JPH0240862B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to an air bleed device used in a carburetor that supplies air-fuel mixture to an automobile engine.

[Background technology]

BACKGROUND ART Air bleed devices convert fuel into an emulsion to promote fuel vaporization and atomize the fuel, and various types of air bleed devices have been conventionally provided.

However, in the conventional air bleed device, the contact area between the fuel and the air is small, and therefore, the emulsion of the fuel is not sufficient, so the air bleed device is provided in several stages.

[Purpose of the invention]

The present invention has been devised in view of these points, and its object is to provide an air bleed device in which fuel can be sufficiently emulsified in one stage.

[Disclosure of the invention]

Therefore, the air bleed device according to the present invention includes a fuel orifice provided at the other end of the fuel pipe whose one end is connected to the fuel chamber, and a fuel orifice having a larger inner diameter than the fuel orifice and whose one end is located above the fuel orifice. and an expansion flow path connected to the fuel orifice and the other end connected to the ventilate, and a gap crossing between the fuel orifice and the expansion flow path is an air orifice communicating with the outside air intake part. As a result, when fuel flows from the fuel orifice to the expanded flow path, the air that flows into the expanded flow path at the same time forms a spiral flow surrounding the fuel, increasing the contact area between the fuel and air and promoting their mixing. , the fuel is sufficiently emulsified.

The present invention will be described in detail below based on illustrated embodiments. The illustrated carburetor is of a downdraft variable ventilator type, and the ventilator is formed in an annular shape. First, the structure of the carburetor will be explained. In the figure, 1 is a housing, which includes an upper housing 11 and a main housing 1.
2, an air passage with a circular cross section passes through the center vertically, an annular fuel reservoir 13 surrounding the air passage is provided at the bottom, and a gasket 1 is provided on the outer surface.
The inside of the float chamber 16 , which is fixed via the fuel tank 5 , and the fuel reservoir 13 communicate with each other through a supply path 29 . A movable body 3 is disposed within the air passage and is coaxial with the air passage and movable up and down along the axial direction.
A throat portion 2 is provided which projects inward and has a reduced diameter so as to form an annular ventilate between the upper outer surface and the outer surface of the upper portion. In the throat portion 2, an annular orifice 5 communicating with the fuel reservoir 13 is provided.
is open all the way around the smallest inner diameter, and fuel is sucked out from the annular orifice 5 into the air passage by the negative pressure generated by the air flowing down the ventilate. On the other hand, what responds to the accelerator pedal is a throttle plate 4 installed in the lower air passage of the housing 1. When the accelerator pedal is depressed, the throttle plate 4 increases or decreases the cross-sectional area of the mixture flow passage by rotating around its axis. do. The movable body 3 is moved up and down not by the accelerator pedal, but by the degree of negative pressure in the air passage, particularly in the vicinity of the ventilate, thereby changing the ventilate area.

To explain these points in more detail, an air cleaner is connected to the upper end of the upper housing 1 that constitutes the housing 1, and an intake manifold is connected to the lower end of the main housing 12. An upper throat portion protrudes from the surface, and a lower throat portion protrudes from the upper inner peripheral surface of the main housing 12. These upper and lower throat portions form the throat portion 2, and at the same time, the upper throat portion and the lower throat portion An annular orifice 5 is formed as a gap with the throat portion, and an annular expansion chamber 18 is formed around the annular orifice 5. fuel reservoir 1
3 is connected to the expansion chamber 18 and to the annular orifice 5 through a fuel pipe 19 whose upper end serves as a fuel orifice 20 and an expansion channel 21 . 2 in the diagram
5 is a float in the float chamber 16;
26 is a needle valve, and 27 is an adjusting screw. Further, the heat exchange flow path 28 provided in the throat portion 2 is used to prevent icing by flowing cold water from the engine.

Next, the movable body 3 will be explained. This movable body 3
is supported slidably in the axial direction of the air passage by a shaft 31 that is erected from the center of the throttle plate 4 stacked on the upper surface of the main throttle plate 30 fixed in the lower end opening of the main housing 12. and a cone portion 32 for controlling the flow rate of air at the top;
A piston 34 forming a hydraulic damper 8 between the lower piston portion 33 and the shaft 31.
It is composed of. The piston part 33 is connected to the shaft 3
A negative pressure chamber 7 is formed internally between the piston part 33 and the head part 40 attached to the lower end of the piston part 33. communicates with the air passage below the
A return spring 42 is housed inside. The piston 34 is attached via a shaft 37 to a retaining screw 36 having a cone portion 32 screwed onto its tip, and is located in an oil reservoir 38 bored in the shaft 31, and is located below the shaft 31. The movable body 3 is provided with a valve body 35 that reduces the area through which oil passes during operation, and forms a hydraulic damper 8 that brakes the downward movement of the movable body 3. 39 is a ventilation hole.

The main throttle plate 30 has a plurality of holes 5.
1 are arranged at equal intervals, and the throttle plate 4 superimposed on the upper surface of the main throttle plate 30 also has the same number of holes 52 as the holes 51, etc., arranged at equal intervals. The center of the throttle plate 4 passes through the center of the main throttle plate 30 and projects downward, and a gear 53 is attached to the lower end. This gear 53 is the throttle shaft 6 that responds to the accelerator pedal.
The rotation of the throttle shaft 6 causes the throttle plate 4 to rotate around the axis in the air passage, thereby connecting the hole 51 of the main throttle plate 30 and its own hole 52. The amount of overlap between the two is changed, thereby controlling the flow rate of the air-fuel mixture. 55 is a spring for returning the throttle plate 4, and 56 is a heat insulating plate for supporting the throttle shaft 6. The throttle plate 4 and the head part 40 are connected by a pin 57, and the cone part 32 and the piston part 33 are connected to the head part 40 by a pin 58, so that as the throttle plate 4 rotates, the movable body 3 is also designed to rotate around its axis. This is because the next motion can be obtained by rotating the movable body 3 as well. In other words, when an excessively rich air-fuel mixture is sent to the engine when starting the engine, and the inside of the engine cylinder becomes wet, it is necessary to send a large amount of air into the engine. For this purpose, when the accelerator pedal is fully depressed, the throttle plate 4 rotates and becomes fully open, and at the same time, the rotation of the movable body 3 forcibly moves the movable body 3 downward in correspondence with the cam means 10, and the ventilator is opened. The area is also increased. Here, as the cam means 10, a pin 60 protruding from the cone portion 32 of the movable body 3 and a guide rod 61 protruding from the inner surface of the upper housing 11 are used. The bent part at the tip of the guide rod 61 connects to the movable body 3 via the pin 60.
It is designed to push down.

Now, the air bleed device 9 according to the present invention includes the fuel orifice 20 at the upper end of the fuel pipe 19 described above.
and the expansion channel 21 that continues above. That is, one or more fuel pipes 1 are provided at equal intervals in the main housing 12.
Although the fuel orifice 20 at the upper end of the fuel orifice 20 and the expansion passage 21 provided in the upper housing 11 are aligned in the axial direction, there is a gap between them that is shaped to surround the air passage. The air gap is connected to the upper part of the air passage by a perforated air pipe 23 in the upper housing 11. When fuel is sucked up from the fuel orifice 20 to the expansion passage 21 by negative pressure in the ventilate, air is simultaneously sucked up from the air orifice 22, which is the gap. Further, the inner diameter of the expansion channel 21 is larger than the diameter of the fuel orifice 20.

However, in this air bleed device 9,
Due to the negative pressure generated by the air flow flowing down the ventilate, the fuel flows from the fuel reservoir 13 to the annular orifice 5 through the fuel orifice 20.
When flowing into the expansion passage 21 through the fuel orifice 20, the fuel flows into the center of the expansion passage 21 because the expansion passage 21 has a larger diameter than the fuel orifice 20. On the other hand, air flows from the air orifice 22 into the expanded flow path 21, and at this time it forms an annular flow surrounding the fuel. In the expanded flow path 21, the pressure at the center is lower than at the periphery, so the air flows toward the center where the fuel flows, but the flow toward the center becomes a vortex. As a result, the air flows in a spiral shape. Therefore, air and fuel have a large contact area with each other, and their contact time is also long.
Furthermore, since the air flow is spiral, the air and fuel are reliably mixed. In addition, in this embodiment, the expansion channel 21 and the orifice 5
An expansion chamber 18 is provided between the expansion chamber 18 and the expansion of the fuel and air that have reached the expansion chamber 18, further promoting emulsion of the fuel and making the emulsion sufficiently and uniformly formed.

Next, the operation of the carburetor will be explained. The fuel in the float chamber 16 flows from the fuel reservoir 13 to the fuel pipe 19 as described above. If the engine is running, the negative pressure during the suction stroke causes the fuel to be sucked up from the fuel orifice 20 to the expansion channel 21, and is premixed with air passing through the air orifice 22, and at the same time expands. do.
This air-fuel mixture then enters the expansion chamber 18 and further expands, receiving heat from the engine cooling water flowing through the heat exchange passage 28, and due to the pressure drop caused by the air flow flowing down the ventilate, the air-fuel mixture enters the annular orifice 5. The fuel is sucked out into the air passage, and in the final expansion part 65 where the cross-sectional area of the lower part of the air passage becomes larger, the fuel is made into finer particles. Since fuel is supplied from all around the throttle plate 4 and emulsion formation is promoted in the premixing stage, a homogeneous mixture is created at each part, and the throttle plate 4
When passing through the hole 52 of the main throttle plate 30 and the hole 51 of the main throttle plate 30, the air-fuel mixture becomes a swirl flow from the positions of both holes 51 and 52, and is distributed and supplied to each cylinder. When the accelerator pedal is depressed, the throttle plate 4 rotates to increase the air-fuel mixture flow rate. As the degree of negative pressure in the intake manifold and the lower part of the air passage increases, the suction force of the movable body 3 in the negative pressure chamber 7 also increases.
The movable body 3 is moved downward against the return spring 42. As a result, the area of the ventilate increases. This movement is controlled by the balance between the spring pressure of the return spring 42 and the degree of negative pressure in the final expansion section 65 in the air passage. Work as you wish. However, when the accelerator pedal is suddenly depressed, such as during sudden acceleration, the originally rapid downward movement of the movable body 3 is suppressed by the damper 8, and an increase in the area of the ventilate is suppressed. The air flow velocity becomes even higher, and as a result, the rich air-fuel mixture necessary for rapid acceleration is supplied for a while. The movable body 3 eventually moves to its original position, but the engine moves smoothly during this time.

Note that the air bleed device 9 can of course be used not only in the illustrated type of vaporizer but also in any type of vaporizer.

〔Effect of the invention〕

As described above, in the present invention, the fuel flowing from the fuel orifice through the gap into the expanded flow path is
Air is taken in from the air orifice between the fuel orifice and the expansion channel, and the air at this time is formed as a gap where the air orifice crosses between the fuel orifice and the expansion channel. It is connected to the fuel flowing into the expansion channel from its entire circumference, and it prevents the diffusion of fuel after it enters the expansion channel with a large inner diameter from the fuel orifice, and the air that enters the expansion channel. In addition to forming a spiral flow, the fuel and air are mixed (emulsion) sufficiently and homogeneously, and a sufficient function can be obtained with just one stage installation. is simple and can be easily installed inside the vaporizer.

[Brief explanation of drawings]

FIG. 1 is a cutaway perspective view of a carburetor equipped with an embodiment of the present invention, and FIG. 2 is a sectional view of the same, in which 9 is an air bleed device, 19 is a fuel pipe, 20 is a fuel orifice, and 21 is a sectional view of the same. 22 represents an air orifice.

Claims (1)

[Claims] 1. A fuel orifice provided at the other end of the fuel pipe whose one end is connected to the fuel chamber, and which has a larger inner diameter than the fuel orifice, and whose one end is connected above the fuel orifice and whose other end is connected to the ventilate. An air bleed device characterized in that the air bleed device is provided with an expanded flow path, and a gap that crosses between the fuel orifice and the expansion flow path is an air orifice that communicates with an outside air intake section.