DESC:FIELD OF INVENTION
[0001] The present invention relates to an internal combustion engine and more particularly to a emission control system for the internal combustion engine.
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 emission production 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] In furtherance to it, the above system also requires a logic controller for controlling the oxidant/reductant injection thus making the overall 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.
[0004] Furthermore, one of the other critical aspects is the timing of injection of the oxidant/ reductant. There are moments and phases within the operation of the internal combustion engine when there is no need of oxidant/reductant to be injected. The temperature of the system itself is either too low or the amount of NOx and CO being produced is comparatively less, which does not requires any extra oxidant/reductant. Thus, maintaining such an injection of oxidant/reductant depending upon the engine conditions is one of the other critical aspects which need to be taken care of.
[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 a temperature based valve in a closed condition in accordance with an embodiment of the present subject matter.
[00012] Figure 7 illustrates a perspective view of the temperature based valve in an open condition in accordance with an embodiment of the present subject matter.
[00013] Figure 8 illustrates a perspective view of a vacuum based valve in a closed condition in accordance with an embodiment of the present subject matter.
[00014] Figure 9 illustrates a perspective view of the vacuum based valve in an open condition in accordance with an embodiment of the present subject matter.
[00015] Figure 9(a) illustrates an enlarged view of space and clearance created in the vacuum based valve while being operated in an open condition in accordance with an embodiment of the present subject matter.
[00016] Figure 10 also illustrates a perspective view of the vacuum based valve in a closed condition in accordance with an embodiment of the present subject matter.
DETAILED DESCRIPTION
[00017] 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 head where the combustion occurs to provide the required power to 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.
[00018] 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 pre-determined 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 is 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.
[00019] 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 a muffler assembly 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.
[00020] 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. 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.
[00021] 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 NOx 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.
[00022] Generally, for operations as such a high pressure pump working in a range of 1000 – 15000 psi is required. Assembly and coupling of such pumps to the internal combustion engine through a camshaft is also known. However, they are generally implemented for a cooling purpose of the internal combustion engine, and moreover none of such operations help in eliminating the emission reduction problems discussed above. Furthermore, to solve problems as such disposing a lower displacement pump working along with the rotation of either of the shafts of the internal combustion engine was implemented. Such pumps work to inject the required oxidant/reductant in the intake pipe of the internal combustion engine to reduce the emissions being generated. Such an arrangement did not require any logic controllers or a high range working pump. However, the present discussed state of art was still unable to solve some of the critical issues. Such issues included the timing of injection of the oxidant/reductant, or the perfect condition of the internal combustion engine during which the oxidant/reductant should be injected. To be more precise, if we take the above example the pump circulating the oxidant/reductant was functioning on the rotation of the camshaft/crankshaft. Meaning, whenever the shaft would rotate the pump would work and inject the oxidant/reductant into the intake pipe. It also meant that as soon as the throttle is opened there would be injection of oxidant/reductant into the intake pipe. Thus, an uncontrolled flow of oxidant/reductant was provided into the intake pipe without any consideration to the timing and running condition of the internal combustion engine. Thus, the current state still faces problems which need to be solved.
[00023] Therefore, an objective of the present subject matter is to provide an assembly for reducing the emissions being generated in the internal combustion. In furtherance to it, the present subject matter provides a system which is cost effective, simple, eliminates the need of high end logic controllers, high range pumps and high end material for the oxidant and reductant injection nozzle. According to another aspect of the present subject matter, the emission reduction technique is refined based on the engine running conditions for a better result, wherein such an objective is met without implementation of any high end logic controllers. Thus, the present subject matter is cost effective and easy to maintain as well.
[00024] 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 of NOx and CO by reducing the combustion temperature. In accordance with the present subject matter, the oxidant and reductant is injected into the intake pipe which is in the upstream of the combustion chamber. 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 one aspect of the present invention, the pump is propelled by rotation of at least one of an engine shafts. Thus, the oxidant/reductant is pumped and injected in the intake pipe based on the throttle opening and engine speed. In addition to it, further technical advancement is done by controlling the flow and injection of the oxidant/reductant based on engine running parameters. This helps in maintaining the injection of oxidant/reductant into the intake pipe only when there is a need of it, which is calculated based on engine running conditions. Thus, cylinder block temperature and intake pipe vacuum is taken as input to control the amount of injection of oxidant/reductant through a temperature based control valve and vacuum based control valve arranged in series. Thus, the oxidant/reductant being supplied into the intake pipe is controlled through the cylinder block temperature and intake pipe vacuum which are the parameters of engine running condition.
[00025] In an embodiment, a reservoir is provided to the store the oxidant and reductant which is to be supplied. The reservoir is connected to a low discharge pump through an inlet hose to maintain and allow a flow of oxidant/reductant (The system can be used either for oxidant and reductant based on the vehicle and engine requirements. Hence for the purposes of this application the term oxidant/reductant is interchangeably used as either of oxidant and reductant, wherein either of them used means the same thing) from the reservoir to the pump. The low discharge pump is mounted on a 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.
[00026] In an embodiment, the low discharge pump comprises of a pump outlet through which the required output of oxidant is sent. The resultant output of oxidant from the low discharge pump travels through an output hose to the temperature based control valve and vacuum based control valve, after which it is sprayed into the intake pipe through an oxidant/reductant injection nozzle. As per an embodiment of the present subject matter, said temperature based control valve and said vacuum based control valve are arranged in series in between the low discharge pump and the intake pipe. As the rotation of the camshaft and crankshaft depends upon the engine RPM, oxidant or reductant flow from the pump depends on the RPM and throttle position which is further controlled and regulated by the temperature control valve and the vacuum based control valve. The temperature control valve and the vacuum based control valves function as ON/OFF valves. The temperature based control valve opens and allows flow of oxidant once the cylinder block temperature reaches a pre-determined temperature. The pre-determined temperature according to one embodiment of the present invention is 60ºC. The vacuum based control valve opens and allows flow of oxidant / reductant once the intake vacuum reaches a pre-determined vacuum. The pre-determined vacuum according to one embodiment of the present invention lies within a range of 240 mbar- 70 mbar. The vacuum based control valve starts opening or gets switched ON at a pressure of 250 mbar and gets switched off at a pressure of 50 mbar. Thus, only when both the valves are in an ON condition and open, the oxidant being pumped by the low discharge pump can be injected into the intake pipe. Therefore, through the present subject matter the oxidant is supplied into the intake pipe depending upon the engine running conditions and not at any moment as soon as the internal combustion is working and the throttle is opened.
[00027] Hence, the present subject matte enables injection of oxidant directly into the intake pipe without any need of extra logic controllers or high end pumps, wherein the injection is being controlled directly through the engine running conditions. As per the present subject matter, the oxidant gets more time to mix with air-fuel mixture before combustion since it is injected directly into the intake pipe 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 with the air-fuel mixture. Higher reduction of combustion temperature helps higher reduction of NOx and CO emissions. Due to formation of a homogeneous mixture of oxidant and air-fuel mixture, the present invention provides secondary benefits in the form of increased power and reduced fuel consumption. As oxidant/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. Since, the injection of oxidant is additionally controlled by the engine running conditions, the oxidant is sprayed only when it is required and the timing is correct. Hence, the results and emission reduction achieved is improved. In addition to it, the current results are achieved without any use of extra sensors or logic controllers. Thus, the system is cost effective and easy to maintain as well.
[00028] 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.
[00029] 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.
[00030] Figure 1 illustrates a side view of an exemplary two-wheeled vehicle (10), 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).
[00031] Figure 2 illustrates an enlarged view of 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, 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 stored in the reservoir (6). The inlet hose (21) comprises of an inlet hose reservoir end (21A) connected to the reservoir (6), and an inlet hose pump end (21B) connected to the low discharge pump (23). The oxidant flows from the reservoir (6) to the low discharge pump (23) through the inlet hose (21). In an embodiment, output (required amount of oxidant) from the low discharge pump (23) is sent to the intake pipe (34) through an outlet hose. An oxidant/reductant injection nozzle (35) is accommodated in the intake pipe (34) through which oxidant and reduction is sprayed into it. However, as per the present subject matter, a temperature based valve (36) and vacuum based valve (37) are disposed in series in the flow path of oxidant between low discharge pump (23) and intake pipe (34). In an embodiment, a first outlet hose (32A) connects the low discharge pump (23) and temperature based valve (36). The oxidant flows from the low discharge pump (23) to the temperature based valve (36), and once it is on the oxidant flows from the temperature based valve (36) to the vacuum based valve (37) through a second outlet hose (32). A third outlet hose (32B) connects the vacuum based pump (37) and the intake pipe (34). Once the vacuum based pump (37) is ON the oxidant flows through the second end (32B) of the hose outlet pipe (32) to the oxidant/reductant injection nozzle (35) accommodate in the intake pipe (34) through which it is sprayed therein. Thus, the present assembly enables a flow and injection of oxidant into the intake pipe (34) based on engine running conditions.
[00032] 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 (41A) which is connected to the inlet hose pump end (21B) to receive oxidant from the reservoir. In an embodiment, the low discharge pump (23) comprises of an outlet (41B) through which the output (required amount of oxidant) is released, and flows to the temperature based valve (36) through first outlet hose (32A).
[00033] Figure 4 illustrates an exploded view of the internal combustion engine (4) and the low discharge pump (23), 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 (31A) 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 (31A) to avoid any leakage of oil. Thus, a rotation of camshaft (50) rotates the pump drive shaft (52) which further rotates the pump shaft (51) of the low discharge pump (23). Once pump shaft (51) of the low discharge pump (23) is rotated, oxidant is pumped from reservoir (6). The fluid flow rate from reservoir (6) to the intake pipe (34) depends upon the camshaft rotational speed which is further a function of throttle rotation and the engine running conditions (i.e. the operation of temperature based valve (36) and vacuum based valve (37)). Hence, the present subject matter can be optimized to provide oxidant flow rate based upon throttle rotation and engine running condition.
[00034] 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 is pumped from the reservoir (6). The oxidant flow rate from reservoir (6) to the intake pipe (34) depends upon the camshaft (50) rotational speed and an ON/OFF condition of the temperature based valve (36) and the vacuum based valve (37). 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. In an embodiment, the low discharge pump (23) can be operably connected to either of the camshaft (50) and crankshaft of the internal combustion engine (4). However, for the purposes of this application the low discharge pump (23) is taken to be connected to the camshaft (50).
[00035] Figure 6 illustrates a perspective of the temperature based valve (36) in a closed condition in accordance with an embodiment of the present subject matter. In an embodiment the temperature based valve (36) is mounted on the cylinder head (31) of the internal combustion engine (4) through a first stud (93) and a second stud (94). Furthermore, the temperature based valve (36) comprises of an oxidant/reductant inlet (90) through which the oxidant enters after being pumped by the low discharge pump (23). The oxidant/reductant inlet (90) is connected to the low discharge pump (23) by the first outlet hose (32A). In an embodiment, the temperature based valve (36) comprises of an oxidant/reductant outlet (97) through which the oxidant flows out when the temperature based valve (36) is open or in an ON condition. The oxidant/reductant outlet (97) is connected to the vacuum based valve (37) through the second outlet hose (32). Furthermore, the temperature based valve (36) also comprises of a spring (91) over which a wax fill (92) and valve stem (95) is mounted. Moreover, a cavity (96) is also provided which in an OFF condition of the temperature based valve (36) is blocked by the valve stem (95). In an ON condition of the temperature based valve (36) the oxidant flows through the cavity (96) after which it passes through the oxidant/reductant outlet (97) to leave the temperature based valve (36). However, in an OFF condition a head portion (98) of the valve stem (95) closes the cavity (96) such that no oxidant can flow past through it and leave the temperature based valve (36). Thus, as per the present subject matter, oxidant enters the temperature based valve (36) through oxidant inlet (90). However, it still trapped within the temperature based valve (36), since the cavity (96) which allows a passage for the oxidant to flow is blocked by the head portion (98) of the valve stem (95). Hence, in an OFF condition the temperature based valve (36) is in a closed not allowing the oxidant to leave the system.
[00036] Figure 7 illustrates a perspective view of the temperature based valve (36) in an open/ON condition in accordance with an embodiment of the present subject matter. In an embodiment, the temperature based valve (36) is mounted on the cylinder head (31) of the internal combustion engine. Hence the functioning of the temperature based valve (36) (i.e. opening and closing) is based on the temperature of the cylinder head (31). The temperature based valve (36) starts opening (ON condition) only after the temperature of the cylinder head has reached a pre-determined temperature, i.e. 60 deg. Celsius or above. When said pre-determined temperature is reached, the wax fill (92) starts to expand which pushes the valve stem (95) down along with the compression of the spring (91). With such a downward motion of the valve stem (95) the head portion (98) formed on top of it also moves down, and hence opens up the cavity (96) to allow a passage for the oxidant to flow. Hence, when the valve stem (95) is pushed down because of the expansion of the wax seal (92) the cavity (96) is no more blocked by its head portion (98), which leads into opening of the cavity (96) allowing the oxidant to flow. Thus, once the cavity (96) is open it allows the oxidant to flow and leave the temperature based valve (36) through oxidant/reductant outlet (97).
[00037] Figure 8 illustrates a perspective view of the vacuum based valve (37) in a closed condition in accordance with an embodiment of the present subject matter. In an embodiment, the vacuum based valve (37) operates in three phases of engine running condition, i.e. when the internal combustion engine (4) has just been switched on, secondly when the internal combustion engine (4) has crossed an idle speed and lastly when the internal combustion engine (4) is running on a high speed full throttle condition. The vacuum based valve (37) operates and switches ON and OFF on these three conditions only because the requirement for oxidant in these three phases is completely different. Thus, when the internal combustion engine (4) is just switched ON the vacuum based valve (37) would be closed (i.e. OFF) not allowing the oxidant to flow. When the internal combustion engine (4) has crossed an idle speed the vacuum based valve (37) is open (i.e. ON) allowing the oxidant to flow. However, when the internal combustion engine (4) is operating at a high speed and on a full throttle condition the vacuum based valve (37) is again switched OFF not allowing the oxidant to flow.
[00038] Such an operational condition of the vacuum based valve (37) is decided because the emission being generated is dependent on the engine running condition, and the oxidant needs to be injected accordingly. To be precise, when the internal combustion engine (4) is just switched ON the temperature is already very low and it takes time for the engine to heat up. Hence, there is no requirement for the oxidant in the internal combustion engine (4) at that time. Moreover, when the internal combustion engine (4) has crosses a certain idle speed, the temperature and working of the internal combustion engine (4) has already built up, there is an optimum amount of air-fuel ration resulting in a stable combustion, meaning emissions are being produced at a substantial amount. Hence, there is a requirement of oxidant at that moment, so the vacuum based valve (37) is switched ON allowing the oxidant to flow. Lastly, when the internal combustion engine (4) is running at high speed and at a full throttle there is a high amount of air-fuel ratio present, meaning the emissions being produced is less and there is no requirement of oxidant at that moment. Hence, the vacuum based valve (37) is closed (i.e. OFF) at a high speed running condition not allowing the oxidant to flow. Thus, the vacuum pressure within the intake pipe varies during all the three phases of engine running condition described above. Based on such pressure readings of the intake pipe only the vacuum based valves (37) operates, i.e. opens and closes (ON/OFF). The vacuum based valve (37) starts opening at intake pipe (34) pressure reading of 250mbar, when the internal combustion engine (4) has crossed the idling speed. Furthermore, the vacuum based valve (37) starts closing at intake pipe (34) pressure reading of 100 mbar and fully closes at an intake pipe pressure reading of 50mbar, i.e. when the internal combustion engine (4) is running at a high speed.
[00039] Hence, the oxidant flows into the intake pipe (34) only when all the above conditions with respect to the temperature based valve (36) and vacuum based valve (37) are satisfied. The oxidant flows out of the temperature based valve (36) only when the cylinder head temperature is above 60 deg. Celsius, i.e. when there is a sufficient combustion within the internal combustion engine (4). After which, the oxidant flows into the vacuum based valve (37) which allows the oxidant to flow into the intake pipe (34) depending upon the vacuum pressure within the intake pipe (34), which also depends upon the running engine speed. Thus, the injection of oxidant into the intake pipe (34) is dependent upon the cylinder head temperature (31) and vacuum pressure within the intake pipe (engine running conditions).
[00040] In accordance to it, Figure 8 illustrates a perspective view of the vacuum based valve (37) in a closed condition when the internal combustion engine has just been switched ON. The vacuum based valve (37) comprises of a vacuum valve inlet (101) through which oxidant enters in, while flowing through the outlet hose pipe (32). Furthermore, the vacuum based valve (37) comprises of a vacuum valve spring (113), over which a float (114) is attached thereto. In an embodiment, the vacuum based valve (37) comprises of a vacuum valve outlet (102) through which the oxidant flows out of the system. A seal (111) is disposed between the vacuum valve outlet (101) and vacuum valve inlet (102) in the oxidant passage of the vacuum based valve (37), wherein the float (114) is disposed within the seal (111). In an embodiment, the seal (111) comprises of a first end (115) and a second end (112). As per the present subject matter, the vacuum based valve (37) operates through the movement of the vacuum valve spring (113). When there is vacuum pressure difference within the intake pipe (34) it pulls the vacuum valve spring (113), and the float (114) attached to it also moves along with it to allow the flow of oxidant. In an OFF condition of the vacuum based valve (37), during the phase when the internal combustion engine (4) has just been switched ON and there isn’t much vacuum pressure difference there is no pulling force experienced by the vacuum spring (113). Thus, in such a condition the float (114) lies undisturbed, i.e. the periphery of the float (114) rests on the first end (115) of the seal (111), such that the whole area is blocked and there is no space for the oxidant to flow. Thus, through such a mechanism the float (114) rests on the first end (115) of the seal (111) not allowing the oxidant to flow.
[00041] Figure 9 illustrates a perspective view of the vacuum based valve (37) in an open condition in accordance with an embodiment of the present subject matter. In an embodiment, after a certain running of the internal combustion engine (4) when it is running above the idle speed, certain amount of vacuum pressure is developed in the intake pipe (34). Due to this vacuum pressure, the vacuum valve spring (113) experiences a pull which leads to its compression. As the vacuum valve spring (113) starts getting compressed, the float (114) attached to it also starts getting lifted from the first end (115) of the seal (111). Hence, due to such a compression of the vacuum valve spring (113) the float (114) is lifted and gets shifted to lie between the first end (115) and second end (112) of the seal. In an embodiment, when the float (114) is lifted and shifted upwards, a certain clearance is created between the seal (111) and periphery of the float (114). The clearance and gap created allows the oxidant to flow around it to leave the vacuum based valve (37) through the vacuum valve outlet (101). Thus, the vacuum based valve (37) is said to be ON (open) when the float is lifted upwards to lie between the first end (115) and second end (112) of the seal, such that oxidant is allowed to flow past through the clearance and space created between the seal (111) and periphery of the float (114). Figure 9(a) illustrates the clearance and space created between the seal (111) and the float (114) when the vacuum based valve (37) is an ON condition. The oxidant flows around the clearance and space shown to leave the vacuum based valve (37) and enter the intake pipe (34).
[00042] Figure 10 illustrates a perspective view of the vacuum based valve (37) in a closed condition in accordance with an embodiment of the present subject matter. In an embodiment, vacuum pressure within the intake pipe (34) further changes as the speed of the internal combustion engine (4) increases. This leads to a further increase in the attraction (pulling force) being experienced by the vacuum valve spring (113). Hence, as the vacuum pressure changes within the intake pipe (34) with the increase in speed, the vacuum valve spring (113) is further pulled which results in its full compression. Moreover, when the vacuum valve spring (113) is fully compressed, the float (114) attached to it is further lifted, such that in a full compression of the vacuum spring (113) the float (114) further moves to rest on the second end (112) of the seal. Hence, now the periphery of the float (114) rests on the second end (112) such that the whole area is blocked and there is no space for the oxidant to flow. This means that the vacuum based valve (37) is again closed (OFF) when the speed of the vehicle increases and the vacuum pressure within the intake pipe (34) changes. Thus, this means that there is no flow of oxidant into the intake pipe (34) when the internal combustion engine (4) is operating at a high speed. This is because the amount of NOx being generated at that moment is less since the air fuel ratio during such operations is high. Thus, the vacuum based valve (37) operates and allows the oxidant to flow based on the vacuum pressure within the intake pipe (34) which is dependent upon the running speed. In an embodiment, the vacuum based valve (37) actually allows the oxidant to enter the intake pipe only when the internal combustion engine (4) is operating at a speed just above the idle speed, and not when it has just been turned ON or is being operated at high speeds.
[00043] Thus, the present subject matter presents a system for reducing the NOx being generated by the internal combustion engine (4) by injecting oxidant into the intake pipe (34), wherein the oxidant is being pumped with respect to rotation of shafts (50) of the internal combustion engine (4) and throttle opening. Furthermore, the oxidant being injected within the intake pipe (34) is dependent upon the running conditions of the vehicle (10) and internal combustion engine (4). Hence, a temperature based valve (36) and a vacuum based valve (37) are provided which allow the oxidant to be injected within the intake pipe (34) based on engine temperature and vacuum pressure being developed within the intake pipe (34).
[00044] 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:We Claim:
1. A system for reducing emission being generated by an internal combustion engine (4), said system comprising:
an engine shaft (50) rotating at a speed proportional to said internal combustion engine (4) speed;
a cylinder head (34) disposed over said internal combustion engine (4) enabling a space for combustion of air-fuel mixture entering;
an intake pipe (34) enabling a passage for air-fuel mixture to enter within said internal combustion engine (4); and
a low discharge pump (23) being operated through engine speed and coupled to said engine shaft (50) to provide a controlled spray of oxidant/reductant into said intake pipe (34) through an oxidant/reductant injection nozzle (35), wherein said spray of oxidant/reductant is controlled based on at least one of a pre-determined range of vacuum pressure inside said intake pipe (34) and a pre-determined temperature of said cylinder head (31).
2. The system as claimed in claim 1, wherein said controlled spray of oxidant/reductant into said intake pipe (34) is achieved through at least one of a temperature based valve (36) connected in series with a vacuum based valve (37).
3. The system as claimed in claim 1, wherein said oxidant/reductant is stored in a reservoir (6) which is connected to said low discharge pump (23) through an inlet hose (21), wherein said inlet hose (21) provides a passage flow for said oxidant/reductant from said reservoir (6) to said low discharge pump (23).
4. The system as claimed in claim 1, wherein said low discharge pump (23) comprises of an outlet (41B) being connected to said temperature based valve (36), wherein said oxidant/reductant being pumped by said low discharge pump (23) flows from said outlet (41B) to said temperature based valve (36) through a first outlet hose (32A) connecting both of them.
5. The system as claimed in claim 2, wherein said temperature based valve (36) and said vacuum based valve (37) are connected in series through a second outlet hose (32).
6. The system as claimed in claim 2, wherein said temperature based valve (36) opens at said pre-determined temperature of said cylinder head (31) allowing said oxidant/reductant to flow to said vacuum based valve (37) through said second outlet hose (32).
7. The system as claimed in claim 1, wherein said pre-determined temperature of said cylinder head (31) at which said temperature based valve (36) opens is 60 degrees Celsius.
8. The system as claimed in claim 2, wherein said vacuum based valve (37) comprises of a vacuum valve outlet (102) connected to said oxidant/reductant injection nozzle (35) through a third outlet hose (32B), wherein said oxidant/reductant flows form said vacuum based valve (37) to said oxidant/reductant injection nozzle (35) through said third outlet hose (32B) to get sprayed within said intake pipe (34).
9. The system as claimed in claim 2, wherein said vacuum based valve (37) opens and closes at said pre-determined range of vacuum pressure inside said intake pipe (34) allowing said oxidant/reductant to flow from said vacuum based valve (37) to said intake pipe (34).
10. The system as claimed in claim 1, wherein said pre-determined range of vacuum pressure inside said intake pipe (34) at which said vacuum based valve (37) starts opening lies at 250mbar and below, and said pre-determined range of vacuum pressure inside said intake pipe (34) at which said vacuum based valve (37) closes lies below 50 mbar.