Internal-combustion engines – Charge forming device – Having fuel vapor recovery and storage system
Reexamination Certificate
1999-04-29
2002-07-30
Miller, Carl S. (Department: 3747)
Internal-combustion engines
Charge forming device
Having fuel vapor recovery and storage system
C123S516000
Reexamination Certificate
active
06425380
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to a canister for an evaporated fuel treatment apparatus which collects a fuel evaporated, for example, from a fuel tank in an internal combustion engine and discharges the collected fuel to an intake system.
2. Description of the Related Art
There is disclosed in U.S. Pat. No. 4,658,796 an evaporated fuel treatment apparatus structured such that only a vapor phase fuel can be introduced to an adsorbent in a canister by arranging a liquid trap for separating a gasoline vapor into a vapor phase and a liquid phase on a passage extending from a tank port communicated with a fuel tank to the adsorbent, thereby preventing the adsorbent from deteriorating due to an attachment of a component having a high boiling point of the liquid phase fuel to the adsorbent.
The apparatus is structured, as shown in
FIG. 9
, such that a second partition wall
20
having both ends extending to a casing
11
is arranged between an opening portion of a tank port
13
, mounted on the casing of a canister
2
, into the casing and a first diffusion chamber
12
on an inlet side of the canister so as to form a liquid trap
21
, and the tank port
13
is opened between the liquid trap
21
and the casing
11
. A first passage
22
for communicating the liquid trap
21
with the first diffusion chamber
12
is provided in the second partition wall
20
. A fuel in a liquid phase flowing into the canister at a time of a sudden turn of a vehicle is supplied to the liquid trap
21
, and only the fuel in a vapor phase flows into the first diffusion chamber
12
via the first passage
22
and is diffused at the first diffusion chamber so as to collect the fuel with the adsorbent
10
.
Further, with respect to the fuel in a liquid phase collected in a lower portion within the liquid trap
21
, air out of the canister
2
rises in temperature to evaporate the liquid phase fuel and the adsorbent
10
adsorbs the fuel via the first passage
22
.
The fuel in a vapor phase flows into a third diffusion chamber
15
from a carburetor float chamber (not shown) after passing through a passage opening/closing valve which is opened when an engine is stopped and further passing through an outer bent port
19
of the canister
2
, and is diffused so as to collect the fuel with the adsorbent
10
.
A second diffusion chamber
14
on an outlet side of the canister
2
is provided between the adsorbent
10
and a lower end of the casing
11
, and is communicated with the atmosphere by a first atmosphere port
18
provided in the casing
11
.
A purge port
17
communicated with an intake passage (not shown) is open to the first diffusion chamber
12
on the inlet side of the canister separated from a third diffusion chamber
15
by a first partition wall
16
having an end buried in the adsorbent
10
.
In accordance with the conventional technique mentioned above, since a position of a lowermost end of the tank port
13
and a position of an upper end of the first passage
22
communicated with the first diffusion chamber
12
receiving the adsorbent
10
therein are close to each other, a distance between the both is short and diameters of the tank port
13
and the first passage
22
are substantially the same, it is hard that the fuel in a vapor phase is liquefied in the liquid trap
21
, so that the fuel in a vapor phase enters into the first diffusion chamber
12
from the first passage
22
without changing it to the liquid phase so as to be adsorbed to an activated carbon
10
as the adsorbent. Accordingly, there has been a problem that a performance of the activated carbon is deteriorated. Further, since the position of the lower end of the tank port
13
is disposed above the liquid trap
21
, there is a little effect that the fuel in a liquid phase flows backward due to a negative pressure within the tank when the fuel tank is cooled, so that the fuel in a liquid phase is easily collected in the liquid trap
21
. When a lot of fuel in a liquid phase is collected in the liquid trap
21
, the fuel in the vapor phase enters into the first diffusion chamber
12
from the first passage
22
without being separated into the vapor phase and the liquid phase so as to be adsorbed to the activated carbon
10
. Accordingly, in this view, there has been a problem that a performance of the activated carbon is deteriorated.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a canister for an evaporated fuel treatment apparatus which can solve the problems mentioned above.
In order to solve the object mentioned above, in accordance with the present invention, there is provided a canister for an evaporated fuel treatment apparatus comprising a liquid trap for separating a gasoline vapor generated from the tank into the vapor phase and the liquid phase, wherein a tank port connected to the tank is arranged in a lower end portion of the liquid trap, an opening portion of a canister communication passage communicated with a diffusion chamber having an adsorbent is arranged in an upper portion within the liquid trap, and an inner diameter of the canister communication passage is set to be smaller than an inner diameter of the tank port.
In general, when the fuel tank is not cooled and the evaporated fuel is rich, the fuel in a vapor phase in a pipe between the tank and the canister is pressurized in a direction of the canister due to a pressure of evaporation. Then, the fuel in a vapor phase introduced into the liquid trap is cooled so as to become a liquid phase. In accordance with this structure of the present invention, a fuel in a liquid phase corresponding to a difference between the position of the lower end of the tank port and the position of the opening portion of the canister communication passage can be collected in the liquid trap. Further, when the fuel tank is cooled and the inner portion of the tank is in a negative pressure state, the fuel in a liquid phase within the liquid trap flows backward, so that the fuel in a liquid phase is not continuously collected within the separation chamber.
Further, since the inner diameter of the canister communication passage is smaller than the inner diameter of the tank port, the pressure of the fuel in a vapor phase increases within the liquid trap so as to be easily liquefied. As a result, an amount of the fuel in a vapor phase adsorbed to the adsorbent is reduced, so that a life of the adsorbent is extended.
REFERENCES:
patent: 2323525 (1943-07-01), Ebel
patent: 3610220 (1971-10-01), Yamada
patent: 3675634 (1972-07-01), Tatsutomi
patent: 3683597 (1972-08-01), Beveridge
patent: 3685504 (1972-08-01), Torazza
patent: 3727597 (1973-04-01), Hensler
patent: 4003358 (1977-01-01), Tatsutomi
patent: 4024848 (1977-05-01), Lee
patent: 4168687 (1979-09-01), Kurahashi
patent: 4658796 (1987-04-01), Yoshida et al.
patent: 63-102960 (1988-07-01), None
patent: 63-104659 (1988-07-01), None
patent: 2-20771 (1990-02-01), None
patent: 4-311661 (1992-11-01), None
patent: 6-307306 (1994-11-01), None
Ishikawa Takashi
Yamada Hideo
Aisan Kogyo Kabushiki Kaisha
Miller Carl S.
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