Claims:We claim:

1. A single-cylinder, naturally aspirated diesel engine (116) with selective catalytic reduction (SCR), said diesel engine comprising:

(a) an air intake pipe (114) connected to inlet port of said diesel engine (116);

(b) an air-filter (112) disposed on said air intake pipe (112);

(c) an exhaust pipe (118) connected to the exhaust port of said diesel engine (116);

(d) a first exhaust after treatment system (120) disposed on said exhaust pipe (118); said first exhaust after-treatment system (120) configured to remove hydrocarbons (HC), carbon monoxide (CO) and particulate matters (PM) present in said exhaust gases;

(e) a second exhaust after treatment system (122) disposed downstream said first exhaust after treatment system (120); said second exhaust after-treatment system (122) configured to remove nitrogen oxides (NOx) present in said exhaust gases; and

(f) a muffler (130) connected downstream said second exhaust after treatment system (122) on said exhaust pipe (118) for releasing the exhaust gases after treatment thereof in said exhaust after-treatment systems (120; 122) to obtain an improved Brake Specific Fuel Consumption (BSFC) by using an appropriate fuel injector configuration.

2. Single-cylinder, naturally aspirated diesel engine (116) as claimed in claim 1, wherein said first exhaust after-treatment system (120) is configured to remove hydrocarbons (HC), carbon monoxide (CO) and particulate matters (PM) present in the exhaust gases produced in said diesel engine (116).

3. Single-cylinder, naturally aspirated diesel engine (116) as claimed in claim 1, wherein said second exhaust after-treatment system (122) is configured to remove nitrogen oxides (NOx) present in the exhaust gases generated in said diesel engine (116).

4. Single-cylinder, naturally aspirated diesel engine (116) as claimed in claim 1, wherein said diesel engine (116) is configured for light commercial vehicles (LCV) with a cubic capacity in the range of 600-700 cc.

5. Single-cylinder, naturally aspirated diesel engine (116) as claimed in claim 4, wherein said first exhaust after-treatment system (120) reduces particulate emissions (PM) by more than 65%.

6. Single-cylinder, naturally aspirated diesel engine (116) as claimed in claim 4, wherein said second exhaust after-treatment system (122) is configured to remove NOx emissions.

7. Single-cylinder, naturally aspirated diesel engine (116) as claimed in claim 6, wherein the NOx conversion efficiency of said second exhaust after-treatment system (122) is greater than 90%.

8. Single-cylinder, naturally aspirated diesel engine (116) as claimed in claim 7, wherein said second exhaust after-treatment system (122) is configured to reduce the overall tail pipe emissions of said diesel engine (116) by more than 65%.
9. Single-cylinder, naturally aspirated diesel engine (116) as claimed in claim 1, wherein said first exhaust after treatment system (120) is configured to remove hydrocarbons (HC), carbon monoxide (CO) and particulate matters (PM) present in the exhaust gases; the reduction in said particulate matter (PM) being greater than 65%.

10. Single-cylinder, naturally aspirated diesel engine (116) as claimed in claim 1, wherein said engine comprises:

(I) said air intake pipe (114) connected to said engine (116) inlet port;

(II) said air-filter (112) disposed on said air intake pipe (112);

(III) said exhaust pipe (118) connected to said engine (116) exhaust port;

(IV) said first exhaust after treatment system (120) disposed on said exhaust pipe (118) to remove hydrocarbons (HC), carbon monoxide (CO) and particulate matters (PM) present in the exhaust gases;

(V) said second exhaust after treatment system (122) disposed downstream said first exhaust after treatment system (120) to remove nitrogen oxides (NOx) present in said exhaust gases; and

(VI) said muffler (130) connected downstream said second exhaust after treatment system (122) to release after treated exhaust gases to obtain an improved Brake Specific Fuel Consumption (BSFC) by using an appropriate fuel injector configuration;

wherein said first exhaust after-treatment system (120) reduces particulate emissions (PM) by more than 65%; said second exhaust after-treatment system (122) having NOx conversion efficiency of greater than 90% and thereby configured to reduce the overall tail pipe emissions of said diesel engine (116) by more than 65%.

Dated this 30th day of September 2019.

Digitally Signed.

(SANJAY KESHARWANI)
APPLICANT’S PATENT AGENT
REGN. NO. IN/PA-2043. , Description:FIELD OF INVENTION

The present invention relates to an improved diesel engine complying with BS-VI (BS6) emission norms. In particular, the present invention relates to an improved diesel engine which uses Selective Catalytic Reduction (SCR) technology instead of EGR system for achieving the required emission characteristics. More particularly, the present invention relates to a single-cylinder, naturally aspirated diesel engine with SCR technology for meeting the stringent BS-VI emission norms.

BACKGROUND OF THE INVENTION

According to the European Parliament’s Directive 2007/46/EC of 05.09.2007, as part of emission standards and other vehicle regulations, the automobile vehicles are classified in different categories depending on the maximum permissible laden or loaded mass thereon. These include motor vehicles of category M including passenger cars with at least four wheels designed and constructed for the carriage of passengers, and category N including commercial vehicles or power-driven vehicles with at least four wheels and designed and constructed for carrying goods. Further, sub-classifications of M and N categories of motor vehicles are briefly described included below:

Category M1 vehicles designed and constructed for the carriage of passengers and comprising no more than eight seats in addition to the driver's seat.

Category M2 vehicles designed and constructed for the carriage of passengers, comprising more than eight seats in addition to the driver's seat, and having a maximum mass not exceeding 5 tons.

Category M3 vehicles designed and constructed for the carriage of passengers, comprising more than eight seats in addition to the driver's seat, and having a maximum mass exceeding 5 tons.

Category N1 vehicles designed and constructed for the carriage of goods and having a maximum mass not exceeding 3.5 tons.

Category N1 vehicles or Light Commercial Vehicles (LCVs) are further divided into three weight classes I, II and III based on their Reference Mass (RW), i.e. the mass of LCV in running order minus the uniform mass of the driver of 75 kg and increased by a uniform mass of 100 kg.

Here, Class 1 pertains to LCVs of RW = 1305 kg, Class 2 pertains to LCVs of 1305 kg < RW = 1760 kg and Class 3 pertains to LCVs of 1760 kg < RW.

Category N2 vehicles designed and constructed for the carriage of goods and having a maximum mass exceeding 3,5 tons but not exceeding 12 tons.

Category N3 vehicles designed and constructed for the carriage of goods and having a maximum mass exceeding 12 tons.

As per the government regulations in India, all M and N category vehicles with diesel engines are required to meet more stringent BS6 (BS-VI) emission norms with effect from 01st April 2020. NOx limit as per BS6 emission norms for M Class and N1 Class 1 vehicle category is 80 mg/km.

This lower and stringent emission standard necessitates the engine manufacturers of such vehicles to develop new technologies to meet these BS6 emission norms.

PRIOR ART

US 2014 0331752 A1, titled- “Exhaust aftertreatment system diagnostic and conditioning” discloses an engine diagnostic tool includes a diagnostic engine calibration module structured to include a plurality of diagnostic processes for operating an internal combustion engine system of an immobilized vehicle. One or more of the pluralities of diagnostic processes is structured to be an intrusive diagnostic process for the internal combustion engine system, wherein the intrusive diagnostic process causes the internal combustion engine system to operate outside of one or more calibration parameters. The diagnostic engine module is further structured to control the order and timing of each diagnostic process in the plurality of diagnostic processes.

An article titled: “Cu-zeolite NH3-SCR catalysts for NOx removal in the combined NSR–SCR technology” published in Chemical Engineering Journal, volumes 207–208, 1 October 2012, Pages 10-17 discusses the challenge of efficient NOx removal from diesel and lean-burn engine exhaust gas by combining NSR and SCR catalyst is studied. Several Cu exchanged zeolites have been prepared, varying the preparation method (ion exchange and impregnation), the copper content (1–6%) and the zeolite (BETA and ZSM5). The prepared catalysts have been characterized, and acidity, surface area, crystallinity and metal reducibility have been compared. SCR experiments under 750 ppm NO, 750 ppm NH3 and 9.5% O2 (Art to balance) discriminated low copper loading, prepared by ion exchange catalyst (Z-IE-1.4 and B-IE-2.1) as the most active for NOx conversion (>95%) in ample temperature range (280–450 °C). These active SCR catalysts were placed downstream a monolith NSR Pt–BaO/Al2O3 catalyst, running under cycled lean–rich conditions, and the improvement on NOx removal and selectivity to only N2 were determined. In an ample range of temperature, from 200 to 400°C, NOx conversion was increased in more than 30%, also notably increasing the production of nitrogen, and reducing production of ammonia and N2O below 3% and 2%, respectively, when comparing the combined NSR–SCR configuration versus the single NSR catalyst.

The highlights of this combined NSR–SCR technology are as follows:

• 1–6 wt.% Cu exchanged BETA and ZSM-5 zeolites are tested in SRC, NSR and dual NSR–SCR systems.

• 2.1% Cu/BETA and 1.4% Cu/ZSM-5 achieved higher activity and wider windows for NH3-SCR reaction.
• ZSM5 based catalysts resulted in higher activity than BETA, related with reducibility of Cu.

• Improvement above 30% in NOx conversion selectively to N2 is achieved when operating dual NSR–SCR systems.

Another article titled: “Emission Control Technologies for Diesel-Powered Vehicles” published in Manufacturers of Emission Controls Association, Washington D.C., USA: December 2007, discusses that diesel engines are important power systems for on-road and off-road vehicles. Most heavy-duty trucks and buses are powered by a diesel engine due to the long record of reliability, high fuel-efficiency, and high torque output. Diesel engines are easy to repair, inexpensive to operate, and extremely durable. It is not uncommon for a diesel engine to last 15-20 years and achieve a one million-mile life. From the standpoint of greenhouse gas emissions, diesel engines can compete with other advanced technologies, like hybrid electric vehicles, due to diesel’s inherent fuel economy relative to conventional spark-ignited, gasoline engines.

Diesel-powered vehicles have demonstrated a 30-40 percent fuel economy advantage over their gasoline counterparts. This translates to about a 20 percent reduction in CO2 emissions.
DISADVANTAGES OF THE EXISTING TECHNOLOGIES OR PRIOR ART

Currently, NOx emissions control strategies available worldwide on diesel engines for small commercial vehicles (LCVs) are exhaust gas recirculation (EGR) and different combustion techniques.

For meeting the abovementioned BS6 emission norms during the course of development of a single-cylinder, naturally aspirated diesel engine, the current EGR strategy was found to be disadvantageous in the light of higher NOx conversion efficiency of SCR system, which also has the advantages of better Brake-Specific Fuel-Consumption (BSFC) and reduced regeneration frequency.

Diesel combustion is more heterogeneous in nature. Although, diesel combustion system is thermally more efficient due to its high-pressure combustion, there are combustion by-products like Soot, CO2, NOX, HC and CO due to this heterogeneous combustion, which produces NOx emissions, a critical parameter for control thereof.

In the currently available diesel engines used on small commercial vehicle (LCVs), the combustion is of a lean mixture with exhaust gas recirculation (EGR) and the engine operation is restricted with the smoke limitation.

Therefore, there is an existing need for controlling NOx emissions by tuning the diesel engine without EGR.

OBJECTS OF THE INVENTION

Some of the objects of the present invention - satisfied by at least one embodiment of the present invention - are as follows:

An object of the present invention is to provide a single cylinder, naturally aspired diesel engine with SCR technology to reduce engine out soot emissions.

Another object of the present invention is to provide a single cylinder, naturally aspired diesel engine with SCR technology to reduce soot entry to Diesel Particulate Filter (DPF) with no EGR.

Still another object of the present invention is to provide a single cylinder, naturally aspired diesel engine with SCR technology to reduce regeneration frequency.

Yet another object of the present invention is to provide a single cylinder, naturally aspired diesel engine with SCR technology to reduce oil dilution and less oil in soot.

A further object of the present invention is to provide a single cylinder, naturally aspired diesel engine with SCR technology which successfully facilitates a compromise in high engine out NOx.

A still further object of the present invention is to provide a single cylinder, naturally aspired diesel engine with SCR technology which has a longer life.

A still object of the present invention is to provide a single cylinder, naturally aspired diesel engine with SCR technology which offers a significant improvement in the fuel economy thereof over LNT system.

A yet further object of the present invention is to provide a single cylinder, naturally aspired diesel engine with SCR technology which has a robust engine out NOx model.

These and other objects and advantages of the present invention will become more apparent from the following description, when read with the accompanying figures of drawing, which are however not intended to limit the scope of the present invention in any way.

DESCRIPTION OF THE INVENTION

The present invention is configured for tuning the diesel engine without EGR for lesser engine out soot with a compromise or trade-off with high engine out NOx. This is achieved by a single cylinder, naturally aspired diesel engine with Selective Catalytic Reduction (SCR) technology and configured in accordance with the present invention.

The single-cylinder, naturally aspirated diesel engine with SCR technology for meeting stringent BS-VI emission norms and configured in accordance with the present invention enables reduced amount of engine out soot emissions and thus less soot entry into Diesel Particulate Filter (DPF) without any EGR system therein, thereby reducing the regeneration frequency as well as oil dilution on this single-cylinder, naturally aspirated diesel engine.

With this approach, the compromise or trade-off is achieved by engine out NOx emissions increase, which is required to be controlled by a high efficiency Selective Catalytic Reduction (SCR) system. In addition, a novel injection strategy is devised for a better brake specific fuel consumption (BSFC) along with a suitable injector configuration.

SUMMARY OF THE INVENTION

In accordance with an embodiment of the present invention, there is provided a single-cylinder, naturally aspirated diesel engine with selective catalytic reduction (SCR), the diesel engine comprising:
(a) an air intake pipe connected to inlet port of the diesel engine;

(b) an air-filter disposed on the air intake pipe;

(c) an exhaust pipe connected to the exhaust port of the diesel engine;

(d) a first exhaust after treatment system disposed on the exhaust pipe; the first exhaust after-treatment system configured to remove hydrocarbons (HC), carbon monoxide (CO) and particulate matters (PM) present in the exhaust gases;

(e) a second exhaust after treatment system disposed downstream the first exhaust after treatment system; the second exhaust after-treatment system configured to remove nitrogen oxides (NOx) present in the exhaust gases; and

(f) a muffler connected downstream the second exhaust after treatment system on the exhaust pipe for releasing the exhaust gases after treatment thereof in the exhaust after-treatment systems to obtain an improved Brake Specific Fuel Consumption (BSFC) by using an appropriate fuel injector configuration.

Typically, the first exhaust after-treatment system is configured to remove hydrocarbons (HC), carbon monoxide (CO) and particulate matters (PM) present in the exhaust gases produced in the diesel engine.

Typically, the second exhaust after-treatment system is configured to remove nitrogen oxides (NOx) present in the exhaust gases generated in the diesel engine.

Typically, the diesel engine is used for light commercial vehicles (LCV) having the cubic capacity in the range of 600-700 cc.

Typically, the first exhaust after-treatment system reduces particulate emissions (PM) by more than 65%.

Typically, the second exhaust after-treatment system is configured to remove NOx emissions.

Typically, the NOx conversion efficiency of the second exhaust after-treatment system is greater than 90%.

Typically, the second exhaust after-treatment system is configured to reduce the overall tail pipe emissions of the diesel engine by more than 65%.

Typically, the first exhaust after treatment system is configured to remove hydrocarbons (HC), carbon monoxide (CO) and particulate matters (PM) present in the exhaust gases; the reduction in the particulate matter (PM) being greater than 65%.

In accordance with another embodiment of the present invention, there is provided an engine, comprising:

(I) the air intake pipe connected to the engine inlet port;

(II) the air-filter (disposed on the air intake pipe;

(III) the exhaust pipe connected to the engine exhaust port;

(IV) the first exhaust after treatment system disposed on the exhaust pipe to remove hydrocarbons (HC), carbon monoxide (CO) and particulate matters (PM) present in the exhaust gases;

(V) the second exhaust after treatment system disposed downstream the first exhaust after treatment system to remove nitrogen oxides (NOx) present in the exhaust gases; and
(VI) the muffler connected downstream the second exhaust after treatment system to release after treated exhaust gases to obtain an improved Brake Specific Fuel Consumption (BSFC) by using an appropriate fuel injector configuration;

wherein the first exhaust after-treatment system reduces particulate emissions (PM) by more than 65%; the second exhaust after-treatment system having NOx conversion efficiency of greater than 90% and thereby configured to reduce the overall tail pipe emissions of the diesel engine by more than 65%.

BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS

The present invention will be briefly described in the following with reference to the accompanying drawings.

Figure 1 shows a comparative chart of the engine out and tail pipe emissions for BS-IV as well as BS-VI engines in terms of particulate matter (PM) and NOx emissions with respect to target values thereof.

Figure 2 shows comparative graph of the improved emission or smoke in terms of filter smoke number and speed with respect to target values thereof by BS6 compliant engine versus BS4 compliant engine.

Figure 3a shows the arrangement of major components of emission system for the conventional or existing BS-IV compliant diesel engine.

Figure 3b shows the arrangement of major components of BS-VI compliant emission system for a single-cylinder, naturally aspirated diesel engine with SCR technology configured in accordance with the present invention.

Figure 4a shows a comparative graphical representation of results of NOx emissions observed in the emission system for conventional BS4 compliant engine versus BS-VI compliant emission system in a single-cylinder, naturally aspirated diesel engine with SCR technology configured according to the present invention.

Figure 4b shows a graphical representation of the comparative results of the particulate/soot emission observed in the conventional emission system for BS4 compliant engine versus the improved emission system in a single-cylinder, naturally aspirated diesel engine with SCR technology configured according to the present invention.

DETAILED DESCRIPTION OF THE ACCOMPANYING DRAWINGS

In the following a single-cylinder, naturally aspirated diesel engine with SCR technology and configured in accordance with the present invention will be described in more details with reference to the accompanying drawings without limiting the scope and ambit of the present invention.

Figure 1 shows a comparative chart of the engine out and tail pipe emissions for BS-IV as well as BS-VI engines in terms of particulate matter (PM) and NOx emissions with respect to targeted values thereof. The engine out soot emission is reduced from 16 mg/km to 12 mg/km and as a trade-off or compromise, NOx emissions (engine out) have steeply increased from 198 mg/km to 780 mg/km. With further fine-tuning of the combustion parameters in cold phase with no EGR, NOx emission (engine out) of 780 mg/km NOx was further reduced to 616 mg/km. By introducing a DPF system with SCR coating used in a prototype vehicle, tail pipe NOx emission of 102 mg/km (616 mg/km engine out) was achieved against the targeted value of 80 mg/km as per BS-VI norms. With this positive outcome in the first phase of trials, NOx emissions could be further reduced to meet the BS-VI target of 80 mg/km by using a high efficiency SCR system along with in-cylinder combustion optimization.
Figure 2 shows comparative graph of the improved emission or smoke in terms of filter smoke number and speed by BS6 compliant engine versus BS4 compliant engine. The graph indicates a 7.2% air flow increment through engine volume increment, a 16.3% reduction in nozzle diameter, a 40% increase in the injection pressure and a 70% effective smoke reduction.

Figure 3a shows an arrangement of major components of emission system 10 for a BS-IV compliant diesel engine. This includes an air filter 12 connected via an intake pipe 14 to a diesel engine 16 and the exhaust gases generated therein are forwarded via an exhaust pipe 18 to an Exhaust After Treatment System (EATS) 20 for removing hydrocarbons (HC) and carbon monoxide (CO) therefrom, before being exhausted to the atmosphere after passing through the muffler 30. In addition, an EGR valve and cooler 15 is on a line connected after air-filter 12 and before EATS 20. EGR helps to control NOx valve for modulating EGR flow, Cooler for cooling the EGR.

Figure 3b shows an arrangement of major components of BS-VI compliant emission system 100 for a single-cylinder, naturally aspirated diesel engine with SCR technology and configured according to the present invention. This includes an air filter 112 connected via an intake pipe 114 to a diesel engine 116 and the exhaust gases generated therein are forwarded via an exhaust pipe 118 to an Exhaust After Treatment System (EATS) 120 for removing hydrocarbons (HC), carbon monoxide (CO) as well as particulate matters (PM) therefrom. However, here a separate Exhaust After Treatment System (EATS) 122 for removing NOx is disposed before the muffler 130, which releases the treated exhaust gases to the atmosphere. Although, EGR helps in reducing NOx emission, it also increases continuous soot regeneration. Therefore, elimination of EGR was necessary. This improved arrangement does not require EGR valve and cooler 15 of Figure 3a. This arrangement is capable of controlling NOx emission by tuning the diesel engine and aftertreatment system even without EGR.
Figure 4a shows a comparative graphical representation of the results of NOx emissions observed in the conventional emission system for BS4 compliant engine versus the results of BS-VI compliant emission system in a single-cylinder, naturally aspirated diesel engine with SCR technology and configured according to the present invention. NOx EATS 122 allows to achieve the conversion efficiency levels of more than 90%, which is turn helps in reducing the tail pipe emission by more than 65%.

Figure 4b shows a graphical representation of the comparative results of the particulate/soot emission observed in the conventional emission system for BS4 compliant engine versus the improved emission system in a single-cylinder, naturally aspirated diesel engine with SCR technology and configured according to the present invention. Similarly, the improved emission system for BS6 compliant engine reduces PM emissions by more than 90%.

TRIALS AND OBSERVATIONS

Current BS-IV engine out emissions were optimized with EGR and other combustion strategies. But, to meet the stringent BS-VI emission norms with respect to NOx as well as soot emissions, there is a need to better strategize and re-define the emission targets to achieve less soot entry to the Diesel Particulate Filter (DPF).

CLOSEST PRACTICE AVAILABLE

The closest practice on low vehicle weight segment is possible only with a Turbocharged 2-cylinder engine with a combination of EGR and SCR or LNT system to achieve equivalent stringent emission norms.

WORLDWIDE APPROACH

Global solution available as on date for passenger cars, SCV and HCV segment vehicles is given below for achieving equivalent stringent norms:

In Heavy Commercial Vehicle (HCV) applications, no EGR strategy (High NOx) is applied. For active regeneration cases, SCR (Copper Zeolite) system is used and for passive regeneration cases, SCR (Vanadium) system is used.

In both the cases, OBD monitoring requires 2 NOx sensors, since NOx emissions are quite high. In Small Commercial Vehicle (SCV) applications, EGR strategy is applied. For active regeneration cases (LNT or SCR), 1 NOx sensor is used for OBD monitoring since NOx emissions are moderate or low.

S. No. Vehicle Category EGR EATS Regeneration OBD NOx
1 HCV No EGR SCR (CuZe)
SCR (Vt) Active
Passive 2 NOx sensors
2 NOx sensors High
High
2 SCV / Passenger cars EGR LNT + cDPF
SCR + cDPF
sDPF Active
Active
Active 1 NOx Sensor
1 NOx Sensor
1 NOx Sensor Low
Low
Low

Currently, the best available solutions for single-cylinder, naturally aspirated diesel engine meets only BS-IV norms in small commercial vehicle (SCV) segment in India.

In accordance with the present invention, a combination of high efficiency SCR system without EGR, one NOx sensor for OBD monitoring and both active and passive regeneration is used to achieve BS-VI emission norms for the same vehicle segment.
S. No Vehicle Category EGR EATS Regeneration OBD NOx
1 Small Commercial Vehicle No EGR SCR (CuZe) Passive & Active 1 NOx sensor High

TECHNICAL ADVANTAGES AND ECONOMIC SIGNIFICANCE

The single cylinder naturally aspirated diesel engine with SCR technology configured in accordance with the present invention offers the following advantages:

• World’s first single-cylinder, naturally aspirated diesel engine with SCR technology to meet stringent BS-VI emission norms.

• Higher regeneration intervals possible with less soot entry to DPF and no EGR.

• Promotes passive regeneration due to cDPF which reduces the regeneration frequency.

• Use of High efficiency SCR (CuZe) with only one NOx sensor.

• OBD with one NOX sensor using robust engine out NOx model.

• Significant improvement in fuel economy over LNT system.

• Longer engine life due to reduced oil dilution and less oil in soot.

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 distinctly understood that the foregoing descriptive matter is to be interpreted merely as illustrative of the invention and not as a limitation. The exemplary embodiments described in this specification are intended merely to provide an understanding of various manners in which this embodiment may be used and to further enable the skilled person in the relevant art to practice this invention.

Although, the embodiments presented in this disclosure have been described in terms of its preferred embodiments, the skilled person in the art would readily recognize that these embodiments can be applied with modifications possible within the spirit and scope of the present invention as described in this specification.

Accordingly, the person skilled in the art can make innumerable changes, variations, modifications, alterations and/or integrations in terms of materials and method used to configure, manufacture and assemble various constituents, components, subassemblies and assemblies, in terms of their size, shapes, orientations and interrelationships without departing from the scope and spirit of the present invention.

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

Throughout this specification, the word “comprise”, or variations such as “comprises” or “comprising”, shall be understood to imply including a described element, integer or method step, or group of elements, integers or method steps, however, does not imply excluding any other element, integer or step, or group of elements, integers or method steps.

The use of the expression “a”, “at least” or “at least one” shall imply using one or more elements or ingredients or quantities, as used in the embodiment of the disclosure in order to achieve one or more of the intended objects or results of the present invention.

The description of the exemplary embodiments is intended to be read in conjunction with the accompanying drawings, which are to be considered part of the entire written description. In the description, relative terms such as “lower”, “upper”, “horizontal”, “vertical”, “above”, “below”, “up”, “down”, “top”, and “bottom” as well as derivatives thereof (e.g. “horizontally”, “downwardly”, “upwardly” etc.) should be construed to refer to the orientation as then described or as shown in the drawing under discussion.

These relative terms are for convenience of description and do not require that the corresponding apparatus or device be constructed or operated in a particular orientation.

Terms concerning attachments, coupling and the like, such as “connected” and “interconnected”, refer to a relationship, wherein structures are secured or attached to one another either directly or indirectly through intervening structures, as well as both movable or rigid attachments or relationships, unless expressly described otherwise.