JPH059478Y2 - - Google Patents

Description

[Detailed description of the invention] [Industrial application field] This invention relates to a carburetor for internal combustion engines, and in particular,
The present invention relates to a carburetor for an internal combustion engine that can prevent over-enrichment of an air-fuel mixture by ventilating a float chamber of the carburetor at high temperatures.

[Prior Art] When the temperature of a carburetor of an internal combustion engine becomes high, the fuel temperature in the float chamber increases and the amount of fuel evaporation increases. For this reason, there is a problem in that the increased evaporated fuel flows into the intake passage and over-enriches the air-fuel mixture, impairing engine operability. Therefore, in order to solve this problem, conventionally,
For example, Japanese Patent Application Publication No. 50-26917, Japanese Patent Publication No. 49-41216
There are some disclosed in Japanese Utility Model Application Publication No. 55-23463.

[Problems to be solved by the invention] However, the methods disclosed in these publications simply introduce increased evaporated fuel into the intake passage, and do not sufficiently prevent over-enrichment of the air-fuel mixture. I couldn't do it.

[Purpose of the invention] Therefore, the purpose of the invention is to realize a carburetor for an internal combustion engine that can sufficiently prevent over-enrichment of the air-fuel mixture by ventilating the float chamber of the carburetor at high temperatures.

[Means for solving the problem] In order to achieve this object, this invention opens to an inlet port in an internal combustion engine air cleaner, and from the inlet port in the air cleaner downstream of the carburetor throttle valve. Two passages leading to each outlet port of the intake passage are provided, and the middle of one of these two passages is communicated with the float chamber of the carburetor, and when the temperature is higher than the set temperature, the two passages are closed. The air cleaner is characterized in that a temperature sensing valve that communicates with the open air is provided at the one introduction port in the air cleaner.

[Function] According to the configuration of this invention, when the temperature is higher than the set temperature, the temperature sensing valve provided at the introduction port in the air cleaner opens and communicates the two passages. As a result, fresh air taken in by the air cleaner is introduced into the intake passage on the downstream side of the carburetor throttle valve through the first passage through the carburetor float chamber, and is also directly introduced through the other passage. It is introduced into the intake passage downstream of the throttle valve from another introduction port.
Therefore, since the float chamber is ventilated with fresh air, evaporation of the fuel can be suppressed and fuel can be diluted to prevent over-concentration. Furthermore, the evaporated fuel drawn into the intake passage can be further diluted by directly introduced fresh air.

[Example] Next, an example of this invention will be described in detail based on the drawings. FIG. 1 shows a first embodiment of this invention. In the figure, 2 is an air cleaner, 4 is a carburetor, 6 is an intake passage, 8 is a throttle valve, 10 is a float chamber, and 12 is a float. Float chamber 10
The fuel inside is sent from a fuel tank (not shown).
A constant amount is always stored by the float 12. In order to prevent this stored fuel from being blown out excessively due to increased intake resistance due to air cleaner clogging, etc., an air vent passage 13 communicating with the intake passage 6 on the upstream side of the carburetor 4 is provided in the float chamber 10. There is.

An intake passage 6 opens into the air cleaner 2 and is connected from the air cleaner 2 to the downstream side of the throttle valve 8 of the carburetor 4.
A single passage 14 is provided leading to. This single passage 14 is connected to an introduction port 16 in the air cleaner 2.
an upstream passage 18 which has one end in communication with the float chamber 10 and the other end with the float chamber 10; and a downstream intake passage 6 of the throttle valve 8 with one end in communication with the float chamber 10 and the other end.
and a downstream passage 22 that communicates with the outlet port 20 of. The introduction port 16 is provided with a temperature sensing valve 24 that closes when the intake air temperature is less than the set intake air temperature and opens when the intake air temperature exceeds the set intake air temperature. Therefore, when the intake air temperature is equal to or higher than the set intake air temperature, the temperature sensing valve 24 opens the passage 14 for communication, so that fresh air taken in by the air cleaner 2 flows from the air cleaner 2 to the intake passage 6 via the float chamber 10. In addition,
In the figure, reference numeral 26 is a throttle provided in the second passage 22 to prevent rapid flow.

According to the configuration of the first embodiment, the float chamber 1
Below the set intake air temperature 0, where the amount of fuel evaporation is small, the temperature sensing valve 24 closes the passage 14 to prevent flow. On the other hand, above the set intake air temperature, where the amount of fuel evaporation increases and there is a risk of an over-rich mixture being produced, the temperature sensing valve 26 opens the passage 14 to communicate. This, combined with the negative pressure state of the intake passage 6 downstream of the throttle valve 8 with which the other end of the second passage 22 communicates, allows fresh air taken in by the air cleaner 2 to flow smoothly toward the intake passage 6 via the float chamber 10. Therefore, at high temperatures, the float chamber 10 is ventilated by the fresh air, suppressing fuel evaporation and diluting the mixture to prevent it from becoming over-rich, thereby ensuring engine operability.

FIG. 2 shows an embodiment of this invention. In the figure, 2 is an air cleaner, 4 is a carburetor, 6 is an intake passage, 8 is a throttle valve, 10 is a float chamber, 12 is a float, and 13 is an air vent passage. In this embodiment, two ports are opened at one inlet port 16 in the air cleaner 2 and extend from the one inlet port 16 in the air port 2 to each outlet port 20, 30 of the intake passage 6 on the downstream side of the throttle valve 8. Passages 14 and 28 are provided.

That is, one introduction port 16 in the air cleaner 2
The float chamber 10 is communicated with the first outlet port 2.
one passage 14 consisting of an upstream passage 18 and a downstream passage 22 leading to 0, and another passage 28 that opens in communication with the upstream passage 18 to communicate with the introduction port 16 and leads to another outlet port 30. Two passages 14 and 28 are provided.

The introduction port 16 in the air cleaner 2 includes:
A temperature sensing valve 24 is provided which closes when the intake air temperature is below the set intake air temperature and opens when the intake air temperature exceeds the set intake air temperature. Therefore, the temperature sensing valve 24 opens and communicates the passages 14 and 28 when the intake air temperature is higher than the set intake air temperature.
It is introduced into the intake passage 6 on the downstream side, and also directly into the intake passage 6 on the downstream side of the throttle valve 8 through another passage 28 . In the figure, reference numeral 26 is a restriction provided in the downstream passage 22 of the first passage 14, and reference numeral 32 is a restriction provided in the other passage 28, which prevents rapid flow.

According to the configuration of this embodiment, the temperature sensing valve 24 closes the passages 14 and 28 when the intake air temperature is lower than the set intake air temperature at which the amount of fuel evaporation in the float chamber 10 is small.
It is blocking distribution. On the other hand, when the intake air temperature exceeds the set intake air temperature, at which the amount of fuel evaporation increases and there is a risk of producing a rich mixture, the temperature sensing valve 26 opens the passages 14 and 28 and communicates with them. As a result, in conjunction with the negative pressure state in the intake passage 6 on the downstream side of the throttle valve 8 with which the outlet port 20 of the first passage 14 communicates, the fresh air taken in by the air cleaner 2 is transferred to the float chamber 10 through the first passage 14. It is introduced from one outlet port 20 into the intake passage 6 on the downstream side of the throttle valve 8 through the other passage 28, and directly introduced from the other outlet port 30 of the intake passage 6 on the downstream side of the throttle valve 8. .

Therefore, at high temperatures, the float chamber 10 is ventilated with fresh air to suppress fuel evaporation, and the air-fuel mixture is diluted to prevent overconcentration, thereby ensuring engine operability. Furthermore, this float chamber 10
In addition to suppression of fuel evaporation and dilution through ventilation, the evaporated fuel taken into the intake passage 6 can be further diluted with fresh air introduced from the other passage 28, thereby preventing over-enrichment of the air-fuel mixture. This can be done more reliably, and engine operability can be ensured more reliably. Furthermore, since the hot idle compensator mechanism consisting of the conventional temperature sensing valve 24 and the passage 28 can be implemented by simply adding the passage 14, the cost can be reduced.

[Effect of the invention] As described above, according to this invention, when the temperature is higher than the set temperature, the fresh air taken in from the air cleaner is
One passage allows the air to be introduced into the intake passage on the downstream side of the throttle valve of the carburetor via the float chamber of the carburetor, and the other passage allows it to be introduced directly into the intake passage on the downstream side of the throttle valve.

For this reason, the float chamber is ventilated with fresh air, which suppresses fuel evaporation and achieves dilution, thereby preventing over-enrichment of the mixture at high temperatures and ensuring engine operability. be able to.

Furthermore, in conjunction with the suppression of fuel evaporation and dilution by ventilation of the float chamber, the evaporated fuel taken into the intake passage can be further diluted with fresh air introduced from another passage. Thereby, over-enrichment of the air-fuel mixture can be more reliably prevented, and engine operability can be more reliably ensured.

Moreover, since it can be implemented by simply adding one passage to the conventional hot idle compensator mechanism consisting of a temperature sensing valve and other passages, it can be implemented at low cost and is advantageous in practice.

[Brief explanation of the drawing]

FIG. 1 is a schematic sectional view of a vaporizer showing a first embodiment, and FIG. 2 is a schematic sectional view of a vaporizer showing an embodiment of this invention. In the figure, 2 is an air cleaner, 4 is a carburetor,
6 is an intake passage, 8 is a throttle valve, 10 is a float chamber,
14 is a passage, 16 is an introduction port, 18 is an upstream passage, 20 is an outlet port, 22 is a downstream passage, 24
28 is a passage, and 30 is an outlet port.

Claims (1)

[Scope of utility model registration request] Two passages are provided that open to one inlet port in the internal combustion engine air cleaner and extend from the one inlet port in the air cleaner to each outlet port of the intake passage on the downstream side of the carburetor throttle valve. The first inlet port in the air cleaner is provided with a temperature sensing valve that communicates the middle of the first passage with the float chamber of the vaporizer and opens and communicates the two passages when the temperature is higher than a set temperature. A carburetor for internal combustion engines.