WO2018069858A1

WO2018069858A1 - Emission reducing system for an internal combustion engine

Info

Publication number: WO2018069858A1
Application number: PCT/IB2017/056309
Authority: WO
Inventors: Hillol KUMAR ROY; Vijayabhaskar ADIGA; Vethanayagam Jayajothi Johnson
Original assignee: TVS Motor Co Ltd
Current assignee: TVS Motor Co Ltd
Priority date: 2016-10-13
Filing date: 2017-10-12
Publication date: 2018-04-19
Anticipated expiration: 2019-04-13

Abstract

The present invention relates to a system for reducing the emissions being generated in an internal combustion engine (4). The present subject matter comprises of a system of spraying and mixing oxidant and reductant along with an air-fuel mixture being sent for combustion. As per the present subject matter, the flow of oxidant and reductant being mixed with the air-fuel mixture is controlled by a low discharge pump (23) being operated at an engine speed.

Description

EMISSION REDUCING SYSTEM FOR AN INTERNAL COMBUSTION

ENGINE

FIELD OF INVENTION

[0001] The present invention relates to an internal combustion engine and more particularly to a mechanism for reducing the emission produced after combustion.

BACKGROUND OF INVENTION

[0002] Generally, an internal combustion engine acts as the power unit of a vehicle. After receiving of an air-fuel mixture, a combustion process is carried out in the internal combustion engine through which power is generated. However, on burning of the air-fuel mixture there are other concerns too which demand due care. One of such concerns is the production of emission comprising NOX and CO components. A substantial amount of NOx and CO emissions are also generated along with the burning of the air-fuel mixture. Various systems and mechanisms to reduce the emissions being produced in the internal combustion engine are known. In general, application of oxidant/reductant-injection for the reduction of NOx and CO emissions by reducing combustion temperature is well known in the art. There are many publications which disclose the reduction in emissions by using oxidant and reductant injection.

[0003] However, an oxidant and reductant injection system which injects oxidant/reductant directly inside the combustion chamber of an internal combustion engine directly inside the combustion chamber during compression stroke requires a high pressure pump in the range of 1000 D 15000 psi for the injection of oxidant/reductant. Such a method is also preferred for high horsepower engine such as 400 to 5000 HP.

[0004] In furtherance to it, the above system also requires a logic controller for controlling the oxidant/reductant injection thus making the over system a sophisticated one which incurs higher cost. Furthermore, as oxidant/reductant is injected directly inside the combustion chamber, oxidant/reductant gets lesser time to mix with air-fuel mixture and this might leads to inhomogeneous mixture of oxidant/reductant with air and fuel. An inhomogeneous mixture of oxidant/reductant with air and fuel might lead to lower reduction of combustion temperature and poor quality of combustion, which might lead to lower reduction of NOx and CO emissions. Also, as the oxidant and reductant injection nozzle being close to the combustion chamber is exposed to higher combustion temperature, the oxidant and reductant injection nozzle requires higher temperature withstanding material resulting in higher cost of the nozzle.

[0005] Hence, there is a requirement of a system which can enable injection of oxidant and reductant in the air-fuel mixture in such a manner which provides time for them to mix properly resulting in a homogeneous mixture. In furtherance to it, the system to be developed needs to simple and low cost, wherein oxidant/reductant can be controllably injected without using complex controllers and without the need of incorporating an expensive oxidant and reductant injection nozzle.

BRIEF DESCRIPTION OF DRAWINGS

[0006] Figure 1 illustrates a side view of an exemplary typical two-wheeled vehicle in accordance with an embodiment of the present subject matter.

[0007] Figure 2 illustrates an enlarged view of a region around internal combustion engine of the exemplary two-wheeled vehicle as shown in Fig. 1, in accordance with an embodiment of the preset subject matter.

[0008] Figure 3 illustrates an enlarged side view of a cylinder head and cylinder head cover in accordance with an embodiment of the present subject matter.

[0009] Figure 4 illustrates an exploded view of the internal combustion engine and a low discharge pump in accordance with an embodiment of the present subject matter.

[00010] Figure 5 illustrates an exploded view of the low discharge pump and a camshaft in accordance with an embodiment of the present subject matter. [00011] Figure 6 illustrates a perspective view of the internal combustion engine of the exemplary two- wheeled vehicle as shown in Fig. 1, in accordance with an embodiment of the present subject matter.

DETAILED DESCRIPTION

[00012] Typically, an internal combustion engine is coupled to the drive wheel, which is generally the rear wheel. Mostly, the internal combustion engine comprises of a cylinder bore where the combustion occurs to provide the needed power for the forward motion of the vehicle. The internal combustion (IC) engine, among other components, comprises of a cylinder on top of which a cylinder head is mounted. The cylinder head is mounted to accommodate and receive the to-and-fro motion of the piston reciprocating from the bottom in an upward direction. On combustion of an air- fuel mixture, the piston transfers the energy generated during combustion to a crankshaft through a connecting rod thereby driving the crankshaft. In this way, the reciprocatory motion of the piston is converted to rotary motion of the crankshaft which in turn powers the vehicle.

[00013] A typical internal combustion engine has an intake system and an exhaust system. The intake system comprises of an air filter and a carburetor (or a fuel injection system). The fuel from the fuel tank is supplied to the carburetor (or a fuel injection system). The carburetor (or a fuel injection system) is calibrated to draw a predetermined amount of air based on a throttle opening and hence form an air-fuel mixture. This air fuel mixture further passes through an intake pipe and sent to intake port of the internal combustion engine. The air fuel combustion mixture is burnt due to a periodical spark generated by a spark plug inside the combustion chamber. The burnt out gases are further expelled from the combustion chamber through an exhaust system. The exhaust system comprises of an exhaust pipe connected to the exhaust port of the engine.

[00014] The combustion of air fuel mixture inside the combustion chamber produces exhaust gases which is a heterogeneous mixture of nitrogen gas, carbon dioxide, oxidant and reductant vapor, oxygen, trace elements, nitrogen oxides, carbon monoxide, particulate matter, hydrocarbons, sulfur dioxide and possible traces which are collectively called as emissions. The emissions generated leave the internal combustion engine as exhaust through an exhaust port disposed on the cylinder head. An exhaust pipe is connected to the exhaust port, which carries the exhaust from the internal combustion, transferring it to the muffler region from where it is finally released into the atmosphere. Reduction of emissions in exhaust gases is of prime concern as emissions are mainly responsible for pollution, greenhouse effects and global increase of temperature. Various mechanisms and devices are incorporated for treating of such emissions. Some of the known mechanisms treat the emissions after they are generated, such as catalytic converters, EGR mechanisms etc. Whereas, some of the other known mechanisms try reducing the emissions from being generated itself. One of such known mechanism is the introduction of oxidant and reductant along with the air-fuel mixture and reducing the temperature of the internal combustion engine during combustion process. Such system and methods help in reducing the NOx and CO emissions being generated after combustion of air-fuel mixture.

[00015] Thus, for reducing the emissions produced a certain amount of oxidant and reductant is injected and mixed with the air-fuel mixture which is to be burnt. Moreover, there is also a need to provide a required amount of oxidant and reductant along with the air-fuel mixture. The desired amount can be calculated on various operating factors of the internal combustion engine. But for calculation and determination of factors as such there is a need to implement a logic controller for controlling the oxidant/reductant injection. Application of such logic controllers makes the system complicated and sophisticated which leads to a higher manufacturing and system cost.

[00016] Typically, the oxidant and reductant is directly injected inside the combustion chamber. Such a mechanism gives very less time to oxidant and reductant to mix with the air-fuel mixture resulting in an inhomogeneous mixture of the oxidant and reductant with the air-fuel mixture. An inhomogeneous mixture of the oxidant and reductant with air-furl mixture might lead to lower reduction of combustion temperature and poor quality of combustion, which might lead to lower reduction of Ox and CO emissions. Furthermore, when the oxidant and reductant is being injected in the combustion chamber the injection nozzle is exposed to higher temperature, wherein such nozzles require higher temperature withstanding material resulting in higher cost of the nozzle.

[00017] However, for such operations as injection of oxidant and reductant there is a need for high pressure pumps working in a range of 1000 D 15000 psi for the injection of oxidant/reductant. Assembly and coupling of such pumps to the internal combustion engine through a camshaft is also known. But, for such operations it is always a high pressure pump which is used and none of these serve the purpose of injection of oxidant and reductant. They are generally implemented for a cooling purpose of the internal combustion engine, and moreover none of such operations help in eliminating the problems discussed above. Furthermore, coupling of pumps onto the camshafts in a known system requires a lot of modifications which needs to be provided to the internal combustion engine and the elements associated to it.

[00018] Therefore, an objective of the present subject matter is to provide a system and method for reducing the emissions being generated in the internal combustion, wherein the system allows a substantial time for the oxidant and reductant to be mixed with the air-fuel mixture. In furtherance to it, the present subject matter provides a system which is low cost, simple eliminating the need of high end logic controllers and high end material for the oxidant and reductant injection nozzle. According to another aspect of the present subject matter, there is no need of implementing a lot of changes to the internal combustion engine or introduction of high pressure pumps.

[00019] Thus, the present subject matter describes a system to obviate the limitations of the prior art by providing a simplified oxidant and reductant injection system for the reduction NOx and CO by reducing combustion temperature. In the present invention oxidant and reductant is injected into the intake pipe which is in the upstream of the combustion chamber. As the pressure in the intake pipe is closer to atmospheric pressure and far lesser than that of the combustion chamber, the present invention does not require high pressure for oxidant and reductant injection. Therefore, the present invention reduces the cost of the pump compared to the previous known arts. In the present invention, oxidant and reductant is injected in the intake pipe using a low pressure positive displacement pump (Hereinafter referred as low discharge pump for the purpose of this invention). According to the present invention, the low discharge pump is operated through the engine speed based on throttle position. According to one aspect of the present invention, the pump is propelled by rotation of at least one of an engine shafts. According to a first embodiment of the present invention, said engine shaft which propels said pump is a camshaft. According to a second embodiment of the present invention, said engine shaft which propels said pump is a crankshaft of the engine. As the rotation of the camshaft and crankshaft depends upon the engine RPM hence, oxidant or reductant flow from the pump depends on the rpm and throttle position and hence is regulated as per the requirements of the engine.

[00020] In an embodiment, a reservoir is provided to the store the oxidant and reductant which is to be supplied. The reservoir is connected to the low discharge pump through an inlet hose to maintain and allow a flow of oxidant and reductant from the reservoir to the pump. The low discharge pump is mounted on the cylinder head of the internal combustion engine being disposed in the cylinder head cover. The inlet hose comprises of an inlet hose reservoir end which is connected to the reservoir and an inlet hose pump end which is attached to an inlet of the low discharge pump. The low discharge pump is operably connected to an engine shaft (camshaft, crankshaft), and rotation of the engine shaft dependant upon engine RPM controls the operation of the low discharge pump. In an embodiment, the low discharge pump is connected to the engine shaft through a pump shaft and a pump drive shaft. The engine shaft comprises of grooves made in it through which the pump drive shaft is connected to it. In furtherance to it, the pump drive shaft is mechanically coupled to the pump shaft through a slot provided in the pump drive shaft. The rotation of the engine shaft is transferred to the low discharge pump through the pump drive shaft and pump shaft. In an embodiment, the low discharge pump is connected to the camshaft, as well as the crankshaft through the same system and mechanism as described above.

[00021] In an embodiment, the low discharge pump comprises of a pump outlet through which the required output of oxidant and reductant is sent. The resultant output of oxidant and reductant is sent from the low discharge pump to an intake pipe carrying the air-fuel mixture, wherein the oxidant and reductant is sprayed in the intake pipe through an oxidant and reduction injection nozzle accommodated in it. The oxidant and reductant is carried from the low discharge pump to the oxidant and reductant injection nozzle through a hose outlet pipe. The hose outlet pipe comprises of an outlet hose pump end connected to the pump outlet of the low discharge pump, and an outlet hose intake pipe end connected to the oxidant and reductant injection nozzle. The oxidant and reductant flows from the low discharge pump to the oxidant and reductant injection nozzle through the hose outlet pipe. In an embodiment, the oxidant and reductant in sprayed through the oxidant and reductant injection nozzle in the intake pipe, wherein itOs cross sectional area is not more than 12 mm square. The air-fuel mixture mixed with the oxidant and reductant goes in the internal combustion engine for combustion. The presence of oxidant and reductant in the air-fuel mixture also helps in reduction of the combustion temperature in the internal combustion engine. Thus, based on the engine speed the required amount of oxidant and reductant is sent through the low discharge pump to the oxidant and reductant injection nozzle, which it sprays into the intake pipe.

[00022] Hence, the present invention does not require any logic controller for operation of the low discharge pump. The invention described herein injects oxidant and reductant into the intake pipe due to which it gets more time to mix with air-fuel mixture before combustion and therefore, prepares a homogeneous mixture. Hence, the present invention increases the probability of higher reduction of combustion temperature due to homogeneous mixture of oxidant and reductant with the air-fuel mixture. Higher reduction of combustion temperature helps higher reduction of NOx and CO emissions. As the oxidant and reductant gets more time to form a homogeneous mixture with air and fuel, the present invention does not require sophisticated system for the control of oxidant and reductant injection and therefore, reduces cost significantly. Due to formation of a homogeneous mixture of oxidant and reductant and air-fuel mixture, the present invention provides secondary benefits in the form of increased power and reduced fuel consumption. As oxidant and reductant injection nozzle of the present invention is exposed to lower temperature of intake pipe, it does not require material with high temperature withstanding capability. The oxidant and reductant injection system as described in the present invention is applicable wherein its cross section is at most 12.0 mm square. In furtherance to it, the preferred pressure of the low discharge pump is less than 5 bar (72.5 psi).

[00023] The aforesaid and other advantages of the present subject matter would be described in greater detail in conjunction with the figures in the following description.

[00024] Arrows provided in the top right corner of each figure depicts direction with respect to the vehicle, wherein an arrow F denotes front direction, an arrow R indicated R direction, an arrow Up denotes upward direction, an arrow Dw denoted downward direction, an arrow Rh denotes right side, an arrow Lh denoted left side, as and where applicable.

[00025] Figure 1 illustrates a side view of an exemplary two-wheeled vehicle, in accordance with an embodiment of present subject matter. The vehicle (10) has a frame assembly (not shown), which acts as the skeleton for bearing the loads. The frame assembly is a mono-tube type frame assembly that includes a head tube, a main tube, a down tube, and a rear tube. The main tube extends rearwardly downward from the head tube. The down tube extends rearward, along a longitudinal axis of the vehicle (10), from a rear portion of the main tube. The rear tube extends in an inclined rearward direction from a rear portion of the down tube towards a rear portion of the vehicle. A handle bar assembly (14) is pivotally disposed through the head tube. The handle bar assembly (14) is connected to a front wheel (3) by one or more front suspension(s) (11). A front fonder (12) is disposed above the front wheel (3) for covering at least a portion of the front wheel (3). A headlamp unit (13) is provided attached and mounted to the frame assembly. A fuel tank (7) is mounted to the main tube of the frame assembly and it is disposed in the front portion F of a step-through space of the frame assembly. In one embodiment of the present invention, a reservoir (6) is placed but not limited to adjacent of the fuel tank (7). In yet another embodiment of the present invention, the reservoir (6) and fuel tank (7) both are covered by a common shroud thus making the reservoir (6) and fuel tank (7) look as one single tank. Further, in yet another embodiment, the reservoir (6) is enveloped by fuel tank (7) when seen from front of the vehicle (10). Furthermore, in yet another embodiment, the reservoir (6) is placed below fuel tank (7) when seen from top of the vehicle (10). An internal combustion engine (4) serving as the power unit is mounted to the down tube. The fuel tank (7) is functionally connected to the internal combustion engine (4). In an embodiment, a piston axis of the engine is horizontal i.e. parallel to a longitudinal axis of the vehicle (10). A rear wheel (2) is rotatably supported by a swing arm of the vehicle (10). One or more rear suspension(s) (15), are connecting the swing arm at an angle, to sustain both the radial and axial forces occurring due to wheel reaction, to the frame assembly. A rear fender (16) is disposed above the rear wheel (2). A seat assembly (1) is disposed at a rear portion R of the step-through space. Further, the seat assembly (1) is positioned above the rear wheel (2).The vehicle (10) is supported by a centre stand mounted to the frame assembly. A floorboard (5) is mounted to the down tube covering at least a portion of the internal combustion engine (4).

[00026] Figure 2 illustrates an enlarged view of an a region around the internal combustion engine (4) of the exemplary two-wheeled vehicle (10) as shown in Fig. 1, in accordance with an embodiment of the present subject matter. In an embodiment, the reservoir (6) is used for storing the oxidant and reductant, wherein oxidant comprises of at least one of water and water-oil emulsion and the reductant comprises of at least one of urea and ammonia. The internal combustion engine (4) comprises of a cylinder head (31) with a cylinder head cover (22) disposed over it. In furtherance to it, the internal combustion engine (4) is provided with an intake pipe (34) through which the air-fuel mixture is sent for combustion. In an embodiment, a low discharge pump (23) is mounted on a side of the internal combustion engine (4) on the cylinder head cover (22). The reservoir (6) is connected to the low discharge pump (23) through an inlet hose (21) to provide a flow of oxidant and reductant stored in the reservoir (6). The inlet hose (21) comprises of an inlet hose reservoir end (21 A) connected to the reservoir (6), and an inlet hose pump end (21B) connected to the low discharge pump (23). The oxidant and reductant flows from the reservoir (6) to the low discharge pump (23) through the inlet hose (21). In an embodiment, output (required amount of oxidant and reductant) from the low discharge pump (23) is sent directly to the intake pipe (34) through a hose outlet pipe (32). An oxidant and reductant injection nozzle (35) is accommodated in the intake pipe (34) through which oxidant and reduction is sprayed into it. The hose outlet pipe (32) comprises of an outlet hose pump end (32 A) connected to the low discharge pump (23) and an outlet hose intake pipe end (32B) connected to the oxidant and reductant injection nozzle (35) accommodated in the intake pipe (34).

[00027] Figure 3 illustrates an enlarged side view of the cylinder head (31) and cylinder head cover (22), in accordance with an embodiment of the present subject matter. In an embodiment, the low discharge pump (23) is mounted on one side of the internal combustion engine (4) on the cylinder head cover (22). The low discharge pump (23) is partially mounted on the cylinder head cover (22) through a first mounting (43), and partially on the cylinder head (31) through a second mounting (42). In an embodiment, the low discharge pump (23) comprises of an inlet (41 A) which is connected to the inlet hose pump end (2 IB) to receive oxidant and reductant from the reservoir. In an embodiment, the low discharge pump (23) comprises of an outlet (41B) through which the output (required amount of oxidant and reductant) is released, and is connected to the outlet hose pump end (32A).

[00028] Figure 4 illustrates an exploded view of the internal combustion engine and the low discharge pump, in accordance with an embodiment of the present subject matter. In an embodiment, the cylinder cover (22) is disposed on a cylinder head top surface (31 A) of the cylinder head. The low discharge pump (23) is disposed in an area between the cylinder block (31) and the cylinder cover (22) operably coupled to a camshaft (50) through a pump shaft (51) and a pump drive shaft (52). In an embodiment, the cylinder cover (22) comprises of a cylinder head cover protrusion (54) enabled to provide a stable mounting of the cylinder head cover (22) over the cylinder block (31). The cylinder head cover protrusion (54) comprises of a housing (53) enabled to accommodate the pump drive shaft (52). In an embodiment, a cylinder head cover seal (59) is provided tightly pressed in between the cylinder head cover (22) and the cylinder head top surface (31 A) to avoid any leakage of oil.

[00029] Figure 5 illustrates an exploded view of the low discharge pump (23) and the camshaft (50), in accordance with an embodiment of the present subject matter. In an embodiment, the present subject matter comprising of pump drive shaft (52) is fitted inside a threaded groove made within the camshaft (50). Thus, through this mechanism the rotation of the camshaft (50) is transferred to the pump drive shaft (52). In furtherance to it, the pump drive shaft (52) is further provided with a slot into which pump shaft (51) is located to provide a mechanical coupling within them, The mechanical coupling described above allows the rotational motion of the camshaft (50) to be transferred to the pump shaft (51) through the pump drive shaft (52). Once pump shaft (51) of low discharge pump (23) is rotated, oxidant and reductant is pumped from the reservoir (6) to the intake pipe (34). The oxidant and reductant flow rate from reservoir (6) to the intake pipe (34) depends upon the camshaft (50) rotational speed which is further a function of throttle position and rotation. Hence, the low discharge pump (23) can be optimized to provide oxidant and reductant flow rate based upon throttle position and rotation. In furtherance to it, the camshaft (50) is provided with cam lobes (40) which help in opening and closing of exhaust and inlet valves. In an embodiment, the pump drive shaft (52) is mechanically coupled to camshaft (50) preferably through but not limited to a thread mechanism. Further, the pump shaft (51) is mechanically coupled to the pump drive shaft (52) preferably through but not limited to a slot and key mechanism wherein the slot is made inside pump drive shaft (52) and pump shaft (51) is provided with a key shaped profile to be inserted inside said slot.

[00030] Figure 6 illustrates a perspective of the internal combustion engine (4) of the exemplary two-wheeled vehicle (10) shown in Fig. 1, in accordance with an embodiment of the present subject matter. In an embodiment, the low discharge pump (23) is mechanically coupled to a crankshaft (72) of the internal combustion engine (4). In a typical internal combustion engine for a two-wheeled vehicle, the crankshaft (72) rotates at a higher angular speed as compared to camshaft (50) (approximately two times higher rpm). Hence, depending upon engine size in yet another embodiment, the low discharge pump (23) is mounted on the crankshaft (72). The crankshaft (72) is coupled to a pump drive shaft (52) through thread provided inside. The pump drive shaft (52) and the pump shaft (51) are mechanically coupled to each other through a key and slot mechanism. In an embodiment, the same mechanism is repeated as described above to provide a required amount of oxidant and reductant within the intake pipe (34) through oxidant and reductant injection nozzle (35), even when the low discharge pump (23) is coupled to the crankshaft (72).

[00031] Thus, the present subject matter provides an internal combustion engine (4) with an efficient NOx reduction mechanism which supplies oxidant and reductant to be mixed with the air-fuel mixture before combustion. The required amount of oxidant and reductant dependant upon engine speed and running condition is supplied in the intake pipe (34) to be mixed with the air-fuel mixture. By allowing the oxidant and reductant to be sprayed in the intake pipe (34), enough time is given for it to mix and from a homogenous mixture with air-fuel mixture. As per the present subject matter, the low discharge pump (23) is mounted on the internal combustion engine (4) and coupled to engine shaft (50, 72), such that it is operated through engine speed (RPM) and throttle position. The intake pipe (34) is provided with oxidant and reductant injection nozzle (35) with a cross sectional area of less than 12 mm square to enable an efficient spray of oxidant and reductant into the intake pipe (34). Thus, the present subject matter eliminates the need of logic controllers to supply exact required amount of oxidant and reductant, and neither does it requires a different expensive material for the oxidant and reductant injection nozzle.

[00032] It is to be understood that the aspects of the embodiments are not necessarily limited to the features described herein. Many modifications and variations of the present subject matter are possible in the light of above disclosure. Therefore, within the scope of claims of the present subject matter, the present disclosure may be practiced other than as specifically described.

Claims

I/WE Claim:

1. A system for reducing NOx being generated by an internal combustion engine (4), said system comprising:

an engine shaft (50, 72) rotating at a speed proportional to said internal combustion engine (4) speed;

an intake pipe (34) enabling a passage for air-fuel mixture into said internal combustion engine (4); and

a low discharge pump (23) being operated through engine speed and coupled to said engine shaft (50, 72) to provide a controlled spray of oxidant and reductant into said intake pipe (34) through an oxidant and reductant injection nozzle (35).

2. The system as claimed in claim 1 , wherein said oxidant and reductant to be

sprayed in said intake pipe (34) is stored in a reservoir (6).

3. The system as claimed in claim 1, wherein said reservoir (6) is connected to said low discharge pump (23) through an inlet hose (21) with ends (21A, 21B) connected to said reservoir (6) and said low discharge pump (23) enabling a passage for flow of said oxidant and reductant therein.

4. The system as claimed in claim 1, wherein said low discharge pump (23) is

operably connected to said engine shaft (50, 72) through a pump shaft (51) and a pump drive shaft (52), wherein said pump drive shaft (52) is connected to said engine shaft (50, 72) through groove made therein, and wherein said pump shaft (51) is mechanically coupled to said pump drive shaft (52) through a slot provided therein.

5. The system as claimed in claim 1, wherein said low discharge pump (23)

comprises of a hose outlet pipe (32) attached therein to provide a passage for flow of said oxidant and reductant to said intake pipe (34) based on said engine speed.

6. The system as claimed in claim 1, wherein said hose outlet pipe (32) comprises of an outlet hose intake pipe end (32B) connected to said oxidant and reductant injection nozzle (35) to provide required oxidant and reductant thereto.

7. The system as claimed in claim 1, wherein said oxidant and reductant injection nozzle (35) comprising of a cross sectional area not more than 12 mm square is accommodated in said intake pipe (34) to spray said oxidant and reductant therein.

8. The system as claimed in claim 1, wherein said low discharge pump (23) is

mechanically coupled to said engine shaft (50, 72) comprising of a camshaft (50).

9. The system as claimed in claim 1, wherein said low discharge pump (23) is

mechanically coupled to said engine shaft (50, 72) comprising of a crankshaft (72).

10. A method for reducing NOx being generated by an internal combustion engine (4), sad method comprising:

receiving flow of oxidant and reductant in a low discharge pump (23), wherein said low discharge pump (23) is operably connected to an engine shaft (50, 72);

spraying said oxidant and reductant into said intake pipe (34) through an oxidant and reductant injection nozzle (35); and

allowing mixing of said oxidant and reductant with an air-fuel mixture flowing through said intake pipe (34), wherein flow of said oxidant and reductant into said intake pipe (34) including said spraying is controlled by said low discharge pump (23), said low discharge pump (23) being operated at engine speed.

11. The method as claimed in claim 10, wherein said receiving flow of said oxidant and reductant to said low discharge pump (23) is accomplished by providing an inlet hose (21) form a reservoir (6) used to store said oxidant and reductant to said low discharge pump (23).

12. The method as claimed in claim 10, wherein said spraying comprises allowing flow of said oxidant and reductant from said low discharge pump (23) to said oxidant and reductant injection nozzle (35) through a hose outlet pipe (32).