JPH01142258A - Treating device for evaporated fuel of vehicle - Google Patents

Abstract

PURPOSE:To improve the treating efficiency of evaporated fuel with a compact structure by providing a means which is opened/closed in accordance with the absorbing/separating condition of evaporated fuel on an air passage which, together with the introduction passage of evaporated fuel and a purging passage, is connected to a device main body. CONSTITUTION:A refueling canister 5 which forms a main device body has the introduction passage 2 of an evaporated fuel generated in the inside of a fuel tank 1, a purging passage 3 connected to the intake air system of an engine, and an air passage 6 connected to the air. After evaporated fuel in the introducing passage 2 is adsorbed by an adsorbing agent, separated by the negative pressure of the intake air system to be sucked into the purging passage 3. In this structure, an air control valve 7 is provided on the air passage 6. The opening/closing of the air control valve 7 is controlled in accordance with the separating condition of the evaporated fuel by a control means 4. Thereby, a large quantity of evaporated fuel can be adsorbingly treated while preventing the evaporated fuel from leaking out of the air passage 6.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is directed to intake treatment of evaporated fuel from a fuel storage chamber such as a fuel tank of a vehicle to prevent the evaporated fuel from being released into the atmosphere. The present invention relates to an evaporative fuel processing device (hereinafter referred to as a canister).

[Conventional technology]

Conventionally, evaporated fuel generated in a fuel storage chamber such as a fuel tank of a vehicle is temporarily adsorbed by activated carbon in a canister to prevent it from being dissipated into the atmosphere, and when the vehicle is running, it is desorbed (purged) by engine negative pressure and released into the intake air. It is designed to be sucked into the tube.

In this configuration, the canister has an atmospheric boat that communicates with the atmosphere, but this atmospheric boat is always open, and the inventors' experiments and studies have shown that the canister is exposed to high temperatures. and purge is OFF
It was discovered that evaporated fuel (low boiling point components) leaked from the atmospheric boat during This phenomenon rarely occurs when the amount of adsorbed evaporated fuel is not large, such as evaporated fuel from fuel stored in a fuel tank or fuel evaporated in the float chamber of a vehicle's carburetor. However, when a large amount of evaporated fuel is generated, such as when refueling with gasoline, a large amount of evaporated fuel is released from the atmospheric boat as shown in FIG. Figure 8 shows 6 points for adsorbent! Ambient temperature 50 when refueling the canister (fuel inflow rate 30 to 40 Il/lll1n)
FIG. 2 is a diagram obtained through experimental study of the relationship between the time in °C and the flow rate of evaporated fuel leaking from an atmospheric boat. Therefore, in order to prevent the generated evaporated fuel from leaking out, the canister must be made larger, resulting in a problem that it becomes difficult to mount it on a vehicle.

The present invention was made in view of the above problems.
To provide a compact evaporated fuel processing device that prevents evaporated fuel from leaking from an atmospheric boat even when a large amount of generated evaporated fuel is generated.

[Means for solving problems]

In order to solve the above problems, the present invention takes the following technical measures.

That is, it has an introduction passage for introducing the evaporated fuel generated in the fuel tank, a purge passage that communicates with the intake pipe, and an atmospheric passage that communicates with the atmosphere, and absorbs the evaporated fuel introduced through the introduction passage into an adsorbent. This is a vehicular evaporative fuel treatment device in which the evaporated fuel adsorbed by the adsorbent is desorbed by the negative pressure generated in the intake pipe and sucked through the purge passage. The present invention is characterized in that an opening/closing means for opening/closing the atmospheric passage according to the desorption state of the vaporized fuel is provided.

〔Example〕

The present invention will be described in detail below based on the drawings.

In FIG. 2, reference numeral 1 denotes a fuel tank for storing gasoline fuel, and this fuel tank 1 has an inlet 1a. Further, a refueling determination switch 14 that is turned ON only when refueling is installed is attached to the inlet 1a, and an output signal of this refueling determination switch 14 is input to a control circuit 4 including a microcomputer.

The upper opening 1b of the fuel tank 1 is connected via a tank hose 2 to an introduction boat 51 of a refueling canister 5 that adsorbs a large amount of evaporated fuel generated during refueling. Further, an introduction amount control valve 3 is provided in the middle of the tank hose 2 to control the flow rate of the vaporized fuel introduced from the upper opening 1b of the fuel tank 1 to the introduction port 51 of the refueling canister 5. The introduction amount control valve 3 is controlled by a control circuit 4 so as to be opened only during refueling.

As shown in FIG. 1, the refueling canister 5 has a cylindrical casing 50 made of resin, with an introduction port 51 and a purge boat 52 formed on its upper surface, and a cylindrical casing 50 formed on its lower surface. atmospheric boat 5
3 is formed.

The inside of the material 50 is filled with an adsorbent made of, for example, activated carbon, and the adsorbent 54 forms an adsorbent layer 55 . A filter 56 made of nonwoven fabric or the like is disposed on the lower surface of the adsorbent layer 55 in the figure, and an upper press plate 57 having communication holes 57a is further disposed on the lower surface thereof. Further, a filter 58 made of nonwoven fabric or the like is arranged on the upper surface of the adsorbent layer 55 in the figure, and an upper presser plate 59 having a communication hole 59a is further arranged on the upper surface.

Note that the filter 56. Temporary upper presser 57. filter 58
．． The upper presser plate 59 is fixed to the inner circumferential surface of the casing 50, thereby fixing its position.

Inside the casing 50, a first space 60 is formed above the adsorbent layer 55, and a second space 61 is formed below the adsorbent layer 55.

Returning to FIG. 2, the purge boat 53 is connected to the purge hose 12.
A purge control valve 13 is provided in the middle of the purge hose 12 to control the amount of purge sucked into the intake pipe. The purge control valve 13 is
It is controlled by a control circuit 4 according to the amount of intake air taken into the engine. (For example, the intake air amount θa is 4 On (
It is controlled such that it is turned on when it is above /h and turned off when it is less than /h. )
Further, the atmospheric boat 53 is open to the atmosphere via an atmospheric hose 6, and an atmospheric control valve 7 is provided in the middle of the atmospheric hose 6. This atmospheric control valve 7 is controlled by the control circuit 4 and controls the amount of air introduced into the casing 50 via the atmospheric boat 53.

Introduction boat 1 of evaporative canister 10 via hose 8
Connected to 0a. The evaporative canister 10 is a conventionally known canister for adsorbing a relatively small amount of evaporated fuel from the fuel stored in the fuel tank 20, and the purge boat 10b of the evaporative canister 10 also draws air (not shown) through a connecting hose 11. connected to the tube. Further, a check valve 9 is provided in the middle of the tank hose 8, so that when the amount of evaporated fuel exceeds a predetermined amount, the evaporated fuel from the evaporative canister 10 is introduced. Note that the passage area of the tank hose 8 is set to be considerably smaller than the passage area of the tank hose 2 to prevent a large amount of evaporated fuel generated during refueling from flowing into the evaporative canister 10. In addition, there is no control valve for controlling the flow rate on the atmospheric boat 10 (side) of the evaporative canister 10, but this is because the capacity of the evaporative canister 10 is small (the amount of adsorption is small), so evaporated fuel leaks from the atmospheric boat 10C. This is because it is so small that it can be ignored.

In the above configuration, the introduction amount control valve 3. Atmospheric control valve7. The purge control valves 13 are each controlled by the control circuit 4, and an example of the structure of the control valve is shown in FIG.

In FIG. 3, the control valve 100 has a casing 101, and a stator core 1 is disposed inside the casing 101.
02 is fixed. An electromagnetic coil 103 is wound around the outer periphery of the stator core 102.
3 generates magnetic force by being supplied with current from the control circuit 4.

Furthermore, a moving core 104 made of a magnetic material is movably disposed within the casing 101, and the moving core 104 is held within the casing 101 by a diaphragm 105. Note that the moving core 104 is biased to the right in the figure by a spring 106. Furthermore, an introduction passage 1 is provided in the casing 101.
07 and a lead-out passage 108 are formed, and communication and isolation between the introduction passage 107 and the lead-out passage 10B is performed by a moving core 104.

In the control valve 100 having the above configuration, when no current is supplied from the control circuit 4, the moving core 104 is biased within the spring 106 to close the opening 107a of the introduction passage 107, and the moving core 104 closes the opening 107a of the introduction passage 107. Aisle 108
Communication with is cut off. Further, when a current is supplied from the control circuit 4 to the electromagnetic coil 103, the electromagnetic coil 103 generates magnetic force, and the moving core 104 is attracted to the left in the figure against the urging force of the spring 106. Therefore, the introduction passage 107 and the outlet passage 10 are in communication.

Next, the operation of this embodiment will be explained using the flowchart shown in FIG.

In FIG. 2, when fuel is supplied from the inlet 1a of the fuel tank 1, the refueling determination switch 14 is turned on, and an electrical signal indicating the refueling state is input to the control circuit 4 (fourth
5TEPI in the figure).

Based on this signal, the control circuit 4 turns the introduction amount control valve 3 into
N, send a command signal to turn off the purge control valve 13 and turn on the atmospheric control valve 7 (STEP 2).

Therefore, a large amount of evaporated fuel generated in the fuel tank 1 during refueling is introduced into the introduction port 51 of the refueling canister 5 through the tank hose 2 from the upper opening 1b of the fuel tank 1. Since the atmospheric control valve 7 is turned on, the vaporized fuel introduced into the refueling canister 5 through the introduction port 51 is adsorbed by the adsorbent layer 55 shown in FIG. 1, and is prepared for the next control.

On the other hand, when fuel is not supplied to the fuel tank 1, the refueling determination switch 14 is OFF, and no electrical signal indicating the refueling state is input to the control circuit 3 (STEP
1'), the introduction amount control valve 4 is OFF. In this case, the engine intake air amount θa detected by an air flow meter (not shown) is input to the control circuit 3 (STEP 3), and the control circuit 3 uses this engine intake air amount θa as the reference intake air that has been input in advance. It is determined whether the amount is less than or greater than the amount θ (STEP 4). This determination determines the intake air amount θa and the reference intake air amount θL, and the reference intake air amount θt is set to a value that does not affect the air-fuel ratio (for example, 40 rrf/h).

According to experimental studies conducted by the present inventors, it has been confirmed that the flow rate of the vaporized fuel desorbed from the refueling canister 5 is almost constant regardless of the operating state.

Here, if it is determined that θa>θt, the control circuit 3
sends a command signal to turn on the purge control valve 13 and turn on the atmospheric control valve 7 (STEP 5). Therefore, the evaporated fuel adsorbed by the refueling canister 5 is desorbed from the adsorbent layer 4 due to the negative pressure generated in the intake pipe during engine operation, and the evaporated fuel desorbed from the evaporative canister 10 via the atmospheric port 52. It is also sucked into the intake pipe.

Further, if it is determined that θa<θt, the control circuit 3 sends a command signal to turn off the purge control valve 13 and turn off the atmospheric control valve 7 (STEP 6). That is,
When the desorption state is OFF or low, the atmospheric port 53 and the purge port 52 are closed, so that even if the refueling canister 5 is exposed to high temperatures, the vaporized fuel adsorbed by the adsorbent layer 55 is transferred to the casing 50.
There is no leakage from the inside to the atmosphere via the atmosphere hose 6.

Note that one routine of the flowchart shown in FIG. 4 is executed by the control circuit 4 for each Room.

Furthermore, when refueling, the ignition switch (not shown) is turned OFF, so the power to the control circuit 4 is not turned OFF at the same time as the ignition switch, but is turned OFF after a predetermined period of time (for example, 10 minutes) after the ignition switch is turned OFF. I try to do it. In addition,
Turn off the power to control circuit 4 at the same time as the ignition switch
F, and when the refueling determination switch 14 is turned on, the power to the control circuit 4 may be turned on for a predetermined period of time (for example, 10 minutes).

As described above, according to this embodiment, by synchronously controlling the atmosphere control valve 7 and the purge control valve 13 according to the amount of intake air, that is, the state of desorption of evaporated fuel, a large amount of air can be obtained without increasing the body size. can adsorb evaporated fuel,
In addition, leakage of vaporized fuel from the atmospheric port 53 can be prevented.

Next, a second embodiment of the present invention will be described using FIGS. 5 and 6.

In FIG. 5 and FIG. 6, the inlet port 1a of the fuel tank 1
is provided with a plate 20 that moves in response to the fluid pressure of fuel supplied during refueling.

As shown in FIG. 7, this plate 20 has an introduction hole 20a formed in the center for introducing fuel, and a protrusion 20b formed on the outer peripheral side. A fitting groove 1d formed on the inner peripheral surface of the opening 1a
It is mated with.

The plate 20 is connected via a wire 21 to a valve member 23 movably disposed within the housing 22;
This valve member 23 opens and closes an opening 22a formed in the housing 22. The valve member 23 also has a spring 24
The valve is always biased in the valve closing direction, and when fuel is supplied during refueling and the plate 20 moves, the valve opens against the force of the spring 24.

An opening 22a formed in the housing 24 is connected to an atmospheric hose 6 via a connecting hose 25, and a check valve consisting of a ball valve 26a and a spring 26b is provided downstream of the connecting portion of the atmospheric hose 6. 26 are provided.

Note that the other configurations are the same as those of the first embodiment, and will therefore be omitted.

Next, the operation of this embodiment will be explained.

When fuel is not being supplied from the inlet 1a of the fuel tank 1, the valve member 23 is biased by the spring 24 and closes the opening 22a. Therefore, the check valve 26 is closed until the differential pressure between the intake pipe negative pressure generated during engine operation and the atmospheric pressure reaches a predetermined value, that is, when the state of desorption of evaporated fuel from the canister 5 is small. Even if the canister 5 is exposed to high temperatures, when the differential pressure between the negative pressure in the intake pipe and the atmospheric pressure generated during steam operation via the atmospheric hose 6 reaches a predetermined value, that is, the desorption state of the evaporated fuel in the canister 5 is determined. If the pressure is high, the check valve 26 is opened due to the pressure difference (the ball valve 26a moves upward in the figure), and air is introduced into the canister 5 via the atmospheric hose 6 and the atmospheric boat 53. The evaporated fuel adsorbed by the canister 5 is sucked into an intake pipe (not shown) via a purge boat 52 and an atmospheric hose 12.

On the other hand, when fuel is supplied from the inlet 1a of the fuel tank 1, the plate 20 moves to the position shown by the chain line in the figure due to the fuel pressure, and the valve member 23 resists the urging force of the spring 24 by the wire 18. The valve is opened by being pulled.

Therefore, when refueling, the canister 5 is connected to the atmospheric port 53.
．． Since the canister 5 communicates with the atmosphere through the atmospheric hose 6 and the connecting hose 25, the vaporized fuel introduced via the introduction boat 51 is adsorbed by the canister 5.

As described above, according to this embodiment as well, a large amount of evaporated fuel generated during refueling can be adsorbed, and the adsorbed evaporated fuel can be prevented from leaking into the atmosphere from the atmospheric port 53.

In this embodiment, the plate 20 is arranged so as to reciprocate within the inlet la by the supplied fuel, but the plate 20 is arranged in the inlet 1a so as to rotate by the supplied fuel. It's okay.

〔Effect of the invention〕

As explained above, according to the present invention, even a large amount of evaporated fuel can be adsorbed without increasing the body size by opening and closing the atmospheric passage according to the desorption state of the evaporated fuel using the opening/closing means. This also makes it possible to prevent vaporized fuel from leaking from the atmospheric passage.

[Brief explanation of the drawing]

1 to 4 relate to the first embodiment of the present invention,
FIG. 1 is a partial sectional view showing the main parts of this embodiment, FIG. 2 is a configuration diagram showing the overall configuration of this embodiment, and FIG. 3 is a sectional view showing the structure of the control valve of this embodiment. FIG. 4 is a flowchart for explaining the operation of this embodiment. 5 to 7 relate to the second embodiment of the present invention,
Fig. 5 is a partial cross-sectional view showing the configuration of the main parts of this embodiment, Fig. 6 is an enlarged view of the part surrounded by ■ in Fig. 5, and Fig. 7 is a perspective view taken along ■ - ■ in Fig. 6. be. FIG. 8 shows the results of an experiment conducted by the present inventors showing the relationship between time and the amount of evaporated fuel leaking from the atmosphere. l...fuel tank, 2...tank hose, 5...
Refurbishing canister, 51...Introduction boat,
52... Purge boat, 53... Atmospheric port, 54
...Adsorbent, 55...Adsorbent layer, 6...Atmospheric hose, 7...Atmospheric control valve. φ Atmosphere Figure 5 Figure 7

Claims (4)

[Claims] (1) It has an introduction passage that introduces the evaporated fuel generated in the fuel tank, a purge passage that communicates with the intake pipe, and an atmospheric passage that communicates with the atmosphere, and the evaporated fuel introduced through the introduction passage. A vehicular evaporative fuel processing device in which the evaporated fuel is adsorbed by an adsorbent, and the evaporated fuel adsorbed by the adsorbent is desorbed by a negative pressure generated in an intake pipe and sucked through the purge passage. An evaporative fuel processing device for a vehicle, characterized in that an opening/closing means for opening and closing the atmospheric passage is provided in the atmospheric passage according to a state of desorption of the evaporated fuel. (2) A patent characterized in that the opening/closing means is a control valve that closes the atmospheric passage when the amount of intake air passing through the intake pipe is below a predetermined value, and opens the atmospheric passage when the amount is above a predetermined value. An evaporative fuel processing device for a vehicle according to claim 1. (3) The evaporative fuel processing device for a vehicle according to claim 1, wherein the opening/closing means is a check valve that opens when the negative pressure generated in the intake pipe exceeds a predetermined value. (4) The fuel vapor processing device for a vehicle according to any one of claims 1 to 3, wherein the introduction passage communicates to introduce fuel vapor only when fuel is supplied.