JPS5851390Y2 - Carburetor for internal combustion engine - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a carburetor for an internal combustion engine, and more particularly to a carburetor equipped with a device for preventing fuel starvation that occurs when a car turns.

A carburetor sucks the fuel in the float chamber out of the main nozzle using the negative pressure in the venturi section, mixes it with the air flowing through the venturi section, atomizes it, and supplies it as a mixture to each cylinder of the engine. be.

Even if this venturi negative pressure is constant, if the oil level of the fuel in the float chamber is tilted and the head difference between the oil level and the tip of the main nozzle changes, the amount of fuel sucked out from the main nozzle will differ. , the mixture concentration will not be constant.

For example, in a carburetor for an internal combustion engine for an automobile, in which the float chamber is arranged in the left-right direction of the vehicle with respect to the mixture passage of the carburetor, when the vehicle is turning, the centrifugal force causes the inside of the float chamber to The fuel oil level is tilted to the left and right of the vehicle, and the head difference between this oil level and the tip of the main nozzle changes.

In particular, when the float chamber is located outside with respect to the turning direction of the vehicle, the head difference H' between the oil level in the float chamber and the main nozzle becomes larger than the head difference H in normal conditions. In extreme cases, the engine may run out of fuel, such as when making sharp turns with a small turning radius or continuing high-speed turns, due to poor suction of fuel by the venturi negative pressure, and in extreme cases, the engine may stop.

As an example of prior art aimed at preventing such fuel shortage when turning a vehicle, the one described in Japanese Patent Publication No. 33-10504 is known.According to this prior art, auxiliary fuel This auxiliary fuel chamber is required to be connected to the float chamber and to be placed facing the float chamber with the air-fuel mixture passage in between, resulting in an increase in the number of parts and structural changes. In addition to the lack of practicality due to the complexity of the device, there are other disadvantages such as the range of application is limited due to the increased size of the device.

Therefore, as a simple measure to prevent the fuel from running out by making some improvements to the normal carburetor, we installed a fuel tank on the wall opposite to the main nozzle of the float chamber of the carburetor at a position higher than the normal oil level. An emergency fuel supply port is provided at a position below the oil level when the oil level tilts due to rotation, and this supply port is connected to the carburetor through an emergency fuel supply passage having an air mixing pipe. A conceivable method is to supply fuel from the emergency fuel supply port to the air-fuel mixture passage when the vehicle turns by means of communication with an emergency fuel discharge nozzle opened downstream from the main nozzle of the air-fuel mixture passage.

However, when this type of fuel shortage prevention measure is implemented, the emergency fuel discharge nozzle, which opens downstream of the main nozzle, communicates with the upper chamber of the float chamber via the emergency fuel supply passage, which prevents the vehicle from operating normally. Sometimes, fuel vapor generated in the float chamber is sucked into the air-fuel mixture passage through the emergency fuel supply system due to the suction negative pressure, resulting in a problem that the air-fuel mixture becomes excessively rich.

The object of the present invention is to provide a carburetor that is configured to eliminate the above-mentioned problems and suppress the tendency of the mixture to become over-enriched during normal operation, in which the above-mentioned measures to prevent fuel exhaustion have been taken. shall be.

For this purpose, the carburetor according to the present invention is provided with an air introduction passage communicating with the emergency fuel supply port side of the emergency fuel passage,
The opening at the tip of this passage faces into the suction system upstream of the venturi of the carburetor and opens toward the upstream side of the intake air.

In addition, there is a related prior art example in which a fuel outlet is provided in the side wall of the float chamber, as described in Japanese Utility Model Publication No. 38-21808, but this outlet is designed to prevent overflow when the oil level rises due to engine vibration. This purpose is different from the emergency fuel supply port in the present invention.

Hereinafter, one embodiment of the present invention will be specifically described with reference to the drawings.

In the figure, reference numeral 1 indicates a carburetor, and reference numeral 2 indicates a mixture passage thereof, the downstream side of which communicates with each cylinder (not shown) of the engine via the throttle valve 3, and the upstream side thereof,
A venturi 5 with an open main nozzle 4 is disposed, and a suction system 6 further upstream of the venturi 5 is communicated with an air cleaner 7.

Further, reference numeral 10 denotes a float chamber, the bottom of which communicates with the main nozzle 4, and the upper part of which communicates with the suction system 6 through a vent pipe 11. Furthermore, a needle valve 12a fi'fH is installed inside the float chamber. A float 12 is housed therein, and the amount of fuel supplied from a fuel tank (not shown) is adjusted so that the float chamber 10
The oil level inside is kept constant, and the head difference H with the main nozzle 4 is kept normal.

The wall surface 10a of the float chamber 10 on the opposite side from the main nozzle 4 is provided at a position higher than the normal oil level. An emergency fuel supply port 13 is bored at a location submerged below the oil level L'.

An emergency fuel passage 14 is provided in the peripheral wall surrounding the float chamber 10 so as to communicate the emergency fuel supply port 13 with the mixture passage 2 downstream of the main nozzle 4.

A metering jet 15 is inserted into this passage 14 to keep the fuel supply amount appropriate, and an emergency nozzle 16 is fitted at the opening end to the mixture passage 2, and the tip thereof is used for mixing It protrudes into the air passageway 2.

Further, the base end portion of an air introduction pipe 210 is inserted from the upper outer wall of the carburetor 1 so as to communicate with the emergency fuel supply port 13 side of the emergency fuel passage 14 .

The tip of this pipe 21 penetrates a pipe wall 22 forming the suction system 6 upstream of the venturi 5 and projects into the suction system 6.
The opening is opened toward the intake upstream side of the suction system 6, that is, toward the air cleaner 7 side, and the pipe 21 forms an air introduction passage.

In the internal combustion engine carburetor configured as described above, if the vehicle equipped with the carburetor makes a sharp turn or continues turning at high speed, and the fuel oil level in the float chamber 10 inclines as shown by L'. , the head difference with main nozzle 4 is H'
It gets bigger and the fuel is no longer sucked out, but
At this time, the emergency fuel supply port 13 is submerged below the oil level L', so the fuel in the float chamber 10 is transferred to the emergency nozzle 1.
It is sucked by the negative pressure in the mixture passage 2, which extends to 6, and is ejected into the mixture passage 2, where it is mixed and atomized.

In this case, since the metering jet 15 is provided in the emergency fuel passage 14, an appropriate amount of fuel is sucked into the mixture passage 2.

Also, when the vehicle is normally running, the oil level returns to L, the emergency fuel supply port 13 sprays onto the oil level, and the upper space 10b of the float chamber 10 and the mixture passage 2 are in communication. Even if the fuel vapor generated in the float chamber 10 passes through the emergency fuel passage 14 and enters the mixture passage 2.
It cannot be sucked inside.

That is, since the base end of the air introduction pipe 210 is connected to the fuel supply port 13 side of the emergency fuel passage 14,
Air from the intake system 6 is introduced into the emergency fuel passage 14 through the air introduction pipe 21.

At this time, according to the present invention, the tip opening of the air introduction pipe 21 protrudes into the suction system 6 and opens toward the upstream side of the intake system, so that the air introduction pipe 21 has a tip opening that is opened toward the upstream side of the intake system. Dynamic pressure acts and the introduced air is forced.

Therefore, this introduced air is not limited to the emergency fuel passage 14,
With the addition of the throttling effect of the metering jet 15 provided in the passage 14, the fuel flows forcefully into the upper space 10b of the float chamber 10 as shown by the arrow through the emergency fuel supply port 13.

As a result, the fuel vapor generated in the float chamber 10 is diluted and swept out into the intake system 6 through the vent pipe 11 as shown by the arrow, and then sucked into the mixture passage 2 through the emergency fuel passage 14. Never.

In the above embodiment, the emergency nozzle 16 was opened in the air-fuel mixture passage 2 upstream from the throttle valve 3, but it may be opened downstream from the throttle valve 3.

Furthermore, it is preferable to make the cross-sectional area of the air introduction passage formed by the air introduction pipe 21 and the like larger than the cross-sectional area of the emergency fuel passage 14, since this increases the fuel vapor scavenging effect.

As explained above, according to the present invention, when the vehicle is turning, fuel is supplied to the mixture passage through the emergency fuel passage, so it goes without saying that the fuel does not run out, and when the vehicle is running normally. Sometimes, the introduced air dilutes the fuel vapor and exhausts it into the intake system, preventing it from being drawn into the mixture passage, preventing the mixture from becoming richer and causing a harmful increase in carbon monoxide in the exhaust gas. It can be prevented.

[Brief explanation of the drawing]

The figure is a sectional view of essential parts of an embodiment of a vaporizer according to the present invention. 1... Carburizer, 2... Mixture passage, 3...
... Throttle valve, 4 ... Main nozzle, 5 ... Venturi, 6 ... Suction system, 7 ... Air cleaner, 10 ... ... Float chamber 10a ... Wall surface, 10b ・
... Upper space, 11 ... Vent pipe, 1
2...Float, 13...Emergency fuel supply port, 14...Emergency fuel passage, 15...
...metering jet, 16...emergency nozzle,
21...Air introduction pipe, 22...Pipe wall.

Claims (1)

[Scope of utility model registration request] An emergency fuel supply port is installed on the wall opposite to the main nozzle of the float chamber of the carburetor at a location that will be submerged below the oil level when the vehicle turns at a higher level than the normal fuel oil level and the oil level slopes. In a carburetor for an internal combustion engine, the supply port and the mixture passage downstream of the main nozzle are communicated by an emergency fuel passage, and an air introduction passage is provided in communication with the supply port side of the emergency fuel passage, A carburetor for an internal combustion engine, characterized in that the tip opening of the air introduction passage faces into the intake system upstream of the venturi of the carburetor and opens toward the intake upstream side.