JPH0248686Y2 - - Google Patents

Description

[Detailed Description of the Invention] Industrial Application Field The present invention is a multi-cylinder internal combustion engine having an independent intake system, in which independent intake pipes are connected through the same communication pipe, and a carbon dioxide gas is connected through the communication pipe. The present invention relates to a control mechanism for a communication pipe in a device for inhaling fuel evaporative gas from a nister into an intake system, which achieves both reduction in emissions due to fuel evaporative gas and improvement in idling stability.

BACKGROUND ART A multi-cylinder internal combustion engine is equipped with a so-called independent intake system in which each cylinder has an independent intake pipe that connects a surge tank or air cleaner to each cylinder, and each independent intake pipe has a throttle valve. In this case, the fuel evaporative gas adsorbed by the coal canister is inhaled into the engine through the purge port provided in the throttle valve of only one cylinder (for example, Japanese Utility Model Application Publication No. 1984-84361), or the intake air of each cylinder is Communication pipe that connects pipes (JP-A-Sho
No. 54-137516) is provided, and the fuel evaporative gas from the charcoal canister is distributed and sucked into each cylinder through the communication pipe for treatment.

Problems that the invention aims to solve However, when using the former method, it causes variations in intake air amount and air-fuel ratio between cylinders, and in cylinders where a large amount of fuel evaporative gas is sucked, fuel evaporative gas There is a problem of inducing the generation of emissions. In addition, when using the latter method, fuel evaporative gas is sucked into the engine through the communication pipe even during idling operation, causing idling instability due to changes in the air-fuel ratio, and There is a problem in that interference occurs and the idle speed increases. This is because when a certain cylinder is on the intake stroke, the air in the intake pipes of other cylinders is close to atmospheric pressure, and air flows from that cylinder through the communication pipe into the intake pipe of the cylinder that is on the intake stroke, causing the idle speed to increase. This is because the amount will rise.

In order to solve the above-mentioned problems, the present invention has an independent intake system, and communicates the independent intake pipes with a communication pipe, so that the communication pipe sucks fuel evaporative gas from the charcoal canister. In a multi-cylinder internal combustion engine, fuel evaporative gas is treated in a way that does not harm the engine operating function, resulting in good emission reduction and good drivability.
The purpose is to achieve both idling stability and prevent interference between cylinders by cutting off communication between each intake pipe during idling.

Means for Solving the Problems In order to achieve this objective, in the present invention, a port is provided downstream of the throttle valve in each intake pipe connected to each cylinder of an internal combustion engine with an independent intake system, and each port is provided with a port downstream of the throttle valve. They are connected to the same communication pipe. The communication pipe is connected by piping to a charcoal canister provided outside for temporarily adsorbing fuel evaporative gas. A circular tube is inserted into the communication tube, which is rotatable within the communication tube and has a slit at a position facing the port, and when the throttle is near idle opening, the port and the slit are not electrically connected. Although there is no such thing, it is linked to the throttle valve so that when the throttle opens more than a predetermined amount above the idle opening, there is electrical continuity between the port and the slit. The control mechanism of the communication pipe of the present invention is composed of the above components.

Effect With the above configuration, when the throttle valve is opened to a predetermined opening degree or more, the ports and slits match, so the fuel evaporative gas from the coal canister is distributed almost equally to each cylinder through the communication pipe. The fuel evaporative gas that is distributed and temporarily adsorbed in the carbon canister is guided into the combustion chamber of the engine and burned without being discharged outside the vehicle. In this state, the amount of air taken into the engine is large, and the fuel evaporative gas is completely combusted, so that there is no increase in emissions due to suction of the fuel evaporative gas.

When the throttle valve reaches the idling opening position, the communication between the port and the slit is cut off, and the suction of fuel evaporative gas from the coal canister is stopped. Therefore, since no air-fuel ratio change occurs due to intake of fuel evaporative gas, idling instability does not occur, and good drivability is ensured. In addition, each port connected to each intake pipe is blocked by the wall of the circular pipe, and the communication between each cylinder through the communication pipe is also blocked, so the idle speed increases due to the flow of intake air from other cylinders. No such phenomenon occurs. Further, the opening area of the slit portion changes analogously in proportion to the throttle opening. For this reason, the opening area is small in the low air volume range with a small throttle opening, and large in the large air volume range with a large throttle opening, minimizing the effects of fuel evaporation on the air-fuel ratio and inter-cylinder interference. It can be stopped.

Embodiments Hereinafter, preferred embodiments of the communication pipe control mechanism according to the present invention will be described with reference to the drawings.

1 through 3 illustrate preferred embodiments of the present invention. In Fig. 3, 1 is an internal combustion engine;
2 is a surge tank or an air cleaner, and both are connected by an independent intake pipe 3. The figure shows the case of a 4-cylinder engine, and the number 3
a, 3b, 3c, and 3d indicate each intake pipe. 4 is an exhaust manifold. Independent intake pipe 3
A, 3b, 3c, and 3d are each provided with a throttle valve 5 downstream of the surge tank or air cleaner 2, and are opened and closed simultaneously by the same connecting shaft 6. This constitutes an independent intake system.

The independent intake pipes 3a, 3b, 3c, 3d are the third
As shown in the figure, downstream of the throttle valve 5, the same communication pipe 7 communicates with each other via a port 8. Code 8a, 8b, 8c, 8d
connect the communication pipe 7 to each intake pipe 3a, 3b, 3, respectively.
It shows ports communicating with ports c and 3d.

The communication pipe 7 consists of a hollow body with one end closed,
A circular tube 9 is rotatably inserted into the interior in sliding contact. The circular tube 9 has a slit 10 extending in the circumferential direction at a position corresponding to the port 8. Symbols 10a, 10b, 10c, and 10d are ports 8a,
The slits corresponding to 8b, 8c, and 8d are shown. One end of the circular tube 9 is closed, and the other end is closed by one end of the communication tube 7, and when the port 8 and the slit 10 match, the inside of the circular tube 9 is closed to each intake tube 3a, 3b, 3c, 3d is formed. Reference numeral 12 denotes a snap ring for axially positioning the circular tube 9 within the communication tube 7 to prevent it from coming off.

The communication space 11 whose one end is closed by one end of the communication pipe 7 is a charcoal canister that temporarily adsorbs fuel vapor through a fuel vapor introduction port 13 formed at one end of the communication pipe 7. It is connected to 14.

One end of a link mechanism 15 is attached to the closed end of the circular tube 9, and the other end of the link mechanism 15 is connected to the connecting shaft 6 of the throttle valve 5. The link mechanism 15 rotates the circular tube 9 in conjunction with the throttle valve 5, thereby making the port 8 and the slit 10 mismatched when the throttle valve opening is near the idle, thereby blocking the port 8 and closing the throttle valve at idle. Port 8 and slit 10 at a predetermined opening degree or more
The intake pipes 3a, 3b, 3c, and 3d are made to communicate with each other through the communication space 11.

In the above configuration, the circular tube 9 is rotated into the communicating tube 7, but the circular tube may be slid into the communicating tube to connect or disconnect the port and the slit 10. In this case, the circular tube is configured to move in the axial direction within the communicating tube in response to rotation of the throttle valve.

Next, the operation of the embodiment will be explained. In conjunction with the rotation of the throttle valve 5, the circular tube 9 is rotated via the link mechanism 15. Throttle valve 5
When the opening is greater than the idle opening, the circular pipe 9 rotates to the position where the port 8 and the slit 10 match, and each intake pipe 3a, 3b, 3c, 3d
are communicated by a communication space 11 via ports 8a, 8b, 8c, 8d and slits 10a, 10b, 10c, 10d. Therefore, the fuel evaporative gas sucked into the communication space 11 from the coal canister 14 by the intake pipe negative pressure is equally distributed and sucked into each intake pipe 3a, 3b, 3c, and 3d. The inhaled fuel evaporative gas enters the combustion chamber of the internal combustion engine 1 and is combusted. In this case, since the throttle valve 5 is opened to a predetermined opening degree or more, the amount of intake air is large, and the fuel evaporative gas is completely combusted, so that no increase in emissions due to the fuel evaporative gas occurs.

On the other hand, when the throttle valve 5 is near the idle opening, the circular pipe 9 is connected to the port 8 and the slit 10.
Since each port 8 rotates to a position that does not match,
a, 8b, 8c, and 8d are blocked by the wall of the circular pipe 9, and communication between the intake pipes 3a, 3b, 3c, and 3d through the communication pipe 7 is blocked. As a result, fuel evaporative gas does not flow into each intake pipe 3a, 3b, 3c, 3d, and each intake pipe 3a, 3b, 3d
c and 3d are completely independent of each other. When the engine is idling, the amount of intake air is small and the cylinder distribution is not uniform, so even if a small amount of fuel evaporation gas is inhaled, the distribution between the cylinders will vary, causing deterioration of drivability and problems with the emission. However, in the present invention, suction of fuel evaporative gas is stopped during idling, so the idle instability caused by suction of fuel evaporative gas as described above does not occur. At the same time, each intake pipe 3a, 3b, 3c, 3
Since the communication between cylinders d and d is cut off, there is no interference between the cylinders, and the idle speed does not increase unnecessarily.

The opening area of the matching portion of the slit 10 and the port 8 changes analogously in proportion to the throttle opening. For this reason, the opening area is small in the low air volume range where the throttle opening is small, and it is large in the large air volume range where the throttle opening is large, minimizing the effects of fuel evaporative gas on the air-fuel ratio and interference between cylinders. It is possible and convenient.

Effects of the Invention As is clear from the above explanation, when using the communication pipe control mechanism of the present invention, the communication pipe that communicates each intake pipe in an independent intake system is communicated with the coal canister, and the A circular tube is installed that cuts off communication near the throttle opening and becomes conductive at a predetermined opening or above, making it possible to stop the suction of fuel evaporative gas into the engine near idle, reducing emissions due to fuel evaporative gas. , and ensuring good drivability.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view along the longitudinal direction of the communication tube in the vicinity of the communication tube of an embodiment of the control mechanism for the communication tube according to the present invention, and FIG. 2 is a cross-sectional view of the apparatus shown in FIG. 1 in the vicinity of the communication tube. FIG. 3 is a plan view of the device shown in FIG. 1 applied to an internal combustion engine. 1...Internal combustion engine, 3, 3a, 3b, 3c, 3d
... Intake pipe, 5 ... Throttle valve, 6 ... Connection shaft, 7 ... Communication pipe, 8, 8a, 8b, 8c, 8
d...Port, 9...Circular tube, 10, 10a, 10
b, 10c, 10d...Slit, 11...Communication space, 13...Fuel evaporative gas inlet, 14...
Charcoal canister, 15... link mechanism.

Claims (1)

[Scope of utility model registration request] In a multi-cylinder internal combustion engine having an independent intake system, a port is provided downstream of the throttle valve in each intake pipe, and each port is connected through the same communication pipe,
The communication pipe is connected by piping to a charcoal canister that temporarily adsorbs fuel evaporative gas, and within the communication pipe is a circular pipe that is rotatable within the communication pipe and has a slit at a position facing the port. Insert
The circular pipe is linked to a throttle valve so that there is no electrical connection between the port and the slit when the throttle is near the idle opening, but there is electrical continuity between the port and the slit when the throttle opens beyond a predetermined amount at or above the idle opening. A communication pipe control mechanism characterized by: