JPS5857059A - Carburetor - Google Patents

Abstract

PURPOSE:To prevent the main fuel from being fed too late by providing an auxiliary fuel passage with its inlet directly opened to a constant oil level chamber and with its outlet opened to the portion between a venturi and throttle valve of a suction path in a carburetor with a main channel and low speed channel in a common form. CONSTITUTION:During the fuel feed, when the aperture of a throttle valve 3 is something like idling, the low speed fuel is sucked into a suction path 1 through the slow port 12 and idle port 13 of a low speed channel 6. When the aperture of the throttle valve 3 is increased and the outlet 19b of the auxiliary fuel passage 19 is located downstream the throttle valve 3, the fuel is fed from the inlet 19a opened to the constant oil level chamber 4 at a suction quantity corresponding to the suction negative pressure and the aperture area of the outlet 19b downstream the throttle valve 3. When the aperture of the throttle valve 3 is further increased and the venturi negative pressure is larger than the suction negative pressure, the fuel is gradually sucked into the suction path 1 through a main nozzle 8, and the negative pressure downstream the throttle valve 3 is made comparatively low, thereby the suction quantity from the outlet 19b is decreased.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a carburetor that can accurately supply the required fuel flow rate at the beginning of main fuel output.

As is well known, the carburetor fuel system is of a common type, in which the low-speed system fuel passage is branched from the main system fuel passage downstream of the main jet, and the low-speed system fuel passage is connected to the constant oil level chamber at 1a. There are connected and independent types.

Most of the carburetors of current automobile engines use a common fuel system, and the fuel that has passed through the main jet is switched between low-speed fuel and main fuel depending on the level of negative pressure acting on the fuel passages of both systems. distributed to In the common type, both systems have the advantage of maintaining pressure balance and making fuel control easy, but on the other hand, if the negative pressure in the low-speed system is strong at the beginning of the main fuel flow, there is a tendency to lag, especially when the main fuel starts to flow. In a carburetor whose venturi diameter is large relative to the amount of intake air, the negative pressure acting on the fuel passage in the main system does not increase in proportion to the amount of intake air, so there is a significant delay in the main fuel supply, resulting in a temporary fuel shortage. .

If this shortage is compensated for by the low-speed system, the negative pressure '' of the low-speed system will act more strongly, leading to a vicious cycle in which the main fuel will fall behind.

The present invention solves these problems of a carburetor in which the main system and the low speed system are common.

The purpose is to provide a carburetor that can accurately obtain the fuel flow rate required by the engine.

The present invention is characterized in that an auxiliary fuel passage is provided, which opens directly into the constant oil level chamber as an inlet, and whose outlet opens in a portion of the intake passage between the bench area and the throttle valve.

Embodiments of the present invention will be described below with reference to the drawings. In FIG. 1, l represents a downward air intake path.

2 is a venturi, 3 is a throttle valve, and 4 is a constant oil level chamber.

Reference numeral 5 indicates a main system, and 6 indicates a low speed system. Further, the low-speed system 6 branches from the fuel passage 9 downstream of the main jet 7 of the main system 5, and is branched from the slow boat 12. Low speed jets in the fuel passage 14 leading to the idle board) 13) 15. First low speed air bleed jet 16. Economizer 17. A second low-velocity air bleed jet 18 is provided.

An auxiliary fuel passage 19 is provided separately from the fuel system,
The port 19a opens directly into the constant oil level chamber 4, and the outlet 19b opens into a portion of the intake path 1 between the venturi 2 and the throttle valve 3.

This passage 19 also has a fuel jet 20. First air bleed jet 21. Economizer 22. A second air bleed jet 23 is provided.

The outlet 19b is preferably provided at a position where a part of the opening is downstream of the throttle valve 3 when the main fuel starts to come out in accordance with the fuel flow rate required by the engine. When a second-stage vaporizer is provided, such as in the case of a second-stage throttle valve, the opening is all located downstream of the throttle valve 3 when the second-stage throttle valve begins to open.

In this embodiment array configured in this way, the slow boat 12 of the low speed system 6 is used when the throttle valve 3 is at a small opening, such as the idle link opening, and the intake air amount is small and the intake negative pressure is high in the low speed rotation range. ．． Low-speed fuel is supplied from the idle port 13, and when the opening degree of the throttle valve 3 gradually increases and the outlet 19b of the auxiliary fuel passage 19 opens downstream of the throttle valve 3, it is sent from the constant oil level chamber 4. Fuel is now being sucked out, and this suction is determined by the suction negative pressure and the opening area of the outlet 19b on the downstream side of the throttle valve.

When the opening degree of the throttle valve 3 becomes larger and the venturi negative pressure becomes higher than the suction negative pressure, the main fuel will mainly be sucked out from the intake passage lK.

At this time, the negative pressure on the downstream side of the throttle valve in the intake passage 1 is lower than when the opening degree of the throttle valve is small, so the auxiliary fuel passage 1
The amount of suction from No. 9 has decreased compared to when the main fuel suction started.

Figure 2 shows the fuel flow from the common fuel system (8 tracks 1), the fuel flow from the auxiliary fuel passage 19 (C curve), and the total fuel flow ( FIG. 3 is a diagram showing how the intake air amount changes in curve A), and shows that when the common type suffers from a temporary fuel shortage, auxiliary fuel compensates for this. In this case, as can be seen from curve A, the fuel flow rate increases beyond the core wall, so the diameter of the main jet 7 is made smaller than before to reduce the fuel flow rate passing through the regular fuel system, and curve A is changed to the engine required fuel flow rate. (curve D). Also, in order to prevent the main fuel from being sucked out at the same time when the auxiliary fuel starts to come out, making the mixture too rich, the venturi diameter should be made large relative to the amount of intake air, or the intake negative pressure should strongly act on the low speed system 6. The effect of the auxiliary fuel can be increased by deliberately delaying the start of the main fuel.

As described above, according to the present invention, an auxiliary fuel passage having the same configuration as a conventional independent low-speed system is provided completely separately from the common type fuel system, and the outlet of this passage is connected to the venturi of the intake passage and the throttle valve. By opening in the area between the two, the delay in the main fuel flow can be compensated for by the fuel from the auxiliary fuel passage, and the fuel flow rate required by the engine can be accurately obtained.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional view showing an embodiment of the present invention. FIG. 2 is a diagram showing the relationship between intake air amount and fuel flow rate. l...Intake path, 2...Venturi, 3
... Throttle valve, 4... Constant oil level chamber, 5...
...Main system, 6...Low speed system, 19...
...Auxiliary fuel passage, 19m ...Population, 19
b...Exit, 20...Fuel jet. 21.2390.10. Air bleed jet, 22・
...Economizer. Agent Mutsuaki Nozawa

Claims (1)

[Claims] A carburetor in which the main system and low-speed system are common, characterized by having an auxiliary fuel passage whose inlet opens directly into the constant oil level chamber and whose outlet opens in the portion of the intake path between the venturi and the throttle box. vaporizer.