JPH0442514Y2 - - Google Patents

Description

[Detailed description of the invention] [Field of industrial application] The present invention relates to a device for treating evaporated fuel generated in a fuel tank of an internal combustion engine by guiding it to the intake system of the internal combustion engine via a canister. be.

[Conventional technology]

The temperature of the fuel in the fuel tank of an internal combustion engine increases as it circulates between the float chamber in the carburetor and the float chamber in the carburetor while the internal combustion engine is in operation. Fuel vapors are generated and leak into the atmosphere.

Therefore, conventionally, as shown in Fig. 3 of Japanese Utility Model Publication No. 59-116561, for example, a canister is connected to the fuel tank, and the fuel evaporative gas generated in the fuel tank is adsorbed in the canister. While adsorbing the canister with the agent,
It is connected to the intake system for the internal combustion engine through a purge passage, and when the internal combustion engine is operating, atmospheric air is sucked through the canister, and the fuel adsorbed by the adsorbent in the canister is introduced into the intake system. The system is configured to purge the adsorbent in the tank.

[The problem that the idea aims to solve]

In this case, the fuel tank communicates with the atmosphere through the canister, and when the internal combustion engine is stopped, the fuel in the fuel tank cools and negative pressure is generated in the fuel tank. teeth,
Since atmospheric air is sucked in from the canister, the negative pressure inside the fuel tank does not increase to the vacuum side.

However, if the adsorbent in the canister becomes clogged due to long-term use, atmospheric air is prevented from being drawn into the fuel tank from the canister, and the negative pressure in the fuel tank increases.
Since it becomes larger toward the vacuum side, the fuel tank is crushed and deformed.

The present invention solves this problem, that is, the crushing deformation of the fuel tank when the adsorbent in the canister is clogged, by reliably preventing the release of fuel evaporative gas in the fuel tank to the atmosphere. The purpose is to solve this problem by

[Means to solve the problem]

In order to achieve this object, the present invention provides a fuel evaporative gas processing device comprising: a canister connected to a fuel tank of an internal combustion engine; and a canister connected to the intake system of the internal combustion engine via a purge passage. An atmosphere introduction passage is connected to the fuel evaporative gas passage leading from the fuel tank to the canister, or the fuel tank or the canister, and at least two check valves are provided in the atmosphere introduction passage so as to open only in the direction toward the fuel tank, The configuration was such that they were installed in series.

[Effect]

In this way, when the air introduction passage with a check valve is connected to the fuel evaporative gas passage from the fuel tank to the canister, or to the fuel tank or canister,
When the adsorbent in the canister is clogged, if the fuel in the fuel tank cools down after the internal combustion engine stops operating, and the pressure in the fuel tank becomes a negative pressure below atmospheric pressure, the atmospheric pressure The check valve in the introduction passage opens, and the atmosphere is sucked into the fuel tank from the atmosphere introduction passage, thereby preventing the negative pressure in the fuel tank from increasing toward the vacuum side.

On the other hand, when fuel vapor is generated in the fuel tank immediately after the internal combustion engine stops operating,
By closing the check valve in the atmosphere introduction passage, fuel evaporative gas is prevented from being released into the atmosphere from the atmosphere introduction passage.

However, in this case, if there is only one check valve provided in the atmosphere introduction passage, it is necessary to prevent the fuel evaporative gas from being released into the atmosphere by using only one check valve. In other words, this single check valve is designed to be a highly accurate check valve that does not leak any fuel evaporative gas into the atmosphere, and that opens and closes accurately in response to minute pressure changes. Therefore, the check valve becomes considerably expensive, resulting in a significant increase in cost.

In contrast, in the present invention, at least two check valves are provided in series in the atmosphere introduction passage, and of the at least two check valves, the first check valve is located near the fuel tank. Even if fuel evaporative gas leaks from the valve due to poor opening/closing operation or improper seating of the valve seat, the first check valve will prevent the leaked fuel evaporative gas from leaking into the atmosphere. Since this can be reliably prevented by the second check valve provided on the atmosphere side, a check valve with an extremely simple structure can be used as the check valve provided in the atmosphere introduction passage.

[Effect of idea]

Therefore, according to the present invention, when the adsorbent in the canister connected to the fuel tank is clogged, it is possible to reliably prevent the fuel tank from collapsing and deforming as the fuel cools. In order to prevent the fuel tank from collapsing and deforming, a check valve with an extremely simple structure can reliably prevent the fuel evaporative gas in the fuel tank from leaking into the atmosphere, reducing costs. have an effect.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings. In the drawings, reference numeral 1 indicates an internal combustion engine, reference numeral 2 indicates an intake manifold for the internal combustion engine 1, and reference numeral 3 indicates a fuel tank for the internal combustion engine 1.
As is well known in the art, between the fuel tank 3 and a float chamber (not shown) in the carburetor 4 attached to the intake manifold 2, there is a space between the fuel tank 3 and a float chamber (not shown) in the carburetor 4 attached to the intake manifold 2. A fuel circulation line (not shown) is provided for sending overflow fuel from the float chamber to the float chamber and returning the overflow fuel from the float chamber to the fuel tank 3.

Reference numeral 5 indicates a canister filled with an adsorbent 6 such as activated carbon. The upper chamber 7 of the canister 5 is connected to the fuel evaporative gas passage 8 so as to lead into the chamber 7, and the upper chamber 7 of the canister 5 is located slightly upstream of the closed position (idle opening degree) of the throttle valve 9 in the carburetor 4. The lower chamber 12 of the canister 5 is connected to a purge port 10 etc. provided in the canister 5 through a purge passage 11.
communicates with the atmosphere, such as the hollow body frame 13 of the automobile.

Further, a valve chamber 14 provided in the fuel evaporative gas passage 8 extending from the fuel tank 3 to the canister 5 includes:
A check valve 15 that opens only toward the canister 5 and a check valve 16 that opens only toward the fuel tank 3 are provided in parallel. A check valve 17 is provided that opens only in the direction toward the port 10.

The valve chamber 14 is connected to an atmosphere introduction passage 19 from an atmosphere communication point such as a hollow body frame 18 of the automobile, and the connection part of the atmosphere introduction passage 19 to the valve chamber 14 is connected to the valve chamber 14 . While providing a first check valve 20 that opens only in the direction of
A second check valve 21 that similarly opens only in the direction toward the valve chamber 14 is provided in the atmosphere introduction passage 19,
The configuration is such that it is provided in series with the first check valve 20.

In this configuration, when the internal combustion engine 1 is stopped, the fuel evaporative gas generated in the fuel tank 3 reaches the canister 5 via the fuel evaporative gas passage 8 and is adsorbed by the adsorbent 6 in the canister 5. Double check valve 2 for air introduction passage 19
0 and 21 are both closed, the evaporative fuel gas in the fuel tank 3 is transferred to the atmosphere introduction passage 19.
It will not be released into the atmosphere.

In this case, even if fuel evaporative gas leaks from the first check valve 20 near the fuel tank 3 due to a defective opening/closing operation or due to improper seating of the valve seat, the leaked fuel evaporative gas The first check valve 20 prevents leakage into the atmosphere.
This can be reliably prevented by the second check valve 21 provided closer to the atmosphere.

On the other hand, when the adsorbent 6 in the canister 5 is clogged, the fuel in the fuel tank 3 cools down after the internal combustion engine 1 stops operating, and the pressure in the fuel tank 3 drops below atmospheric pressure. When the pressure becomes negative, the check valves 20 and 21 for the air introduction passage 19 open, and air is sucked into the fuel tank 3 from the air introduction passage 19, so that the negative pressure inside the fuel tank 3 increases toward the vacuum side. can be prevented from happening.

Note that the atmosphere introduction passage 19 is connected to the fuel tank 3.
Alternatively, it may be directly connected to the canister 5, and the number of check valves provided in series with the atmosphere introduction passage 19 is not limited to two as in the above embodiment, but may be three. A plurality of the above may be used.

[Brief explanation of the drawing]

The drawings are diagrams showing embodiments of the present invention. 1...Internal combustion engine, 2...Intake manifold, 3
...Fuel tank, 4...Carburizer, 5...Canister, 8...Fuel evaporative gas passage, 11...Purge passage, 19...Atmospheric introduction passage, 20...First check valve, 21... Second check valve.

Claims (1)

[Scope of utility model registration request] In a fuel evaporative gas processing device comprising a canister connected to a fuel tank of an internal combustion engine, and the canister connected to an intake system of the internal combustion engine via a purge passage, a fuel evaporative gas passage leading from the fuel tank to the canister. or an internal combustion engine, characterized in that an atmosphere introduction passage is connected to the fuel tank or canister, and at least two check valves are provided in series in the atmosphere introduction passage so as to open only in the direction toward the fuel tank. A treatment device for fuel evaporative gas in an engine.