JP3406655B2 - Canister structure - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention, for example, adsorbs vaporized fuel (so-called evaporation) from a fuel tank to an adsorbent and utilizes the negative pressure of adsorption when the engine is driven to remove the vaporized fuel of the adsorbent from the adsorbent. The present invention relates to a canister structure that is detached and supplied to an intake system of an engine.

[0002]

2. Description of the Related Art Generally, in the canister structure described above, an activated carbon (charcoal) as an adsorbent is housed in a canister casing, and the evaporated fuel from a fuel tank is adsorbed by the adsorbent when loaded. And release clean air into the atmosphere while purging
At times, after the evaporated fuel adsorbed by the adsorbent is released, it is configured to be supplied to the intake system of the engine by negative pressure of intake air.

By the way, when the height of the adsorbent layer is H and the cross-sectional area of the adsorbent layer is D, the working capacity at the time of loading (capacity for adsorbing the evaporated fuel from the fuel tank to the canister) is shown in FIG. As shown in FIG. 5, the larger the H / D is, the better the characteristics are. On the other hand, as shown in FIG. 6, the smaller the H / D is, the smaller the flow rate is, the degassing can be performed, and the characteristics are contradictory to each other.

In order to solve such a problem, for example, a canister structure disclosed in Japanese Utility Model Laid-Open No. 60-127465 has already been invented. That is, as shown in FIGS. 7 and 8, the inside of the canister casing 62 having the adsorbent 61 built therein is divided by the two partition walls 63 and 64 extending substantially in the axial direction of the canister casing 62 to form an odd number of adsorbent chambers 65, 66 and 67, and an inflow chamber 72 connected to the fuel tank 69 through a port 68 and connected to an intake system 71 of the engine through another port 70 at the inlet of the first adsorbent chamber 65. An air chamber 74 communicating with the atmosphere via a port 73 is provided at the outlet of the third adsorbent chamber 67, and the diffusion chamber 7 is provided between the outlet and the inlet of the adsorbent chamber adjacent to each other.
5, 76, and these diffusion chambers 75, 76 are connected to the above-mentioned inflow chamber 72 or atmosphere chamber 74 via check valves 77, 78.
The check valves 77 and 78 are connected to the inflow chamber 7 described above.
The canister structure is configured to open when a predetermined intake negative pressure acts on the second side.

According to this conventional structure, at the time of the rod for adsorbing the evaporated fuel from the fuel tank 69 on the adsorbent 61, the check valves 77 and 78 are closed, so that the above-mentioned structure is performed as shown by the arrow in FIG. By connecting the three adsorbent chambers 65, 66 and 67 in series, the H / D can be increased and the working capacity can be improved, and the evaporated fuel adsorbed by the adsorbent 61 can be transferred to the engine by the intake negative pressure. At the time of purging to supply the intake system 71, more specifically, to the downstream of the throttle valve 79, the check valves 77 and 78 are opened, so that the three adsorbent chambers 65, 66 and 67 described above are opened as indicated by arrows in FIG. Are connected in parallel, the H / D is reduced, and the purging performance can be improved.

However, according to this conventional structure, one of the two check valves 77, 78 is located below the adsorbent 61, and the port 73 communicating with the atmosphere is provided in the canister casing 62. Due to the openings formed on the lower surface, the following problems occur.

That is, when the engine is stopped after running for a long time, the evaporated fuel adsorbed by the adsorbent 61 is cooled and liquefied, and the liquid fuel flows down and adheres to the check valve 78. Since the valve 78 is made of rubber, there is a problem that the valve durability deteriorates, the valve becomes inoperable, and liquefied liquid fuel is released into the atmosphere from the lower port 73 communicating with the atmosphere. It was

[0008]

According to the first aspect of the present invention, the chamber communicating with the atmosphere is formed on the upper side of the adsorbent chamber, and the atmosphere is introduced from the upper side at the time of purging. At the same time, by disposing the adjusting valve above the adsorbent chamber, it is possible to prevent the liquefied liquid fuel from adhering to the adjusting valve, prevent deterioration of valve durability, and release the liquid fuel into the atmosphere. An object of the present invention is to provide a canister structure that can prevent the occurrence of damage.

According to the second aspect of the present invention, in addition to the object of the first aspect of the invention, the number of adsorbent chambers is set to an even number and the adsorbent chambers in the two adsorbent chamber assemblies are provided. By setting the number to the same number, it is possible to inevitably arrange the adjusting valve above the adsorbent chamber, and it is possible to reliably prevent the liquefied liquid fuel from adhering to the adjusting valve, and to improve valve durability. An object of the present invention is to provide a canister structure that can prevent deterioration even better.

[0010]

According to a first aspect of the present invention, the adsorbent adsorbs the evaporated fuel from the fuel tank, and the adsorbent adsorbs the evaporated fuel by intake negative pressure. The canister structure is configured so that the value obtained by dividing the height of the adsorbent by the cross-sectional area can be changed at the time of purging to supply to the system, and the adsorbent chambers and the adsorbent chambers are assembled. The two adsorbent chamber assemblies, a first chamber arranged above the adsorbent chamber and communicating with the atmosphere, a second chamber connected to the fuel tank, and a first chamber connected to the intake system of the engine. 3 chambers, arranged between the first chamber and the second chamber, and closed at the time of loading to connect the second chamber, two adsorbent chamber assemblies and the first chamber in series. On the other hand, at the time of the purge, the valve is opened to connect the first chamber and the second chamber to each other, and the two adsorbents are Connect the assembly in parallel, the air and an adjustment valve that flows into the third chamber, characterized in that it is a canister structure in which above the adsorbent chamber the adjustment valve.

According to a second aspect of the present invention, in addition to the configuration of the first aspect of the invention, the number of the plurality of adsorbent chambers is set to an even number and the two adsorbent chamber assemblies are formed. It has a canister structure in which the number of adsorbent chambers is set to the same number.

[0012]

According to the first aspect of the present invention, at the time of the rod for adsorbing the evaporated fuel from the fuel tank to the adsorbent, the adjusting valve is closed, and the second chamber and the two chambers are closed. Since the adsorbent chamber assembly and the above-mentioned first chamber are connected in series, the value H / D obtained by dividing the height of the adsorbent by the cross-sectional area becomes large, and the working capacity can be improved.

Further, at the time of purging for supplying the evaporated fuel adsorbed by the adsorbent to the intake system by the intake negative pressure, the above-mentioned adjusting valve is opened to connect the above-mentioned first chamber and second chamber, Two
Two adsorbent chamber assemblies are connected in parallel, and the atmosphere is exposed to the above-mentioned third
Since it flows into the chamber, the H / D becomes small and the purging performance can be improved.

Moreover, since the first chamber communicating with the atmosphere is arranged above the adsorbent chamber and the adjusting valve described above is arranged above the adsorbent chamber, when the engine is stopped after running for a long time, etc. In addition, the evaporated fuel adsorbed by the adsorbent is cooled and liquefied, but it is possible to prevent the liquid fuel from adhering to the above-mentioned regulating valve and prevent deterioration of the durability of the regulating valve. It is possible to prevent the liquid fuel from being released into the atmosphere.

According to the second aspect of the present invention,
In addition to the effect of the invention described in claim 1, the number of the plurality of adsorbent chambers is set to an even number, and the number of adsorbent chambers in the two adsorbent chamber aggregates is the same among the aggregates. Since the adjustment valve described above can be inevitably arranged above the adsorbent chamber, as a result, liquefied liquid fuel is reliably prevented from adhering to the adjustment valve, and the durability of the adjustment valve is increased. There is an effect that the deterioration of the sex can be prevented more satisfactorily.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described in detail below with reference to the drawings. The drawing shows the canister structure, and in FIG.
A canister casing 2 accommodating activated carbon (charcoal) 1 ... As an adsorbent is provided inside, and a total of four adsorbent chambers C1, C2 are formed by vertical walls 3, 4, 5 extending in the canister casing 2 in the vertical direction. The two adsorbent chambers C1 and C2 are divided into C3 and C4, and two adsorbent chamber aggregates U1 and U2 are formed by collecting C3 and C4.

Here, the plurality of adsorbent chambers C1 to C4 described above are used.
Is set to an even number (a multiple of 2), and the number of adsorbent chambers in the above two adsorbent chamber assemblies U1 and U2 is set to the same number (two chambers in this embodiment).

Further, each of the first to third adsorbent chambers C described above
The lateral wall 6 is stretched over the upper portions of 1, C2, C3 to form a first chamber R1 communicating with the atmosphere above the fourth adsorbent chamber 4.
An atmosphere communication port 7 is formed on the upper part of the chamber wall of the first chamber R1. Further, a second chamber R2 connected to the fuel tank 8 is formed above the first adsorbent chamber C1.
A tank communication port 9 is formed on the chamber wall of the chamber R2.

Further, a surge tank as an intake system for the engine is provided above the second and third adsorbent chambers C2 and C3 via a pipe located above the canister casing 2 and a purge solenoid valve 10. A third chamber R3 connected to 11 is formed, and a purge port 12 is formed on the upper part of the wall of the third chamber R3.

The lower portions of the first adsorbent chamber C1 and the second adsorbent chamber C2 which are adjacent to each other are communicated with each other in the communication chamber 13, and
The lower portions of the third adsorbent chamber C3 and the fourth adsorbent chamber C4 which are adjacent to each other are communicated with each other in the communication chamber 14.

By the way, the above-mentioned first chamber R1 and second chamber R2
A check valve 15 as a regulating valve is arranged at a position above the first adsorbent chamber C1 in the lateral wall 6 that divides the and the upper and lower parts.

The check valve 15 is loaded (see FIG. 2).
(Refer to FIG. 3), the second chamber R2 and the two adsorbent chamber assemblies U1 and U2 and the first chamber R1 are connected in series while the valve is opened during purging (see FIG. 3). The first chamber R1 and the second chamber R2 described above are connected to connect the two adsorbent chamber assemblies U1 and U2 in parallel, and each of the elements 7 and R is connected.
1, C4, 14, C3 and 7, R1, 15, R2, C
The atmosphere is configured to flow into the above-mentioned third chamber R3 via 1, 13, C2.

The set valve opening pressure of the check valve 15 is higher than the internal pressure (about -100 mmAq) of the fuel tank 8 at the time of back purge (see FIG. 4), and the intake negative pressure (at the time of purge (see FIG. 3)). (Less than about 200 mmAq), the pressure difference is set to open between about 130 to 170 mmAq, and the check valve 15 is closed at the time of back purging. As shown in FIG. The air flowing in from each element R1, C4, 1
4, C3, R3, C2, 13, C1 and 9 are back-purged into the fuel tank 8 and the atmosphere communication port 7
Air from the fuel tank 8 via the check valve 15
Back purging inside is prevented, and each adsorbent chamber C is
By making the back purge through 4, C3, C2, C1, the back purge is effectively used,
It is configured to achieve miniaturization of the canister.

When the height of the adsorbent chambers C1, C2, C3, C4 is H and the cross-sectional area is D, the H / D of the fourth adsorbent chamber C4 on the atmosphere communication port 7 side is set to the other adsorbent chambers. C1, C2, C
Set a small value for H / D of 3 (however, not shown),
In order to improve the deaeration performance of the fourth adsorbent chamber C4, to prevent the evaporation of evaporative air into the atmosphere due to migration (a phenomenon in which evaporated fuel adsorbed on activated carbon is liquefied when the engine is stopped after running for a long time). I am configuring. Here, in order to reduce the H / D of the fourth adsorbent chamber C4 described above, the height H may be set small, the cross-sectional area D may be set large, or both may be combined.

Further, the ventilation resistance during purging is set so that the first and second adsorbent chambers are higher on the C1 and C2 sides and lower on the third and fourth adsorbent chambers C3 and C4 sides. A large amount of purge air is circulated through the activated carbon layer on the communication port 7 side, and the same side is quickly degassed to prevent evaporative emission into the atmosphere.

Furthermore, the first on the tank communication port 9 side
By disposing the adsorbent chamber C1 on the front side of the vehicle and cooling the activated carbon layer of the first adsorbent chamber C1 having the largest heat generation amount with the traveling wind generated when the vehicle is traveling, the working capacity is improved. I am trying.

In the figure, 16 is a throttle body, 17
Is a throttle chamber, 18 is a throttle valve, and the purge of the evaporated fuel is executed to the surge tank 11 downstream of the throttle.

The illustrated embodiment is constructed as described above, and the operation will be described below. At the time of loading when the evaporated fuel from the fuel tank 8 is adsorbed on the activated carbon 1 as the adsorbent, the above-mentioned check valve 15 is closed, so that the evaporated fuel from the fuel tank 8 is separated by the elements 9 as shown by arrows in FIG. , C
1,13, C2, R3, C3,14, C4, R1 and the clean air after the evaporative fuel trap is discharged from the atmosphere communication port 7 into the atmosphere.

That is, at the time of loading, the above-mentioned second chamber R2, two adsorbent chamber assemblies U1 and U2, and the above-mentioned first chamber R1 are connected in series, and the H / D becomes large. As is clear from the characteristic diagram, working capacity is improved.

On the other hand, after the vaporized fuel adsorbed on the activated carbon 1 in each of the adsorbent chambers C1 to C4 is released, the surge tank 11 downstream of the throttle valve 18 is caused by the negative pressure of the intake air of the engine.
The above-mentioned check valve 15 is opened at the time of purging to supply to the air. Therefore, due to the pressure difference between the air (atmospheric pressure) flowing in from the atmosphere communication port 7 and the intake negative pressure acting on the purge port 12, as shown in FIG. As shown by the arrow, one of the air flowing into the first chamber R1 from the atmosphere communication port 7 passes through the fourth adsorbent chamber C4, the communication chamber 14, and the third adsorbent chamber C3,
The evaporated fuel adsorbed on each of the activated carbons 1 and 1 is released and guided to the third chamber R3, and the other of the air flowing into the first chamber R1 is passed through the open check valve 15 to the second chamber R3.
After reaching 2, the first adsorbent chamber C1, the communication chamber 13, the second
After passing through the adsorbent chamber C2, the evaporated fuel adsorbed by the activated carbons 1 and 1 is separated and guided to the third chamber R3, and the evaporated fuel joined in the third chamber R3 is discharged from the purge port 12 to the upper pipe of the canister casing. Is supplied to the surge tank 11 via the purge solenoid valve 10 which is opened based on the duty control.

That is, at the time of purging, the above-mentioned first chamber R1
And the second chamber R2 are communicated with each other to form two adsorbent chamber assemblies U
1, U2 are connected in parallel and the atmosphere is exposed to the above-mentioned third chamber R
Since H / D becomes small, the H / D becomes small, and the purging performance can be improved, as is clear from the characteristic diagram of FIG.

Moreover, the first chamber R1 communicating with the atmosphere is arranged above the adsorbent chambers C1 to C4, and the above-mentioned check valve 15 is arranged above the adsorbent chamber C1. When you stop the engine,
Although the evaporated fuel adsorbed by the activated carbon 1 is cooled and liquefied, it is possible to prevent the liquid fuel from adhering to the above-mentioned check valve 15 and prevent deterioration of durability of the check valve 15. It is possible to prevent the liquid fuel such as gasoline from being released into the atmosphere.

In addition, the above-mentioned plurality of adsorbent chambers C1 to C4
Is set to an even number, and the number of adsorbent chambers in the above-mentioned two adsorbent chamber assemblies U1 and U2 is set to be the same between the aggregates, so that the check valve 15 described above is inevitably used. It is possible to dispose the check valve 15 above, and as a result, it is possible to reliably prevent the liquefied liquid fuel from adhering to the check valve 15, and to prevent the deterioration of the durability of the check valve 15 even better. There is.

In the correspondence between the configuration of the present invention and the above-described embodiment, the intake system of the present invention corresponds to the surge tank 11 of the embodiment, and similarly, the adsorbent corresponds to the activated carbon 1 and is adjusted. The valve corresponds to the check valve 15, but the present invention is not limited to the configuration of the above-described embodiment.

[Brief description of drawings]

FIG. 1 is a system diagram showing a canister structure of the present invention.

FIG. 2 is an explanatory diagram at the time of loading.

FIG. 3 is an explanatory diagram at the time of purging.

FIG. 4 is an explanatory diagram at the time of back purging.

FIG. 5 is a characteristic diagram showing a relationship of working capacity with respect to H / D.

FIG. 6 is a characteristic diagram showing purge performance with respect to the magnitude of H / D.

FIG. 7 is an explanatory view at the time of loading in the conventional canister structure.

FIG. 8 is an explanatory diagram at the time of purging in the conventional canister structure.

[Explanation of symbols]

1 ... Activated carbon (adsorbent) 8 ... Fuel tank 11 ... Surge tank 15 ... Check valve C1-C4 ... Adsorbent chamber R1 ... Room 1 R2 ... Room 2 R3 ... Room 3 U1, U2 ... Adsorbent chamber assembly

Claims (2)

(57) [Claims] 1. The height of the adsorbent is set during loading when adsorbing the evaporated fuel from the fuel tank to the adsorbent and during purging when the evaporated fuel adsorbed by the adsorbent is supplied to the intake system by negative intake pressure. A canister structure configured such that a value divided by a cross-sectional area is variable, and a plurality of adsorbent chambers, two adsorbent chamber aggregates in which the plurality of adsorbent chambers are assembled, and the adsorbent chamber Of the first chamber, which is disposed on the upper side of the vehicle and communicates with the atmosphere, the second chamber which is connected to the fuel tank, the third chamber which is connected to the intake system of the engine, the first chamber and the second chamber. The second chamber, the two adsorbent chamber assemblies, and the first chamber are connected in series by being closed at the time of the loading, and opened at the time of the purging to be connected to the first chamber. The two adsorbent chamber assemblies are connected to each other in parallel by communicating with the second chamber, and the atmosphere is introduced into the third chamber. An adjusting valve, a canister structure in which above the adsorbent chamber the adjustment valve. 2. The canister structure according to claim 1, wherein the number of the plurality of adsorbent chambers is set to an even number, and the number of adsorbent chambers in the two adsorbent chamber assemblies is set to the same number.