JPH08121268A - Evaporative fuel processing device - Google Patents

Abstract

PURPOSE: To perform smooth oil feeding and efficiently adsorb/desorb evaporative fuel in fuel feeding and unfeeding and to carry out desorption while gently changing concentration of fuel fed to an engine. CONSTITUTION: The first adsorbent chamber A1, the second adsorbent chamber A2, and the third adsorbent chamber B, in each of which adsorbent is filled, are arranged, while the first communication path 4 which communicates the first adsorbent chamber A1 and the second absorbent chamber A2 to each other and introduces evaporative fuel from a fuel tank to them, is arranged above the first adsorbent chamber A1 and the second adsorbent chamber A2. A dedicated path 7, which is arranged above the third adsorbent chamber B and is connected to the atmosphere, and the second communication path 8, which is arranged below the first adsorbent chamber A1, the second adsorbent chamber A2, and the third adsorbent chamber B for communicating them mutually, are arranged, and the second communication path 8 is provided with a one-way valve 9, which is arranged in the position corresponding to between the first adsorbent chamber A1 and the second adsorbent chamber A2 and allows gas to flow only in the direction toward the third adsorbent chamber B, and an emitting port 10, which is connected to an intake pipe and is arranged in the position corresponding to the lower side of the first adsorbent chamber A1.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an evaporative fuel processing system for preventing evaporative fuel generated in a fuel tank of a vehicle from being released into the atmosphere.

[0002]

2. Description of the Related Art Generally, a fuel supply system for a vehicle engine is provided with a canister filled with an adsorbent such as activated carbon in order to prevent evaporative fuel generated from a fuel tank from being released to the atmosphere. Therefore, the evaporated fuel adsorbed by the adsorbent is desorbed by the negative pressure of the intake pipe and supplied to the engine.

As a canister of this type, Japanese Patent Laid-Open No. 1-1 is known.
As shown in No. 59455 and the like, a plurality of adsorbents in the canister are used to increase the adsorbent adsorption efficiency by increasing L / D (L: adsorbent height, D: adsorbent diameter). It is known that the adsorbent layer is divided into adsorbent layers (rooms), and the plurality of adsorbent layers adsorb both the vaporized fuel generated during refueling and the vaporized fuel generated during non-fuel refueling.

[0004]

However, in the above conventional canister, the evaporated fuel is configured to sequentially pass through each adsorbent layer in time series. From the viewpoint of the passage of the evaporated fuel, The adsorbent layers are connected in series.

Therefore, at the time of refueling when the inflow rate of the evaporated fuel is high, the ventilation resistance becomes so large that smooth refueling tends to be impossible.

On the other hand, in order to solve this problem, if the diameter of each adsorbent layer is increased, the above L / D becomes smaller, and when the inflow speed of the evaporated fuel is slow except when refueling, it depends on the transfer of the adsorbed vapor. This causes a new problem that the performance is deteriorated.

Further, when desorbing the adsorbed fuel vapor, the concentration change of the fuel supplied to the engine is moderated,
It was also desired to suppress the change in the air-fuel ratio of the engine as much as possible.

The present invention has been made under such a background, and an object thereof is to perform smooth refueling, and to efficiently adsorb and desorb evaporated fuel during refueling and at times other than refueling.
Another object of the present invention is to provide an evaporated fuel processing device that can be desorbed in such a manner that the concentration change of the fuel supplied to the engine is moderated.

[0009]

In order to achieve the above object, the fuel vapor processing apparatus according to claim 1 is a first adsorbent chamber, a second adsorbent chamber, and a third adsorbent chamber each filled with an adsorbent. Chamber, and a first communication passage that is provided above the first adsorbent chamber and the second adsorbent chamber and that introduces evaporated fuel from a fuel tank so that the first adsorbent chamber and the second adsorbent chamber can communicate with each other. And a second communication passage that is provided above the third adsorbent chamber and communicates with the atmosphere, and that is provided below the first adsorbent chamber, the second adsorbent chamber, and the third adsorbent chamber. The third adsorbent is a communication passage that connects the first adsorbent chamber, the second adsorbent chamber, and the third adsorbent chamber, and is located at a position corresponding to between the first adsorbent chamber and the second adsorbent chamber. It has a one-way valve that allows only the flow of gas in the chamber direction, and has a desorption port communicating with the intake pipe at a position corresponding to the lower part of the first adsorbent chamber. And a triple path.

In order to achieve the above object, the evaporated fuel processing apparatus according to a second aspect of the present invention is such that a first adsorbent filled with each adsorbent is provided.
An adsorbent chamber, a second adsorbent chamber, a third adsorbent chamber, and the first adsorbent chamber and the second adsorbent chamber are provided above the adsorbent chamber and the first adsorbent chamber and the second adsorbent chamber can communicate with each other. A first communication passage for introducing the evaporated fuel from the fuel tank to the second adsorbent chamber, a second communication passage provided at an upper portion of the third adsorbent chamber and communicating with the atmosphere, the first adsorbent chamber, the second adsorbent chamber , A communication passage that is provided below the third adsorbent chamber and connects the first adsorbent chamber, the second adsorbent chamber, and the third adsorbent chamber, and the first adsorbent chamber and the second adsorbent chamber A third communication passage having a solenoid valve at a position corresponding to the chamber and a desorption port communicating with the intake pipe at a position corresponding to a lower portion of the first adsorbent chamber; and the solenoid valve when the engine is stopped. And a control means for opening and closing the solenoid valve according to operating conditions during engine operation.

[0011]

In the evaporated fuel processing device according to claim 1, when the evaporated fuel from the fuel tank is introduced into the first communication passage,
Since the adsorption is performed in parallel in the first adsorbent chamber and the second adsorbent chamber, the speed in the activated carbon (adsorbent) layer is reduced. After that, the remaining evaporated fuel flows into the third adsorbent chamber through the one-way valve and is adsorbed, so that the adsorption efficiency of the adsorbent is improved. Further, even when the inflow speed of the evaporated fuel becomes high at the time of refueling, the evaporated fuel is dispersed and introduced into the first and second adsorbent chambers, and thereafter, toward the third adsorbent chamber by the action of the one-way valve. Since the process proceeds smoothly, the increase in ventilation resistance is suppressed, and the fuel can be smoothly refueled.

Further, since the desorption port is provided on the lower side of the first adsorbent chamber having a lower adsorption rate on the side opposite to the introduction side having a higher adsorption rate, the fuel concentration change at the initial stage of desorption is small. It becomes gradual, and the change in the air-fuel ratio becomes small.

In the evaporative fuel processing apparatus according to the second aspect, the control means causes the evaporative fuel to run in parallel in the first adsorbent chamber and the second adsorbent chamber by constantly opening the electromagnetic valve when the engine is stopped. By adsorbing the adsorbent in the third adsorbent chamber after adsorbing the adsorbent, the adsorbent can be adsorbed efficiently, and the ventilation resistance at the time of refueling can be suppressed from increasing, so that the oil can be smoothly refueled.

Further, the control means, during engine operation,
For example, under operating conditions with little desorbed air, the solenoid valve is opened to cause desorption in the third adsorbent chamber alone, thereby reducing the desorption amount of adsorbed fuel and reducing the amount of fuel. The change in concentration is made gentle and the change in air-fuel ratio is made small.

[0015]

Embodiments of the present invention will be described below with reference to the drawings.

[First Embodiment] FIG. 1 is a diagram showing the structure of a canister in an evaporative fuel treatment system according to the first embodiment of the present invention, in which a canister C is made of a resin and is an adsorbent filled with an adsorbent. The chamber includes the first separator 1a and the second separator
The separator 1b divides the first adsorbent chamber A1, the second adsorbent chamber A2, and the third adsorbent chamber B into three chambers. In addition,
These three chambers have the same size, and the adsorbent volume ratio is 1: 1: 1.

First, second and third adsorbent chambers A1, A2, B
A filter 3 made of non-woven fabric or the like is fixed to the upper and lower surfaces of the sheet by a breathable holding plate 2. An air passage is formed above the first, second, and third adsorbent chambers A1, A2, B, but the second separator 1b that partitions the second, third adsorbent chambers A2, B is It penetrates the road,
As a result, a first communication passage 4 that connects the first and second adsorbent chambers A1 and A2 and a dedicated ventilation passage 5 dedicated to the third adsorbent chamber B are formed. An introduction port 6 for introducing the evaporated fuel from the gas layer portion of the fuel tank is opened in the upper part of the first communication passage 4, and an atmosphere port 7 communicating with the atmosphere is opened in the upper part of the dedicated ventilation passage 5. Has been done.

First, second and third adsorbent chambers A1, A2, B
A second communication passage 8 that communicates these chambers is formed in the lower part of the second communication passage 8. At a position in the second communication passage 8 corresponding to the first separator 1a, the evaporated fuel is directed toward the third adsorbent chamber B. A one-way valve 9 is provided for the flow to. Also, the second
A desorption port 10 for desorbing the adsorbed evaporated fuel and supplying it to the engine via an intake pipe 16 (see FIG. 3) is opened at an end of the communication passage 8 on the first adsorbent chamber A1 side. ing.

FIG. 2 is a view showing an example of the structure of the one-way valve 9, in which a partition plate 9b having a hole 9a is arranged at the position of the second communication passage 8 directly below the first separator 1a. There is.
On the third adsorbent chamber B side of the partition plate 9b, a rubber plate 9c is attached by a fixed plate 9d so as to close the hole 9a. As shown, the size of the rubber plate 9c is
It is larger than a, and the fixed plate 9d is a rubber plate 9c.
The size is almost the same as that of the third adsorbent chamber B, and the shape is curved in the direction of the third adsorbent chamber B.

Therefore, the gas such as the evaporated fuel flowing out from the first adsorbent chamber A1 can flow up toward the third adsorbent chamber B by pushing up the rubber plate 9c along the fixed plate 9d. However, the flow from the third adsorbent chamber B to the first adsorbent chamber A1 is prohibited.

Next, referring to FIG. 3, the canister C of FIG.
The flow of evaporative fuel and the like will be described. Fuel tank 11
At the time of refueling, the solenoid valve 13 provided in the charge passage 12 is opened, and the one-way valve 9 can flow only in the direction of the third adsorbent chamber B as described above. The solenoid valve 15 provided in the purge passage 14 is closed. Therefore, as shown by the solid line in the figure, when a large amount of evaporated fuel flows in at high speed from the inlet port 6 during refueling, the evaporated fuel is diffused into the first communication passage 4 and the first, second The evaporative fuel that has been adsorbed by the adsorbent little by little while advancing in a decelerating state while advancing in the adsorbent chambers A1 and A2 in parallel and flowing into the second communication passage 8 through the first adsorbent chamber A1 is unidirectional. Valve 9
To the third adsorbent chamber B through the second adsorbent chamber A2
The vaporized fuel that has passed through and has flowed into the second communication passage 8 advances toward the third adsorbent chamber B as it is. Then, these evaporated fuels are almost completely adsorbed through the third adsorbent chamber B, and the remaining air is discharged from the atmosphere port 7.

Thus, the first and second adsorbent chambers A1, A
The adsorbent in 2 is in a state of being connected in parallel to the flow of the evaporated fuel, and further divided into three chambers of the first, second and third adsorbent chambers A1, A2 and B. L /
Since D (L: height of adsorbent, D: diameter of adsorbent) is large, the adsorption efficiency of the adsorbent is greatly improved. Further, even when the inflow rate of the evaporated fuel increases at the time of refueling, the evaporated fuel is dispersed and introduced into the first and second adsorbent chambers A1 and A2, and then the third adsorbent is actuated by the action of the one-way valve 9. Since the air flow smoothly proceeds in the direction of the chamber B, the increase in ventilation resistance is suppressed and the fuel can be smoothly refueled.

On the other hand, when a negative pressure is generated in the intake pipe 16 during engine operation, the negative pressure causes the negative pressure as shown by the broken line in the figure.
The atmosphere is introduced from the atmosphere port 7 and flows into the second communication passage 8 through the third adsorbent chamber B. Then, due to the backflow prevention action of the one-way valve 9, the atmosphere advances toward the second adsorbent chamber A2 and flows into the first adsorbent chamber A1 via the first communication passage 4,
It is delivered to the purge passage 14 through the second communication passage 8 and the desorption port 10. The evaporated fuel adsorbed by the adsorbents in the first, second, and third adsorbent chambers A1, A2, B is desorbed during the passage of the atmosphere and sent out to the purge passage 14, and the solenoid valve 15 Is sucked into the intake pipe 16 via.

Next, as shown in FIGS. 1 and 3, the significance of providing the desorption port 10 on the side opposite to the introduction port 6 will be described in comparison with the comparative example of FIG.

In the comparative example shown in FIG. 4, the adsorbent chamber is divided into two chambers, the main adsorbent chamber a and the sub-adsorbent chamber b, and the desorption port 10
Is arranged in the upper part of the main adsorbent chamber a together with the inlet 6, and the atmosphere port 7 is arranged in the upper part of the adsorbent chamber b. Then, the adsorption of the evaporated fuel proceeds from the main adsorbent chamber a toward the sub-adsorbent chamber b, and the desorption of the evaporated fuel proceeds from the sub-adsorbent chamber b toward the main adsorbent chamber a. ing.

By the way, it is known that the adsorption rate of the evaporated fuel becomes higher as it gets closer to the inlet port and lower as it gets closer to the atmospheric port. In the comparative example shown in FIG.
Is installed near the inlet 6 with a high adsorption rate,
At the initial stage of desorption, a high concentration of adsorbed fuel is desorbed and a large amount of evaporated fuel is desorbed (see the solid line in FIG. 5), and the change in the air-fuel ratio becomes large.

On the other hand, in the present embodiment shown in FIGS. 1 and 3,
The desorption port 10 is provided on the lower side of the first adsorbent chamber A1 having a lower adsorption rate on the side opposite to the inlet 6 having a higher adsorption rate. Therefore, in the initial stage of desorption, the adsorbed fuel having a lower concentration than that in the comparative example is desorbed and a smaller amount of the evaporated fuel is desorbed (see the broken line in FIG. 5), and the change in the air-fuel ratio becomes small.

As described above, in this embodiment, the introduction port and the desorption port for the evaporated fuel are arranged on both sides of the adsorbent chamber,
The desorption amount of the evaporated fuel at the initial stage of desorption is reduced to suppress the change in the air-fuel ratio as much as possible.

[Second Embodiment] FIG. 6 is a view showing the arrangement of an evaporated fuel processing apparatus according to the second embodiment. Instead of the one-way valve in the first embodiment, a solenoid valve 17 controlled by an ECU 17 is used. It is characterized by the provision of. Although the known two-way valve 18 is newly provided in the second embodiment, this two-way valve 18 can also be applied to the first embodiment.

When the engine is stopped, the solenoid valve 17 is constantly controlled to be in the "open" state, and the evaporated fuel of the fuel stored in the fuel tank 11 is firstly passed through the two-way valve 18 and the inlet 6.
It flows into the communication passage 4 and enters the first and second adsorbent chambers A1 and A2. Then, after the adsorption is performed simultaneously in the first and second adsorbent chambers A1 and A2, they enter the third adsorbent chamber B through the second communication passage 8 and are adsorbed in the third adsorbent chamber B. Done.
Further, since the solenoid valve 13 is controlled to be in the “open” state during refueling, the evaporated fuel generated during refueling flows into the first communication passage 4 via the solenoid valve 13 and the introduction port 6, and similarly the first ，
After the adsorption is simultaneously performed in the second adsorbent chambers A1 and A2, the adsorption is performed in the third adsorbent chamber B.

Further, when the engine is operating, the solenoid valve 17 is controlled to open and close according to the set operating conditions. When the solenoid valve 17 is controlled to be in the "open" state during engine operation, desorption is performed only in the third adsorbent chamber B, and during operation of the engine, the solenoid valve 17 is released.
Is controlled to be in the "closed" state, the desorption proceeds in the order of the third adsorbent chamber B, the second adsorbent chamber A2, and the first adsorbent chamber A1 as in the first embodiment. .

As a case where the solenoid valve 17 is controlled to be in the "open" state so that desorption is performed only in the third adsorbent chamber B, for example, an operating condition with little desorbed air can be considered. By desorbing the third adsorbent chamber B alone, it is possible to reduce the desorbed amount, moderate the concentration change of the fuel supplied to the engine, and reduce the change in the air-fuel ratio. Since the basic configuration of the second embodiment is the same as that of the first embodiment, it goes without saying that the same effects as the first embodiment can be obtained in the second embodiment.

The present invention is not limited to the above-mentioned embodiment, and for example, the first adsorbent chamber A1, the second adsorbent chamber A2,
The adsorbent capacity ratio of the third adsorbent chamber B is 1-2: 1-2:
It may be arbitrarily changed within the range of 1. Further, the adsorbent capacity ratio of the first adsorbent chamber A1 and the second adsorbent chamber A2 is determined in consideration of the ventilation resistance at the time of introducing the evaporated fuel, and further ((first adsorbent chamber A1 + second adsorbent chamber A1 + second adsorbent chamber The adsorbent capacity ratio between the chamber A2) and the third adsorbent chamber B can be determined in consideration of the adsorption capacity (working capacity) and the ventilation resistance.

[0034]

As described above, according to the evaporated fuel processing apparatus of the first aspect, when the evaporated fuel from the fuel tank is introduced into the first communication passage, the first adsorbent chamber and the first adsorbent chamber Adsorption is performed in parallel in the two adsorbent chambers, and then the remaining evaporated fuel flows into the third adsorbent chamber through the one-way valve and is adsorbed, so that the adsorption efficiency of the adsorbent is improved. To do.

Further, even when the inflow velocity of the evaporated fuel increases at the time of refueling, the evaporated fuel is dispersed and introduced into the first and second adsorbent chambers, and then the third adsorbent chamber is operated by the action of the one-way valve. Since it smoothly progresses in the direction of, the increase in ventilation resistance is suppressed, and it becomes possible to smoothly refuel.

Furthermore, since the desorption port is provided on the lower side of the first adsorbent chamber having a lower adsorption rate on the side opposite to the introduction side having a higher adsorption rate, the fuel concentration change at the initial stage of desorption It becomes gradual, and the change in the air-fuel ratio becomes small.

According to another aspect of the fuel vapor treatment apparatus of the present invention, the control means always opens the electromagnetic valve when the engine is stopped so that the vaporized fuel is supplied to the first adsorbent chamber and the second adsorbent chamber.
Since the adsorbent is adsorbed in parallel with the adsorbent chamber and then adsorbed in the third adsorbent chamber, the adsorption efficiency of the adsorbent is improved, and the ventilation resistance at the time of refueling is suppressed from increasing, so that the oil can be smoothly refueled. Like

Further, the control means is
For example, when the operating condition is such that the amount of desorbed air is small, the solenoid valve is opened to perform desorption in the third adsorbent chamber alone, thereby reducing the desorption amount of the adsorbed fuel and changing the fuel concentration. It is possible to make it gentle and reduce the change in the air-fuel ratio.

[Brief description of drawings]

FIG. 1 is a diagram showing a configuration of a canister of an evaporated fuel processing apparatus according to a first embodiment of the present invention.

FIG. 2 is a diagram showing a configuration example of a one-way valve.

FIG. 3 is a diagram showing a configuration of an evaporated fuel processing apparatus according to a first embodiment of the present invention.

FIG. 4 is a diagram showing a configuration of a fuel vapor treatment apparatus according to a comparative example used for verifying the effect of the present invention.

FIG. 5 is an explanatory diagram for explaining the effect of the present invention.

FIG. 6 is a diagram showing a configuration of an evaporated fuel processing device according to a second embodiment of the present invention.

[Explanation of symbols]

 A1 ... 1st adsorbent chamber A2 ... 2nd adsorbent chamber B ... 3rd adsorbent chamber 4 ... 1st communicating passage 5 ... Exclusive ventilation passage 6 ... Introducing port 7 ... Atmosphere port 8 ... 2nd communicating passage 9 ... One direction Valve 10 ... Release port 11 ... Fuel tank 12 ... Charge passage 13, 15, 17 ... Electromagnetic valve 14 ... Purge passage 16 ... Intake pipe

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Takuji Yamada 1-4-1 Chuo, Wako-shi, Saitama Inside Honda R & D Co., Ltd. (72) Inventor Masaru Nakano 4-6-3 Higashiikebukuro, Toshima-ku, Tokyo Stock Company Tsuchiya Factory

Claims (2)

[Claims] 1. A first adsorbent chamber, a second adsorbent chamber, and a third adsorbent chamber, each of which is filled with an adsorbent, and which are provided above the first adsorbent chamber and the second adsorbent chamber, respectively. A first communication passage for introducing evaporated fuel from a fuel tank so that the first adsorbent chamber and the second adsorbent chamber can communicate with each other; and a second communication passage provided at an upper portion of the third adsorbent chamber and communicating with the atmosphere. And a communication passage that is provided below the first adsorbent chamber, the second adsorbent chamber, and the third adsorbent chamber and that connects the first adsorbent chamber, the second adsorbent chamber, and the third adsorbent chamber. The first adsorbent chamber and the second
A one-way valve that allows only the flow of gas toward the third adsorbent chamber is provided at a position corresponding to the adsorbent chamber, and intake is provided at a position corresponding to a lower portion of the first adsorbent chamber. A third communication passage having a desorption port communicating with the pipe, and a vaporized fuel processing device. 2. A first adsorbent chamber, a second adsorbent chamber, and a third adsorbent chamber that are respectively filled with an adsorbent, and are provided above the first adsorbent chamber and the second adsorbent chamber. A first communication passage for introducing evaporated fuel from a fuel tank so that the first adsorbent chamber and the second adsorbent chamber can communicate with each other; and a second communication passage provided at an upper portion of the third adsorbent chamber and communicating with the atmosphere. And a communication passage that is provided below the first adsorbent chamber, the second adsorbent chamber, and the third adsorbent chamber and that connects the first adsorbent chamber, the second adsorbent chamber, and the third adsorbent chamber. The first adsorbent chamber and the second
A solenoid valve is provided at a position corresponding to the adsorbent chamber,
A third communication passage having a desorption port communicating with the intake pipe at a position corresponding to the lower part of the adsorbent chamber, the solenoid valve is normally opened when the engine is stopped, and the solenoid valve is opened according to operating conditions during engine operation. An evaporative fuel treatment apparatus comprising: a control unit that controls opening and closing.