JPS5830460A - Carburetter - Google Patents

Abstract

PURPOSE:To promote the atomization of fuel by dashing a high-speed jet stream to the fuel. CONSTITUTION:The air conducted through an air cleaner is compressed by a pump 24, and controlled at a fixed level in its delivery pressure by a constant- pressure valve device 19 to be jetted out from a nozzle 17. The fuel in a float chamber 9 is jetted out from a fuel jet unit 8 by the air from the nozzle 17. Meanwhile, a metering needle 6 is moved by a lever 5 connected with a suction flow detection diaphragm 11, and the effective sectional area of a fuel jet 7 is changed for measuring the fuel in accordance with the suction flow. This construction permits to atomize the fuel in accordance with the flow of air by a jet stream and improve the cost of fuel.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a carburetor that actively promotes atomization of fuel using a high-speed jet of air or the like.

Generally, the fuel ejected from the fuel injection part of the carburetor is atomized by the airflow passing through it.
In order to avoid reducing the volumetric efficiency of the engine, the air velocity at the fuel injection part cannot be increased too much.

As a result, the atomization of the fuel becomes poor (this tendency is particularly noticeable in fixed venturi carburetors), the distribution of fuel to each cylinder, the startability and responsiveness of the engine are poor, and the fuel efficiency deteriorates.

In order to solve these drawbacks, the present invention aims to actively promote atomization of fuel by colliding high-speed jets when jetting compressed air etc. with fuel, and will be explained below with reference to the drawings. .

FIG. 1 shows an embodiment of a carburetor according to the present invention, in which the air that has passed through the air cleaner is compressed by a pump 24 driven by the output shaft/camshaft of the engine, or an electric motor (motor), and the discharge pressure is adjusted. The pressure is maintained at a constant level by a constant pressure valve device 19, and the water is violently ejected from the nozzle 17.

When air is ejected from the nozzle 17 at high speed, it is first reduced to the ambient pressure, and then becomes lower than the ambient pressure (negative pressure) due to its own velocity energy, and is released from the fuel injection part 8 into the float. Fuel in chamber 9 (always under atmospheric pressure) is jetted out.

The fuel in the float chamber 9 is led to a fuel jet 7, from where it reaches a fuel jet section 8, where it is atomized by a high-speed jet from a nozzle 17. Since the speed is constant as described above (because the discharge pressure of the pump 24 is always constant), the pressure (negative pressure) acting on the fuel injection part 8 is always constant.

Therefore, by using some method to change the effective cross-sectional area of the fuel jet 7 (the effective cross-sectional area through which the fuel passes) to match the intake flow rate taken into the engine, it is possible to form the mixture ratio required by the engine. .

On the other hand, a throttle valve 2 is installed in an intake passage 1 of the carburetor, and a plate valve 3 fixed to a plate valve shaft 4 is provided upstream of the throttle valve 2 .

Now, when the intake air passes through the plate valve 3, negative pressure is generated behind it.

This negative pressure is led to the negative pressure chamber 13 of the intake flow rate detection diaphragm device 11, so that the diaphragm 12 is pulled while compressing the spring 14, and the diaphragm 12 is pulled through the lever 10 fixed to the plate valve shaft 4. Open the plate valve 3 (closing torque may also be applied to the plate valve 3 in advance using a spring or the like).

As a result, the negative pressure in the negative pressure chamber 13 tends to weaken, but eventually the plate valve 3 comes to rest at a position relative to the intake flow rate, and thus the intake flow rate detection diaphragm device 11 detects the intake flow rate according to the intake flow rate. The plate valve shaft 4 is placed as close to the throttle valve 2 as possible in order to reduce the overall height of the carburetor, and the plate valve 3 and the throttle valve In order to avoid collision with the plate valve 2, the position of the plate valve shaft 4 is eccentric to the intake passage 1 as shown in the figure.As a result, the plate valve shaft 4 is subjected to a closing torque due to the pressure difference before and after the plate valve 3. However, the effective area of the diaphragm 12 is sufficiently large to overcome this closing torque and open the plate valve 3).

At the same time, a metering needle 6 is moved by another lever 5 fixed to the plate valve shaft 4, changing the effective cross-sectional area of the fuel jet 7 and metering fuel commensurate with the intake flow rate.

In this way, the effective cross-sectional area of the fuel jet 7 is changed by the plate valve 3 and the intake flow rate detection diaphragm device 11, which operate according to the intake flow rate, and fuel corresponding to the intake flow rate is ejected from the fuel injection portion 8.

In this case, the position of the fuel injection part 8 should be moved closer to the center of the intake passage 1 as shown in Fig. 3 (a small venturi 25 is also installed to promote mixing with air). (For the same purpose, the nozzle 17 is directed toward the center of the throttle valve 2 in FIG. 1).

Next, since the discharge pressure of the pump 24 generally pulsates and is thought to fluctuate greatly, it is necessary to keep it constant using the constant pressure valve device 19.

That is, when the pressure on the downstream side of the constant pressure valve 22 is higher than the specified value, the constant pressure valve 22 moves in the closing direction against the spring 21 (reducing the air passage cross-sectional area), and the pressure is lower than the specified value. At this time, the spring 21 moves the nozzle 17 in the opening direction (increasing the air passage cross-sectional area) to keep the pressure just in front of the nozzle 17 constant.

If the discharge pressure of the pump 24 fluctuates significantly, it is preferable to install two constant pressure valve devices 19 in series.

In other words, the first constant pressure valve device keeps the pump's discharge pressure almost constant at a level slightly higher than the specified value, and the next constant pressure valve device adjusts it to the specified value correctly to keep the discharge pressure constant. .

The ball valve 1 is a simple structure of the constant pressure valve device 19.
It is 8.

That is, when the pressure immediately before the nozzle 17 is larger than the specified value, the air leakage area is increased by the ball valve 18, and when it is smaller than the specified value, the air leakage area is reduced, and the air leakage area is increased by the ball valve 18. It keeps the pressure constant.

In general, the constant pressure valve device 19 and the ball valve 18 can keep the pressure immediately in front of the nozzle 17 constant and the pressure (negative pressure) acting on the fuel injection part 8 constant. It is preferable to include a damper chamber 23 as shown in FIG. , ball valve 18, etc. can be removed).

Alternatively, the constant pressure valve device 19 may be of a type that releases pressure to the suction side of the pump 24.

This is shown in Figure 2. When the pressure on the upstream side of the constant pressure valve 22' is larger than the specified value, the air leakage area is increased (the constant pressure valve 22' moves in the direction of opening), and the pressure on the upstream side of the constant pressure valve 22' is larger than the specified value. When the air leakage area is small, the air leakage area is reduced to keep the pump discharge pressure constant.

As described above, according to the present invention, the jet flow ejected from the nozzle 17 has a very high jet speed, so that the fuel is atomized extremely well.

Therefore, the ability to distribute fuel to each cylinder, the startability and responsiveness of the engine are excellent, and fuel efficiency can be greatly improved, and harmful components in exhaust gas are also reduced.

In this case, the higher the ejection velocity of the jet from the nozzle 17, the better the atomization of the fuel will be, but on the other hand, the negative pressure acting on the fuel injection part 8 will become larger, and the effective cross-sectional area of the fuel jet 7 (metering needle 6)
must be made extremely small, so it is desirable to install an air bleed jet 16 as shown in the figure to weaken the negative pressure and facilitate manufacturing.

Incidentally, if a spiral groove is formed in the nozzle 17 so that the air is ejected in a spiral motion, the atomization of the fuel and the mixing with the air can be further improved.

It goes without saying that the pump 24 does not need to be dedicated only to atomizing fuel, and that air may be guided to the nozzle 17 from a pump for other purposes (in the case of a two-stroke engine, it may be used in the crank chamber). It is also conceivable to introduce the pressure of

FIG. 4 shows an embodiment in which the fuel ejected from the fuel injection part 8 in FIG. 1 is directly supplied to the downstream part of the throttle valve 2.

That is, the fuel metered by the fuel jet and the metering needle (which is omitted because it is the same as in Fig. 1 and also omitted in Fig. 3) is ejected from the fuel injection part 8, and is ejected from the nozzle. It is atomized by the high-speed jet flow from 17 and is directly supplied to the downstream side of the throttle valve 2.

In this case, the diameter of the atmospheric passage 26 (
Since the cross-sectional area (cross-sectional area) is sufficiently large, even if the negative pressure acting on the nozzle 27 is extremely strong, the pressure in the atmospheric passage 26 is approximately atmospheric pressure.

Therefore, the pressure (negative pressure) acting on the fuel injection part 8 due to the high-speed jet flow from the nozzle 17 is always kept constant as in FIG. 1.

In order to further promote atomization of the fuel ejected from the nozzle 27, the nozzle 27 may be extended as shown by the two-dot chain line, and the high-speed jet from the nozzle 29 may collide with this tip.

Figure 5 shows a twin-barrel carburetor made by integrally forming two of the above-mentioned carburetors, and in order to simplify the structure, one metering needle (not shown) and one fuel jet 7 are provided. The intake flow rate detection diaphragm device 11 shown in FIG.
This allows each plate valve 3 to be opened and closed at the same time.

In a four-cylinder engine, each carburetor serves two cylinders, and the distribution jet 30 divides the fuel from the fuel jet 7 into two equal parts.

(The fuel flow rate ejected from each fuel injection part 8 is made equal.) 31 is a balance passage, which makes the negative pressure behind each plate valve 3 equal.

If an air bleed jet is installed, it should be installed immediately in front of each fuel injection part 8.

Incidentally, if the fuel that has passed through the distribution jet 30 is further divided into two equal parts as shown in FIG. (Needless to say, the negative pressures acting on the fuel jets 8 are made equal to each other), the fuel from the fuel jet 7 is divided into four equal parts, and if this is applied to a four-cylinder engine, the seventh As shown in the figure, fuel can be injected from the fuel injection part 8 for each cylinder (independently).

32 is an intake pipe.

Next, FIG. 8 shows an embodiment in which an intake flow rate detection plate is used in place of the plate valve 3 and the intake flow rate detection diaphragm device 11 in FIG. 1.

That is, in FIG. 8, the intake flow rate detection plate 33 is
When the intake air passes through, it receives a valve opening torque due to the pressure difference before and after it, and is opened to the opening degree that balances the valve closing torque given in advance by a spring or the like to the intake flow rate detection plate 33, and the intake flow rate is detected. do.

At the same time, as in FIG. 1, the metering needle moves to change the effective cross-sectional area of the fuel jet (both not shown) and meter the fuel to match the intake flow rate.

In this case, the upstream part 35 of the intake flow rate detection plate 33 with respect to the rotating shaft 34 has an appropriate inclination angle so that when it approaches the fully open state, it receives airflow and can easily open fully, and the downstream part 36 has an appropriate inclination angle. As shown in the figure, it is bent at a position slightly higher than the rotating shaft 34 to prevent collision with the throttle valve 2.

FIG. 9 shows an example in which the eccentricity of the intake flow rate detection plate 33 with respect to the rotating shaft 34 is extremely increased.

In FIG. 9, reference numeral 37 denotes a damper chamber, which is provided to ensure operational stability of an intake flow rate detection plate 33' that detects the intake flow rate taken into the engine.

In this case, when the throttle valve 2 is suddenly opened, the intake flow rate detection plate 33' is also suddenly opened, but the negative pressure acting on the fuel injection part 8 is
Because it is always kept constant by high-speed jets from
Problems such as dilution of the air-fuel mixture do not occur (this also applies to other embodiments of the present invention).

Therefore, the damping effect of the damper chamber 37 does not need to be strong, and it is sufficient to prevent the intake flow rate detecting plate 33' from opening too much due to inertia and wobbling due to intake pulsation.

Needless to say, the metering needle 6 is moved by a lever 38 fixed to the rotating shaft 34' and a driving lever 39 interlocked with the lever 38, and the effective cross-sectional area of the fuel jet 7 is changed to measure the fuel commensurate with the intake flow rate. stomach.

Note that in order to smoothly operate the metering needle 6, a roller 15 is used, and the roller 15 and the drive lever 39 are brought into contact by a spring 40 (also in FIG. 1, the roller 15 and the lever 5 are -Not shown-
(contacted by).

41 is a small venturi.

FIG. 10 shows an embodiment of the invention shown in FIG. 8 equipped with a damper device.

That is, in FIG. 10, the negative pressure introduction chamber 43 has the negative pressure passage 4.
Negative pressure behind the intake flow rate detection plate 33 is introduced through the rotation shaft 3, and the negative pressure introduction chamber 43 and the damper chamber 45 are connected to the rotation shaft 3.
A damper plate 44 fixed to the parts 4 communicates with each other through an extremely small leakage area.

Therefore, the pressure in the damper chamber 45 cannot immediately follow changes in the pressure in the negative pressure introduction chamber 43 (pressure behind the intake flow rate detection plate 33), so if the pressure behind the intake flow rate detection plate 33 suddenly changes, Torque is generated in the damper plate 44 that prevents rapid movement (opening/closing action) of the intake flow rate detection plate 33.

This prevents the intake flow rate detection plate 33 from opening too much and wobbling.

The embodiment shown in FIG. 12 uses an intake flow rate detection piston device 48 as the intake flow rate detection device.

Its operating principle is the same as that of the SU type variable venturi carburetor, so a description thereof will be omitted.

52 is a metering needle, 51 is a fuel injection part, 50
53 is a fuel jet (the tip of the fuel jet 50 serves as the fuel injection part 51), and 53 is a nozzle from which a high-speed jet of air or the like is ejected, and the negative pressure acting on the fuel injection part 51 is kept constant at all times. It is.

FIG. 11 shows an embodiment in which the fuel ejected from the fuel injection part 8 in FIG. 1 is directly supplied to the downstream side of the throttle valve 2 while preventing the fuel from adhering to the throttle valve 2 as much as possible.

That is, in FIG. 11, when the fuel metered to match the intake flow rate by a fuel jet and a metering needle (both not shown) is ejected from the fuel injection part 8 (located near the throttle valve 2), The particles are atomized by a high-speed jet from the nozzle 17 and directly supplied to the downstream side of the throttle valve 2 through a hole 46 formed in the throttle valve 2 .

As a result, almost no fuel adheres to the throttle valve 2.

Note that it is preferable from the viewpoint of fuel distribution that the hole 46 (and thus the fuel injection part 8 and nozzle 17) be placed as close to the center of the throttle valve 2 as possible.

As described above, the present invention provides an intake flow rate detection device (a plate valve and an intake flow rate detection diaphragm device) that operates according to the intake flow rate in a carburetor that supplies fuel to an engine by ejecting fuel from a fuel jet from a fuel injection part. , an intake flow rate detection plate, an intake flow rate detection piston device, etc.) to measure the fuel by changing the effective cross-sectional area of the fuel jet, and further to collide a high-speed jet with the fuel jet to adjust the pressure acting on the fuel jet. Since it is kept constant, the fuel ejected from the fuel injection part is extremely well atomized, resulting in excellent fuel distribution to each cylinder, excellent engine startability and responsiveness, and greatly improved fuel efficiency (
improvement).

In the present invention, fuel is injected from a single point only from the fuel injection part, but a low-speed fuel system in a normal fixed venturi carburetor may also be used in combination, and this allows for idling adjustment (mixture ratio adjustment). This has the advantage that the adjustment results do not affect the (medium) high intake flow rate region.

[Brief explanation of drawings]

Figures 1, 3, 4, 8, 9, 11, and 12 are cross-sectional views of the carburetor according to the present invention, Figure 2 is a cross-sectional view of the constant pressure valve device, and Figures 5 and 6 are
・Figures 7 and 10 are diagrams of a vaporizer according to the present invention.

Claims (1)

[Claims] (1) In a carburetor that supplies fuel to an engine by ejecting fuel from a fuel jet from a fuel injection part, the effective cross-sectional area of the fuel jet is changed by an intake flow rate detection device that operates according to the intake flow rate to fuel the engine. A vaporizer characterized in that the pressure acting on the fuel injection part is kept constant by impinging a high-speed jet on the fuel injection part, and the fuel ejected from the fuel injection part is atomized. .