JPS5963355A - Carburetor - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a carburetor of an internal combustion engine. A jet communicating with a fuel discharge port is provided in the carburetor, and the air-fuel ratio to be supplied is controlled by a needle moving back and forth to the jet. I know about vaporizers. A needle guide is provided around this needle.

Mainly when the needle operates with high air collapse, air is sucked into the jet through this needle guide, making the air-fuel ratio leaner.

This may result in a decrease in torque.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems and provide a carburetor that provides high engine output under high loads.

The structure of the carburetor according to the present invention has a needle for metering the fuel to be discharged in cooperation with a jet formed in the float chamber of the carburetor, and a hollow space is provided around the needle with a gap therebetween. In a vaporizer in which a cylindrical needle guide is arranged, the needle guide is provided with a through hole for venting air.

The implementation f11 of the present invention will be described and explained below with reference to the drawings.

FIG. 1 is a schematic cross-sectional view of an embodiment of a vaporizer to which the present invention is applied. This carburetor is configured as a double carburetor having two intake passages 2 and 3 in a carburetor body 1. −
A venturi 4 is formed in the next flll1 passage 2, and a primary throttle valve 5 is disposed downstream of the venturi 4, which is a general structure. still.

Although not shown, a fuel discharge nozzle is opened in the ventili 4.

A secondary throttle valve 6 is arranged in the secondary passage 3,
- The downstream throttle valve 5 and the secondary throttle valve 6 are connected by a link 7 such that the secondary throttle valve 6 opens when the load is high. A secondary nozzle 8 is opened upstream of the secondary throttle valve 6.

Furthermore, air pulp 9 is arranged upstream thereof. The air pulp 9 is mounted eccentrically on the shaft 10, so that the air pulp 9 can be opened in proportion to the amount of air passing through the secondary passage 3 after the secondary throttle valve 6 is opened.

A fuel passage 12 leads from the carburetor float chamber 1.111 to a secondary nozzle 8 opening into the secondary passage 3 with a fuel passage (not shown) leading to a nozzle opening into the venturi 4 of the primary otq passage 2. Formed. A jet 13 opening with a taper is formed at the float chamber side entrance of the secondary field old passage 12.

A needle 14 extending vertically is provided to engage with this jet 13, and the needle 14 is connected to the air pulp shaft 1o by a link 15, and is moved in the vertical direction according to the opening degree of the air pulp 9. l.

The amount of fuel to be discharged from the secondary nozzle 8 is determined by the size of the gap between the jet 13 and a portion of the lower end. A needle guide 16 is arranged around the needle 14.

FIG. 2 is an enlarged detailed view of the part where the needle 14 of the float chamber 11 of the vaporizer is arranged, and the arrangement of the wall surface and other parts is
Although it looks a little different from the figure, Figure 2 is said to be closer to the actual shape.

Reference numeral 17 indicates a wall of the carburetor body forming a float chamber, and reference numeral 18 indicates a wall of an air horn, and a suitable sealing function is provided between them except for necessary passages. Then, the primary side passage 2 and the secondary side passage 3 merge at the upstream part of the air horn, 7t,
The space 19 where the needle 1o is arranged (Figure 1) Ic is also the one where the air inside the air horn communicates.

The needle guide 16 has a hollow cylindrical shape, and the needle 14 is disposed in the hollow part to prevent unnecessary deflection of the needle 14. For example, the outer diameter of the needle 14 is 2.5 t between the needle 14 and the needle guide 16.
There is a gap as shown by the dimensions of the rvn and the inner diameter of the needle guide 16.

Vertical movement of the needle 14 is free. The dashed line indicated by 20 represents the fuel oil level. A hole 21 passing through the hollow wall of the needle guide 16 is provided below the oil level 20. Furthermore, eleven through holes 22 are provided above the oil level 20.

The above-mentioned carburetor is - next flll + throttle valve 50
The amount of air flowing through the primary elevation 1 passage 2 is controlled by rotation.
, fuel is discharged at the same time. -Next f1 xuro sotol valve 5
When the opening degree becomes large in a high nitrogen air mass region, the secondary full throttle valve 6 opens in conjunction with this. Air pulp 9 due to changes in air volume caused by engine load
is opened and fuel is discharged from the secondary nozzle 8. Depending on the amount of air flowing through the secondary passage 3 at this time,
The needle 14 linked to the air pulp shaft 10 moves up and down, and the space area between the needle 14 and the jet 13 allows one stream of fuel to be discharged.

When the air is high, the needle 14 moves upward and the space between the needle 14 and the jet 13 becomes wider, and more fuel is discharged. At this time, the intake air in the air horn is communicated to the inside of the needle guide 16, and
Due to the relatively large flow velocity in the region, some air flows into the fuel through the needle guide 16, and is sucked into the jet 13 along with the fuel flow tL.

For this reason, the fuel discharged 7 from the secondary nozzle 8 to the secondary 6111 passage 31 via the secondary passage 12 becomes insufficient, and the air-fuel ratio becomes thinner than a predetermined air-fuel ratio, making it difficult to obtain high output. The phenomenon in which air is sucked into the jet 13 through the fuel in the high air kl region has been confirmed as a result of experiments and observations, and the cause thereof has been estimated as explained above.

To prevent air from being sucked into the jet 13,
In the present invention, the needle guide 16 is provided with through holes 21,22. Although the through hole can be provided above or below the oil level, experimental results show that the through hole 21 is provided below the oil level.
It was found that the effect was greater when this is,
Air V hitting the oil surface in the hollow part of the needle guide 16
Normally, it does not have the pressure to enter the fuel, but due to fuel flow and pressure fluctuations, some of it is sucked in as bubbles, and becomes large particles as it rides on the fuel flow toward the jet. It seems to be Hime. On the other hand, is there J above the oil level? If the j through hole 22 is provided, of course this kan 1 hole 22
Although the air flowing from the air horn to the needle guide 16 is infinite, air can escape from the needle guide 16 under the oil surface and cannot be released.

For this reason, it seems to be more effective if the 1-1 through hole 21 is located below the oil level. (7) There are shellfish under the oil surface l111.1
By providing the TL 21, the air contained in the fuel within the needle guide 16 can exit into the fuel from the sides thereof, and may be located relatively far from the jet 13 or may grow into large particles. Flow to jet 13
This will allow you to rise above the surface of the liquid before climbing onto it. Therefore, the sky ζ(
3 ratio dilution is prevented.

As explained above, the air-fuel ratio control 1 is performed as expected in the carburetor which controls the fuel to be discharged by the needle and the jet, and this has the effect of improving the output of the engine using this trick.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view of a carburetor to which the present invention is applied, taken along the line F4'f, and FIG. 2 is a partially detailed view of the float chamber of the carburetor. 1... Carburetor body, 2.3... Intake 1m path. 5.6... Throttle valve, 8... Secondary [11+
nozzle. 9... Air pulp, 11... Float chamber. 12...Fuel passage, 13...Jet. 14... Needle, 16... Needle guide. Patent Applicant: Toyota Motor Corporation Patent Attorney: Akira Aoki, Patent Attorney, Kazuyuki Nishidate, Patent Attorney, Takashi Nakayama, Patent Attorney: Akira Yamaguchi

Claims (1)

[Claims] It has a needle for discharging fuel to be discharged in cooperation with a jet formed in a float chamber of the carburetor, and a hollow cylindrical needle guide is arranged around the needle with a gap therebetween. A vaporizer characterized in that the needle guide is provided with four holes for venting air.