JPS614856A - Evaporated-fuel treating apparatus in ganged carburetor - Google Patents

Abstract

PURPOSE:To supply the mixed gas having a uniform air-fuel ratio into all cylinders by purging the evaporated fuel adsorbed into an evaporated-fuel adsorbing apparatus during the operation of a car only into a front carburetor between the carburetors installed at the front and rear parts of the car. CONSTITUTION:The upper space of the float chambers 6 of the first and the second carburetors B and C installed at the front and rear part of a car is connected to an evaporated-fuel adsorbing apparatus 24 through evaporated-fuel induits 21 and 22 and a solenoid valve 23. In this case, a purging port 26 is formed onto the inner wall surface of a suction passage 2 in the vicinity on the upstream side of a throttle valve 5 at the idling position of the first carburetor B, and connected to the apparatus 24 through an evaporated-fuel purging conduit 27. Since the first carburetor B is installed at the front of the car, said carburetor can be cooled by the passage wind, and the temperature is lower than that of the second carburetor C. Therefore, though the mixed gas supplied from the first carburetor B becomes lean, this phenomenon can be compensated by feeding the evaporated fuel from the purging port 26.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to an evaporated fuel processing device for an internal combustion engine equipped with multiple carburetors.

When a conventional engine is stopped at a high temperature, fuel vapor generated in the carburetor float chamber flows into the intake passage and accumulates therein. Therefore, when attempting to restart the engine in such a state, in addition to the fuel supplied from the carburetor, the fuel vapor accumulated in the intake passage is supplied into the engine cylinder, so that the air-fuel mixture supplied into the engine cylinder is reduced. There is a problem in that the amount of fuel becomes too rich, thus making it difficult to restart the engine.

Therefore, in order to solve such problems, as described in, for example, Japanese Utility Model Application Publication No. 59-43653,
The upper space of the float chamber of the carburetor is connected to the evaporated fuel adsorption device via a solenoid valve, and when the engine stops, the solenoid valve is opened and the fuel vapor generated in the float chamber is sent into the evaporated fuel adsorption device. Vaporized fuel processing devices are known that are designed to prevent vapor from flowing into the intake passage. In such an evaporative fuel processing device, the evaporative fuel adsorbed in the evaporative fuel adsorption device is usually purged into the intake passage and sent into the engine cylinder during engine operation.

However, if an internal combustion engine is equipped with a pair of carburetors, and one carburetor is installed at the front of the vehicle and the other carburetor is installed at the rear of the vehicle, the carburetor installed at the front of the vehicle The amount of fuel vapor generated in the carburetor float chamber located at the front of the vehicle is generated in the carburetor float chamber located at the rear of the vehicle because it is cooled by the running wind more than the carburetor installed at the rear of the vehicle. Furthermore, the amount of fuel vapor supplied from the carburetor provided at the front of the vehicle is smaller than that of the fuel vapor provided from the carburetor provided at the rear of the vehicle. As a result, there is a problem in that the air-fuel mixture supplied to the cylinders to which fuel is supplied from the carburetor provided at the front of the vehicle becomes too lean.

Problems to be Solved by the Invention The present invention purges the evaporated fuel adsorbed in the evaporated fuel adsorption device during vehicle operation into the intake passage of the carburetor installed at the front of the vehicle, thereby uniformly airing the fuel cylinder. An object of the present invention is to provide an evaporative fuel processing device that supplies a mixture with a specific fuel ratio.

Means for Solving the Problem In order to solve the above problem, the configuration of the present invention includes a first carburetor provided at the front of the vehicle and a second carburetor provided at the rear of the vehicle. Float chamber and second part of the vaporizer
In a fuel vapor processing device in which a float chamber of a vaporizer is connected to a fuel vapor adsorption device via a fuel vapor passage, the fuel vapor adsorption device is connected only to an intake passage of a first vaporizer via a fuel vapor purge passage. It is in.

Embodiment In FIG. 1, A is the engine body, B is the first variable venturi carburetor, C is the second variable venturi carburetor, and D is the engine body.
, E indicate the intake manifold, and arrow F indicates the front of the vehicle.

Therefore, the first carburetor B is provided at the front of the vehicle, and the second carburetor C is provided at the rear of the vehicle. The first carburetor B and the second carburetor C have similar structures, so first, the structures of these carburetors B and C will be explained simultaneously with reference to FIG. 2.

Referring to FIG. 2, 1 is a carburetor main body, 2 is a carburetor intake passage, 3 is a suction piston that moves laterally within the intake passage 2, 4 is a needle attached to the tip surface of the suction piston 3, and 5 is a suction piston that moves laterally within the intake passage 2. 6 indicates a throttle valve provided in the intake passage 2 downstream of the suction piston 3, 6 indicates a carburetor float chamber, and a venturi portion 7 is formed between the tip surface of the suction piston 3 and the inner wall surface of the intake passage 2. . A hollow cylindrical casing 8 is fixed to the carburetor body, and this casing 8 is provided with a guide sleeve 9 extending in the axial direction of the casing 8 inside the casing 8 . A guide rod 10 is fixed to the suction piston 3 and is slidably inserted into the guide sleeve 9. The interior of the casing 8 is divided into a negative pressure chamber 11 and an atmospheric pressure chamber 12 by the suction piston 3, and a compression spring 3 is inserted into the negative pressure chamber 11 to constantly press the suction piston 3 toward the venturi section 7. Ru. The negative pressure chamber 11 is connected to the venturi section 7 through a suction hole 14 formed in the suction piston 3, and the atmospheric pressure chamber 12 is connected to the intake passage 2 upstream of the suction piston 3 through an air hole 15.

On the other hand, a fuel passage 16 extending in the axial direction of the needle 4 is formed in the carburetor body so that the needle 4 can enter therein, and a metering jet 17 is provided within the fuel passage 16. A fuel passage 16 upstream of the metering jet 17 is connected into the float chamber 6 via a downwardly extending fuel pipe 18.
The fuel in the float chamber 6 is sent into the fuel passage 16 via this fuel pipe 18. Needle 4 is nozzle 19
and extends through the metering jet 17 so that the fuel is metered by the annular gap formed between the needle 4 and the metering jet 17 and then fed into the intake passage 2 through the nozzle 19 . A raised bridge 20 is formed on the inner wall surface of the intake passage 2 facing the tip surface of the suction piston 3.
Flow rate control is performed between this bridge 2° and the end surface of the suction piston 3. When engine operation is started, air flows downward in the intake passage 2. At this time, negative pressure is generated within the venturi portion 7, and this negative pressure is guided into the negative pressure chamber If through the suction hole 14.

The suction piston 3 moves so that the pressure difference between the negative pressure chamber 11 and the atmospheric pressure chamber 12 becomes a substantially constant pressure determined by the spring force of the compression spring 13, that is, the negative pressure inside the venturi section 7 becomes substantially constant. do.

Referring to FIG. 2, the upper space of the float chamber 6 of the first carburetor B and the upper space of the float chamber 6 of the second carburetor C are connected through vaporized fuel conduits 21 and 22, respectively, and further through a magnetic valve 23. and is connected to an evaporated fuel adsorption device 24 consisting of a charcoal canister. This solenoid valve 23 is connected to an ignition switch 25, and when the ignition switch 25 is turned on, the solenoid valve 23 is closed, and when the ignition switch 25 is turned off, the solenoid valve 23 is opened. On the other hand, in the first carburetor B, a purge port 26 is formed on the inner wall surface of the intake passage 2 near the upstream side of the throttle valve 5 at the idling position. coupled to device 24; A temperature-sensitive valve 30 equipped with a bimetallic element 29 that responds to the ambient temperature in the engine room is inserted into the vaporized fuel purge conduit 27 . This temperature-sensitive valve 30 is closed as shown in the figure when the ambient temperature is lower than a predetermined temperature, and when the ambient temperature is higher than a predetermined temperature, the bimetal element 29 is bent in the opposite direction. As a result, the temperature-sensitive valve 30 opens. The upper space of the float chamber 6 of each carburetor B, C is connected to the intake passage 2 upstream of the succilon piston 3 via an inner vent 31.

When the engine is operating, the ignition switch 25 is on, so the electromagnetic valve 23 is closed, and therefore communication between the float chamber 6 and the evaporated fuel adsorption device 24 is cut off. At this time, if the ambient temperature is higher than a predetermined temperature, the temperature-sensitive valve 30 is opened.
The vaporized fuel adsorbed on the activated carbon 32 is transferred to the purge port 26.
is supplied into the intake passage 2 of the first carburetor B.

Since the first carburetor B is provided at the front of the vehicle, it is cooled by the running wind, so the temperature of the first carburetor B is lower than the temperature of the second carburetor C. Therefore, the amount of evaporated fuel flowing out from the inner vent 31 of the first carburetor B into the intake passage 2 is smaller than that of the second carburetor C.
The vaporization of the fuel supplied from the second carburetor C is worse than that of the fuel supplied from the second carburetor C. Therefore, the air-fuel mixture supplied from the first carburetor B into the corresponding engine cylinder becomes lean, but since the vaporized fuel is supplied from the purge port 26, the air-fuel ratio of the air-fuel mixture supplied to all cylinders becomes uniform. In this way, stable operation without torque fluctuation can be ensured.

When the ignition switch 25 is turned off and the engine is stopped, the electromagnetic valve 23 is opened, and the evaporated fuel in the float chamber 6 is adsorbed by the activated carbon 32 of the evaporated fuel adsorption device 24. Therefore, it is possible to control the flow of the vaporized fuel generated in the float chamber 6 into the intake passage 2 after the engine is stopped, so that the engine can be restarted easily.

Effects of the Invention Since a mixture having a uniform air-fuel ratio can be supplied to all cylinders, stable engine operation without torque fluctuation can be ensured.

[Brief explanation of drawings]

FIG. 1 is a plan view of the internal combustion engine, and FIG. 2 is an overall view of the evaporated fuel processing device. 2... Intake passage, 3... Suction piston, 21, 22... Evaporative fuel conduit, 23... Solenoid valve, 24... Evaporative fuel adsorption device, 26... Purge port, B...・First vaporizer, C...second vaporizer.

Claims (1)

[Claims] The vehicle includes a first carburetor provided at the front of the vehicle and a second carburetor provided at the rear of the vehicle. A fuel vapor processing device connected to a fuel vapor adsorption device, wherein the fuel vapor adsorption device is connected only to an intake passage of the first vaporizer via a fuel vapor purge passage.