JPH033067B2 - - Google Patents

Description

Detailed Description of the Invention (Industrial Application Field) The present invention introduces evaporated fuel generated in a fuel tank or a float chamber of a carburetor into an engine intake passage through a canister, and converts it into a part of the fuel. The present invention relates to an evaporative fuel processing device for an engine that performs combustion processing.

(Prior Art) In order to prevent evaporated fuel generated in a fuel storage chamber in a vehicle, such as a fuel tank or a float chamber of a carburetor attached to an engine, from being dissipated into the atmosphere, the evaporation generated in the fuel storage chamber is Fuel is stored in a canister containing an adsorbent such as activated carbon, and when the engine is running, the intake negative pressure is used to guide the fuel into the intake passage through a purge passage that opens into the intake passage, where it is consumed as part of the fuel. What is being done is being done. As described above, a device that stores the vaporized fuel generated in the fuel storage chamber in the canister and then guides it to the intake passage of the engine and burns it, that is, a device that processes the vaporized fuel, that is, the vaporized fuel processing device, has conventionally used, for example,
As described in Japanese Patent Publication No. 55-119949, the communication path between the fuel storage chamber and the canister is
Normally, a canister is opened to the opening side of a purge passage provided above the canister and guiding vaporized fuel in the canister to an intake passage.

In the evaporative fuel processing device in which the communication passage between the fuel storage chamber and the canister is opened to the opening side of the purge passage in the canister, the evaporated fuel introduced into the canister from the fuel storage chamber is turned into air. Since it has a relatively large weight, it flows toward the lower part of the canister, which is open to the atmosphere, and at that time, it is adsorbed by the layer of intake agent such as activated carbon contained in the canister, and is retained in the canister. It turns out. The evaporated fuel accumulated in the canister is removed by opening the purge passage when the engine is operating (excluding when the amount of fuel supplied to the engine is relatively small, such as when idling). The intake negative pressure generated in the intake passage of the engine is used, mixed with air introduced from the atmosphere opening part of the canister (hereinafter referred to as purge air), and guided to the intake passage through the purge passage.

(Problems to be Solved by the Invention) However, as described above, the communication passage between the fuel storage chamber and the canister, and the purge passage that communicates the canister with the intake passage of the engine,
In the case of evaporative fuel processing devices that are opened at the top of the canister, when the engine is in operation and the purge passage is open, most of the evaporative fuel introduced into the canister from the fuel storage chamber is , it will be introduced into the intake passage via the purge passage without remaining in the canister. Therefore, when the engine is in operation and the purge passage is open, if a relatively large amount of evaporated fuel is introduced into the canister from the fuel storage chamber, a large amount of evaporated fuel is drawn into the canister through the purge passage. Conversely, if only a small amount of evaporated fuel is introduced into the canister, only a small amount of evaporated fuel will be introduced into the intake passage through the purge passage. As a result, the air-fuel ratio of the mixture combusted in the combustion chamber of the engine changes significantly depending on the amount of evaporated fuel, causing undesirable fluctuations in the combustion state in the combustion chamber, and furthermore, the exhaust gas This may cause an inconvenience in that the cleanliness of the gas may vary.

Such inconvenience can be solved, for example, by opening the communication path between the fuel storage chamber and the canister at the lower part of the canister, that is, toward the atmosphere opening side, so that the evaporated fuel from the fuel storage chamber is drained into the canister when the engine is operating. This can be reduced by introducing the adsorbent from below the adsorbent layer and leading it to the purge passage from above. That is, by opening the communication passage between the fuel storage chamber and the canister to the atmosphere opening side of the canister, even when the engine is in operation and the purge passage is open, the communication passage from the fuel storage chamber to the canister can be opened. The evaporated fuel introduced into the intake passage can be guided to the purge passage through the adsorbent layer, and the amount of evaporated fuel introduced into the intake passage via the purge passage can be averaged.

However, when the communication path between the fuel storage chamber and the canister is opened to the atmosphere opening side of the canister, when the engine is not in operation, the evaporation introduced from the fuel storage chamber into the canister is prevented. There is a possibility that a part of the fuel may not be sufficiently adsorbed by the adsorbent layer and may be released to the outside from the atmosphere opening part.

In view of this, the present invention averages the amount of evaporated fuel introduced from the canister to the engine intake passage through the purge passage when the engine is in operation and the purge passage is open. and when the engine is not in operation,
It is an object of the present invention to provide a evaporated fuel processing device for an engine that can sufficiently adsorb and hold evaporated fuel introduced into a canister from a fuel storage chamber inside the canister.

(Means for Solving the Problems) In order to achieve the above-mentioned object, an evaporative fuel processing device for an engine according to the present invention includes a canister that is provided with an atmosphere opening part and that retains evaporative fuel from a fuel storage chamber; The canister is communicated with the intake passage of the engine, and the purge passage that guides the evaporated fuel from the canister to the intake passage is communicated with the fuel storage chamber, so that the opening on the canister side is connected to the atmosphere opening side of the canister. a first evaporated fuel introduction path located therein, and a second evaporated fuel introduction path that similarly communicates the fuel storage chamber and the canister, and whose opening on the canister side is located on the opening side of the purge passage in the canister; A passage switching means is arranged to selectively open these first and second vaporized fuel introduction passages. The passage switching means is configured to open the first evaporative fuel introduction passage and shut off the second evaporative fuel introduction passage, at least when the evaporative fuel from the canister is guided to the intake passage of the engine.

(Function) In the evaporated fuel processing device for an engine according to the present invention as described above, when the evaporated fuel generated in the fuel storage chamber is in a state where the evaporated fuel from the canister is led to the intake passage of the engine, the first At other times, for example, when the engine is not in operation, the vaporized fuel is introduced into the canister's purge passage opening via the second vaporized fuel introduction path. introduced to the side. In this way, when the evaporated fuel from the canister is introduced into the intake passage of the engine, the evaporated fuel from the fuel storage chamber is introduced into the canister from the atmosphere opening side through the first fuel introduction path. The evaporated fuel introduced into the canister is assumed to be guided to the purge passage through the adsorbent layer inside the canister. Even when evaporated fuel is introduced into the canister, the amount of evaporated fuel introduced from the canister into the intake passage through the purge passage does not increase significantly. That is, the amount of evaporated fuel introduced into the intake passage from the canister is balanced, and fluctuations in the air-fuel ratio of the air-fuel mixture are alleviated.

In addition, when the engine is not in operation, the evaporated fuel from the fuel storage chamber is introduced from the opening side of the purge passage in the canister through the second evaporated fuel introduction path, so that the evaporated fuel introduced into the canister is Fuel is sufficiently adsorbed and retained inside the canister, and vaporized fuel is prevented from being released to the outside.

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

FIG. 1 shows an example of an engine evaporative fuel processing device according to the present invention, together with a part of an engine intake system to which the device is applied. In FIG. 1, the intake system of the engine is provided with an intake passage 4 that guides air supplied from an air cleaner 2 to an intake port portion of the engine (not shown), and at a predetermined position within this intake passage 4. , a vaporizer 5 is interposed. The carburetor 5 has a primary side intake passage section and 2
A primary intake passage is provided, and a main throttle valve 6 that opens and closes according to the amount of depression of the accelerator pedal is disposed in the primary intake passage.
A sub-throttle valve 7 that opens later than the main throttle valve 6 is arranged in the next intake passage.

One end of an evaporation passage 12 is connected to the upper part of the fuel tank 10, and the other end of this evaporation passage 12 is connected to an electromagnetic switching valve 14.
The inlet port 14a is connected to the inlet port 14a of the inlet port 14a. The electromagnetic switching valve 14 has an inlet port 14a, a solenoid 19, and two outlet ports 16a and 16b.
When 9 is not energized, inlet port 1
4a and the outlet port 16b,
When the solenoid 19 is energized, the valve arrangement is changed to bring the inlet port 14a and outlet port 16a into communication. And the solenoid 19 has a battery 18.
Excitation current is supplied from the ignition switch 17 through the ignition switch 17.

In addition, there is an evaporated fuel adsorbent layer 2 such as an activated carbon layer inside.
A canister 22 having a number of
Atmospheric release port 22a and vaporized fuel delivery port 2
2b is provided. In the vicinity of the atmosphere release port 22a of the canister 22, the other end of a communication passage 26, one end of which is connected to the outlet port 16a of the electromagnetic switching valve 14, is opened. Further, in the vicinity of the evaporated fuel delivery port 22b of the canister 22, the other end of a communication passage 28, one end of which is connected to the outlet port 16b of the electromagnetic switching valve 14, is opened.

That is, in this example, the evaporation passage 12 and the communication passage 26 constitute a first evaporative fuel introduction passage, and the evaporation passage 12 and the communication passage 28 constitute a second evaporation fuel introduction passage, and the electromagnetic switching valve 14 , the ignition switch 17, the battery 18, and the like constitute passage switching means for selectively opening the first evaporative fuel introduction passage and the second evaporative fuel introduction passage.

Evaporative fuel delivery port 22b of canister 22
is a purge valve 30 having a diaphragm mechanism.
, one end of which communicates with a purge passage 34 connected to a purge port 32 provided downstream of the main throttle valve 6 in the intake passage 4 . The purge valve 30 has its negative pressure introduction chamber 30
When a predetermined negative pressure is introduced into a, the opening is set to open the purge passage 34, and at other times, the opening is set to the closed state where the purge passage 34 is closed.

A negative pressure supply port 36 is provided upstream of the main throttle valve 6 in the intake passage 4 . One end of a negative pressure introduction passage 38 is connected to the negative pressure supply port 36, and the other end of this negative pressure introduction passage 38 is connected to the negative pressure introduction chamber 30a of the purge valve 30.

In an example of the evaporative fuel processing device for an engine according to the present invention having such a configuration, when the engine is not in operation, that is, when the ignition switch 17 is turned off, the solenoid 19 is turned off. is not energized, and the electromagnetic switching valve 14 is connected to the inlet port 14a and outlet port 1.
A valve arrangement is adopted to communicate with 6b. Therefore, the evaporated fuel generated in the fuel tank 10 is introduced into the evaporated fuel adsorbent layer 20 of the canister 22 through the evaporation passage 12 and the communication passage 28.
At this time, the negative pressure introduction chamber 30a of the purge valve 30
Since the predetermined negative pressure is not introduced into the purge passage 34 through the negative pressure introduction passage 38, the purge passage 34 is closed, and the evaporated fuel flows as shown by the arrow _F1 in FIG. In the fuel adsorbent layer 20,
It is gradually adsorbed and retained from above.

Next, when the ignition switch 17 is turned on and the engine is put into operation, the solenoid 19 is energized and the electromagnetic switching valve 14 takes a valve arrangement that communicates the inlet port 14a and the outlet port 16a. . Therefore, the evaporated fuel generated in the fuel tank 10 is introduced into the evaporated fuel adsorbent layer 20 of the canister 22 through the evaporation passage 12 and the communication passage 26. At this time, when the engine is in an idling state, the predetermined negative pressure is not introduced into the negative pressure introduction chamber 30a of the purge valve 30 via the negative pressure introduction passage 38, so the purge passage 3
4 is maintained in a closed state, and the evaporated fuel is retained in the evaporated fuel adsorbent layer 20.

When the engine is caused to shift from an idling operating state to a running operating state in which the main throttle valve 6 is opened to a predetermined opening or more, the intake negative air is introduced from the negative pressure supply port 36 into the negative pressure introduction passage 38. The pressure becomes equal to or higher than a predetermined pressure, and intake negative pressure equal to or higher than the predetermined pressure is introduced into the negative pressure introducing chamber 30a of the purge valve 30. As a result, the purge valve 30 is opened, the purge passage 34 is opened, and the evaporated fuel retained in the evaporated fuel adsorbent layer 20 of the canister 22 is introduced from the atmosphere opening port 22a of the canister 22. After being mixed with commercial air, the air is introduced into the intake passage 4 through the purge passage 34.

Therefore, for example, when a relatively large amount of evaporated fuel is introduced from the fuel tank 10 into the evaporated fuel adsorbent layer 20 of the canister 22 when the engine is in running operation, the evaporated fuel adsorbent layer of the canister 22 The vaporized fuel introduced into the vaporized fuel adsorbent layer 20 flows into the vaporized fuel adsorbent layer 20 as shown by the arrow _F2 in FIG. At the same time, a part of the evaporated fuel adsorbed and held on the evaporated fuel adsorbent layer 20 is sucked into the intake passage 4 through the purge passage 34 along with the purge air introduced into the canister 22 from the atmosphere release port 22a. be done.

In this way, by switching the introduction position of the evaporated fuel generated in the fuel tank 10 into the canister 22 between the vicinity of the atmosphere release port 22a and the vicinity of the evaporated fuel delivery port 22b, a relatively large amount of evaporated fuel can be introduced into the canister 22. When fuel is introduced, much of the evaporated fuel can be retained in the canister 22, and therefore a situation in which a large amount of evaporated fuel is introduced into the intake passage 4 through the purge passage 34 can be avoided. can.

FIG. 2 shows another example of the evaporative fuel processing device for an engine according to the present invention, together with an intake passage section of the engine to which the device is applied. In FIG. 2, parts corresponding to those shown in FIG. 1 are designated by the same reference numerals as those in FIG. 1, and redundant explanation thereof will be omitted.

In this example, a negative pressure responsive valve 40 having a diaphragm mechanism is used as passage switching means for selectively opening the first evaporative fuel introduction passage and the second evaporative fuel introduction passage. . The negative pressure responsive valve 40 has a negative pressure introduction chamber 41 to which the negative pressure introduction passage 38 is connected, and an inlet port 40a that communicates with the fuel tank 10 via the evaporation passage 12 and a canister via the communication passage 26. The outlet port 42a has an outlet port 42a that communicates with the vicinity of the atmosphere release port 22a in the canister 22, and an outlet port 42b that communicates with the vicinity of the evaporated fuel delivery port 22b of the canister 22 via the communication path 28.

The negative pressure responsive valve 40 opens the inlet port 40 when a predetermined negative pressure is introduced into the negative pressure introduction chamber 41.
In other cases, the valve arrangement is changed so that the inlet port 40a and the outlet port 42b communicate with each other. In addition, the negative pressure responsive valve 40
The diaphragm mechanism that makes up the purge valve 30 has the same diaphragm diameter, set load, spring force, etc. as the diaphragm mechanism that makes up the purge valve 30.

With this configuration, when the engine is not operating or is in an idling state, the negative pressure introduction chamber 3 of the purge valve 30
Since the predetermined negative pressure is not introduced into the negative pressure introducing chamber 41 of the negative pressure responsive valve 40 through the negative pressure introducing passage 38, the negative pressure responsive valve 40 is connected to the inlet port 40a and the outlet port 42b. A valve arrangement is used to communicate with the Therefore, the evaporated fuel generated in the fuel tank 10 is transferred to the evaporation passage 12.
The evaporated fuel adsorbent layer 20 of the canister 22 is introduced through the communication path 28 . At this time, since the purge passage 34 is closed, the evaporated fuel flows as shown by the arrow F1 in FIG. ₂ , and is gradually adsorbed and retained in the evaporated fuel adsorbent layer 20 from above. It will be done.

Next, the engine is shifted from the idling operating state to the running operating state, and the main throttle valve 6 is opened to a predetermined opening degree or more, and the intake negative air is introduced from the negative pressure supply port 36 into the negative pressure introduction passage 38. When the pressure exceeds the predetermined pressure, the purge valve 3
Intake negative pressure equal to or higher than a predetermined pressure is introduced into the negative pressure introduction chamber 30a of the engine 0 and the negative pressure introduction chamber 41 of the negative pressure responsive valve 40. As a result, the negative pressure responsive valve 40 takes a valve arrangement that communicates the inlet port 40a and the outlet port 42a, and the evaporated fuel generated in the fuel tank 10 is evaporated in the canister 22 through the evaporation passage 12 and the communication passage 26. The fuel adsorbent is introduced into the fuel adsorbent layer 20 .

On the other hand, the purge valve 30 assumes an open state substantially in synchronization with this, thereby opening the purge passage 34. Therefore, the evaporated fuel retained in the evaporated fuel adsorbent layer 20 of the canister 22 flows within the evaporated fuel adsorbent layer ₂₀ as shown by the arrow F2 in FIG. Most of the evaporated fuel is adsorbed and retained in the adsorbent layer 20 and a part of the evaporated fuel adsorbed and retained in the adsorbent layer 20 is transferred to the canister 22.
The purge air is introduced into the intake passage 4 through the purge passage 34 along with the purge air introduced from the atmosphere opening port 22a.

(Effects of the Invention) As is clear from the above description, according to the evaporative fuel processing device for an engine according to the present invention, there are two states in which the evaporative fuel stored in the canister is guided to the intake passage of the engine and other states. The introduction position of the evaporated fuel from the fuel storage chamber into the canister is
Since the canister is switched between the atmosphere opening side and the purge passage opening side, when the engine is not in operation, the evaporated fuel from the fuel storage chamber can be sufficiently adsorbed and retained inside the canister. In addition, when the engine is in operation and the purge passage is open, even if a relatively large amount of evaporated fuel is introduced into the canister from the fuel storage chamber, most of the evaporated fuel is not transferred into the canister. The amount of evaporated fuel introduced from the purge passage to the intake passage of the engine can be averaged. This results in
Not only can the dissipation of evaporated fuel to the outside be significantly reduced, but also the situation where the air-fuel ratio of the air-fuel mixture changes significantly due to fluctuations in the amount of evaporated fuel introduced into the intake passage through the purge passage when the engine is operating. be able to avoid it.

[Brief explanation of the drawing]

FIG. 1 is a schematic configuration diagram showing an example of an engine evaporative fuel processing device according to the present invention together with a part of the engine intake system to which it is applied, and FIG. 2 is a schematic diagram showing an example of an engine evaporative fuel processing device according to the present invention. FIG. 3 is a schematic configuration diagram showing another example together with a part of an intake system of an engine to which the example is applied. In the figure, 4 is an intake passage, 10 is a fuel tank, 12
14 is an evaporation passage, 14 is an electromagnetic switching valve, 22 is a canister, 22a is an atmosphere release port, 22b is an evaporative fuel delivery port, 26 and 28
30 is a communication passage, 30 is a purge valve, 32 is a purge port, 34 is a purge passage, 38 is a negative pressure introduction passage,
40 is a negative pressure responsive valve.

Claims (1)

[Claims] 1. A canister having an atmosphere opening part and retaining the evaporated fuel from the fuel storage chamber; a purge passage that communicates the canister with the intake passage of the engine to lead the evaporated fuel to the intake passage of the engine; a first evaporated fuel introduction passage which is opened into the fuel storage chamber and whose other end is opened to the atmosphere opening side of the canister; A second evaporative fuel introduction path opened toward the opening side of the purge passage, and a second evaporative fuel introduction path that is arranged to selectively open the first evaporative fuel introduction path and the second evaporative fuel introduction path, and at least the canister. and passage switching means for opening the first evaporative fuel introduction passage and blocking the second evaporative fuel introduction passage when the evaporative fuel from the evaporative fuel is introduced into the intake passage of the engine. Fuel processing equipment.