Note: Descriptions are shown in the official language in which they were submitted.
~ 1049869
This invention relates to internal combustion engines and is par-
ticularly directed to improved apparatus for oxidizing HC and C0 in the
exhaust gases in order to minimize the quantity of these pollutants discharged
into the atmosphere. The invention is particularly useful where the exhaust -
gases are oxygen-rich as a result of operating the engine on an overall air-
fuel ratio leaner than the stoichiometric ratio. By way of illustration,
this invention will be described in connection with a three-valve, prechamber,
torch ignition, stratified charge engine having a plurality of cylinders. ;
The combination of the present invention is for use with an internal
combustion engine which discharges exhaust gases from a plurality of cylin-
ders and comprises a generally Y-shaped exhaust pipe having a pair of exhaust
pipe sections of equal length each connected to receive exhaust gases from a
pair of adjacent cylinders of different exhaust timing and an outlet section
connected to receive exhaust gases from both said exhaust pipe sections, a
first reaction chamber connected to receive exhaust gases from said outlet
section, said first reaction chamber having a continuous passage extending
therethrough, said exhaust pipe sections, outlet section and continuous
passage having essentially the same cross sectional area, a second reaction
chamber surrounding and enclosing said first reaction chamber and surrounding
and enclosing said exhaust pipe sections and said outlet section, means for
discharging exhaust gases from the first reaction chamber into the second
reaction chamber, and means whereby exhaust gases are discharged from said
second reaction chamber.
In order to maintain temperatures of the exhaust gases at a high
level, exhaust pipes each receiving exhaust gases from a plurality of cylin-
ders of different exhaust timing are employed. These exhaust pipes merge
into a singlè outlet pipe which delivers exhaust gases into the first
reaction chamber.
The heat of reaction in oxidizing HC and CO also contributes to
maintenance of high temperature for long residence time. In order to prevent
lowering of exhaust gas temperatures by reason of expansion of the gases, the
exhaust pipes, the outlet pipe, and the continuing passageway through the
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first reaction chamber all have substantially the same effective cross
section area.
Other features and advantages will appear hereinafter.
In the drawings:
Figure 1 is a sectional elevation showing a preferred embodiment of
this invention.
Figure 2 is a sectional plan view taken substantially on the lines
2--2 as shown in Figure 1.
Figure 3 is a sectional elevation taken substantially on the lines
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1049869
3--3 as shown in Figure 1.
Referring to the drawings, each cylinder 4 of the internal com-
bustion engine 1 has a main combustion chamber 2 and an auxiliary combustion
chamber 3 connected by a torch opening 6. Each of the four cylinders 4 is
provided with an exhaust valve 5 and these are arranged in adjacent pairs, -
as shown in Figure 2. Each of these valves 5 controls the flow of exhaust
gases through a passage 8 in the cylinder head 7. One pair of exhaust
passages 8 discharges through exhaust port 9 and the other pair of exhaust
passages 8 discharge through exhaust port 10.
An exhaust pipe 11 has an open end lla receiving exhaust gases
discharged through exhaust port 9. Similarly, exhaust pipe 12 has an open
end 12a receiving exhaust gases discharged through exhaust port 10. The
exhaust pipes 11 and 12 and liner 14 are each constructed of thin wall
metal of good thermal conductivity. The exhaust pipes 11 and 12 are joined
together to form a single and common exhaust outlet pipe 13 at their
junction, and the outlet pipe 13 opens into the liner 14 containing a first
reac~ion chamber 20. Both the exhaust pipes 11 and 12 and the outlet pipe
13 leading into the first reaction chamber 20, as well as the passages
through the first reaction chamber 20, are substantially equal in cross
section area for substantially their entire length. In this way, any
temperature drop caused by expansion of the exhaust gas is eliminated; such
a disadvantage would be likely to occur if the passage size were to expand ~
downstream from the open ends lla-and 12a. The exhaust pipes and the ~ ;
reaction chamber 20 are maintained at high temperature, and this is ~ - -
effective in accelerating the reaction of exhaust gas for minimizing air
pollutants CO and HC.
Each of the exhaust pipes 11 and 12 and the liner 14 are enclosed
within a double wall shell 15 having inner and outer walls separated by an
air space 18. A second reaction chamber 21 is formed by the space between
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10498~;9
the liner 14 and the inner wall of the shell 15. A thick wall housing 17
spaced from and enclosing the double wall shell 15 provides rigidity for
the assembly. The liner 14 has laterally extending supports 19 received in
corresponding recesses provided in the double wall shell 15. The liner 14
is also supported by contact between the double wall shell 15 and the outer
periphery of the exhaust pipes 11 and 12 near their respective open ends lla
and 12a. The double wall shell 15 has a discharge pipe 23 fixed with respect
thereto and slidably mounted within a sealing assembly 26 carried on the
thick wall housing 17. The double wall shell 15 is secured by means of
threaded members 27 to the mounting ring 28 fixed to the housing 17 near
the opening 29.
From the foregoing description it will be understood that the
exhaust pipes 11 and 12 are enclosed within the double wall shell 15 and
that these exhaust pipes 11 and 12 have a common outlet pipe 13 which feeds
the first reaction chamber 20 by way of reversing elbow 30. The hot gases
then pass through the liner space 31, again reversing direction and
emerging from the lower portion of the liner 14 through the opening 22. The
exhaust gases then pass through the liner space 32 into the second reaction
chamber 21 which surrounds the first reaction chamber 20, The hot gases in
the second reaction chamber 21 act through the opening 29 to heat the walls
33 and 34 and then pass outward to the discharge pipe 23. The lean mixture
from the main carburetor barrel 24 is heated through the wall 33 prior to
introduction into the main combustion chambers 2, and the rich mixture from
the auxiliary carburetor barrel 25 is heated through the wall 34 prior to
introduction into the auxiliary combustion chambers 3. The secondary barrel
24a of the carburetor operates only when the engine is under load to deliver
a lean mixture to the main combustion chambers 2, but that mixture is
substantially unheated.
Since exhaust gas is discharged sequentially from the cylinders 4
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1049869
in a predetermined order, the junction of the exhaust pipes 11 and 12 is
maintained at high temperature to accelerate the reaction of exhaust gas.
Also, at any given lnstant exhaust gas of lower temperature existing in one
of the exhaust pipes 11 or 12 is activated by exhaust gas of higher
temperature flowing from the other exhaust pipe. Thus the heat of exhaust
gas discharged through one exhaust pipe prevents undue loss of heat from
the other exhaust pipe, because of sequential pulses of hot exhaust gases
from the cylinders 4. Also, each thin wall metal exhaust pipe 11 and 12 is
surrounded by the shell 15 so that the heat of reaction resulting from
oxidation of C0 and HC assists in maintaining the exhaust pipes at high
~! temperature. Furthermore~ the cross section area of the continuing passage-
way through the exhaust pipes 11 and 12, exhaust outlet pipe 13, reversing
elbow 30, the passage including liner space 31, through the first reaction
chamber 20, opening 22 and liner space 32 are substantially equal for
substantially the full length of the passageway. Thus~ the hot exhaust
gases then pass into the second reaction chamber 21 outside the liner 14
and inside the double wall shell 15, the temperature being sufficiently high
to continue rapid oxidation of C0 and HC.
Having fully described our invention, it is to be understood that
we are not to be limited to the details herein set forth but that our
invention is of the full scope of the appended claims.
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