DESC:TECHNICAL FIELD
[001] The embodiments herein generally relate to air fuel mixture devices for an engine and more particularly but not exclusively to a carburetor for a 400 cc internal combustion engine for a three wheeler vehicle.
BACKGROUND
[002] In all internal combustion (i.e.) engines the air/fuel ratio (A/F) is of great importance to the function of the engine. To obtain a proper combination of low fuel consumption, low exhaust gas emissions, good operability and high power the A/F ratio must be kept within relatively close limits.
[003] Conventionally, carburetors are widely used for controlling A/F ratios in two wheelers due to their low cost. The carburetors are of constant depression and variable depression types. The carburetors use flow control devices such as fuel jets, needle jets and throttle valve to supply the air/fuel mixture to the engine under different operating conditions of the vehicle. Mechanically controlled carburetor is characterized by variable venturi, variable depression design (VD). The throttle valve is situated in a venturi zone and when a rider operates the throttle, both the effective venturi area and the venturi depression changes. The fuel delivery will take place according to the throttle position and the engine speed.
[004] For engines with capacities in the range of 150-600cc, Variable depression carburetors are usually preferred over constant depression carburetors. However engine with variable depression carburetor will deliver excessive fuel when engine runs at lower engine speed with full throttle conditions as throttle opening is controlled by the driver. Further in most cases where an engine with higher capacity uses variable depression carburetors, the fuel efficiency and vehicle performance are often compromised. The fuel efficiency and vehicle performance are often compromised.
[005] Therefore, there is a need for a constant depression carburetor for an engine with 400cc capacity, which can obviate the aforementioned drawbacks of variable depression carburetors.

OBJECT
[006] The principal object of the embodiments of this invention is to provide a carburetor device for internal combustion engine of 400 cc capacity.
[007] Another object of the embodiments of this invention is to provide a carburetor device for a three wheeled automotive vehicle of 400cc engine capacity.
[008] Yet another object of the embodiments of this invention is to provide a carburetor device having a carburetor for controlling Air-fuel (A/F) mixture accurately and automatically adjust the A/F ratio for the 400cc engine associated with the carburetor.
[009] Also another object of the embodiments of this invention is to provide a comparison of variable depression and constant depression carburetors.
[0010] Still another object of the embodiments of this invention is to provide a method of providing a carburetor device 100 for an internal combustion engine of 400cc capacity.
[0011] These and other aspects of the embodiments herein will be better appreciated and understood when considered in conjunction with the following description and the accompanying drawings. It should be understood, however, that the following descriptions, while indicating embodiments and numerous specific details thereof, are given by way of illustration and not of limitation. Many changes and modifications may be made within the scope of the embodiments herein without departing from the spirit thereof, and the embodiments herein include all such modifications.
BRIEF DESCRIPTION OF DRAWINGS
[0012] The embodiments of this invention are illustrated in the accompanying drawings, throughout which like reference letters indicate corresponding parts in the various figures. The embodiments herein will be better understood from the following description with reference to the drawings, in which:
[0013] FIG. 1 depicts a constant depression carburetor, according to embodiments as disclosed herein;
[0014] FIG. 2 is a graph of engine torque versus engine speed of a variable depression and constant depression carburetors, according to embodiments as disclosed herein;
[0015] FIG. 3 is a graph of engine power versus engine speed of a variable depression and constant depression carburetors, according to embodiments as disclosed herein;
[0016] FIG. 4 is a graph of BSFC versus engine speed of a variable depression and constant depression carburetors, according to embodiments as disclosed herein;
[0017] FIG. 5 is a chart depicting fuel economy of variable depression carburetor and constant depression carburetor, according to embodiments as disclosed herein; and
[0018] FIG. 6 depicts a flowchart of a method of providing a carburetor device 100 for an internal combustion engine, according to embodiments as disclosed herein.

DETAILED DESCRIPTION
[0019] The embodiments herein and the various features and advantageous details thereof are explained more fully with reference to the non-limiting embodiments that are illustrated in the accompanying drawings and detailed in the following description. Descriptions of well-known components and processing techniques are omitted so as to not unnecessarily obscure the embodiments herein. The examples used herein are intended merely to facilitate an understanding of ways in which the embodiments herein may be practiced and to further enable those of skill in the art to practice the embodiments herein. Accordingly, the examples should not be construed as limiting the scope of the embodiments herein.
[0020] The embodiments herein achieve a carburetor device for internal combustion engine. Further, the embodiments achieve a carburetor device having a carburetor for controlling Air-fuel (A/F) mixture accurately and automatically adjust the A/F ratio for the engine associated with the carburetor. Referring now to the drawings, and more particularly to FIG. 1 through 6, where similar reference characters denote corresponding features consistently throughout the figures, there are shown embodiments.
[0021] In an embodiment, the carburetor device 100 includes a carburetor body 106 having an upper portion 102 and a lower portion 104, a diaphragm 108, a piston valve spring 110, a piston valve 112, a jet needle 114, a needle jet 116, a main air jet 118, a needle valve 120, a main jet 122, a pilot jet 124, a throttle valve 126, a float chamber 128, a venturi passage P and a bore E on an engine manifold side.
[0022] FIG. 1 shows a sectional view of the carburetor device, according to embodiments as disclosed herein. In an embodiment, the carburetor device 100 includes the carburetor body 106 having the upper portion 102 and the lower portion 104.
[0023] In an embodiment, the carburetor device 100 includes the diaphragm 108 disposed at the upper portion 102 of the carburetor body 106. In an embodiment, the diaphragm 108 is covered by a diaphragm cover (not shown) in a liquid-proof manner on the upper portion 102 of the carburetor body 106. In an embodiment, the diaphragm 108 is divided into an upper chamber A (not shown) and lower chamber B (not shown).
[0024] In an embodiment, the diaphragm 108 is formed in a predetermined shape, for example, a doughnut-shape. In an embodiment, the diaphragm includes a flange portion 130.
[0025] In an embodiment, the diaphragm 108 is connected to the venturi passage P by means of a communicating or connecting passage (not shown) formed around the piston valve 112. The connecting passage (not shown) has an opening O1 (not shown) at an upper end thereof which opens into the upper chamber A, and an opening O2 (not shown) at a lower end thereof which opens into the venturi passage P.
[0026] In an embodiment, the carburetor device 100 includes the piston valve 112. In an embodiment, the piston valve 112 is vertically movable within the venturi passage P. In an embodiment, the head portion of the piston valve 112 is fixed to a central portion of the diaphragm 108. In an embodiment, a head portion of the piston value 112 includes a recess R which is configured to rest in the flange portion 130 of the diaphragm 108. In an embodiment, the flange portion 130 of the diaphragm 108 and the recess R of the piston valve 112 are sealed in a liquid-tight manner. In an embodiment, the piston valve 112 is configured to slide along with a piston valve spring 110.
[0027] In an embodiment, the carburetor device 100 includes the venturi passage P which includes a restriction to cause increase in air speed while passing through a venturi section. In an embodiment, the venturi passage size used is 24.6mm. In an embodiment, the carburetor device 100 includes the bore E extending from the venturi passage P towards an engine manifold. In an embodiment, the bore E of the carburetor device 100 on the engine side is 26mm.
[0028] In an embodiment, the carburetor device 100 includes the throttle valve 126. In an embodiment, the throttle valve 126 is configured to control the amount of air entering the engine. In an embodiment, the throttle valve 126 is a butterfly valve that regulates the airflow. In an embodiment, the throttle valve 126 is disposed at the entrance of the intake manifold. In an embodiment, an opening angle of the throttle valve 126 determines the amount of fresh air or air/fuel mixture to flow into the intake manifold. In an embodiment, the angle of the throttle valve 126 used is 105 deg. In an embodiment, the throttle valve 126 includes at least one opening 205 of predetermined diameter.
[0029] In an embodiment, the carburetor device 100 includes a pilot jet system (not shown) (comprising of pilot air jet, pilot fuel jet and pilot fuel screw) configured to control the throttle opening from 0% to about 25%. Further, the throttle valve is configured to control 0% to 35% of the throttle opening. Furthermore, the needle jet 116 and jet needle 114 is configured to control the throttle opening from 15% to 80% and the main jet is configured to control the throttle opening from 60% to 100%.
[0030] In an embodiment, the carburetor device 100 includes the jet needle 114. In an embodiment, the jet needle 114 is a long tapered rod configured to control the amount of fuel drawn into the venturi passage P. In an embodiment, the taper portion of the jet needle 114 is provided thinner to achieve a rich A/F mixture, while the taper portion of the jet needle 114 is provided thicker to attain a lean A/F mixture as the thicker taper would not allow much fuel into the venturi passage P. In an embodiment, the taper portion is designed to provide different mixtures at different throttle openings.
[0031] In an embodiment, the carburetor device 100 includes the needle jet 116. In an embodiment, the needle jet 116 includes a bore (not shown) to receive the jet needle 114. In an embodiment, the jet needle 114 slides within the needle jet 116. In an embodiment, the needle jet 116 and jet needle 114 are configured to work together to control the fuel flow to the venturi passage P. In an embodiment, the setting of needle jet 116 is P-2M.
[0032] In an embodiment, the carburetor device 100 includes the main jet 122. In an embodiment, the main jet 122 is configured to control the fuel flow. In an embodiment, when the throttle is opened fully and the jet needle 114 is pulled out of the needle jet 116, a predetermined size of opening M (not shown) defined in the main jet 122 is configured to regulate the fuel flow. In an alternate embodiment, the carburetor device 100 includes a plurality of main jets. In an embodiment, the opening M (not shown) may be made up of different size to achieve at least of lean mixture or rich mixture. In an embodiment, the setting of the main jet 122 used is 95 m3/s.
[0033] In an embodiment, the carburetor device 100 includes the main air jet 118. In an embodiment, the main air jet 118 is connected to the needle jet 116 perpendicularly at the lower portion 104 of the carburetor body 106. In an embodiment, the setting for main air jet used is 0.8 m/s.
[0034] In an embodiment, the carburetor device 100 includes the pilot jet 124. In an embodiment, the pilot jet 124 controls the throttle opening from 0% to about 25%. In an embodiment, a pilot jet air screw (not shown) is used in conjunction with the pilot jet 124. The pilot jet air screw is adapted to achieve at least of lean mixture or rich mixture. In an embodiment, the setting used for the pilot jet 124 and pilot air jet is 15 m/s and 147.5 m/s respectively.
[0035] In an embodiment, a plurality passages are provided to connect the pilot jet 124 into the carburetor body 106 that connects to at least one hole 305 in front of the throttle valve 126. In an embodiment, the carburetor includes plurality of holes 305 defined in front of the throttle valve 126, depending on the carburetor design. In an embodiment, the diameter of the holes 305 is 1 mm.
[0036] In an embodiment, the carburetor device 100 includes the float chamber 128 defined at the lower portion 104 of the carburetor body 106. In an embodiment, the float chamber 128 is configured to meter the fuel supply to the engine. In an embodiment, the fuel flows between the needle valve 120 and a valve seat (not shown) and enters the float chamber 128. In an embodiment, the float chamber 128 is provided with the needle valve 120 at an upper portion thereof and a float (not shown) associated with the needle valve 120. As the fuel enters the float chamber, the float (not shown) moves upward to a pre-determined level because of buoyancy effect. In an embodiment, the needle valve 120 includes a rubber tip (not shown) and is spring loaded to ensure proper function of the needle valve 120 under vibrating conditions.
[0037] FIG. 2 is a graph of engine torque versus engine speed of a variable depression and constant depression carburetors, according to embodiments as disclosed herein. In an embodiment, the engine torque is plotted along the y-axis while the engine speed is plotted in the x-axis. As is evident from FIG. 2, the engine torque with the constant depression carburetor 100 (the plot 120C) is more than the engine torque with the variable depression carburetor (the plot 120V).
[0038] FIG. 3 is a graph of engine power versus engine speed of a variable depression and constant depression carburetors according to embodiments as disclosed herein. In an embodiment, the engine power is plotted along the y-axis while the engine speed is plotted in the x-axis. The plot 130C corresponds to the constant depression carburetor 100 according to the embodiments specified herein and plot 130V corresponds to a variable depression carburetor. As is evident from FIG. 3, the engine power of the constant depression carburetor 100 (the plot 130C) is almost equivalent to the engine power with a variable depression carburetor (the plot 130V).
[0039] FIG. 4 is a graph of BSFC versus engine speed of a variable depression and constant depression carburetors according to embodiments as disclosed herein. In an embodiment, the BSFC is plotted along the y-axis while the engine speed is plotted in the x-axis. The plot 140C corresponds to the constant depression carburetor 100 according to the embodiments of specified herein and plot 140V corresponds to a variable depression carburetor. In an embodiment, it can be inferred from the graph that the fuel efficiency of the constant depression carburetor is more compared to the fuel efficiency of the variable depression carburetor.
[0040] FIG. 5 is a chart depicting fuel economy when each of variable depression carburetor and constant depression carburetor is used. As is evident from the chart, the fuel economy achieved by the engine with 400cc using a constant depression carburetor 100 is more than the fuel economy achieved by the same engine using a variable depression carburetor. In an embodiment, the fuel economy achieved by the constant depression carburetor is 18.4 % more than the fuel economy achieved by the same engine using a variable depression carburetor.
[0041] In an embodiment, a method of providing a carburetor device 100 for an internal combustion engine is depicted in FIG. 6. The method includes steps of, providing a carburetor body 106 having an upper portion 102, a lower portion 104, a diaphragm 108 disposed at the upper portion 102. Further, the method includes, providing a venturi passage P extending horizontally through the carburetor body 106. Furthermore, the method includes, defining a bore E extending from the venturi passage P towards an engine manifold. Moreover, the method includes, connecting a piston valve 112 to the diaphragm 108 in the upper portion 102 of the carburetor body 106, wherein the piston valve 112 vertically moves within the venturi passage P. In addition, the method includes, connecting a jet needle 114 to the piston valve 112, wherein the jet needle 114 having a tapered portion slides into a needle jet 116 provided in the lower portion 104 of the carburetor body 106. Also, the method includes, connecting a main air jet 118 perpendicular to the needle jet 116 in the lower portion 104 of the carburetor body 106. Further, the method includes, connecting a main jet 122 parallel to the needle jet 116 at a lower end of the needle jet 116. Furthermore, the method includes, providing a pilot jet 124 at the lower portion 104 of the carburetor body 106 and having at least one opening 305 into the venturi passage P. Moreover, the method includes, defining a float chamber 128 at the lower portion 104 of the carburetor body 106. In addition, the method includes providing a needle valve 120 in the float chamber 128. Also the method includes mounting a throttle valve 126 within the bore E.
[0042] The foregoing description of the specific embodiments will so fully reveal the general nature of the embodiments herein that others can, by applying current knowledge, readily modify and/or adapt for various applications such specific embodiments without departing from the generic concept, and, therefore, such adaptations and modifications should and are intended to be comprehended within the meaning and range of equivalents of the disclosed embodiments. It is to be understood that the phraseology or terminology employed herein is for the purpose of description and not of limitation. Therefore, while the embodiments herein have been described in terms of embodiments, those skilled in the art will recognize that the embodiments herein can be practiced with modification within the spirit and scope of the embodiments as described herein.
Referral numerals
Carburetor device 100
Upper portion 102
Lower portion 104
Carburetor body 106
Diaphragm 108
Piston valve spring 110
Piston valve 112
Jet needle 114
Needle jet 116
Main air jet 118
Needle valve 120
Main jet 122
Pilot jet 124
Throttle valve 126
Float chamber 128
Flange portion 130
Venturi passage P
Bore E
Recess R
,CLAIMS:STATEMENT OF CLAIMS
We claim,
1. A carburetor device 100 for an internal combustion engine of 400 cc capacity, the carburetor device 100 comprising:
a carburetor body 106 having an upper portion 102, a lower portion 104, a diaphragm 108 disposed at the upper portion 102;
a venturi passage P extending horizontally through the carburetor body 106;
a bore E extending from the venturi passage P towards an engine manifold;
a piston valve 112 connected to the diaphragm 108 in the upper portion 102 of the carburetor body 106 and vertically movable within the venturi passage P, wherein the piston valve 112 is configured to slide with a piston valve spring 110, wherein the piston valve 112 having a head portion is fixed to a central portion of the diaphragm 108;
a jet needle 114 connected to the piston valve 112, wherein the jet needle 114 having a tapered portion slides into a needle jet 116 provided in the lower portion 104 of the carburetor body 106;
a main air jet 118 connected perpendicular to the needle jet 116 in the lower portion 104 of the carburetor body 106;
a main jet 122 connected parallel to the needle jet 116 at a lower end of the needle jet 116;
a pilot jet 124 disposed at the lower portion 104 of the carburetor body 106 and having at least one opening 305 into the venturi passage P;
a float chamber 128 disposed at the lower portion 104 of the carburetor body 106;
a needle valve 120 disposed in the float chamber 128, wherein the needle valve 120 is configured to control a flow rate of fuel into the float chamber 128; and
a throttle valve 126 mounted within the bore E, wherein the throttle valve 126 includes at least one opening 205 of a predetermined diameter.
2. A method 600 of providing a carburetor device 100 for an internal combustion engine, the method comprising steps of:
providing a carburetor body 106 having an upper portion 102, a lower portion 104, a diaphragm 108 disposed at the upper portion 102;
defining a venturi passage P extending horizontally through the carburetor body 106;
defining a bore E extending from the venturi passage P towards an engine manifold;
connecting a piston valve 112 to the diaphragm 108 in the upper portion 102 of the carburetor body 106 and vertically movable within the venturi passage P, wherein the piston valve 112 is configured to slide with piston valve spring 110, wherein the piston valve 112 having a head portion is fixed to a central portion of the diaphragm 108;
connecting a jet needle 114 to the piston valve 112, wherein the jet needle 114 having a tapered portion slides into a needle jet 116 provided in the lower portion 104 of the carburetor body 106;
connecting a main air jet 118 perpendicular to the needle jet 116 in the lower portion 104 of the carburetor body 106;
connecting a main jet 122 parallel to the needle jet 116 at a lower end of the needle jet 116;
providing a pilot jet 124 at the lower portion 104 of the carburetor body 106 and having at least one opening 305 into the venturi passage P;
defining a float chamber 128 disposed at the lower portion 104 of the carburetor body 106;
providing a needle valve 120 disposed in the float chamber 128, wherein the needle valve 120 is configured to control a flow rate of fuel into the float chamber 128; and
mounting a throttle valve 126 within the bore E, wherein the throttle valve 126 includes at least one opening 205 of a predetermined diameter.
3. The carburetor device 100 as claimed in claim 1, wherein the venturi passage P includes a diameter of 24.6 mm.
4. The carburetor device 100 as claimed in claim 1, wherein the bore E includes a diameter of 26mm.

5. The carburetor device 100 as claimed in claim 1, wherein the main jet 122 is operated at 95 m3/s.
6. The carburetor device 100 as claimed in claim 1, wherein the main air jet 118 is operated at 0.8 m/s.
7. The carburetor device 100 as claimed in claim 1, wherein the needle jet 116 is operated at P-2M.
8. The carburetor device 100 as claimed in claim 1, wherein the pilot jet 124 and pilot air jet are operated at 15 m/s and 147.5 m/s.
9. The carburetor device 100 as claimed in claim 1, wherein the throttle valve 126 is operated at an angle of 105?.
10. The carburetor device 100 as claimed in claim 1, wherein the carburetor body 106 includes at least one opening 305 of diameter 1 mm connecting the pilot jet 124 with the venturi passage P.