FIELD OF INVENTION

[0001] The present subject matter relates generally to an evaporative emission control apparatus for an automobile and more particularly to a carburetor for an internal combustion engine.

BACKGROUND OF INVENTION

[0002] Generally, a vehicle comprises of an internal combustion engine acting as the power unit of the vehicle. The internal combustion engine is functionally connected to a rear wheel of a vehicle to provide a motion to the vehicle. Typically, the internal combustion engine is supplied with an air-fuel mixture which is burnt to supply the required power to the vehicle.

[0003] Typically, the vehicle is provided with a fuel tank/reservoir which stores the fuel to be supplied to the vehicle. However, some of the fuel stored escapes in form of vapors. Hence, to absorb such fuel vapors the vehicle is provided with a canister which absorbs it and later recirculates it for combustion. Mostly, the vehicle is provided with a carburetor which mixes the air and fuel and sends it to the internal combustion engine for combustion. Thus, the canister or any other evaporative emission control apparatus used in place of it absorbs and recirculates the fuel to the carburetor, wherein the carburetor sends it to the internal combustion engine. In this way the fuel vapors are not wasted and neither is transmitted to the atmosphere which might be harmful.

[0004] However, the moments at which the fuel vapors need to be sent are also important. It cannot be sent directly when the internal combustion engine has started. The ideal time it should be sent is when the engine has cranked. Hence, the instant and timing at which the fuel vapors are sent is also important. Thus, it is highly important to redirect and circulate the fuel vapors to the carburetor or intake system. In addition to it, the timing and instant at which it is to be sent and redirected is even more critical, which the present subject matter aims for. BRIEF DESCRIPTION OF DRAWINGS

[0005] The detailed description of the present subject matter is described with reference to the accompanying figures. Same numbers are used throughout the drawings to reference like features and components.

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

[0007] Figure 2 illustrates a plain enlarged side view of an internal combustion engine of the exemplary two-wheeled vehicle in accordance with an embodiment of the present subject matter.

[0008] Figure 3 illustrates a perspective view of a carburetor in accordance with an embodiment of the present subject matter.

[0009] Figure 4 illustrates a top view of the carburetor in accordance with an embodiment of the present subject matter.

[00010] Figure 5 illustrates a perspective view of a piston valve in accordance with an embodiment of the present subject matter.

[00011] Figure 6 illustrates a cross sectional view of the carburetor in a running condition of the internal combustion engine in accordance with an embodiment of the present subject matter.

[00012] Figure 7 illustrates a cross sectional view of the carburetor in an idle condition of the internal combustion engine in accordance with an embodiment of the present subject matter.

DETAILED DESCRIPTION

[00013] Generally, the internal combustion engine which is the power unit of the vehicle 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 the 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.

[00014] However, the vehicle faces a problem of fuel evaporation which needs to be taken care of to avoid pollution arising out the evaporative emission. A certain amount of fuel stored evaporates which is harmful to the environment as well. Thus, the fuel vapors being transmitted need to be controlled and recirculated within the intake system of the vehicle. Therefore, in order to control evaporative emissions, an evaporative emission control device, commonly referred to as canister is being increasingly used. Use of a canister aids in controlling evaporative emissions. The canister also enables reuse of the evaporated fuel without releasing it to the atmosphere. [00015] Moreover, since the evaporative emissions are nothing but fuel vapors which can be further burnt and fed to the intake system of the engine as fuel charge, it is important to ensure that evaporative vapors generated from the fuel tank are properly routed to the intake system of the vehicle and used as fuel. Through such a measure the release of the evaporative emission in the atmosphere can also be avoided. Directing evaporative emissions during starting the engine is not desirable. Once engine has cranked, then introduction of evaporative emissions into the engine is desirable. Hence, it becomes equally important the instances in which the evaporative emissions are being sent to the intake system of the engine. Hence, there is a need to create an effective system for evaporative fuel emissions introduction into the intake system of the engine. [00016] Some of the known arts provide a mechanism to control the fuel vapors redirected to the carburetor of the vehicle. Such known prior arts implement a use of additional screws which controls the opening and closing of valves, allowing the fuel vapors to be sent at a particular time through suitable purge control valve. However, such known arts use a lot of additional elements and parts which increases the manufacturing cost, and the serviceably becomes hard. In addition to it, the construction and configuration of the intake system needs to alter to adjust such mechanism making it more complex. [00017] Therefore, an objective of the present subject matter is to provide a system for reintroduction of evaporative fuel vapors into the intake system and carburetor depending upon the running condition of the vehicle. In addition to it, the present subject matter enables the above described process without any requirement of extra elements to be added. [00018] In an embodiment, the vehicle is provided with an internal combustion engine connected to a carburetor. The carburetor is provided with an empty slot on its body which channelizes the evaporative fuel emission at appropriate instances during normal operation of the internal combustion through the slot disposed within the body of the carburetor. According to requirements, the appropriate instances may include an instance when the throttle has been operated beyond a pre- determined rotation within zero to hundred percentage of allowed operation of the throttle.

[00019] An aspirator is an instrument or apparatus for aspirating fluid from a vessel or cavity and this aspiration principle is used in the carburetor. A carburetor has a piston valve which functions on the venturi effect and gets lifted upwards to suck fuel from a fuel reservoir functioning on an aspirator principle. The piston valve comprises of a cut out portion and a grove. The cut out portion is used to adjust an initial lift of the float to calibrate the carburetor for idle fuel flow during idling conditions. The grove is used as a guide to insert the piston valve in a pre-determined manner.

[00020] According to one embodiment of the present invention, a through slot is formed on the carburetor body inside the passage where the piston valve is inserted. This passage communicates with a purge control valve which purges the evaporative fuel emission into the carburetor. In an embodiment, the evaporative fuel emissions are entering through a hole disposed on the through slot. According to one embodiment of the present invention, the evaporative emission hole is above said cut out portion on the piston valve during idling condition. Under this condition, the evaporative emission vapors travel through the slot on the carburetor body and reach the throttle body outlet side. Such an operation and arrangement is possible in a throttle closed condition. In yet another embodiment of the present invention, the emission hole is below said cut put portion of the piston valve during a throttle open condition. Under this condition, the evaporative emission vapors are directly released into the throttle body outlet through said hole in the carburetor body. Hence, at least two passages are formed inside the carburetor for effective propagation of evaporative emissions.

[00021] Hence according to the present invention a passage is provided in the carburetor body to accommodate a piston valve. The passage is provided with a slot formed at its inner surface. A hole/nozzle through which fuel vapor enter is also provided in the slot. The piston valve comprises of a cut put portion through which it is rested on an idle screw. The idle screw is adjusted depending on the requirement. In one aspect of the embodiment, when the throttle valve is closed the cut out portion is below the hole/nozzle and the fuel vapors take a path. In another aspect of the embodiment, when the throttle valve is open the cut out portion is above the hole/nozzle and the fuel vapors take a different path. In an embodiment, the slot is provided on the inner surface of the passage to allow a passage and area for the fuel vapor to flow, which would had been accumulated and could not flow if the clearance in the form of slot would not had been provided. Hence, the present subject matter enables a flow of fuel vapor in an open and closed condition of throttle as well.

[00022] 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.

[00023] 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.

[00024] Fig. 1 illustrates a right side view of an exemplary two-wheeled vehicle (10), in accordance with an embodiment of the present subject matter. However, the present subject matter can be used for multi-wheeled vehicles comprising of two-heeled and three- wheeled vehicles. Henceforth, for the purposes of this application the multi-wheeled vehicle may be referred as a two-wheeled vehicle or a vehicle. The vehicle (10) includes a frame assembly (not shown) that extends from a head tube (not shown), which is disposed in the front portion of the vehicle (10). The frame assembly includes a mainframe (not shown) comprising a main tube extending rearward from a rear portion of the head tube and a down tube (not shown) that extends rearwardly downward from the head tube. The frame assembly may further comprise a sub-frame formed by a pair of rear tubes (not shown) that extend obliquely rearward from the main frame. An internal combustion engine (5) is supported by the main frame of the frame assembly. The internal combustion engine (5) acts as the power unit of the vehicle (10), wherein the power unit may also include a traction/electrical motor (not shown). A front portion of a swing arm assembly is swingably connected to the main frame of the frame assembly and rear portion of the swing arm assembly rotatably supports a rear wheel (3). The rear wheel (3) is functionally coupled to the internal combustion engine (5) through a transmission system. A rear fender (4) disposed upwardly of the rear wheel (3) covers at least a portion of the rear wheel (3). Further, the swing arm assembly is coupled to the frame assembly through one or more rear suspension(s). A pair of front forks (7) supports a front wheel (6) and is steerably supported by the head pipe. A handlebar assembly (1) is connected to an upper portion of the pair of front fork (7). Further, a front fender assembly (11) covers at least a portion of the front wheel (6) and the front fender assembly (11) is mounted to the front forks (7). [00025] A fuel tank (9) is mounted to the main tube of the frame assembly and disposed rearwardly of the handlebar assembly (1). A seat assembly (2) is disposed rearwardly of the fuel tank assembly (1) and supported by the pair of rear tubes. Further, the vehicle (10) comprises a visor assembly (12) that is disposed forwardly over the headlamp (8). A tail cover assembly (13) is disposed rearwardly of the side panel assembly (not shown) and extends along the pair of rear tubes thereby covering at least a portion of the pair of rear tubes. The tail cover assembly (13) extends towards a rear portion of the frame assembly and the tail cover assembly (13) is adapted to accommodate a pillion handle (14) attached to its side.

[00026] Figure 2 illustrates a plain enlarged side view of a cylinder block (25) of the internal combustion engine (5) of the exemplary two-wheeled vehicle (10) in accordance with an embodiment of the present subject matter. Generally, the internal combustion engine (5) comprises of a cylinder block (25) which accommodates a reciprocating piston (not shown) and a cylinder head (24) where the combustion of the air-fuel mixture occurs. In furtherance to it, a carburetor (26) is provided in the throttle body which supplies the required air content to the internal combustion engine (5). The cylinder head (24) comprises of an inlet port (21) through which the air-fuel mixture enters the internal combustion engine (5) and an exhaust port (22) through which the exhaust generated after combustion leaves the internal combustion engine (5). An inlet pipe (23) connects the carburetor (26) and the inlet port (21) to form the intake system to supply the air-fuel mixture into the internal combustion engine (5). The exhaust generated after combustion of the air-fuel mixture leaves the internal combustion engine (5) through an exhaust pipe connected to the exhaust port (22) disposed on the cylinder head (24).

[00027] Figure 3 illustrates a perspective view of the carburetor (26) in accordance with an embodiment of the present subject matter. In an embodiment, fuel flows from the fuel tank (9) and gets stored inside the fuel reservoir (98) within the carburetor. Due to aspiration effect it gets mixed and carried with the air which enters through an inlet (31). In an embodiment, fuel that must get into the fuel-air mixture passage during idling conditions is adjusted by an idle adjustment screw (36) through a piston- spring mechanism located inside a piston valve housing (38) provided in the carburetor body. A cap (37) is provided to close the piston valve housing (38) and hold a piston valve (shown in fig. 5) through a spring. An EVAP inlet (35) is provided on the carburetor (26) through which fuel vapors enter the system. Thus, the present figure illustrates the basic structure and elements of the carburetor (26) in accordance with an embodiment of the present subject matter.

[00028] Figure 4 illustrates a top view of the carburetor (26) in accordance with an embodiment of the present subject matter. In an embodiment, the piston valve housing (38) provided in the carburetor (25) holds the piston valve (shown in fig. 5). The present figure also illustrates an enlarged cross sectional view of the piston valve housing (38). In an embodiment, the piston valve housing (38) comprises of an inner housing (53). The inner housing (53) is the inner surface of the piston valve housing (38) with which the float would be in contact with. As per an embodiment of the present subject matter, the inner housing (53) is provided with an EVAP slot (51). The fuel vapor entering through the EVAP inlet (35) is sprayed through a nozzle (62) provided in the EVAP slot (51) of the inner housing (53). A screw tip (52) of the idle screw (36) is also disposed in the inner housing (53). According to this first embodiment of the present invention, the EVAP slot (51) is blocked by a lateral surface of the piston valve. Hence, during the idling condition, the fuel vapors travel from the nozzle (62) to the upper portion of the piston valve housing (38) through the EVAP slot (51) and through an idle groove (74) (shown in Fig. 5) formed on said piston valve and later gets channelized into a fuel air mixture (charge) passage. As per another embodiment of the present subject matter, the EVAP slot (51) can extend even beyond the nozzle (62) to get formed throughout the height (H) of the inner housing (53). Hence, the EVAP slot (51) is a clearance formed on the inner housing (53) of the piston valve housing (38) which allows the fuel vapor to flow in a closed and open condition of the throttle valve. The fuel vapors do not get accumulated because of the EVAP slot (51) and the amount of fuel vapor passing varies based on the engine running condition, as in whether the vehicle is at idling speed or in a throttle open condition.

[00029] Figure 5 illustrates a perspective view of the piston valve (70) in accordance with an embodiment of the present subject matter. In an embodiment, the piston valve (70) is disposed in the inner housing (53) of the piston valve housing (38) under compression using a compressed spring. In an embodiment, the piston valve (70) comprises of a cut out portion (73) which rests on the screw tip (52) of the idle screw (36). When the idle adjustment screw (36) is tightened it pushes the piston valve (70) upwards against the compression spring. When the idle adjustment screw (36) is loosened the piston valve (70) travels downward under the tension of the compressed spring. The piston valve (70) further comprises of a guide slot (74) which aligns with a pip on the surface of the housing inner (53) to guide the piston to travel inside the piston valve housing (38) during assembly of the piston valve (70) in the carburetor (26). In an embodiment, the guide slot (74) also provides a passage for the fuel vapors to travels in a closed condition of the throttle valve, when the piston valve (70) is pushed inwards because of the compression spring. [00030] Figure 6 illustrates a cross sectional view of the carburetor (26) in a running condition of the internal combustion engine (5). In an embodiment, during a running condition of the internal combustion engine (5) the throttle valve is open. The piston valve (70) is pulled by a spring (96). In an embodiment, the cut portion (73) does not rest on the screw tip (52) of the idle screw (36) when the piston valve (70) is pulled upwards. Thus, in such a condition ample amount of space and area is provide for the fuel vapor to flow, wherein the fuel vapors enter through the EVAP inlet (35) and the fuel vapor flow path is represented as 91. The present figure illustrates an enlarged view of the working of the present subject matter when the piston valve (70) is pulled upwards by spring (96). The fuel vapor path (91) is shown flowing through the EVAP inlet (35) to get sprayed through the nozzle (62) in the carburetor (26). Thus, in a pulled condition of the piston valve (70) there is no surface blocking the nozzle (62) allowing the fuel vapor to easily flow which is shown as fuel vapor path (91) in the present figure. In addition to it, the EVAP slot (51) provides a path for fuel vapors to flow and not get accumulated anywhere be it above the piston valve (70) or anywhere.

[00031] Figure 7 illustrates a cross sectional view of the carburetor (26) in an idle condition of the internal combustion engine (5). In an embodiment, during an idle condition of the internal combustion engine (5) the throttle valve is closed. Hence, the piston valve (70) does not experience any force by the spring (96). Thus, the cut out portion (73) of the piston valve (70) rests on the screw tip (52) of the idle screw (36). In such a condition the idle fuel vapor flow is blocked. Hence, in such a case the EVAP slot (51) helps in fuel vapor flow being illustrated by 91. The EVAP slot (51) does not allow the fuel vapor to accumulate. In an embodiment, the fuel vapor path (91) follows path of going through the EVAP slot (51) in an upwards direction above the piston valve (70). Later the fuel vapor path (91) flows through the guide slot (74). In such a scenario, the amount of fuel vapor flowing is less. In fact the requirement in such a condition is also less because the engine is in an idle condition. Thus, the EVAP slot (51) does not allows the fuel vapor being sprayed through the nozzle (62) to accumulate, and maintains a flow based on the running condition of the engine.

[00032] Thus, the present subject matter provides an internal combustion engine (5) with a carburetor (26). The carburetor (26) comprises of a piston valve housing (38), wherein the piston valve housing (38) comprises of an inner housing (53) to accommodate a piston valve (70). The inner housing (53) comprises of an EVAP slot formed therein which channelizes the fuel vapor flow, allowing it to flow in an open and closed condition of the throttle valve.

[00033] 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.