JPH087084Y2 - Vaporizer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to a carburetor mounted on an engine of an automobile or the like.

[Prior Art] In this type of vaporizer, as shown in FIG. 4, a hollow slow jet holder 52 having a slow jet 51 at the lower end is provided.
It is usual that the upper end 52a and the fuel passage 53 for throwing are located at substantially the same height. In such a structure, when the fuel 54 in the slow jet holder 52 is sucked up by the negative pressure and reaches the upper end 52a thereof, the fuel 54 is mixed with the air 56 introduced from the bleed air passage 55, and then the fuel passage 53 for throwing is discharged. It is designed to be guided to the idle port side.

However, such a configuration has a liquid level of the fuel 54 in the slow jet holder 52 when the engine is stopped,
The difference from the upper end 52a of the slow jet holder 52 (hereinafter referred to as the head difference) is relatively small. Therefore, the change in the head difference causes the fuel 5 at the upper end 52a of the slow jet holder 52 to change.
The impact on the supply of 4 will be large. That is, even if the head difference becomes large when the vehicle is tilted, the negative pressure from the idle port at the upper end 52a of the slow jet holder 54 is substantially constant, so when the head difference becomes large, the supply amount of the fuel 54 decreases, When the difference becomes smaller, the supply amount of the fuel 54 tends to increase. In this way, when the fuel supply amount becomes unstable due to the change in the head difference, the fuel 54
As shown in FIG. 5, fuel 54 is not mixed well with 56
Become lumps and are likely to be intermittently conveyed from the throw fuel passage 53 to the idle port side. As described above, when the air-fuel mixture has an intermittent flow, hunting or the like is likely to occur, and idle rotation when the vehicle leans becomes unstable.

Further, the smaller the head difference when the engine is stopped, the larger the ratio of the change amount of the head difference when the vehicle is leaning, so that the problem is more likely to occur.

In order to eliminate such a problem, as a prior art of the present invention, for example, as shown in Japanese Utility Model Laid-Open No. 63-132862, while the upper end of the slow jet holder is positioned above the fuel passage for throw, There is also a so-called opposed type in which a communication hole for communicating the internal passage and the fuel passage for throwing is provided in the middle in the lateral direction. However, according to this, since the fuel and the air introduced from the bleed air passage can be opposed to each other to promote the mixing of the two, a stable air-fuel mixture can be supplied to the engine and combustion can be stabilized. Has the effect of

[Problems to be Solved by the Invention] However, in the structure as shown in the above-mentioned prior art, when the outside air is in a low temperature and high humidity in winter, moisture contained in the air introduced from the bleed air passage is formed. However, the temperature of the slow jet holder is lowered due to the mixing of the fuel and air (when the fuel and air are mixed, the temperature is lowered by about 10 ° to 15 ° C. due to the heat of vaporization). Such a problem is unlikely to occur after mixing fuel and air, but is likely to occur in a narrow passage through which only air passes. For this reason, if the bleed air passage is closed on the head side of the slow jet holder due to freezing and the amount of air is insufficient, the air-fuel ratio of the mixed base becomes overrich, and engine stall may occur.

The present invention aims to solve the above problems all at once.

[Means for Solving the Problem] In order to achieve the above object, the present invention employs the following configuration.

That is, in the carburetor according to the present invention, a hollow slow jet holder having a slow jet at its lower end has a lower end portion of a head continuing downward from the upper end located near a starting end portion of a fuel passage for throwing, and said upper end portion. Is located in the vicinity of the bleed air passage that is provided above the throw fuel passage, and an annular passage that connects the throw fuel passage and the bleed air passage is provided on the outer periphery of the head. Characterize.

[Operation] With such a configuration, when the engine is idling or rotating at low speed, the fuel introduced into the slow jet holder through the slow jet is stored in the slow jet holder by the negative pressure of the engine. It is sucked up at the top. Then, while being mixed with the air introduced from the bleed air passage, it descends through the annular passage provided on the outer periphery of the head of the slow jet holder and is introduced into the fuel passage for throw. Moreover, according to such a structure, the lower end of the head continuing downward from the upper end of the slow jet holder is located in the vicinity of the starting end of the throw fuel passage, and the upper end is located above the throw fuel passage. Since they are located in the vicinity of the bleed air passages provided separately from each other, the head difference can be increased without increasing the vertical dimension between the slow jet and the throw fuel passage. Therefore, it is possible to prevent the fuel supplied from the upper end of the slow jet holder from becoming unstable when the vehicle or the like is tilted while minimizing the structural change in the carburetor.

[Embodiment] An embodiment of the present invention will be described below with reference to FIGS. 1 to 3.

This carburetor is mounted on an engine of an automobile or the like, and is provided with a slow jet holder 5 between an idle port 3 opening to an intake passage 2 in a barrel 1 and a float chamber 4.

In the barrel 1, a small venturi 6, a large venturi 7, a throttle valve 8 and the like are arranged. Atmospheric pressure is introduced into the float chamber 4 through an air vent 9, and fuel is introduced through a needle valve or the like (not shown) provided in the float 10.

The slow jet holder 5 has a slow jet at the lower end 5a.
It is a hollow one provided with a tube 12 having 11 and a holder main body 13 holding this tube 12, and the fuel in the float chamber 4 is introduced into an internal fuel passage 14. The upper end 5b of the slow jet holder 5 is located in the vicinity of the bleed air passage 16 which is provided above the throw fuel passage 15 with a space therebetween. The head portion 5c of the slow jet main body 5 continuing downward from the upper end 5b is located at the lower end portion in the vicinity of the starting end portion of the throw fuel passage 15. Therefore, the head portion 5c is located closer to the bleed air passage 16 than the throw fuel passage 15, and is set as long as possible. An annular passage 17 that connects the throw fuel passage 15 and the bleed air passage 16 is provided on the outer periphery of the head portion 5c. Throw fuel passage 15
Has a starting end portion formed in a horizontal direction, and an idle adjusting screw 18 and a slow cut solenoid valve 19 are disposed near the idle port 3 at the end. The annular passage 17 has, for example, an outer diameter of about 6 mm and an inner diameter (the head of the slow jet holder 5).
(Corresponding to the outer diameter of 5c) is set to about 4.5 mm and provided in the up-down direction, and the upper end thereof is continuous with the bleed air passage 16 and the lower end is continuous with the throw fuel passage 15.

With such a configuration, when the engine is idling or running at low speed, the slow jet 11
The fuel introduced into the slow jet holder 5 via the is sucked up by the upper end 5b of the slow jet holder 5 by the negative pressure downstream of the throttle valve 8. Then, as shown in FIG. 3, the air introduced from the bleed air passage 16
Slow jet holder 5 while being mixed with 20 and being miniaturized
It is dropped in a film form from the annular passage 17 provided on the outer periphery of the head portion 5c of the head 5c and introduced into the fuel passage 15 for throwing.
Therefore, since the atomized fuel 21 is discharged from the idle port 3 together with the air 20 and supplied to the combustion chamber, it is possible to stabilize combustion and improve idle stability. it can.

Further, the upper end 5b of the slow jet holder 5 is located above the throw fuel passage 15, that is, the head 5c.
Is set to be as long as possible between the throw fuel passage 15 and the bleed air passage 16, so that the vertical dimension between the slow jet 11 and the throw fuel passage 15 should be increased. Therefore, a large head difference can be obtained. Therefore, it is possible to prevent the fuel supplied from the upper end 5b of the slow jet holder 5 from becoming unstable when the vehicle is tilted while minimizing the structural change in the carburetor. That is, according to this, even when the vehicle is leaning, the slow jet holder 5 is caused by the negative pressure of the engine.
The fuel sucked inside is guided from the upper end 5b to the annular passage 17 and drops while mixing with the air 20. Therefore, the air-fuel mixture introduced into the slow fuel passage 15 is unlikely to be an intermittent flow, and the atomized fuel is led out together with air from the idle port 3 and supplied to the combustion chamber.
As a result, it is possible to stabilize the combustion when the vehicle is leaning and to effectively suppress the irregularity of idle rotation.

Moreover, in such a case, the fuel is led out from the upper end 5b of the slow jet holder 5 and descends the outer periphery of the head portion 5c thereof, so the slow jet holder 5 is introduced from the bleed air passage 16. Not directly exposed to air 20. Therefore, it is possible to effectively prevent the head portion 5b side of the slow jet holder 5 from being frozen due to moisture in the air during the winter season or the like. Therefore, the air 20 can be stably introduced from the bleed air passage 16 to the fuel passage 15 for throwing, so that the disturbance of the air-fuel ratio of the air-fuel mixture can be suppressed, and the engine stall can be effectively prevented from occurring. it can. Further, the fuel 21 is sucked out from the upper end 5b of the slow jet holder 5, and the annular passage 17 is provided on the outer periphery thereof.
By lowering, the contact area between the air 20 and the fuel 21 can be widened as compared with the conventional one.
Therefore, the mixing of the air 20 and the fuel 21 can be effectively promoted, and atomization of the fuel 21 can be effectively enhanced.

Note that, in FIGS. 2 and 3, the throw fuel passage and the like are shown in reverse to those in FIG.

Although one embodiment of the present invention has been described above, it goes without saying that the present invention is not limited to the above embodiment. For example, the slow jet holder may be composed of a single piece.
Further, the height position of the upper end of the slow jet holder can be changed in the upper position of the throw fuel passage in accordance with the negative pressure of each engine.

[Advantage of Invention] Since the present invention has the above-described configuration, the head portion of the slow jet holder can be set as long as possible, and as a result, the fuel and air can be sufficiently mixed. An annular passage can be provided to stably mix the air introduced from the bleed air passage with the fuel drawn from the inside of the slow jet holder, without being influenced by the posture of the carburetor. In addition, it is possible to effectively promote miniaturization of the fuel. Therefore, it is possible to provide a carburetor having an excellent function of adjusting the air-fuel mixture, which can effectively prevent the idle rotation from being disturbed by the posture of the vehicle or the like.

Moreover, since the slow jet holder is not directly exposed to the air introduced from the bleed air passage,
It is possible to effectively prevent the head side from freezing due to moisture in the air. Therefore, since the air can be stably introduced from the bleed air passage, the disturbance of the air-fuel ratio of the air-fuel mixture can be suppressed, and the engine stall can be effectively prevented from occurring.

[Brief description of drawings]

1 to 3 show an embodiment of the present invention, FIG. 1 is a vertical cross-sectional view showing the entire structure, FIG. 2 is a vertical cross-sectional view showing the main parts, and FIG. is there. 4 and 5 show a conventional example, FIG. 4 is a vertical sectional view corresponding to FIG. 2, and FIG. 5 is a vertical sectional view for explaining a defect. 5 …… Slow jet holder 5a …… Lower end 5b …… Upper end 5c …… Head 11 …… Slow jet 15 …… Slow fuel passage 16 …… Bleed air passage 17 …… Circular passage

Claims (1)

[Scope of utility model registration request] 1. A hollow slow jet holder having a slow jet at its lower end, the lower end of a head portion continuing downward from the upper end is located in the vicinity of the starting end of the throw fuel passage, and the upper end is said slow fuel. A carburetor characterized in that it is located near a bleed air passage provided apart from the passage and an annular passage is provided on the outer periphery of the head portion to connect the throw fuel passage and the bleed air passage. .