JPS6090965A - Fuel supplying device in internal-combustion engine - Google Patents

Abstract

PURPOSE:To stabilize an air/fuel ratio in spite of the fluctuation of running condition by a method wherein a float chamber in a carburettor is communicated with an air introducing path at the upstream side of a cleaner element of an air cleaner. CONSTITUTION:The carburettor 4, connected to cylinder heads 2 extending in the fore and back direction of the body of a vehicle in the condition of V-shape, is provided with the float chamber 5, reserving temporarily the fuel flowing thereinto from a fuel tank, at the lower part thereof. In this case, the float chamber 5 is communicated with the air introducing path 27 at the upstream side of the cleaner element 8 of the air cleaner 7 through a communicating pipe 6. The communicating pipe 6 is arranged so that the tip end thereof is opposed to the opening 27a of the air introducing path of the air cleaner 7 to permit to impress the dynamic pressure of air stream, flowing into the aircleaner 7, onto the float chamber 5. According to this method, the carburettor will never be affected by the external disturbance and blow-back in accordance with the change of the running condition and the A/F ratio may be stabilized.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a fuel supply device for an internal combustion engine. 1 The 2L carburetor used in internal combustion engines has the function of atomizing fuel, mixing it with air, and pumping out a mixed gas to be supplied into the cylinder. Using the pressure difference created by the desired air flow, the fuel stored in this float chamber is sucked in by the appropriate amount, and the sucked fuel flows from the air cleaner. The float chamber includes a suction passageway that mixes purified air and supplies the mixture to the downstream cylinder.The float chamber is open to the atmosphere through a communication pipe and communicates with the upper part of the suction passageway through another communication passageway. (The latter is called an outer vent type vaporizer and the latter is called an inner vent type vaporizer) so that its internal pressure is always maintained within an appropriate range.

Figure 1 shows the output characteristics of internal combustion engines for both motorcycles equipped with an outer vent type carburetor and motorcycles equipped with an inner vent type carburetor, with the vertical axis representing the output and the horizontal axis representing the vehicle speed. Each is taken. In an internal combustion engine equipped with an outer vent type carburetor (A in the figure), setting the carburetor is easy, but as shown in (A) in the figure, a valley is formed in a certain vehicle speed range. Output may decrease. On the other hand, in an internal combustion engine equipped with an inner vent type carburetor (B in the figure), the extreme valley seen in the continuous speed range of the internal combustion engine (0) equipped with an outer vent type carburetor is not formed. Although this is not the case, the output may decrease in the high speed range of ←).

Therefore, the present inventors focused on the fact that the A/F (ratio of air to fuel in the mixed gas) has a great influence on the output characteristics of an internal combustion engine. The output characteristics of both internal combustion engines and internal combustion engines equipped with inner vent type carburetors were investigated from the viewpoint of A/F.

FIG. 2 shows an investigation of the CO concentration in exhaust gas, which is uniquely inversely proportional to A/F, and it is possible to estimate A/F based on this. In the figure, the vertical axis represents the CO concentration, and the horizontal axis represents the vehicle speed. In an internal combustion engine equipped with an outer vent type carburetor (A in the figure), the location shown in (A) in Figure 1 corresponds to (C) in Figure 1, and the CO It can be seen that the degree of obscurity is increasing. In other words, it can be seen that the A/F becomes low in this vehicle speed range, which causes a decrease in output. Furthermore, in an internal combustion engine equipped with the same outer vent type carburetor, the amount of change in CO concentration is large, making the A/F unstable. The reason why an internal combustion engine equipped with an outer vent type carburetor has such characteristics is that the end of the communication pipe that opens the float chamber to the atmosphere is exposed to the outside, so it is difficult to avoid changes in running conditions due to changes in running conditions. This is because it is easily affected by external disturbances. Incidentally, if the A/F is unstable, not only will it cause a drop in output, but if it is too high, the combustion temperature will easily reach a high temperature, and if it is too low, carbon etc. will build up inside the cylinder and the head of the piston. This causes problems such as a decrease in the durability of the engine and an increase in the amount of harmful components in the exhaust gas.

On the other hand, in an internal combustion engine equipped with an inner vent type carburetor (B in the figure), the overall change in CO concentration is small and stable, but at high speeds (in the figure) the CO concentration decreases. I'm here 25). In other words, A in the high speed range
/F becomes high, and this causes a decrease in output.75) There are 7 reasons why an internal combustion engine equipped with an inner vent carburetor has the above-mentioned characteristics.
The zero float chamber is communicated with the suction passage for air flowing in from the air cleaner side, so it is affected by blowback from the combustion chamber, and the pressure inside the float chamber increases as the airflow speed increases in the high-speed range. This is because the

In addition, in internal combustion engines equipped with an inner vent type carburetor, the pressure in the shift float chamber is affected by blowback as described above, so it is difficult to adjust the carburetor (main jet, air jet, etc.). It has the following disadvantages.

In other words, while internal combustion engines equipped with conventional outer vent carburetors have advantages such as easy carburetor setting, they are susceptible to disturbances caused by changes in driving conditions, and A/F On the other hand, internal combustion engines equipped with an inner vent type carburetor have the advantage of stable A/F, but on the other hand, they suffer from low output at high speeds. However, it has drawbacks such as difficulty in setting the carburetor.

The present invention has been made in view of the above circumstances, and is less affected by disturbances and blowback, and can stabilize the A/F at an appropriate value by preventing a pressure drop in the float chamber in high-speed ranges. It is an object of the present invention to provide a fuel supply device for an internal combustion engine that is capable of producing high output in the range of engine speed and that can easily set up a carburetor.

Hereinafter, one embodiment of the present invention will be described with reference to the drawings.

FIG. 3 shows an internal combustion engine equipped with a fuel supply system according to the present invention, in which reference numeral 1 denotes a crankcase, 2 a cylinder head extending in a V-shape in the longitudinal direction of the vehicle body from the crankcase 1, and 3 a cylinder. It is a herad cover. 6+I
A carburetor 4.4 is connected to each of the cylinder heads 2.2.

At the bottom of the carburetor 4, there is a fuel tank (
A float chamber 5 is provided to temporarily store fuel flowing in from a pipe (not shown). It is connected to 27. Further, an air passage 9 is provided above the float chamber 5 to guide the air flowing in from the air cleaner 7 to the intake boat of the cylinder head 2, and the air passage 9 is connected to the throttle valve 10.
The opening degree is adjusted by. The air passage 9 and the lower part of the float chamber 5 are communicated with each other by a needle jet 11, and a jet needle 12 is inserted into the needle jet 11 so as to be vertically movable. The jet needle 12 also has a piston 1 which is disposed perpendicular to the air passage 9 and whose vertical position τ is determined by the pressure of the air passage 9.
It is connected to 3. Then, when the throttle valve 10 is opened by an appropriate amount and air flows into the air passage 9 from the air cleaner 7 side, the piston 13 and jet needle 12 are pulled up by an appropriate amount due to the pressure difference caused by the sudden airflow, and the needle The fuel in the float chamber 5 is sucked into the suction passage 9 through the gap between the jet 11 and the jet needle 12, mixed with air, and then guided to the intake boat of the cylinder head 2. In addition, 14 is a float, which controls the amount of soot flowing in from the fuel tank and keeps the liquid level in the float chamber 5 at a constant position.The air cleaner 7 is as shown in FIG. The air cleaner case 15 is connected to a cylindrical cleaner element 8 disposed at a predetermined position in the air cleaner case 15, and the air cleaner case 15 is connected to a case body 17, which is provided at the lower part of the case body 17, and is connected to the carburetor. A cleaner element (8) is provided between the case space 18 connected to the air passage 9 of 4 and the bottom plate 19 screwed to the case body 17.
and a lid 20 that clamps and fixes the. Further, as shown in FIG. 6, the case body 17 is provided with a rectifying plate 21 which is opened in the opposite direction to the opening 17a connected to the case space 18.

As shown in FIGS. 5, 7, and 7, the lid 20 has a substantially trapezoidal upper plate 23 disposed above the lid substrate 22 in parallel with the lid substrate 22 and at a predetermined interval. , a side plate 24 connecting the J-side edge of the upper plate 23 and the lid base plate 22, an opening 25 formed below the upper plate 23 at the center of the inner base plate 22, and a cylindrical body 26 extending downward from the opening 25. , a sudden air introduction passage 27 is formed, and the upstream side of the cleaner element 8 is connected to the air cleaner 7 via this air introduction passage 27.
communicated with the outside.

Further, a tube 28 projects outward from the side plate 24 facing the external opening 27a of the air introduction passage 27.

According to the internal combustion engine configured as described above, since the float chamber 5 in the carburetor 4 is communicated with the air introduction passage 27 in the air cleaner 7 and upstream of the cleaner element 8, running conditions can be improved. It has the advantages of an inner vent type carburetor, such as being able to stabilize the A/F without being affected by disturbances and blowback caused by changes, and it is easy to set up the carburetor. It also has the advantages of an outer vent type vaporizer. In addition, since the float chamber 5 is communicated and opened at a point close to atmospheric pressure, the pressure in the float chamber 5 can be prevented from decreasing in the high speed range, and the A/F can be maintained at an appropriate value, even in the high speed range. Can produce high output. (Refer to Figure 1 and Figure 1θ) In addition, in this embodiment, since the current plate 21 is provided on the downstream side of the cleaner element 8 of the air cleaner 7, the influence on the float chamber 5 caused by blowback can be reduced. It can be further reduced and the A/F can be further stabilized.

Moreover, the tip of the communication pipe 6 communicating with the float chamber 5 is
Since the air cleaner 7 is disposed opposite to the air introduction opening 27a of the air cleaner 7, the float chamber 5 is provided with the air cleaner 7.
Dynamic pressure of the air flowing into the float chamber 5 is added to the air flow, and as a result, the pressure inside the float chamber 5 can be increased in proportion to the amount of intake air, thereby ensuring more stable A/F in the high speed range. (can.

Furthermore, the float chambers 5.5 of both carburetors 4.4 are connected to separate l-operated cleaners 7 through separate communication pipes 6.
Since the cylinders are in communication with each other, even when used in an internal combustion engine where both cylinders explode at unequal intervals, interference of pressure fluctuations to the float chamber 5 due to mutual combustion within the cylinders is prevented. can do.

In the above embodiment, the tip of the communication pipe 6 extending from the float chamber 5 is provided to face the air introduction passage opening 27a of the air cleaner 7, but the present invention is not limited to this. As shown in FIG.
A pipe 31 extends through the side plate 24a perpendicular to 7a and extends through the side plate 24b facing the opening 27a, as shown by reference numeral (E). It may be communicated. When connecting the tips of the communicating tubes 6 as described above, the symbols (E) and (E) are used.
, (G), the pressure inside the float chamber 5 during traveling can be set higher according to the same order as in 2.

Further, in the above embodiment, the float chambers 5 of both carburetors 4 are communicated with the air cleaner 7 through separate communication pipes, but the present invention is not limited to this, and the float chambers 5 of both carburetors 4 are communicated with the air cleaner 7 through a common communication pipe. You can.

As explained above, according to the present invention, the air chamber formed inside the carburetor is communicated with the air introduction passage upstream of the cleaner element of the air cleaner, so that It is not affected by disturbances and blowback caused by fluctuations, and the A/F can be made constant, allowing high output to be achieved in all vehicle speed ranges.Moreover, the carburetor can be easily centered. can. Furthermore, even when using an elastic member such as a rubber tube as the part that connects the float chamber to the air introduction passage, the end of the tube can be firmly fixed to the air cleaner.
To prevent the tube end from preforming.

I can do it.

[Brief explanation of drawings]

Figure 1 is a diagram showing the zero output characteristics of a motorcycle equipped with an outer pent type carburetor and a motorcycle equipped with an inner vent type carburetor, and Figure 2 shows the CO concentration characteristics in the exhaust gas of both motorcycles. Figure 3 is a partially cutaway side view showing a schematic configuration of an internal combustion engine according to an embodiment of the present invention, Figure 3 is a partially cutaway side view of a carburetor, and Figure 3 is a partially cutaway side view of an air cleaner. Figure 4 is a side view, Figure 7 is a plan view of the case body, Figure 7 is a plan view of the air cleaner lid, Figure 3 is a bottom view with the lid opened, and Figure 4 is a diagram of a motorcycle equipped with an internal combustion engine according to book 4111. A diagram showing the output characteristics, Figure 1O is a diagram showing the CO concentration characteristics in the exhaust gas of the motorcycle, and Figure 1 and Figures 1 and 2 are explanations of main parts showing other embodiments of this Kinmei. It is a diagram. 4... Carburizer, 5... Float chamber, 6
...Communication pipe, 7...Air cleaner, 8
...Cleaner element, 27... air introduction passage, 28 ... pipe. Fig. 6 17 Fig. 9 base λ Li Fig. 11/

Claims (1)

[Claims] Upstream of the air cleaner cleaner element (i1+1
In a fuel supply device (I) for an internal combustion engine, the air is opened to the atmosphere through an air inlet passage (b), and the downstream side of the cleaner element of the air cleaner is connected to the suction passage of a carburetor (b), in which air is supplied to the inside of the carburetor. A fuel supply device for an internal combustion engine, wherein the formed float chamber is communicated with an air introduction passage upstream of a cleaner element of the air cleaner.