Exhaust cleaning system for marine propulsion engine

Details Exhaust cleaning system for marine propulsion engine Exhaust cleaning system for marine propulsion engine

1996-11-21

2002-09-17

Avila, Stephen (Department: 3617)

Marine propulsion

Means for accomodating or moving engine fluids

Means for handling exhaust gas

C060S299000

Reissue Patent

active

RE037848

ABSTRACT:

BACKGROUND OF THE INVENTION
This invention relates to an exhaust cleaning system for a
mrine

marine
propulsion engine and particularly to a catalytic exhaust system for such an engine.
In watercraft it is well known that the exhaust gases from the powering internal combustion engine are silenced and cooled by an exhaust system which may include a water jacket that surrounds at least a part of the exhaust system and/or by the discharge of liquid coolant into the exhaust gases for discharge back into the body of water in which the watercraft is operating along with the exhaust gases. The exhaust gas discharge is either disposed below the water level or in proximity to it. Although this type of exhaust system is quite advantageous, there are some disadvantages with it and certain problems which may arise.
For example, it is desirable to provide a catalyzer in the exhaust system so as to insure against the emission of unwanted exhaust gas constituents either into the atmosphere or into the body of water in which the watercraft is operating. Catalyzers are particularly useful in conjunction with two cycle engines wherein there may be lubricating oil mixed with the exhaust gases. The catalyzer can render the lubricating oil relatively harmless to the amorphous in addition to treating the exhaust gases themselves.
However, most catalyzers operate with ceramic type beds and if any water strikes the catalyzer bed, the bed can shatter or become damaged. This is particularly true because of the high temperature at which the catalyzer bed must be at to be operative. These problems are particularly acute with certain types of watercraft which, by their sporting nature, may be capsized and easily righted. During such capsizing operation, water can enter the exhaust system and when the watercraft is again righted, the water can flow back to the catalyzer and cause it damage, as aforenoted.
FIG. 1
of the drawings shows a small watercraft of the type with which the problem aforenoted is particularly relevant, with the watercraft being identified generally by the reference numeral
11
. The watercraft
11
includes a hull
12
having a rearwardly positioned seat
13
on which one or more riders may sit in straddle, tandem fashion. A watercraft control, such as a handle bar assembly
14
, is positioned forwardly of the seat
13
for controlling the steering of the watercraft and the speed.
The watercraft hull
12
defines an engine compartment that is positioned forwardly of the seat
13
and which contains an internal combustion engine
14
of any known type. For example, the engine
14
may be a two cylinder in-line engine operating on the two stroke principal. The engine
14
has a drive shaft that coupled to an impeller shaft of a jet propulsion unit, indicated generally by the reference numeral
15
and positioned in a tunnel
16
at the rear underside of the hull
12
for powering the watercraft
11
in a known manner.
Conventionally, the engine
14
is provided with an exhaust system which transfers the exhaust gases from the exhaust port to an exhaust discharge and a portion of this exhaust system constructed in accordance with a prior art type of construction is shown in FIG.
2
. As may be seen in this figure, the engine
14
has a pair of exhaust ports
17
that discharge into a combined exhaust manifold and expansion chamber
18
. An exhaust elbow, indicated generally by the reference numeral
19
delivers these exhaust gases to a further expansion chamber device, indicated generally by the reference numeral
21
. It should be noted that the exhaust manifold
18
, exhaust elbow
19
and expansion chamber device all have a double walled construction and form respective cooling jackets
22
,
23
and
24
each of which receive coolant from the engine
14
in a well known manner. The coolant may be delivered to the cooling jackets
22
,
23
and
24
by independent conduits or the coolant may be delivered to one or both of the cooling jackets
22
and
23
in series or parallel fashion from the engine cooling jacket and then delivered to the cooling jacket
24
of the expansion chamber
21
.
This coolant from the cooling jackets
22
,
23
and
24
is normally discharged back into the exhaust gases that flow from the exhaust port
17
and as may be seen in
FIG. 2
, the expansion chamber
21
has an inner shell
25
that has a discharge opening
26
that communicates with an outlet pipe
27
but which passes through the cooling jacket
24
so that the engine coolant will be mixed with the exhaust gases as they pass through the exhaust outlet
27
. A flexible conduit
28
extends from the exhaust outlet
27
rearwardly as will be described in conjunction with FIG.
1
. The cooling jackets
22
,
23
and
24
effectively cool the exhaust gases and also insure that the manifold
18
, elbow
19
and expansion chamber
21
, which are all positioned within the hull
12
, will not be overheated.
Referring now again to
FIG. 1
, it should be seen that the flexible exhaust conduit
28
extends to a water trap device
29
positioned at the rear portion of the hull. The water trap device
29
has an outlet portion
31
that extends to the tunnel
16
so as to deliver the exhaust gases and entrained coolant back to the atmosphere and body of water in which the watercraft is operating.
The type of watercraft
11
is very sporting in nature and can be easily capsized and righted. The water trap device
29
insures that water which may enter the exhaust outlet
31
will not pass back to the exhaust port
17
and interiorly to the engine. However, since coolant from the engine is discharged into the flexible conduit
28
, such inversion and righting can cause water from the engine coolant jacket to flow backwardly into the expansion chamber
21
, elbow
19
and exhaust manifold
18
and thus possibly enter the engine.
It is desirable to provide a catalyzer, as aforenoted, for treating the exhaust gases and with the aforedescribed construction, water from the cooling jackets
22
,
23
and
24
may easily impinge upon the catalyst and damage it.
It, therefore, a principal object to this invention to provide an improved exhaust system for a watercraft wherein a catalyzer may be employed and the catalyzer will be protected from possible damage from the coolant present in the exhaust system and/or water from the body of water in which the watercraft is operating.
It is a further object of this invention to provide an improved catalytic exhaust cleaning system for a marine propulsion engine.
It is a yet further object of this invention to provide an improved exhaust cleaning system for an engine that embodies a catalyzer and an effective device for insuring that the exhaust system may be partially cooled by the engine coolant but this engine coolant cannot come into contact with the catalyzer.
SUMMARY OF THE INVENTION
This invention is adapted to be embodied in a an exhaust system for a watercraft that is comprised of a hull containing an internal combustion engine and having at least one exhaust port. The exhaust system is comprised of an exhaust conduit having an inlet end communicating with the exhaust port for receiving exhaust gases therefrom and an outlet end for discharging the exhaust gases to the atmosphere in proximity to the body of water in which the watercraft is operating in at least some conditions of the watercraft. The exhaust conduit includes means defining an expansion chamber and a tube containing a catalyzer bed communicating at one end with the expansion chamber and through which the exhaust gases must pass. Means are provided for precluding water in the exhaust conduit from entering the tube end and impinging on the catalyzer bed.


REFERENCES:
patent: 4353208 (1982-10-01), Völker et al.
patent: 4735046 (1988-04-01), Iwai
patent: 4773883 (1988-09-01), Nakase et al.
patent: 4787869 (1988-11-01), Shiozawa
patent: 4811560 (1989-03-01), Nakase et al.
patent: 4957461 (1990-09-01), Nakayama
patent: 4965997 (1990-10-01), Suzuki et al.
patent: 4989409 (1991-02-01), Nakase et al.
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