JP3146570B2 - Evaporative fuel control device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel vapor control system.

[0002]

2. Description of the Related Art FIG. 14 shows a conventional fuel vapor control apparatus mounted on a vehicle. The fuel tank 60 and the canister 61 are connected by a vapor pipe 62 and the canister 6
1 and the engine intake pipe 63 are connected by a purge pipe 64. Then, the evaporated fuel generated in the fuel tank 60 flows into the activated carbon 61a of the canister 61 through the vapor pipe 62 and is adsorbed. The adsorbed fuel vapor is drawn into the engine intake pipe 63 through the purge pipe 64 when fresh air from the air inlet 61b of the canister 61 is drawn into the engine intake pipe 63, and is burned by the engine.

[0003]

However, when the fuel vapor is adsorbed and desorbed from the activated carbon 61a of the canister 61, the activated carbon 61a of the canister 61 is accompanied by an exothermic reaction and an endothermic reaction. As the capacity decreases and the temperature decreases, the desorption capacity decreases. In particular, there is a problem that the temperature of the activated carbon 61a is high after the vehicle stops running, and almost no evaporative fuel to be adsorbed by the activated carbon 61a can be adsorbed.

[0004] It is an object of the present invention to provide an evaporative fuel control device capable of preventing a decrease in the ability of adsorbing and desorbing evaporative fuel to activated carbon.

[0005]

According to the present invention, there is provided a canister in which a casing is partitioned into a first chamber and a second chamber by a partition wall, and activated carbon is disposed in both chambers; A first passage connecting the first chamber and the second chamber; an engine intake pipe and the first chamber and the second chamber of the canister;
A second passage connecting the chamber and the first passage,
First switching means for communicating between the fuel tank and the first chamber of the canister or between the fuel tank and the second chamber of the canister; provided in the second passage; a first chamber of the engine intake pipe and the canister; Alternatively, a second switching means for communicating the engine intake pipe with the second chamber of the canister; and controlling the first switching means to control the fuel tank and the canister.
The first chamber of the stirrer is brought into a communicating state, and the second switching means is controlled to control the communication between the engine intake pipe and the canister.
By communicating state the second chamber, while adsorbing the evaporated fuel in the fuel tank to the activated carbon of the first chamber of the canister Canny <br/> engine intake pipe evaporated fuel adsorbed in the activated carbon of the second chamber of the static A first switching state for purging the first
Control means for switching the fuel tank and the canister.
The two chambers are in communication with each other and the second switching means is controlled.
Controlling the engine intake pipe and the first chamber of the canister.
In the communication state, the second switching state in which the evaporated fuel adsorbed on the activated carbon in the first chamber of the canister is purged to the engine intake pipe while the evaporated fuel in the fuel tank is adsorbed on the activated carbon in the second chamber of the canister. The gist of the present invention is a fuel vapor control apparatus provided with a switching control means for alternately switching between the two.

[0006]

The switching control means controls the first and second switching means to adsorb the fuel vapor in the fuel tank to the activated carbon in the first chamber of the canister while adsorbing the fuel vapor in the second chamber of the canister. To purge the engine into the engine intake pipe
And a second switching state in which the evaporated fuel adsorbed on the activated carbon in the first chamber of the canister is purged to the engine intake pipe while adsorbing the evaporated fuel in the fuel tank on the activated carbon in the second chamber of the canister. Switch to. That is, each activated carbon partitioned by the partition in the canister independently adsorbs and desorbs the evaporated fuel. As a result, the desorption efficiency is improved by switching to the purge in a state where the heat is generated by the progress of the adsorption, and the adsorption efficiency is improved by switching to the adsorption in the state of the cool by the progress of the purge. In addition, the activated carbons transfer heat to each other, so that the efficiency does not decrease.

[0007]

【Example】

(First Embodiment) An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 shows the overall configuration of the fuel vapor control system. First, the canister 1 will be described. FIG. 2 shows a plan view of the canister 1. As shown in FIGS.
The casing 2 of the canister 1 has a cylindrical shape as a whole, and the casing 2 is made of resin or metal. The casing 2 is a main casing 3 having a closed cylindrical shape.
And a cap casing 4 for closing the lower opening of the main casing 3. In the casing 2, a cylindrical partition plate 5 is arranged concentrically with the main casing 3, and the partition plate 5 is made of a thin metal. The inside of the casing 2 is partitioned by the partition plate 5 into an inner central chamber R1 and an outer peripheral chamber R2. The central chamber R1 is filled with a central activated carbon layer 6, and the outer peripheral chamber R2 is filled with an outer activated carbon layer 7. The activated carbon layers 6 and 7 have a property of adsorbing gasoline.

On the upper and lower surfaces of the activated carbon layers 6 and 7, filter paper filters 8 and 9 are disposed in contact with each other, and on the lower surface of the lower filter 9, a holding plate 10 having a large number of ventilation holes 10a is provided. Have been. Vapor inlet pipes 11 and 12 and vapor purge pipes 13 and 14 are formed on the upper surface of the casing 2 (see FIG. 2). A guide 15 extending into the central activated carbon layer 6 is formed below the vapor inlet pipe section 11, and has a shoulder 16 for positioning the filter 8 above the guide 15. Also, the vapor inlet pipe 1
2 is a guide 1 extending inside the activated carbon layer 7 at the outer periphery.
7 are formed, and a filter 18 is disposed at the tip thereof. The shoulder 1 is also located on the upper outer periphery in the casing 2.
9 are formed to ensure the fixing of the filter 8.
In addition, a projection 20 is formed on the upper surface in the casing 2, and the positioning of the partition plate 5 is facilitated by the projection 20.

The holding plate 10 is urged upward by a spring 21 in FIG. The cap casing 4 serves as a seat for the spring 21 and is fixed to the main casing 3 at the outer peripheral portion by bonding or the like. Further, an air inlet 22 is formed in the cap casing 4.

The vapor purge pipe 13 communicates with the filter 8 and a central space 23 surrounded by the casing 2, and the vapor purge pipe 14 communicates with the filter 8 and an outer peripheral space 24 surrounded by the casing 2. . The vapor purge pipe sections 13 and 14 are connected to a purge three-way valve 27 via conduits 25 and 26. The other port of the three-way purge valve 27 communicates via a conduit 28 with a purge port 31 provided downstream of the throttle valve 30 of the engine intake pipe 29.

A fuel outlet 32 is formed in the fuel tank 32 and is connected to a three-way valve 35 for vapor supply by a vapor line (conduit) 34. Three-way valve for vapor supply 3
The two sides 5 are connected to the vapor inlet pipe sections 11 and 12 of the canister 1 by conduits 38 and 40, respectively. Non-return valves 36, 37 which allow the flow to the canister 1 side are arranged in the middle of the conduits 38, 40.

A three-way valve 35 is provided, which branches off from a conduit 38 between the check valve 36 and the vapor inlet pipe portion 11 and permits flow to the fuel tank 32 side.
Is connected to the upstream vapor line 34. Similarly,
A check valve 41 which branches off from a conduit 40 between the check valve 37 and the vapor inlet pipe section 12 and allows a flow to the fuel tank 32 side.
And is connected to a vapor line 34 upstream of the vapor supply three-way valve 35.

When a voltage is applied to the three-way valve 35 for vapor supply and the three-way valve 27 for purge, that is, when the voltage is on, the vapor flows in the direction of the solid line in FIG. 1, and when it is off, it flows in the direction of the broken line.

A key switch 43 and a coil 44a of a timer contact circuit 44 are connected in series to a battery 42. When the key switch 43 is turned on, the timer contact circuit 44 first turns on the three-way valve 35 for vapor supply, turns off the three-way valve 35 for vapor supply after a predetermined time (for example, after five minutes), and simultaneously turns off the three-way valve 27 for purging. Work to turn on.

In this embodiment, the partition plate 5 constitutes a partition, the central chamber R1 constitutes a first chamber, the outer peripheral chamber R2 constitutes a second chamber, and the vapor line 34, conduits 38, 40.
Constitutes a first passage, conduits 25, 26, and 28 constitute a second passage, a three-way valve 35 for vapor supply constitutes first switching means, and a three-way valve 27 for purge. The second switching means constitutes, and the timer contact circuit 44 constitutes the switching control means.

Next, the operation of the evaporative fuel control device thus configured will be described with reference to FIGS. When the key switch 43 is turned on and the engine is started, the three-way valve 35 for vapor supply is turned on by the timer contact circuit 44 (FIG. 3).
At the timing of t1), the vapor line 34 and the vapor inlet pipe 11 communicate with each other via the check valve 36. At this time, the purge three-way valve 27 is off. In this state, the vapor (evaporated fuel) generated in the fuel tank 32 passes from the vapor line 34 through the vapor supply three-way valve 35 (in the direction of the solid line in FIG. 1) to the check valve 36. At this time, when the vapor pressure reaches the set valve opening pressure of the check valve 36 (for example, 15 mmHg) or more, the vapor is sent from the vapor inlet pipe 11 to the central activated carbon layer 6.
And begins to adsorb.

On the other hand, the vapor adsorbed on the outer peripheral activated carbon layer 7 allows the flow in the direction of the broken line in FIG. Negative pressure acts on 31 and the air inlet 22
Is purged from the vapor purge pipe section 14 into the engine intake pipe 29 together with fresh air from the engine. Therefore, in this case, the central activated carbon layer 6 performs only adsorption, and the outer peripheral activated carbon layer 7 performs only purging.

Here, activated carbon is characterized by an exothermic reaction when adsorbed by vapor and an endothermic reaction when purged (desorbed). However, the higher the temperature, the more difficult it is to adsorb and the easier it is to purge. Conversely, the lower the temperature, the easier it is to adsorb and the harder it is to purge. Therefore, when purging, the temperature of activated carbon decreases, but it is better to suppress the decrease as much as possible. When adsorbing, activated carbon generates heat, but it is preferable to suppress the rise in temperature as much as possible.

The temperature of the central activated carbon layer 6 rises as the adsorption proceeds. On the other hand, the temperature of the outer activated carbon layer 7 decreases as the purging proceeds. At this time, heat flows through the partition plate 5 to prevent the temperature of the outer peripheral activated carbon layer 7 from decreasing due to the heat generated by the central activated carbon layer 6, and conversely, the temperature of the central activated carbon layer 6 is less likely to rise. Therefore, the outer peripheral activated carbon layer 7
Is easily purged, and the activated carbon layer 6 at the central portion has a large amount of adsorption, so that vapor overflowing from the air inlet 22 can be prevented.

Thereafter, when a predetermined time (5 minutes) elapses (timing t2 in FIG. 3), the three-way valve 35 for vapor supply is turned off and the three-way valve 27 for purging is turned on by the timer contact circuit 44. In this case, the vapor supply three-way valve 35
In FIG. 1, since the vapor flows in the direction of the broken line, the vapor flows into the outer peripheral activated carbon layer 7 from the vapor inlet pipe 12 through the check valve 37. On the other hand, in the purge three-way valve 27, FIG.
Since the flow is allowed in the direction of the solid line, the vapor adsorbed on the central activated carbon layer 6 is purged from the vapor purge pipe section 13 to the engine intake pipe 29. At this time, since the central activated carbon layer 6 has been adsorbed and generated heat, it can be easily purged. Further, since the outer peripheral activated carbon layer 7 has been cooled after being purged, the adsorption capacity is increased.

By repeating this action every predetermined time, efficient use is possible even if the same amount of activated carbon is used. When the engine is stopped, the three-way purge valve 27,
All three-way valves 35 for vapor supply are turned off. Therefore, the vapor generated somewhat after the engine is stopped is reduced by the check valve 37.
Flows into the outer peripheral activated carbon layer 7 through After a lapse of time after the stop, the fuel temperature in the fuel tank 32 decreases, and the tank pressure also decreases. When the tank is sufficiently cooled, the pressure in the tank tends to be negative, but air from the air inlet 22 of the canister 1 passes through the two activated carbon layers 6, 7 and the check valves 39 and 41, and further passes through the vapor line 34 and the fuel tank. It is sucked into 32. At this time, some of the vapor is
Will be returned within.

As described above, in this embodiment, the inside of the casing 2 of the canister 1 is separated from the central chamber R1 by the partition plate 5 (partition wall).
(First chamber) and an outer peripheral chamber R2 (second chamber), the activated carbon layers 6 and 7 are disposed in both chambers R1 and R2, respectively, and a central chamber R1 and an outer peripheral chamber R of the fuel tank 32 and the canister 1 are arranged.
2 through a vapor line 34 and conduits 38 and 40 (first passages), and connects the engine intake pipe 29 with the central chamber R1 and the outer peripheral chamber R2 of the canister 1 via conduits 25 and 2.
6, 28 (second passage). Also, vapor line 3
4 is provided with a three-way valve 35 for vapor supply (first switching means), and a central chamber R1 of the fuel tank 32 and the canister 1,
Alternatively, the outer peripheral chamber R2 of the fuel tank 32 and the canister 1
And the communication with the conduit 25,
A purge three-way valve 27 (second switching means) is provided at 26 and 28.
Is arranged so that the engine intake pipe 29 and the central chamber R1 of the canister 1 or the engine intake pipe 29 and the outer peripheral chamber R2 of the canister 1 can be communicated with each other. Further, the timer contact circuit 44 (switch control means) controls the three-way valve 35 for vapor supply and the three-way valve 27 for purging,
The fuel vapor in the fuel tank 32 is supplied to the central chamber R of the canister 1.
The first switching state in which the fuel vapor adsorbed in the activated carbon layer 6 of the canister 1 and the vaporized fuel adsorbed in the activated carbon layer 7 of the outer peripheral chamber R2 of the canister 1 are purged into the engine intake pipe 29, A second switching state in which the fuel vapor adsorbed in the activated carbon layer 6 of the central chamber R1 of the canister 1 is purged to the engine intake pipe 29 while being adsorbed on the activated carbon layer 7 of the outer peripheral chamber R2 is alternately switched. As a result, the desorption efficiency is improved by switching to the purge in a state where the adsorption of the activated carbon layers 6 and 7 is advanced and the heat is generated, and the adsorption efficiency is improved by switching to the adsorption in a cooled state where the purge is advanced. In addition, the activated carbon layers 6 and 7 do not transfer heat to each other and do not lower the efficiency. In this manner, it is possible to prevent a reduction in the ability of the activated carbon to adsorb and desorb the fuel vapor.

As an application of this embodiment, only one vapor inlet pipe portion 11 or 12 is used, but several vapor inlet pipe portions 11 and 12 may be arranged in the circumferential direction for uniform adsorption. Also, the check valve 36,
37, 39 and 41 may be built in the canister 1,
Further, the same effect can be obtained even without the check valve. (Second Embodiment) Next, a second embodiment will be described focusing on differences from the first embodiment.

As shown in FIG. 4, a temperature sensor 45 is disposed inside the activated carbon layer 6 at the center,
Is output to Further, the three-way valves 27 and 35 are operated according to a command from the ECU 46.

The degree of adsorption and desorption of the central activated carbon layer 6 can be detected by the temperature sensor 45. That is, when the adsorption proceeds, heat is generated, and when the temperature exceeds 80 ° C., almost no adsorption is made, and the vapor passes through and leaks to the atmosphere. Therefore, the adsorption is stopped at a temperature lower than 80 ° C., and the active carbon layer 7 is switched to the outer peripheral portion. Is preferred. A temperature sensor 45 is used to grasp the temperature. On the other hand, when purging, the temperature of the activated carbon layer 6 in the central part is lowered, so that the vapor is allowed to flow in a state having a sufficient capacity for adsorption.

Next, the operation will be described. FIG.
Is a flowchart showing the processing executed by the user, and FIG. 6 is a time chart. When the program starts in FIG. 5, the ECU 46 turns on the vapor supply three-way valve 35 and turns off the purge three-way valve 27 in step 100 (timing t1 in FIG. 6). Then, the vapor generated in the fuel tank 32 of FIG. 4 flows in the direction of the solid line arrow of the vapor supply three-way valve 35 and flows into the central activated carbon layer 6. On the other hand, the purge three-way valve 27 allows the flow in the direction of the broken line in FIG. Then, the ECU 46
Reads the activated carbon temperature Tc from the signal from the temperature sensor 45 at step 110. Due to the adsorption of the vapor, the temperature of the central activated carbon layer 6 rises, and the ECU 46 proceeds to step 120.
It is determined whether the activated carbon temperature Tc is 70 ° C. or more. ECU 46
If the temperature has not reached 70 ° C, the condition is continued.
If this is the case, it is determined that the adsorption is sufficient, and the routine proceeds to step 130, where the three-way valve 35 for vapor supply is turned off. At the same time, the purge three-way valve 27 is turned on, and the activated carbon layer into which the vapor flows is switched (timing t2 in FIG. 6).

Then, the vapor adsorbed on the central activated carbon layer 6 is purged into the engine intake pipe 29, so that the temperature starts to decrease. Therefore, the ECU 46
Proceeds to step 140, and determines whether the activated carbon temperature Tc is 50 ° C. or less. If it is 50 ° C or higher, continue the state,
If the temperature is lower than 50 ° C., the purge is sufficient, and it is determined that there is adsorption capacity. Then, the process returns to step 100 to turn on the three-way valve 35 for vapor supply and turn off the three-way valve 27 for purge (FIG. 6).
At t3).

By repeating such operations thereafter, efficient adsorption and desorption are performed. (Third Embodiment) Next, a third embodiment will be described focusing on differences from the second embodiment.

This embodiment is different from the second embodiment in the control of the vapor supply three-way valve 35 by the ECU 46. That is, it controls whether the three-way vapor supply valve 35 is turned on or off when the engine is stopped. FIG. 7 shows a process (flowchart) based on a periodic interruption to the process of FIG. 5, and FIG. 8 shows a time chart.

As described in the second embodiment, the three-way valve 2
Engines 7 and 35 are operated while being switched by the activated carbon temperature Tc. During the process, the ECU
46 reads the activated carbon temperature Tc in step 200 of FIG. 7, and if the key switch is turned off in step 210, the activated carbon temperature Tc at that time is 60 ° C. in step 220.
It is determined whether or not the above. If the temperature is 60 ° C. or higher, the ECU 46 determines that the adsorption capacity of the central activated carbon layer 6 is inferior to that of the outer peripheral activated carbon layer 7 and proceeds to step 230, turns off the vapor supply three-way valve 35, and continues after the stop. The vapor is led to the outer peripheral activated carbon layer 7. If the activated carbon temperature Tc is equal to or lower than 60 ° C. in step 220, the ECU 46 determines that the central activated carbon layer 6 has a higher adsorption capacity, and determines in step 2
Proceeding to 40, the vapor supply three-way valve 35 is turned on to guide the vapor to the central activated carbon layer 6 (timing t1 in FIG. 8).
This operation is performed regardless of whether the vapor supply three-way valve 35 is on or off immediately before the key-off, and the activated carbon temperature T
It is determined by c. (Fourth Embodiment) Next, a fourth embodiment will be described focusing on differences from the second embodiment.

As shown in FIG. 9, in this embodiment, a temperature sensor 47 is also arranged in the outer peripheral activated carbon layer 7. That is, the temperature sensor 45 detects the temperature Tca of the central activated carbon layer 6 and the temperature sensor 47 detects the temperature Tcb of the outer activated carbon layer 7. During operation of the engine, the three-way valve 35 for supplying vapor is turned on / off by the output of the temperature sensor 45 of the activated carbon layer 6 at the center.
The activated carbon temperatures Tca and Tcb of the two activated carbon layers 6 and 7 change as shown in FIG. That is, when the three-way valve for vapor supply 35 is turned on and the vapor flows into the central activated carbon layer 6, the central activated carbon temperature Tca gradually rises, and at this time, the outer peripheral activated carbon layer 7 is purged and gradually falls. .

FIG. 10 shows a process (flowchart) of the process of FIG. 5 by a periodic interruption. This FIG.
The processing when the engine is stopped will be described using FIG. First, EC
U46 determines two activated carbon temperatures Tca and Tcb in step 300.
Read. When the key switch is turned off in step 310, the ECU 46 proceeds to step 320 to compare the activated carbon temperatures Tca and Tcb at that time. When Tca is higher than Tcb, the ECU 46 determines that the adsorption capacity of the central activated carbon layer 6 is low. And
Proceeding to step 330, the three-way valve 35 for vapor supply is turned off, and the vapor after stopping is guided to the outer peripheral activated carbon layer 7.

On the other hand, the ECU 46 determines in step 320 that Tca
Is lower than Tcb, it is determined that the adsorption capacity of the central activated carbon layer 6 is high, and the routine proceeds to step 340, where the three-way valve 35 for vapor supply is turned on, and the vapor is guided to the central activated carbon layer 6. FIG. 11 shows a state in which Tca is lower than Tcb and the vapor supply three-way valve 35 is turned on at the timing of t1 in FIG. As a result, compared to the third embodiment, the actual temperature at two locations is compared, and after stopping to the lower one (activated carbon layer), the vapor is guided, so that efficient control can be performed more reliably and efficiently. (Fifth Embodiment) Next, a fifth embodiment will be described focusing on differences from the first embodiment.

In this embodiment, the shape and the partition state of the canister 1 are different from those in the first embodiment. FIG. 12 shows the overall configuration of the present embodiment, and FIG. 13 shows a plan view of the canister 1.

The casing 49 of the canister 48 has an elliptical cylindrical shape, and has a partition wall 50 extending linearly in the major axis direction. Due to the partition wall 50, the inside of the casing 49 becomes first.
An activated carbon layer 53, 54 is disposed in each of the chambers 51, 52, which is partitioned into a chamber 51 and a second chamber 52. Then, the vapor generated in the fuel tank 32 reaches the three-way valve 35 for vapor supply from the vapor line 34 and flows in the direction of the solid line arrow in FIG. 12 when turned on. It flows into 53. Activated carbon layer 54
The vapor adsorbed to the purge gas flows toward the purge three-way valve 27 together with the air flowing from the air introduction port 22 through the vapor purge pipe portion 57, and the purge three-way valve 27 is off at this time and flows in the direction of the broken line in FIG. Inhaled into tube 29. Reference numeral 58 denotes a vapor inlet pipe to the activated carbon layer 54, 59 denotes a filter, and 65 denotes a vapor purge pipe of the activated carbon layer 53.

As described above, in this embodiment, the canister 48
Because the casing of the present invention has an elliptical cylindrical shape and a partition wall is provided at the long diameter portion, the contact area between the activated carbon layers is increased and heat is easily transmitted as compared with a case where a canister of a true cylindrical shape is divided in half.

[0038]

As described in detail above, according to the present invention,
An excellent effect of preventing a reduction in the ability of adsorbing and desorbing the fuel vapor to the activated carbon is exhibited.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating an overall configuration of an evaporative fuel control device according to a first embodiment.

FIG. 2 is a plan view of the canister of the first embodiment.

FIG. 3 is a time chart for explaining the operation of the first embodiment.

FIG. 4 is a diagram illustrating an overall configuration of an evaporative fuel control device according to a second embodiment.

FIG. 5 is a flowchart for explaining the operation of the second embodiment.

FIG. 6 is a time chart for explaining the operation of the second embodiment.

FIG. 7 is a flowchart for explaining the operation of the third embodiment.

FIG. 8 is a time chart for explaining the operation of the third embodiment.

FIG. 9 is a diagram illustrating an overall configuration of an evaporative fuel control device according to a fourth embodiment.

FIG. 10 is a flowchart for explaining the operation of the fourth embodiment.

FIG. 11 is a time chart for explaining the operation of the fourth embodiment.

FIG. 12 is a diagram showing an overall configuration of an evaporative fuel control device according to a fifth embodiment.

FIG. 13 is a plan view of a canister according to a fifth embodiment.

FIG. 14 is a diagram showing an overall configuration of a conventional evaporative fuel control device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Canister 2 Casing 5 Partition plate as a partition 6 Central activated carbon layer 7 Peripheral activated carbon layer 25 Conduit constituting a second passage 26 Conduit constituting a second passage 27 Three-way valve for purging as second switching means 28 conduit constituting a second passage 29 engine intake pipe 32 fuel tank 34 vapor line as a first passage 35 three-way valve for vapor supply as a first switching means 38 conduit as a first passage 40 first passage 44 A timer contact circuit as a switching control means R1 A central room as a first room R2 An outer peripheral room as a second room

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int. Cl. ⁷ , DB name) F02M 25/08 F02M 25/08 301 F02M 25/08 311

Claims (3)

(57) [Claims] 1. The casing has a first chamber and a second chamber defined by a partition wall.
A canister in which activated carbon is disposed in both chambers; a first passage connecting the fuel tank to the first and second chambers of the canister; an engine intake pipe and a first chamber of the canister And a second passage connecting the fuel tank and the canister, and a first switch provided in the first passage to establish a communication state between the fuel tank and the first chamber of the canister or the fuel tank and the second chamber of the canister. means and said provided second passage, and a second switching means for an engine intake pipe and the first chamber of the canister, or an engine intake pipe and the second chamber of the canister in communication with said first switch Means for controlling said fuel tank and said key.
The first chamber of the canister is communicated with the engine intake pipe and the canister by controlling the second switching means.
When the second chamber of the canister is in communication , the evaporated fuel in the fuel tank is adsorbed on the activated carbon of the first chamber of the canister while the evaporated fuel adsorbed on the activated carbon of the second chamber of the canister is discharged from the engine. first and switching state to be purged into the intake pipe, the first
Controlling the switching means of the fuel tank and the canister
And the second switching means.
To control the first of the engine intake pipe and the canister.
The second switching is such that, by making the chambers communicate, the evaporated fuel in the fuel tank is adsorbed on the activated carbon in the second chamber of the canister while the evaporated fuel adsorbed on the activated carbon in the first chamber of the canister is purged to the engine intake pipe. Switching control means for alternately switching between a state and a state. 2. The switching control means according to claim 1, wherein said switching control means comprises:
2. The evaporative fuel control device according to claim 1, wherein the switching state and the second switching state are alternately switched. 3. The evaporative fuel control device according to claim 1, wherein the switching control means alternately switches between a first switching state and a second switching state according to the temperature of the activated carbon of the canister.