piston slides with respect to the cylinder wall as the piston reciprocates inside the cylinder and includes a piston crown a piston skirt. The piston crown has a receiving cavity recessed on an operative top face thereof. The receiving cavity is so profiled that a first curved sub-profile proximal to an operative top face of the piston and extending inwardly to valve pockets and a second curved sub-profile defining side wall profile of the receiving cavity are connected by a first straight sub-profile. The first straight sub-profile is orthogonal to the operative top face of the piston and connects the first curved sub-profile to the second curved sub-profile for defining throat opening for facilitating fuel sprayed by the injector to reach the interior of the receiving cavity and mixing of air and fuel inside the receiving cavity. The piston skirt extends from the piston crown.

Further, a third curved sub profile and a fourth curved sub profile disposed on sides of the operative bottom most portion of the receiving cavity are connected by a second straight sub-profile for defining landing area for fuel received inside the receiving cavity. The landing area facilitates in directing fuel to intricate interior of the receiving cavity, thereby facilitating mixing of air and fuel inside the receiving cavity.
Generally, the dimension of the third curved sub profile and the fourth curved sub profile are equal.
Typically, the dimension of the second straight sub-profile is in range of 1 percent to 5 percent of cylinder bore diameter.
In accordance with an embodiment of the present disclosure a pip height defined as depth of vertex configured at center of the receiving cavity from operative top face of said piston is in range of 4 percent to 9 percent of cylinder bore diameter.
Typically, the angle included by the vertex is in the range of 120 to 144 degrees.
In accordance with an embodiment, the angle included between tangent to third curved sub profile and the operative top face of the piston is in range of 30 to 60 degrees.
Typically, the first curved sub-profile, the first straight sub-profile and the second curved sub-profile are connected to configure smooth, continuous profile.

Typically, the ratio of depth (H1) of the center of curvature of the third curved sub profile from operative top face of the piston to depth of cavity (H) is in the range of 0.55 to 0.65.
BRIEF DESCRIPTION
The objects and features of the present disclosure will be more clearly understood from the following description of the disclosure taken in conjunction with the accompanying drawings, in which,
Figure 1 illustrates a schematic representation depicting profile of a piston crown receiving bowl of a conventional combustion chamber in comparison with the profile of the piston crown receiving bowl of the combustion chamber in accordance with an embodiment of the present disclosure, wherein the profiles are 2-dimensional representation of receiving cavity as viewed along sectional plane passing through centres of the convention piston crown and piston crown in accordance with an embodiment of the present disclosure respectively;

Figure 2 illustrates a schematic representation of the piston crown receiving bowl of the combustion chamber in accordance with the present disclosure;

Figure 3a and Figure 3b illustrates a schematic representation depicting the interaction between the spray of fuel introduced inside the combustion chamber with the internal walls of the piston crown receiving bowl of Figure 2;
Figure 4 illustrates a graphical representation depicting comparative analysis of variation of emission parameters, particularly smoke emission with respect to different operating conditions of the engine, particularly with respect to different speeds of the engine for conventional combustion chamber and combustion chamber of the present disclosure;
Figure 5 illustrates graphical representation depicting comparative analysis of various parameters such as mixing characteristics, NOx and particulate matter trade-off and Fuel efficiency for conventional combustion chambers having different configurations and combustion chamber of the present disclosure;

Figure 6a illustrates a graphical representation depicting variation of particulate matter emission (in g/km) with respect to NOx emissions (in g/km) for conventional combustion chambers having different configurations and combustion chamber of the present disclosure;

Figure 6b illustrates a graphical representation depicting variation of fuel efficiency (kmpl) with respect to NOx emissions (in g/km) for conventional combustion chambers having different configurations and combustion chamber of the present disclosure;

Figure 6c illustrates a graphical representation depicting variation of carbon-monoxide emission (in g/km) with respect to NOx emissions (in g/km) for conventional combustion chambers having different configurations and combustion chamber of the present disclosure;

Figure 7a illustrates a graphical representation depicting variation of soot emission (in g/km) with respect to NOx emissions (in g/km) for conventional combustion chamber and combustion chamber in accordance with different embodiments of the present disclosure;

Figure 7b illustrates a graphical representation depicting variation of CO emission (in g/km) with respect to NOx emissions (in g/km) for conventional combustion chamber and combustion chamber in accordance with different embodiments of the present disclosure;
Figure 7c illustrates a graphical representation depicting variation of fuel efficiency (in km/l) with respect to NOx emissions (in g/km) for conventional combustion chamber and combustion chamber in accordance with different embodiments of the present disclosure;

Figure 7d illustrates a graphical representation depicting variation of HC+NOx emission (in g/km) with respect to NOx emissions (in g/km) for conventional combustion chamber and combustion chamber in accordance with different embodiments of the present disclosure.

DETAILED DESCRIPTION

The disclosure will now be described with reference to the accompanying drawings which do not limit the scope and ambit of the disclosure. The description provided is purely by way of example and illustration.

The embodiments herein and the various features and advantageous details thereof are explained with reference to the non-limiting embodiments in the following description. Descriptions of well-known components and processing techniques are omitted so as to not unnecessarily obscure the embodiments herein. The examples used herein are intended merely to facilitate an understanding of ways in which the embodiments herein may be practiced and to further enable those of skill in the art to practice the embodiments herein. Accordingly, the examples should not be construed as limiting the scope of the embodiments herein.

The foregoing description of the specific embodiments will so fully reveal the general nature of the embodiments herein that others can, by applying current knowledge, readily modify and/or adapt for various applications such specific embodiments without departing from the generic concept, and, therefore, such adaptations and modifications should and are intended to be comprehended within the meaning and range of equivalents of the disclosed embodiments. It is to be understood that the phraseology or terminology employed herein is for the purpose of description and not of limitation. Therefore, while the embodiments herein have been described in terms of preferred embodiments, those skilled in the art will recognize that the embodiments herein can be practiced with modification within the spirit and scope of the embodiments as described herein.

Figure 1 illustrates a schematic representation depicting profile of a piston crown receiving bowl 10 of a conventional combustion chamber in comparison with the profile of the piston crown receiving bowl, also referred to as receiving cavity 100 of the combustion chamber in accordance with an embodiment of the present disclosure. Referring to Figure 2 and Figure 3a, the profile of the piston crown receiving bowl 100 is such that a curved sub-profile 30 that has a radius of curvature R1 and a curved sub-profile 27 that has a radius of curvature R5 along with the other curved sub-profiles such as a curved sub-profile 29 that has a radius of curvature R3 and a curved profile 30 that has a radius of curvature R4 define the profile of the piston crown receiving bowl 100. The piston crown receiving bowl 100 is profiled to define valve pockets disposed on sides of a central axis “C” of the piston crown receiving bowl 100.

The curved sub-profile 30 and the curved sub-profile 27 are also referred to as first and second curved sub-profiles respectively and are connected by a first straight line sub-profile 40 unlike an inclined profile used for connecting the sub-profiles having radius of curvatures R1’ and R5’ in case of the conventionally known piston crown receiving bowl 10. The straight line sub-profile 40 is orthogonal to the operative top face of the piston. The first curved sub-profile 30, the straight line sub-profile 40 and the curved sub-profile 27 are connected so as to configure smooth, continuous profile. With such configuration of the piston crown receiving bowl 100, the piston crown receiving bowl 100 has a wider throat opening, thereby providing better access to the intricate interior portions of the bowl portion of the combustion chamber. With such configuration of the piston crown receiving bowl 100, the machining of the intricate interior portions of the bowl portion of the combustion chamber is convenient because of wider throat opening in case of the piston crown receiving bowl 100. Accordingly, the piston crown receiving bowl configuration 100 of the combustion chamber is easy to manufacture, simple in construction and efficient in operation.

The piston crown receiving bowl 100 of the combustion chamber is having such a profile that the spray angle of the fuel 22 sprayed by the injector nozzle 21 relative to chamber corner area and position of spray from the position of chamber pip point, vertical distance of the injector tip from the bottom face of the cylinder, chamfer radius, landing face and bowl/chamber included angles and swirl are such so as to provide better mixing conditions inside the combustion chamber. The injector nozzle 21 is disposed along the central axis “C” of the piston crown receiving bowl 100. The piston crown receiving bowl 100 of the combustion chamber improves the NOx and soot emissions trade-off from engine by improving the uniform index of air-fuel mixture inside the cylinder. The piston crown receiving bowl 100 of the combustion chamber facilitates improved mixing of the fuel and air inside the portion of combustion chamber that is away from the cylinder head. The piston crown receiving bowl 100 of the combustion chamber improves engine efficiency and results in lower NOx and soot emissions. Such configuration of the piston crown receiving bowl 100 of the combustion chamber further improves the engine structural stability and fuel economy.
The combustion chamber having the piston crown receiving bowl 100 can be machined and assembled to any internal combustion engine with and without valve pockets. The combustion chamber having the piston crown receiving bowl 100 can be machined and assembled to any internal combustion engine having cylinder head with intake and exhaust valve (s) having in-cylinder fuel injection system injecting fuel at higher pressure. The piston crown receiving bowl 100 of the combustion chamber is radially in warded from the top face of piston. The piston crown receiving bowl 100 of the combustion chamber includes sub-profile portion having compound radius R1 is at a radial distance L1 from centre of the bowl. Radius R1 is connected to and extends inwardly to valve pockets. The centres defining curved profiles 29 and 31, also referred to as the third and fourth curved sub-profiles 29 and 31 respectively and that are having radius of curvature R3 and R4 respectively are at a height of (H1) from top face of the piston and both third and fourth curved profiles 29 and 31 are connected with a second flat line profile 23. The third curved sub-profile 29, the second flat line profile 23 and fourth curved sub-profile 31 respectively are connected so as to configure smooth, continuous profile. More specifically, the sub-profiles are so connected to configure the profile of the receiving bowl 100 that the profile of the receiving bowl 100 is a smooth, continuous profile. With such configuration, the flow path of the fuel sprayed by the injector nozzle 21 is such that there is proper mixing of the air and fuel in the receiving bowl 100. The flat face at bottom area of the bowl will act as a landing area to take appropriate direction to improving mixing index of air-fuel. The bowl depth (H) is functional fraction of cylinder bore of the engine. The connecting distance (t) of radius R3 and R4 is approximately between 1% and 5% of engine cylinder bore diameter in combination with height of the bowl depth (H). Referring to Figure 2 the various parameters associated with the piston crown receiving bowl 100 of the combustion chamber and the various inter-relations there-between are defined as follows:
H : Depth of the Bowl/Combustion Chamber.

The range of H/B in combination with t and H1 is 0.17 to 0.21. In a further embodiment the height of the bowl depth can be 0.185 of bore diameter in combination of ‘t’ being 2% of bore diameter;

H1 : Height or position of R3 and R4 circles/compound radius from top face of the piston. The ratio of H1/H is 0.55 to 0.65. In a further embodiment the R3 and R4 can be equal and connected with flat face having dimension equal to 2% of bore diameter;

B: Bore Diameter of Internal Combustion Engine is in the range of 60mm to 150 mm. In a further embodiment the bore diameter can be in the range of 70mm to 120mm;

h: Minimum Depth Position from Piston Face called as pip height. The pip height is defined as depth of vertex 25 configured at center of the receiving cavity 100 from operative top face of the piston. The pip height is in range of 4 percent to 9 percent of cylinder bore diameter. The height ‘h’ varies between in the range of 4% to 9% of the bore diameter. In a further embodiment the ‘h’ can be in the optimum range of 6 to 6.5% of the bore diameter;
W: Bowl Center Off-set with respect to Piston Center can vary depending on design features of injector position and type of engine configuration.

? : Included Angle of Chamber Pip Connected to the Radius R2 in both sides in the range of 1200 and 1440. In a further embodiment the ‘?’ can be in the range of 1240 to 1380

?1: The tangent angles connected from top of the piston face to the radius R3 and R4 is in the range of 300 to 600.

Further, the annular portion of bowl is connected to top face of piston by the curved sub-profile 30 that has radius of curvature R1 that is in the range of 0 to 2 mm and curved sub-profile 30 that has radius of curvature R5 that is in the range of 2 to 3.5 mm. The radius R3 is connected to R5 with a tangent. R3 is joining with flat face ‘t’. The R3 is more or less equal to R4. The bottom flat faces thickness (t) range from 1% to 5% of bore diameter. The flat ‘t’ is connected to R4. Both the profiles R3 and R4 are in the range of 5 to 10 mm with respect to bowl volume in cubic centimeter and compression ratio. 5. Joining of R4 with pip of bowl through the R6 and inclined line with an included angle of ?. The value of ? ranges from 120° and 144°. The ratio H1/H and ratio H/B ratio is between 0.55 to 0.65 and 0.17 to 0.21 respectively.

Figure 3a and Figure 3b illustrates interaction between the spray of fuel introduced inside the combustion chamber with the internal walls of the piston crown receiving bowl 100. As illustrated in figure the spray impinges to and adheres to maximum surface area of the crown receiving bowl 100 and as such providing favourable conditions for mixing of the fuel with the air inside the combustion chamber, thereby providing complete combustion of the fuel inside the combustion chamber. Such a configuration of the crown receiving bowl 100 enhances combustion of the fuel and eliminates drawbacks associated with incomplete combustion such as higher NOx and soot emissions, reduced efficiency, in-efficient performance of the engine and reduced service life of the engine. Further, with such configuration of the piston crown receiving bowl 100, there is formation of uniform and homogeneous mixture of fuel and air inside the combustion chamber. Such configuration of the piston crown receiving bowl 100 addresses the drawbacks the existing re-entrant combustion chamber shape which result in heterogeneous mixture formation or poor uniform index of fuel-air within the combustion chamber of diesel engine.

TEST DATA

Tests and experiments were performed under similar set of operating conditions on the engine equipped with combustion chamber having piston receiving bowl 100 of the present disclosure and the combustion chamber having conventionally known piston receiving bowl 10 to determine the effectiveness of combustion chamber having piston receiving bowl 100 of the present disclosure in providing better mixing between the air and the fuel inside the combustion chamber, achieving complete combustion and preventing soot and NOx emissions. It was observed that combustion chamber having piston receiving bowl 100 showed better results and prevented NOx emission, soot emission and provided better fuel efficiency.

Several bowls of existing and also new configuration were thoroughly analyzed using both computation and experimental approach. The piston receiving bowl 100 has shown improved uniform index. The improved uniform index has reflected with lower NOx and soot emissions with fractional benefit in fuel consumption. In full load operating zone the piston receiving bowl 100 has shown significant improvement in reducing smoke.

Figure 4 illustrates a graphical representation depicting comparative analysis of variation of emission parameters, particularly smoke emission with respect to different operating conditions of the engine, particularly with respect to different speeds of the engine for conventional combustion chamber having piston receiving bowl 10 and combustion chamber having piston receiving bowl 100. The curve c1 represents variation of smoke emission with respect to different speeds of the engine for conventional combustion chamber having piston receiving bowl 10. The curve c2 represents variation of smoke emission with respect to different speeds of the engine for combustion chamber having piston receiving bowl 100. From the above graph it is clear that there is significant improvement in reducing both PM and NOx emissions in case of combustion chamber having piston receiving bowl 100 as compared to combustion chamber having piston receiving bowl 10, particularly during low speed conditions.

Figure 5 illustrates graphical representation depicting comparative analysis of various parameters such as mixing characteristics, NOx and particulate matter trade-off and Fuel efficiency for conventional combustion chambers having different configurations and combustion chamber having the piston receiving bowl 100 of the present disclosure. The star sign depicts the PM emission and the fuel efficiency in case of the combustion chamber having the piston receiving bowl 100.

Figure 6a illustrates a graphical representation depicting variation of particulate matter emission (in g/km) with respect to NOx emissions (in g/km) for conventional combustion chambers having different configurations and combustion chamber having the piston receiving bowl 100. The star sign depicts the particulate matter emission (in g/km) in case of the combustion chamber having the piston receiving bowl 100 and as is clear in the graph is within the rectangle depicting the allowable range particulate matter emission (in g/km). If the same factors of improvement /deterioration of cooler bypass is applied to the piston receiving bowl 100, then the Nox value reaches.200 g/km.

Figure 6b illustrates a graphical representation depicting variation of fuel efficiency (kmpl) with respect to NOx emissions (in g/km) for conventional combustion chambers having different configurations and combustion chamber having the piston receiving bowl 100. Figure 6c illustrates a graphical representation depicting variation of carbon-monoxide emission (in g/km) with respect to NOx emissions (in g/km) for conventional combustion chambers having different configurations and combustion chamber having the piston receiving bowl 100. From the above graphs it is clear that the soot emission is reduced by 20 percent, Nox emission is reduced by 7.22 percent and the fuel efficiency is improved by 0.7 percent.

Figure 7a illustrates a graphical representation depicting variation of soot emission (in g/km) with respect to NOx emissions (in g/km) for conventional combustion chamber having the piston receiving bowl 10 and combustion chamber having the piston receiving bowl 10. Referring to Figure 7a, the point P0 represents engine out limit, P1 represents the soot emission in case of the conventional combustion chamber having the piston receiving bowl 10 and p2, p3, p4 and p5 represents the soot emission in case of the combustion chamber having the piston receiving bowl 100.

Figure 7b illustrates a graphical representation depicting variation of CO emission (in g/km) with respect to NOx emissions (in g/km) for conventional combustion chamber having the piston receiving bowl 100 and combustion chamber in accordance with different embodiments of the present disclosure. Referring to Figure 7b, p1’ represents the CO emission (in g/km) in case of the conventional combustion chamber having the piston receiving bowl 10 and p2’, p3’, p4’ and p5’ represents the CO emission (in g/km) in case of the combustion chamber having the piston receiving bowl 100.

Figure 7c illustrates a graphical representation depicting variation of fuel efficiency (in km/l) with respect to NOx emissions (in g/km) for conventional combustion chamber and combustion chamber in accordance with different embodiments of the present disclosure. Referring to Figure 7c, p1’’ represents the fuel efficiency (in km/l) in case of the conventional combustion chamber having the piston receiving bowl 10 and p2’’, p3’’, p4’’ and p5’’ represents the fuel efficiency (in km/l) in case of the combustion chamber having the piston receiving bowl 100.

Figure 7d illustrates a graphical representation depicting variation of HC+NOx emission (in g/km) with respect to NOx emissions (in g/km) for conventional combustion chamber and combustion chamber in accordance with different embodiments of the present disclosure. Referring to Figure 7d, p1’’’ represents the HC+NOx emission (in g/km) in case of the conventional combustion chamber having the piston receiving bowl 10 and p2’’’, p3’’’, p4’’’ and p5’’’ represents the HC+NOx emission (in g/km) in case of the combustion chamber having the piston receiving bowl 100.

TECHNICAL ADVANCEMENTS

The combustion chamber for a diesel engine in accordance with the present disclosure has several technical advantages including but not limited to the realization of:

• a combustion chamber having a piston crown receiving bowl configuration that is easy to manufacture;
• a combustion chamber having a piston crown receiving bowl configuration that is simple in construction;
• a combustion chamber that improves mixing characteristics and facilitate proper mixing of the air and fuel introduced inside the engine;
• a combustion chamber for a diesel engine that improves performance of the engine and enhances service life of the engine;
• a combustion chamber for a diesel engine that eliminates incomplete combustion by ensuring proper mixing of the air and fuel introduced inside the combustion chamber; and
• a combustion chamber that eliminates drawbacks associated with incomplete combustion such as higher NOx and soot emissions, reduced efficiency, in-efficient performance of the engine and reduced service life of the engine.

Throughout this specification the word “comprise”, or variations such as “comprises” or “comprising”, will be understood to imply the inclusion of a stated element, integer or step, or group of elements, integers or steps, but not the exclusion of any other element, integer or step, or group of elements, integers or steps.
The use of the expression “at least” or “at least one” suggests the use of one or more elements or ingredients or quantities, as the use may be in the embodiment of the disclosure to achieve one or more of the desired objects or results.

Any discussion of documents, acts, materials, devices, articles or the like that has been included in this specification is solely for the purpose of providing a context for the disclosure. It is not to be taken as an admission that any or all of these matters form a part of the prior art base or were common general knowledge in the field relevant to the disclosure as it existed anywhere before the priority date of this application.

The numerical values mentioned for the various physical parameters, dimensions or quantities are only approximations and it is envisaged that the values higher/lower than the numerical values assigned to the parameters, dimensions or quantities fall within the scope of the disclosure, unless there is a statement in the specification specific to the contrary.

While considerable emphasis has been placed herein on the components and component parts of the preferred embodiments, it will be appreciated that many embodiments can be made and that many changes can be made in the preferred embodiments without departing from the principles of the disclosure. These and other changes in the preferred embodiment as well as other embodiments of the disclosure will be apparent to those skilled in the art from the disclosure herein, whereby it is to be distinctly understood that the foregoing descriptive matter is to be interpreted merely as illustrative of the disclosure and not as a limitation. ,CLAIMS:1. A combustion chamber for an engine adapted to receive air from an intake port and fuel to be combusted in the form of droplets from an injector, said combustion chamber defined by:
• a cylinder comprising:
o a cylinder head; and
o a cylinder wall extending from said cylinder head;
• a piston adapted slide with respect to said cylinder wall as said piston reciprocates inside said cylinder, said piston comprising:
o a piston crown with a receiving cavity recessed on an operative top face thereof, said receiving cavity being so profiled that
a first curved sub-profile proximal to an operative top face of said piston and extending inwardly to valve pockets;
a second curved sub-profile defining side wall profile of said receiving cavity;
a first straight sub-profile orthogonal to said operative top face of said piston and connecting said first curved sub-profile to said second curved sub-profile for defining a throat opening for facilitating fuel sprayed by said injector to reach the interior of said receiving cavity and mixing of air and fuel inside said receiving cavity; and
o a piston skirt extending from said piston crown.

2. The combustion chamber system as claimed in claim 1, wherein a third curved sub profile and a fourth curved sub profile disposed on sides of said operative bottom most portion of said receiving cavity are connected by a second straight sub-profile for defining landing area for fuel received inside said receiving cavity, said landing area facilitate directing fuel to intricate interior of said receiving cavity, thereby facilitating mixing of air and fuel inside said receiving cavity.

3. The combustion chamber system as claimed in claim 3, wherein dimension of said third curved sub profile and said fourth curved sub profile are equal.

4. The combustion chamber system as claimed in claim 3, wherein dimension of said second straight sub-profile is in range of 1 percent to 5 percent of cylinder bore diameter.

5. The combustion chamber system as claimed in claim 1, wherein pip height defined as depth of vertex configured at center of said receiving cavity from operative top face of said piston is in range of 4 percent to 9 percent of cylinder bore diameter.

6. The combustion chamber system as claimed in claim 6, wherein angle included by said vertex is in the range of 120 to 144 degrees.
7. The combustion chamber system as claimed in claim 3, wherein angle included between tangent to third curved sub profile and said operative top face of said piston is in range of 30 to 60 degrees.

8. The combustion chamber as claimed in claim 1, wherein said first curved sub-profile, said first straight sub-profile and said second curved sub-profile are connected to configure smooth, continuous profile.

9. The combustion chamber as claimed in claim 2, wherein ratio of depth (H1) of the center of curvature of said third curved sub profile from operative top face of said piston to depth of cavity (H) is in the range of 0.55 to 0.65.