JPS6321715Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to an evaporative fuel processing device for an engine in which a compressor of a supercharger is disposed at a position upstream of a throttle valve in an intake passage.

Evaporated fuel treatment that prevents air pollution caused by evaporated fuel by storing evaporated fuel generated in the fuel tank or float chamber of the carburetor in the canister instead of releasing it into the atmosphere, and consuming it as part of the fuel during engine operation. As a device, the one published in Japanese Utility Model Publication No. 52-9454 has been proposed. In this prior art, the extraction port of the evaporated fuel extraction passage connected to the canister is opened to the intake passage at a position slightly upstream of the idle position of the throttle valve, and is suitable for general engines without a supercharger. It was developed.

If this prior art is applied as it is to the above-mentioned supercharged engine, negative pressure will be applied to the extraction port in the region where the opening degree of the throttle valve is small, and the evaporated fuel in the canister will pass through the evaporated fuel extraction passage and be drawn into the intake air. The vaporized fuel in the canister is extracted into the canister and works effectively in the same way as when applied to an engine without a supercharger, but when the supercharger operates and positive pressure is applied to the extraction port, the vaporized fuel in the canister The air cannot be extracted into the intake passage. As a result, the canister's ability to adsorb evaporated fuel deteriorates, causing deterioration in engine restartability, and part of the evaporated fuel leaking from the canister into the atmosphere, making it necessary to increase the canister capacity. This will cause financial damage.

This invention was devised in view of the above, and
The purpose of this invention is to provide an evaporated fuel processing device that can extract the evaporated fuel in the canister into the intake passage even in the region where the supercharger operates, eliminates the disadvantages of the prior art, and has a simple structure. .

In order to achieve the above object, the present invention provides a two-way evaporative fuel extraction passage in a canister communicating with an evaporative fuel generation source such as a fuel tank in an engine in which a compressor of a supercharger is arranged upstream of a throttle valve in an intake passage. and the extraction port of the evaporated fuel extraction passage of the first path is opened to the intake passage at a position slightly upstream of the idle position of the throttle valve, at the idle position, or at a position downstream of the idle position, while the second passage The extraction port of the evaporated fuel extraction passage of the route is opened to the intake passage at a position upstream of the compressor of the supercharger, and
The present invention is characterized in that a check valve for blocking the flow of gas from the intake passage side to the canister side is disposed in each of the evaporated fuel extraction passage of the second passage and the second passage.

The present invention will be explained in detail below based on embodiments shown in the drawings.

The inside of the canister 1 is divided into upper and lower parts by an adsorbent layer 7 made of activated carbon or the like, and the upper space 8 communicates with the fuel tank 2 and the float chamber 4 of the carburetor 3 via the communication pipes 5 and 6, while the lower space The space 9 is open to the atmosphere via a vent 10.

The upper space 8 of the canister 1 is connected to an intake passage 13 by two evaporative fuel extraction passages 11 and 12. The intake passage 13 is provided with a throttle valve 14, a turbocharger compressor 15 located upstream of the throttle valve 14, an air cleaner 16 located most upstream, and the like.

The extraction port (hereinafter referred to as the first extraction port) 11a of the vaporized fuel extraction passage (hereinafter referred to as the first extraction passage) 11 of the first route is located at a position slightly upstream of the idle position of the throttle valve 14. It opens into the intake passage 13. A normally closed check valve 17 (hereinafter referred to as the first check valve) is disposed on the first extraction passage 11, and is operated only when the pressure at the first extraction port 11a becomes lower than a predetermined negative pressure. The valve is configured to open.

The extraction port (hereinafter referred to as the second extraction port) 12a of the evaporated fuel extraction passage (hereinafter referred to as the second extraction passage) 12 of the second route is located at the upstream side of the compressor 15 and the downstream position of the air cleaner 16. It opens to the intake passage 13 at. On this second extraction passage 12, there is a normally closed check valve (hereinafter referred to as a second
It is called a check valve. ) 18, which is configured to open and close only when the pressure of the second extraction port 12a becomes more vacuum than a predetermined negative pressure. Further, the second extraction port 12a opens into a ventilate portion 19 provided in the intake passage 12.

In the illustrated embodiment, the first extraction passage 11 and the second extraction passage 12 are connected to a common base pipe 20 and a branch pipe 2.
1 and 22, and a first check valve 17 and a second check valve 18 are disposed on the branch pipes 21 and 22, respectively.
A first extraction passage 11 and a second extraction passage 1 with a main conduit
It is also possible to configure 2. Note that 23 is the engine body.

Next, the operation of the above embodiment will be described. When the engine is temporarily stopped, the expanding gas warmed in the fuel tank 2 and float chamber 4 flows into the upper space 8 of the canister 1 via the communicating pipes 5 and 6 together with the evaporated fuel. At this time, the first and second check valves 17 and 18 are closed, so the expanding gas passes through the adsorbent layer 7 and flows out through the vent hole 10. At this time, the evaporated fuel in the expanding gas is adsorbed by the adsorbent layer 7.
This makes it possible to prevent the atmosphere from being polluted by evaporated fuel.

When the engine is idling, the first extraction port 1
Since the valve 1a is located upstream of the throttle valve 14, no negative pressure is applied to it, and as a result, the first check valve 1
7 remains closed. The second check valve 18 is also closed. Therefore, the evaporated fuel flows through the intake passage 1.
3, and it is possible to prevent the predetermined air-fuel ratio during idling from being disturbed by the evaporated fuel.

When the throttle valve 14 gradually opens and its upper end is located upstream of the first extraction port 11a, the pressure near the first extraction port 11a becomes negative pressure.
When this negative pressure becomes more vacuum than a predetermined negative pressure, the first check valve 17 opens and the first extraction passage 11 opens. Therefore, the evaporated fuel adsorbed on the adsorbent layer 7 of the canister 1 and the evaporated fuel accumulated in the upper space 8 are moved to the first extraction passage 1 by the suction force of the negative pressure.
1 into the intake passage 13. In this way, when the opening degree of the throttle valve 14 is small, the first
Evaporated fuel is extracted into the intake passage 13 through the extraction passage 11, but since the pressure near the second extraction port 12a is close to atmospheric pressure, the second check valve 18 is closed and the second extraction passage 11 remains blocked. . If the second check valve 18 is not provided, the negative pressure of the first extraction port 11a is applied to the first extraction passage 1.
1 and acts on the canister 1 through the second extraction passage 12, and at the same time acts on the second extraction port 12a through the second extraction passage 12. Therefore, in addition to the normal path, air flows through the second extraction passage 12a → second extraction passage 12 → first extraction passage. 11
→It will flow into the engine body 23 through the abnormal path of the first extraction port 11a, resulting in a situation where the air-fuel ratio becomes leaner than expected. The second check valve 18 has the function of preventing such malfunctions.

When the opening of the throttle valve 14 increases and the compressor 15 of the supercharger starts operating, the pressure near the first extraction port 11a changes to positive pressure and the first check valve 17 closes. For this reason, the first extraction passage 1
The extraction of evaporated fuel through the canister 1 is cut off, and the air-fuel mixture can be prevented from flowing out to the canister 1 side by the first check valve 17. On the other hand, the operation of the compressor 15
The flow rate of the intake air upstream of the canister 1 increases, and the pressure near the second extraction port 12a becomes a negative pressure on the vacuum side from the predetermined negative pressure, the second check valve 18 opens, and the evaporated fuel in the canister 1 2 is extracted into the intake passage 13 through the extraction passage 12.

As described above, in the present invention, when the opening degree of the throttle valve 14 is small, the canister is extracted through the first extraction passage 11, and when the opening degree of the throttle valve 14 is large and the compressor 15 is operated, the canister is extracted through the second extraction passage 12. Since the structure is such that the evaporated fuel in the canister 1 is extracted into the intake passage 13, the ability of the canister 1 to adsorb the evaporated fuel can be maintained in a good state even during supercharging. It is possible to prevent some of it from leaking into the atmosphere, and
Engine restartability can be improved.
In addition, the present invention provides a first extraction passage 11 and a second extraction passage 1.
To prevent air from flowing into the engine body 23 through an abnormal route during low load operation by adding a simple structure in which the first check valve 17 and the second check valve 18 are arranged in each of the engine parts 2 and 2. At the same time, it is possible to prevent the air-fuel mixture from flowing out to the canister 1 side during high-load operation.

Although the above embodiment relates to an engine equipped with a turbocharger type supercharger, it is possible to implement the present invention in an engine equipped with other types of superchargers such as a fuel injection type engine. Further, in the above embodiment, the fuel tank 2 and the float chamber 4 of the vaporizer 3 are used as vaporized fuel generation sources, and these are communicated with the canister 1, but the present invention is of course not limited to this. Furthermore, in the above embodiment, the first extraction port 11a is configured to open into the intake passage 13 at a position slightly upstream of the idle position of the throttle valve 14, but if the engine can appropriately control the air-fuel ratio at idle, then The first extraction port 11a may be opened to the intake passage 13 at the idle position of the throttle valve 14 or at a position downstream of the idle position.

[Brief explanation of the drawing]

The drawing is an overall view showing an embodiment of the present invention. 1... Canister, 2... Fuel tank, 3...
Carburetor, 4... Float chamber, 11... Fuel vapor extraction passage of the first route, 12... Fuel vapor extraction passage of the second route, 13... Intake passage, 14... Throttle valve, 15... Turbocharger compressor, 1
7,18...Check valve.

Claims (1)

[Scope of utility model registration request] In an engine in which a compressor for a supercharger is arranged upstream of a throttle valve in an intake passage, two evaporated fuel extraction passages are connected to a canister that communicates with an evaporated fuel generation source such as a fuel tank, and a first evaporated fuel The extraction port of the extraction passage is opened to the intake passage at a position slightly upstream of the idle position of the throttle valve, at the idle position, or at a position downstream of the idle position, while the extraction port of the vaporized fuel extraction passage of the second route is opened to the intake passage. is opened into the intake passage at a position upstream of the compressor of the supercharger,
A supercharged engine characterized in that a check valve for blocking gas flow from the intake passage side to the canister side is arranged in each of the vaporized fuel extraction passages of the first route and the second route. evaporative fuel processing equipment.