Note: Descriptions are shown in the official language in which they were submitted.
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G-7892 C-4312
VAPOR CANISTE:R WITH LIQUID TRAP
Technical Field
This invention relates to a vehicle fuel
evaporation loss con~rol sy~tcm in general, and
specifically to a fuel vapor storage canister that
contains a liquid trap that can be installed in the
vehicle in a number of possible orientations.
Background of the Invention
In most current evaporative systems, fuel
vapor that accumulates in the fuel tank vents to a
vapor storage canister located in a remote location
from the fuel tank in the vehicle. The fuel vapor is
captured by an adsorbent bed; u ually composed of
~0 charcoal. Liquid fuel from condensation or direct
entry into the canister can contaminate or degrade the
efficiency of the adsorbent bed, therefore many
evaporative systems have incorporated liquid traps to
prev~nt liquid entering ~he adsorbent bed.
One example of a liquid trap can be sQen in
U.S Patent No. 4,750,465 i~sued June 14, 1988 in the
names of J. Fornuto, W. E. Gi~:ford, and R. M. M~yer.
In that patent the~bottom of the:canister has a cone
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shaped shell beneath the adsorbent bed. A tube
connected to the fuel tank extends thr-ough the
adsorbent bed and opens into the cone ~haped shell.
Any liquid component of the fluid from the fuel tank
collects in the apex of the shell. ~ ;
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In u.s. Patent No. 4,655,189 issued ~pril 7,
1987 in the name of I. Roga, a separating chamber at
the upper end of the canister prevents the liquid
component from flowing into the adsorbent bed. AS the
fluid enters the canister, the liguid component is
collected at the bottom of the separating chamber.
Openings to the adsorbent bed are located above the
surface of ~he liquid component in the separating
chamber to allow only the gaseous component to be
stored in the adsorbent bed.
One disadvantage of these canisters is that
they can only be placed in the vehicle one way. These
canisters lack the versatility to be placed in some
engine compartments. In U.S. Patent No.~ 4,853,009
issued August 1, 1989 in the names of K. W. Turner, R.
H. Simons, Jr. and G. R. Paddock, a canister has a
number of liquid trap kits that can be connected to the
canister to allow for various installation orientations
in the vehicle.
Summary of the Invention
The current invention is a canister with a
liquid fuel trap that has the capability of multi-
orientation installations in the vehicle without thenecessity o~ supplying a number of assembly~kits to fit
on a particular canister for a particular vehicle. One
canister provides the necessary liquid fuel trap with
the convenience of positioning it in the vehicle in a
number of various orientations.'
The canister is filled with an adsorbent
material such as charcoal. Within the canister housing
the interior is divided longitudinally into two ~
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compartments, a main and auxiliary compartment. The
two compartments communicate with each other by a
connecting passage. At the end opposite the connecting
passage is an air aperture which opens into the
auxiliary compartment. At the same end of the canister
is a box-shaped trap housing which encloses a
separating chamber that collects the liquid ~omponent
of the fluid. ~he trap housing is situated next to the
main compartment of the canister. In the center of the
1~ box-shaped trap housing is a purge tube that extends
through the separating chamber and opens into the main
compartment of the canister. Situated in one corner of
the trap housing is the tank vent tube that receives
fluid vented from the fuel tank. The tank vent tube
extends to near the bottom of the separating chamber.
Within the separating chamber is a raised inlet tube
that opens from about the middle of the separating
chamber and extends into the main compartment of the
canister.- ay positioning the canister in the vehicle
so that the tank vent tube is in the low position in
relation to the inlet tube, the liquid component will
not flow into the inlet tube and into the adsorbent
bed. Because the inlet tube is not visible by looking
at the canister's exterior housing, the tank vent tube
will be in the low position in relation to the inlet
tube if it is oriented to be in the low position in
relation to the purge tube. In this way any liquid
entering the trap housing will remain in the separatiny
chamber while the gaseous component will be allowed to
flow through the inlet tube to the adsorbent bed in the
canister.
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The details of a preferred embodiment of thi~
invention are set forth in the remainder of the
specification and are shown in the drawings.
Summary of the Drawings
Fig. 1 is a sectional view of a canister
employin~ this invention.
Fig. 2 is a top view of the canister from the
perspective of line 2-2 in Fig. 1.
Figs. 3A-3C are partial sectional views of the
three possible installation orientations of the
canister, showing how liquid is trapped.
Detailed Description
The canister 10 has a generally elongated
rectangular housing 12 with rounded corners. Fig. 1
displays the canister with the elongation being on a
~o vertical axis. The cross section of canister 10 has
different width W and length L, as illustrated in
Fig. 2. The housing 12 is usuaIly made of a plastic
material and includes an end face 14 that encloses the
canister 10 at the one end. In the preferred
~S embodiment, the other end lS of the canister 10 has a
volume compensator 16. The current invention is not
dependent upon such a co~pensator and the other end 15
o~ the canister 10 could be closed by a cap.
The housing 12 encloses an interior volume,
containing an adsorbent bed 18 that is charged with
activated charcoal granules, or ~he like. The interior
volume is partitioned parallel to its elongated axis
into a main compartment 20 and an auxiliary compartment
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22. A partition 24 separates the main compartment 20
and the auxiliary compartment 22, and has a passage 26
at the end 15 of said housing 12 that allows vapor to
pass between the two compartment6. Sandwiched between
the adsQrbent bed 18 and the volume compensator 16 is a
foam screen 28. Foam screens 30 separate the end face
14 o~ the canister housing 12 and the adsorbent bed 18.
The side o~ the end face 14 that abuts the foam screens
30 may have ribs 31 to prevent the foam screens 30 from
moving and obstructing air flow to and from the
absorbent bed 18. In said end face 14 is a tubular air
aperture 32 which opens into the auxiliary compartment
22 of the canister 10.
A box-shaped trap housing 34,- also made of a
plastic material, is welded to the end face 14, and it
encloses a separating chamber 36. Said trap housing 34
has an end wall 38 spaced from and parallel to said end
face 14 of the canister 10. In the center of the end
wall 38 is a purge tube 42 that extends through the
separating chamber 36 and opens through an aperture 43
into the main compartment 20 of the canister 10. The
purge tube 42 is adapted for connection to the engine
vacuum source. In one corner of the end wall 38 is a
tank vent tube 44, which extends through the end wall
38 to near the end face 14 of the separating chamber
36. The tank vent tube 44 is adapted for connection to
the fuel tank. Within the separating chamber 36 is an
lnlet tube 46 which is located on the opposite side of ~
the.purge tube 42 from~the tank vent tube 44. It : :
starts beyond the end~face 14 and extends into ~he main
compartment 20 of the canister 10. Gaseous fluid that
has ente:red the separating chamber 36 through the tank
vent tube 44 from the'fuel tank wiIl flow through the
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inlet tube 46 to the adsorbent bed 18 in the main
compartment 20. Any liquid fluid entering the
separating chamber 36 will settle in the low psint of
said chamber 36. It will remain there until it ei~her
evaporates and then flows through the inlet tube 46 to
the adsorbent bed 18 or is purged back to the fuel tank
when the tank pressure falls below atmospheric
pressure. ~t the end point of the inlet tube 46
located in the main compartment 20 is a nylon mesh
filter 48 that is press set on~o the inlet tube 46.
5aid filter 48 prevents charcoal granules from entering
the separating chamber 36.
The tank vent tube 44 is located in a corner
of the trap housing 34 so that it can always be
situated at a low point in relation to the inlet tube
46 and thereby keep the liquid component near to the
connection to the fuel tank and out of the adsorbent
bed 18. Since the inlet tube 46 is not visible by
looking a~ the canister housing 12 or the trap housing
34, the purge tube 42 can be used as a reference point.
If the tank vent tube 44 is oriented to be at a low
point in relation to the purge tube 42, this will have
the same result as being at a low point in relation to
the inlet tube 46.
During purge, vacuum will be applied to the
purge tube 42. Atmospheric air will enter the air
aperture 32 and flow through the auxiliary 22 and main
compartment 20 of the canister 10. Vapor that has been
captured in the adsorbent bed 18 will be de~orbed and
sent to the engine induction system through the purge
tube 42.
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Figs. 3A-3C represent the three possible
different orientation installations of the canister lQ,
and show the separating chamber 36 partially filled
with liquid 50. For example, Fig. 3A shows the
canister 10 in an upright position with its
longitudinal axis vertical, where the liquid trap 34 is
on the top of said eanister 10.' The canister 10 can be
turned around about its vertical axis in any direction
since the tank vent tube 44 will not be higher than the
purge tube 42. AS seen in Figs. 3B and 3C, the
canister 10 can also be installed with its longitudinal
axis horizontal. In ~ig. 3B said canister 10 is shown
with its major transverse axis vertical, and in Fig. 3C
with its minor transverse axis verticai. In both Figs.
3B and 3C it is important where the tank vent tube 44
is located in relation to the purge tube 42. In both
these orientations, the trap housing 34 must be
installed so that the tank vent tube 44 is at the low
point in relation to the purge tube 42. This will then
ensure that the inlet tube 46 is at a higher;position
than the tank vent tube 44, so that the liquid 50 will
collect in the separating chamber 36 and will not reach
the inlet tube 46 that lerds to tne adsorbent bed l8.
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