JPS60230553A - Carburetor - Google Patents

Abstract

PURPOSE:To perform the flow regulation of main fuel in a simple manner as well as to aim at improvements in a link between low-speed fuel and the main fuel, by making air suck out of the inlet of an air passage being opened to a central symmetrical position at the narrowest part of a large Venturi, while forming suction air at the downstream of the narrowest part into the promotion of a laminar flow. CONSTITUTION:At a suction passage 2 of a carburetor body 1, there are provided with a double Venturi consisting of a small Venturi 3 and a large Venturi 4 and a throttle valve 5, and at this small Venturi 3, a main nozzle 6 for fuel is opened. In the above-mentioned, each of small diametral outlets 7 and 10 is formed in the narrowest part 4a of the large Venturi 4 while two air passages 8 and 11 being opened at a central symmetrical position are formed in the carburetor body 1, respectively. And, each of inlets 9 and 12 of these elements is located at the upstream side of the suction passage 2 whereby these inlets are opened in spots where no influence of suction pressure by these Venturis 3 and 4 is received. And, a regulating mechanism 13, which makes a passage effective area vary in a stepless range from zero to the full open of maximum, is installed in the air passage 11 leading to the outlet 10 on one side.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates primarily to a carburetor for supplying a fuel/air mixture to an automobile engine.

As is well known, a carburetor is equipped with a main system, a low-speed system, an acceleration system, etc. as a fuel system that supplies fuel to the intake system, but exhaust gas regulations are mainly applied during steady operation of the engine where fuel is supplied from the main system. Due to this, fuel flow tolerance has become limited to an extremely narrow range.

As a countermeasure, there is a system in which the main jets in the main system are made variable with adjustment needles so that the fuel flow rate can be adjusted, but adjustment is rather difficult because the adjustment sensitivity is too sensitive.

There are also systems in which the main air bleed in the main system is made variable with an adjustment needle so that the bleed air flow rate can be adjusted, but this cannot be expected to be very effective in areas where the amount of engine intake air is small.

Furthermore, it is a well-known fact that the air-fuel ratio temporarily becomes quite lean when the solvent supply is switched from the low-speed system to the main system, and it is necessary to eliminate such temporary fluctuations in the air-fuel ratio. Ashi.

Furthermore, in response to engine demands, for example, in a carburetor that has characteristics such as making the air-fuel ratio leaner at low speeds and richer at high speeds, changes in the air-fuel ratio should be kept as much as possible from the viewpoints of engine stability, fuel economy, and exhaust gas regulations. It is preferable to make it small.

Conventionally, there has been no vaporizer equipped with functions that meet all of the above requirements.

In addition to adjusting the flow rate of the main fuel, the purpose of the present invention is to improve the connection between the low-speed fuel and the main fuel.

An object of the present invention is to provide a carburetor that can improve air-fuel ratio change characteristics depending on engine rotational speed with a single mechanism.

In order to achieve the above object, the present invention provides a carburetor having multiple venturis in the intake passage and a main fuel nozzle opening into a small venturi.

An air passage having an inlet on the upstream side of the large bench lily is provided, two outlets of this air passage are opened at centrally symmetrical positions at the narrowest part of the large bench lily, and the air passage leading to one of the outlets is effective as a passage. The structure is equipped with an adjustment mechanism to control the area.

Example Embodiments of the present invention will be described based on the drawings.

1 and 2, a double venturi consisting of a small bench lily 3 and a large vent lily 4 and a throttle 9 valve 5 are installed in the suction air passage 2 of the carburetor main body 1, and the main fuel nozzle 6 is connected to the small vent lily 3. It is open to large bench lily 4
A small-diameter outlet lower 10 is placed in the narrowest part 4a of the carburetor main body 1.
These inlets 9, 12 are opened in the upstream side of the venturi of the intake passage 2 and are not affected by the negative pressure caused by the small bench lily 3 and the large bench lily 4.

In FIG. 1, an air passage 11 leading to one outlet 10 is provided with a manually operated adjustment mechanism 13, and this adjustment mechanism 13 adjusts the effective passage area of the air passage 11 steplessly from zero to fully open the light. It is comprised of an adjusting screw 15 screwed into the carburetor main body 1, which has a conical valve body 14 at its tip that changes the temperature.

In FIG. 2, an adjustment mechanism 16 operated by an electric signal is provided in the air passage 11 leading to one outlet 010.
The valve body 17 is made to reciprocate by an electric signal sent from, for example, an electronic control unit.

Here, it is known that when the air flowing through the large bench lily 4 passes through the narrowest part 4a, a turbulent flow accompanied by a separation phenomenon from the wall surface is generated in the part where the downstream cross section gradually expands.

According to this embodiment, the negative pressure generated when the air taken into the engine passes through the large bench lily 4 causes the two outlet lowers to
Air is sucked out from 10, and this air works to eliminate turbulence on the downstream side of the narrowest part 4a and make the intake air flow laminar. Therefore, it is clear that the negative pressure acting on the main nozzle 6 of the small bench lily 3 is different depending on whether the air is sucked out from the outlet lower 10 or not.

In this embodiment, the outlet 10 on the right side in the figure is closed and air is sucked out only from the lower outlet on the left side.

The intake air flow of the intake passage 2 tends to be laminar on the left side and turbulent on the right side on the downstream side of the narrowest part 41, compared to the case where air is sucked out from the two outlet lowers 10 and the case where it is not sucked out. The negative pressure acting on the main nozzle 6 is also different. From this state, when the air passage 11 on the right side is opened and air is sucked out, the right side also becomes a laminar flow (the negative pressure acting on the main nozzle 6 changes).

That is, as the turbulent flow gradually becomes a laminar flow, the loss gradually decreases, and the negative pressure acting on the main nozzle 6 also gradually increases, resulting in an increase in the fuel flow rate. On the contrary, it can also be controlled to reduce the amount of air sucked out to create appropriate turbulence and reduce the fuel flow rate.

In the embodiment shown in FIG. 1, the effective passage area of the air passage 11 is adjusted in advance by manually turning the adjustment screw 15, but in the embodiment shown in FIG. The amount of air from the outlet 11 is controlled by opening and closing.

Incidentally, the actuator 18 shown in FIG. 2 may be constituted by an electric motor, and the effective passage area of the air passage 11 may be controlled steplessly from zero to the maximum by an electric signal. It goes without saying that the present invention can also be applied to a triple venturi carburetor.

According to the present invention, air is sucked out from the outlet of the air passage opened at a centrally symmetrical position in the narrowest part of the large bench lily, and the turbulent flow of intake air generated downstream of the narrowest part is brought closer to a laminar flow, so that the main nozzle The diameter of the two outlets is to increase the negative pressure acting on the main fuel and adjust the flow rate of the main fuel.

The adjustment sensitivity can be arbitrarily selected by appropriately selecting the shape of the valve body of the adjustment mechanism, and the flow tolerance of the main fuel can be limited to an extremely narrow range. The improvement of the air-fuel ratio characteristics depending on the engine speed is achieved by a single mechanism.

[Brief explanation of the drawing]

1 and 2 are longitudinal sectional views of different embodiments of the present invention. 2...Intake path, 3...Small bench lily,
4...Large bench lily, 6...Main nozzle, 7.10...Outlet, 8.11...Air passage, 9.12... ...Input 0.13°16...
...Adjustment mechanism, 14.17... Valve body, 15
...Adjustment screw, 18...Actuator.

Claims (3)

[Claims] (1) In a carburetor that has multiple venturis in the intake passage and the main fuel nozzle opens into a small venturi, an air passageway with an inlet upstream of the large bench lily is provided, and two outlets of this air passageway are provided. What is claimed is: 1. A carburetor, characterized in that an air passage which is opened at a centrally symmetrical position in the narrowest part of a large bench lily and which leads to one outlet thereof is provided with an adjustment mechanism for controlling the effective area of the passage. (2) The carburetor according to claim (1), wherein the adjustment mechanism comprises a manual adjustment screw having a valve body at the tip. (3) Claim (1) in which the adjustment mechanism is constituted by an actuator that has a valve body at the tip and is operated by an electric signal.
The vaporizer described in .