JPH0318688Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention relates to an evaporative fuel processing device for an engine that processes evaporative fuel generated in a fuel tank, a float chamber of a carburetor, etc.

(Prior Art) Conventionally, it has been undesirable from the viewpoint of air pollution prevention to directly release evaporated fuel generated in fuel tanks, float chambers of vaporizers, etc. into the atmosphere. The upper space of the engine is connected to an evaporated fuel storage device having an adsorbent inside, so that the evaporated fuel is temporarily stored in the storage device. An engine vaporized fuel processing device is known in which vaporized fuel is supplied from a container to an intake passage and combusted (see, for example, Japanese Utility Model Publication No. 49-22885).

(Problem that the invention aims to solve) However, if evaporated fuel is supplied to the intake system when the throttle valve opens above a certain level, the evaporated fuel will make the fuel rich, making it difficult to drive. Performance and emission performance may be adversely affected.

This invention purges evaporated fuel into the intake passage during specific driving situations such as deceleration when fuel is cut, thereby making it possible to efficiently purge evaporated fuel without adversely affecting driving performance or emission performance. The purpose of the present invention is to provide an evaporative fuel processing device.

(Means for Solving the Problems) The present invention is based on an engine evaporative fuel processing device that cuts fuel during specific engine operations, and is connected to the upper space of the fuel tank via an evaporative passage to remove evaporative fuel. a first purge passage connecting the evaporative fuel reservoir and the intake passage immediately upstream of the throttle valve; and a first purge passage connecting the evaporative fuel reservoir and the downstream side of the throttle valve. The structure includes a second purge passage having a larger passage area than the second purge passage, a control valve that is interposed in the second purge passage and opens when fuel is cut, and a catalyst device disposed in the exhaust passage.

(Operation) When fuel is cut, the control valve opens and the second purge passage is communicated. As a result, the evaporated fuel in the evaporated fuel reservoir is sucked out by the intake negative pressure downstream of the throttle valve. In this case, no fuel is being supplied, so even if a large amount of evaporated fuel is purged,
It does not become overrich, does not affect driving performance, and does not have the problem of becoming overlean when there is no evaporated fuel. Therefore, the vaporized fuel is burned in the catalyst device in the exhaust passage, and does not adversely affect the emission performance.

On the other hand, during operation except during deceleration, the control valve is closed and the second purge passage is cut off, so the evaporated fuel is purged through the first purge passage when the opening of the throttle valve reaches or exceeds the set opening. At this time, the first purge passage has a smaller passage area than the second purge passage, and only a small amount of evaporated fuel is purged into the intake passage, so there is almost no change in the air-fuel ratio, which has a negative impact on driving performance and emission performance. not give. Furthermore, even during steady high-speed driving where there is no deceleration period during which fuel is cut, the evaporated fuel is purged into the intake passage little by little, so there is no risk of overflow.

(Example) Hereinafter, an example of the present invention will be described in detail with reference to the drawings.

In FIG. 1 showing the overall configuration of an evaporative fuel processing device for an engine, 1 is an engine, and an intake passage 2 and an exhaust passage 3 are connected to each other. An air cleaner 4, a throttle valve 6, and a fuel injection valve 7 are arranged in this order from the upstream side in the intake passage 2, while a catalyst device 8 is interposed in the exhaust passage 3.

Reference numeral 9 denotes a fuel tank, and its upper space 9a is connected to the intake passage 2 immediately upstream and downstream of the throttle valve 6 via an evaporative fuel reservoir 11 having an adsorbent 10 therein. That is, the upper space 9a
is connected to the vaporized fuel inlet 11a on one side of the reservoir 11 via the evaporative passage 12, and the vaporized fuel supply ports 11b and 11c on the same side are connected to the first and second vaporized fuel inlets 11a on the same side.
The purge port 1 immediately upstream and downstream of the throttle valve 6 of the intake passage 2 is connected via the purge passages 13 and 14.
5 and 16, and purges the evaporated fuel stored in the reservoir 11 into the intake passage 2 through the purge ports 15 and 16. The second purge passage 14 has a larger diameter and a larger passage area than the first purge passage 13, and is provided with an electromagnetic control valve 17 that opens and closes depending on the operating state of the engine.

On the other hand, an atmosphere opening port 11d is provided on the opposite side of the reservoir 11 from the inlet port 11a and the supply ports 11b and 11c.

The electromagnetic control valve 17 is the control unit 1
The control unit 18 detects the opening of the throttle valve 6 when the throttle opening sensor 19 detects the opening of the throttle valve 6 and signals from the engine speed sensor 20 indicate that the throttle opening is below the set opening and the engine is running. The electromagnetic control valve 17 is opened only when it is determined that the rotational speed is equal to or higher than the set rotational speed and the fuel injection valve 7 is in a fuel cut region (see FIG. 2) in which no fuel is injected.

With the above configuration, when the control unit 18 determines that it is deceleration time when fuel is cut based on the signals from the throttle opening sensor 19 and the engine speed sensor 20, the electromagnetic control valve 1
An excitation signal is output to 7, and the control valve 17 opens,
A second purge passage 14 is communicated.

As a result, the evaporated fuel in the reservoir 11 is sucked out by the intake negative pressure downstream of the throttle valve 6. In this case, fuel injection is not performed, so even if a large amount of evaporated fuel is purged, it will not become overrich and will not affect driving performance, and the problem is that it will become overlean when there is no evaporated fuel. Nor. Therefore, the evaporated fuel is removed from the exhaust passage 3.
is combusted in the catalyst device 8, and does not adversely affect emission performance.

On the other hand, during operation except during deceleration, the solenoid control valve 1
7 is closed and the second purge passage 14 is cut off, the evaporated fuel is purged through the first purge passage 13 when the throttle valve 6 reaches the set opening degree or more. At this time, the first purge passage 13 is
The passage area is smaller than the purge passage 14, and only a small amount of evaporated fuel is purged into the intake passage 2, so there is almost no fluctuation in the air-fuel ratio, improving driving performance.
Does not adversely affect emission performance. Furthermore, even during steady high-speed driving where there is no deceleration period during which fuel is cut, the evaporated fuel is purged into the intake passage 2 little by little, so there is no risk of overflow.

In the case of an engine with cylinder number control, a second purge passage equipped with a control valve that opens when fuel is cut is connected to the intake passage of the cylinder whose fuel is cut off during cylinder reduction operation, and the second purge passage is connected to the intake passage of the cylinder whose fuel is cut off during cylinder reduction operation. By opening the control valve of the passage, it can be applied in the same manner as in the above embodiment.

Furthermore, in the case of an engine equipped with a carburetor, the present invention can be applied in the same manner as in the above embodiment by connecting the evaporation passage to the upper space of the float chamber of the carburetor.

(Effects of the invention) As described above, the present invention opens the control valve at the time of fuel cut when fuel is not being supplied, and purges the evaporated fuel into the intake passage through the second purge passage. Even if a large amount of fuel is purged, it does not become overrich and does not affect driving performance, and there is no problem of becoming overlean when there is no evaporated fuel. Therefore, the vaporized fuel is burned in the catalyst device in the exhaust passage, and does not adversely affect the emission performance.
In addition, the control valve is closed during operation other than when fuel is cut, and the evaporated fuel is purged into the intake passage through the first purge passage, which has a smaller passage area than the second purge passage, so a small amount of evaporated fuel is purged into the intake passage. There is almost no change in the air-fuel ratio, and there is no negative effect on driving performance or emission performance. Furthermore, even during steady high-speed driving with no fuel cut-off, the evaporated fuel is purged little by little into the intake passage through the first purge passage.
There is no risk of overflow.

[Brief explanation of the drawing]

The drawings show an embodiment of the present invention, and FIG. 1 is an overall configuration diagram of an evaporative fuel processing device for an engine, and FIG. 2 is an explanatory diagram of a fuel cut area. DESCRIPTION OF SYMBOLS 1...Engine, 2...Intake passage, 3...Exhaust passage, 6...Throttle valve, 8...Catalyst device, 1
DESCRIPTION OF SYMBOLS 1... Evaporated fuel storage device, 13... First purge passage, 14... Second purge passage, 17... Solenoid control valve.

Claims (1)

[Scope of claim for utility model registration] An evaporative fuel storage device connected to the upper space of a fuel tank via an evaporation passage and storing evaporative fuel in an engine that cuts fuel during a specific operation of the engine; a first purge passage that connects the evaporated fuel storage device and the intake passage immediately upstream of the throttle valve; a second purge passage that connects the vaporized fuel storage device and the downstream side of the throttle valve and has a larger passage area than the first purge passage; An evaporative fuel processing device for an engine, comprising: a control valve that is disposed in the second purge passage and opens when fuel is cut; and a catalyst device that is disposed in the exhaust passage.