JPS6114618Y2 - - Google Patents

Description

[Detailed description of the invention] The present invention is a device for introducing fuel evaporative gas generated from a fuel reservoir such as a fuel tank or a float chamber of a carburetor into an intake system or an exhaust system of an engine, mainly in an internal combustion engine for an automobile. It is related to.

Conventionally, fuel evaporative gas generated in the fuel tank, etc. during engine operation has been sucked into the intake system of the engine along with ventilation air in the fuel tank, etc., while the fuel vapor gas generated in the fuel tank, etc. during engine operation has been sucked into the intake system of the engine. Fuel evaporative gas generated in a fuel reservoir such as a chamber is collected by a carbon canister filled with a fuel adsorbent such as activated carbon or a collector such as a reservoir appropriately formed in a car body member having a space. When the engine is operated, atmospheric air is sucked into the intake system of the engine together with ventilation air from the fuel tank, etc. The collection capacity of the collector is being purged.

However, introducing purge air from a collector such as a charcoal canister and ventilation air from the fuel reservoir into the engine intake system in this way means that the purge air and ventilation air contain fuel evaporative gas. Because it contains a large amount of carbon dioxide, the air-fuel ratio of the intake air mixture to the engine becomes rich, and the amount of carbon monocarbonate (CO) in the exhaust gas increases.

Additionally, some proposals have been made to introduce purge air from the collector and ventilation air from the fuel reservoir into the engine exhaust system as secondary air for exhaust gas purification, but this method Fuel evaporative gas contained in the purge air and ventilation air causes the temperature of the exhaust gas purification device to rise abnormally, reducing the durability of the purification device and accelerating the deterioration of its catalyst. In addition, the extent to which the purifier exerts an adverse thermal influence on other parts increases.Moreover, the fuel evaporative gas that enters the exhaust system together with the secondary air does not contribute to the output of the engine, so the fuel consumption increases. This was because it involved a loss of .

In this way, the present invention introduces the purge air from the collector and the ventilation air from the fuel reservoir into the intake system or exhaust system of the engine. A gas-liquid separator is installed in the engine to separate and recover the fuel evaporative gas, reduce the content of the fuel evaporative gas, and introduce it into the intake system or exhaust system.

The embodiments shown in the drawings will be explained below. In the drawings, 1 is an internal combustion engine, 2 is an intake air cleaner 3
and an intake manifold equipped with a carburetor 4; 5 indicates an exhaust gas purification device such as a catalytic converter or a reactor connected to an exhaust port of the engine via an exhaust passage 6; and a secondary air supply passage 7 connected to the exhaust passage 6. A check valve 8 is provided at one end of the exhaust passage 6, and when the check valve 8 opens and closes due to exhaust pulsation within the exhaust passage 6, secondary air is sucked and supplied into the exhaust passage 6.

Reference numeral 9 indicates a fuel tank, which is one of the fuel reservoirs, and 10 indicates a charcoal canister, which is an example of a collector for fuel evaporative gas. The lower chamber 12 communicates through a passage 13 with the atmosphere side of a car body structural member having a space, while the upper chamber 14 is built in a layered manner.
Evaporative gas introduction passage 15 with electromagnetic passage opening/closing valve 16
It communicates with the upper space of the float chamber 17 in the vaporizer 4 via the vaporizer 4, and communicates with the upper space of the fuel tank 9 via an evaporative gas introduction passage 18 with a fuel gas-liquid separator (not shown). The on-off valve 16 is related to an engine starter switch (not shown), etc., and is configured to be open when the engine is stopped and closed when the engine is started, and the upper chamber 14 of the canister 10 is a passage dedicated to purging and ventilation. 23 to an inlet 25 of a gas-liquid separator 24 (described in detail later) for fuel evaporated gas, and an outlet 26 of the gas-liquid separator 24 is connected to the vaporizer 4 through a passage 21 with a check valve 22. It communicates with a purge port 20 which is provided at an appropriate location upstream of the closed position (idle opening) of the throttle valve 19. in this case,
When purge air and ventilation air extracted from the purge and ventilation passage 23 extending from the upper chamber 14 of the canister 10 are introduced into the exhaust system as secondary air, the outlet 26 of the gas-liquid separator 24 is connected to the purge port. 20, it may be connected to the inlet of the check valve 8 via a passage 27 shown by a two-dot chain line.

The gas-liquid separator 24 is constructed as shown in FIG. That is, the inlet 25 is provided with a throttle nozzle 28 that opens into the gas-liquid separator 24, and the gas-liquid separator 24 is provided with a partition wall 29 that faces the throttle nozzle 28 at an appropriate interval. A valve chamber 30 is provided at the bottom of the gas-liquid separator 24, and the gas-liquid separator 24 and the valve chamber 30 are disposed in the valve chamber 30.
A valve body 32 is provided to normally close the communication hole 31 with the valve body. The valve body 32 is formed into an umbrella shape made of a soft material such as rubber so as to be opened by slight pressure, and connects the valve chamber 30 to the upper space of the fuel tank 9 via a fuel return passage 33. be.

In this configuration, when the engine is stopped, the on-off valve 16 is open, so that the fuel vapor generated in the float chamber 17 of the carburetor 4 enters the upper chamber 12 of the canister 10 via the vaporized gas introduction passage 15. At the same time, fuel evaporative gas generated in the fuel tank 9 is also introduced via the evaporative gas introduction passage 18,
Only clean air that is adsorbed by the adsorbent 11 in the canister 10 is discharged from the passage 13 to the atmosphere.

Then, when the engine is started and operated, the on-off valve 16
is closed, and communication between the float chamber 17 of the carburetor 4 and the canister 10 is cut off. In this case, in the idling operating range where the throttle valve 19 is in the closed position, the purge port 20 is located upstream of the throttle valve 19 and no negative pressure is generated in the purge port 20, so there is no suction to the purge port 20. However, when the throttle valve 20 is opened, negative pressure is generated in the purge port 20, so the canister 10
Purge air that enters the upper chamber 14 through the adsorbent 11 from the passage 13 and ventilation air that enters from the fuel tank 9 via the evaporative gas introduction passage 18 enter the upper chamber 14 through the passage 23 dedicated to purge and ventilation, and the The liquid is sucked into the intake manifold 2 from the purge port 20 via the liquid separator 24 and the passage 21 .

In this case, the purge air and ventilation air containing fuel evaporative gas in the upper chamber 14 of the canister 10 enter the gas-liquid separator 24 through the throttle nozzle 2 of the inlet 25.
When it flows in from 8 and is opened to a wide space, it expands adiabatically. As the temperature decreases due to this adiabatic expansion, the fuel evaporative gas in the purge air and ventilation air condenses and deposits into droplets, which are separated from the air when they hit the partition wall 29 or the inner wall surface of the gas-liquid separator, and are separated from the air. The gas flows through the outlet 2 of the gas-liquid separator 24 and accumulates at the bottom.
The amount of fuel evaporative gas in the purge air and ventilation air exiting from the gas-liquid separator 24 is reduced by the amount separated by the temperature drop caused by adiabatic expansion in the gas-liquid separator 24. The fuel that has accumulated at the bottom can be removed by stopping the engine and making sure that the pressure in the gas-liquid separator becomes approximately equal to the pressure in the fuel tank.
When the fuel reaches a high temperature, the valve body 32 is opened and the fuel is collected into the fuel tank 9 via the fuel return passage 33.

As described above, the present invention connects the evaporative gas introduction passage from a fuel reservoir such as a combustion tank or a float chamber of a vaporizer to a fuel evaporative gas collector. and a passage dedicated to ventilation, and connect the passage dedicated to purge and ventilation to a purge port provided at an appropriate location upstream of the closed position of the throttle valve in the carburetor or to a secondary air supply passage to the exhaust system of the engine. A gas-liquid separator is installed in the connecting passage, and a fuel passage to the fuel tank is connected to the gas-liquid separator, and the fuel vapor gas contained in the purge air and ventilation air is separated into gas and liquid. Since the fuel is separated into gas and liquid within the vessel and then introduced into the exhaust system or intake system, it is possible to significantly reduce fuel evaporative gas in the purge air and ventilation air introduced into the engine intake system or exhaust system.

Therefore, according to the present invention, when purge air and ventilation air are introduced into the intake system of an engine, it is possible to reduce the richness of the intake air mixture and reduce the amount of richness in the exhaust gas.
It is possible to prevent an increase in CO, and when purge air and ventilation air are introduced into the engine exhaust system as secondary air, it is possible to reduce the temperature rise of the exhaust gas purification device and reduce fuel loss. It is.

Note that a zigzag passage system may be used as the gas-liquid separator, but a structure that separates by temperature drop due to adiabatic expansion as in this example has a simpler structure and can achieve a greater separation effect. Therefore, it is advantageous in terms of space and cost.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing an embodiment of the present invention, and FIG. 2 is a longitudinal sectional front view of the gas-liquid separator in FIG. 1. 1...Internal combustion engine, 2...Intake manifold, 4
... Carburizer, 5 ... Exhaust gas purification device, 6 ... Exhaust passage, 9 ... Fuel tank, 10 ... Charcoal canister, 17 ... Float chamber, 7 ... Secondary air supply passage, 19 ...Throttle valve, 20...
Purge port, 24... air separator, 25... inlet, 28... throttle nozzle.

Claims (1)

[Scope of utility model registration request] The evaporative gas inlet passage from the fuel reservoir such as the combustion tank or the float chamber of the vaporizer is connected to the fuel evaporative gas collector, while the passage dedicated to purging and ventilation is connected to the fuel evaporative gas collector. However, in the passage that connects the passage dedicated to purge and ventilation to a purge port provided at an appropriate upstream side of the closed position of the throttle valve in the carburetor or a secondary air supply passage to the exhaust system of the engine, 1. A fuel vapor introduction device for an internal combustion engine, comprising a gas-liquid separator and a fuel return passage to a fuel tank connected to the gas-liquid separator.