After-burning preventive and flame-out apparatus

For use in a muffler of an internal combustion engine improved flame-out apparatus includes first and second L-shaped screens each having a longitudinal section and a transverse section. The transverse sections are axially spaced apart and the space therebetween is occupied by a pair of axially spaced apart, transversely oriented perforated partition plates and flame extinguishing means.

BACKGROUND OF THE INVENTION 
The present invention relates to an after-burning preventive and flame-out 
apparatus for an internal combustion engine. 
In the operation of a vehicle having an internal combustion engine mounted 
thereon, the engine is in such a state that it is prone to an accidental 
fire immediately after either running on a long sloping road, sudden speed 
reduction, racing, or gear change, and the said state might possibly 
result in after-burning in some cases. Besides, in general practice, a 
certain quantity of a live gas is suctioned into the engine due to the 
continuation of the motion of the engine by inertia, and is exhausted 
thereafter in the form of a non-ignited gas, through an exhaust system, 
even after the engine is switched off. Therefor, in case a heat source 
(hot spot) as is sufficient to ignite the live gas is present, such a live 
gas as ought to be exhausted as a non-ignited gas through the exhaust 
system is subjected to combustion in the exhaust system, to thus result in 
explosive after-burning. The flame that results from said explosive 
after-burning reaches as far as the live gas that fills the entirety of 
the exhaust system, especially as far as the live gas that stagnates in 
the main muffler, thus being subjected to explosive combustion, until the 
pressure is raised, whereby the gas is caused to be exhausted through the 
outlet of the exhaust system at the speed well equivalent to the acoustic 
velocity, and this has thus far constituted such a series of defects as 
affect in a harmful manner the respective sections of a vehicle having an 
internal combustion engine mounted thereon as well as the environment 
outside the vehicle, as well as the exhaust system itself. To put it 
otherwise, such explosive after-burning often generates a quite high level 
of knocking, so also does it give off sparks out of a tail pipe at the 
outlet of the exhaust system in some case, which has thus far constituted 
a hazard. 
Introduced to date as the methods of preventing the after-burning of this 
category have been: (1) means for causing a non-ignited gas mixture as is 
discharged from an engine to be subjected to combustion in an upstream 
section of a sound deadening apparatus, (2) means that subjects either an 
exhaust manifold or a thermal reactor to cooling in a proper manner to 
thus keep a non-ignited gas mixture free from being subjected to 
spontaneous ignition, and (3) means providing that, in case explosion 
should take place in the course of running of a non-ignited gas mixture 
through the exhaust system of a sound deadening apparatus, the flame 
and/or the explosive sound resulting thereby are so controlled as to be 
properly extinguished and/or deadened by means of a flaming-out apparatus 
and/or a sound deadening apparatus at the outlet of an exhaust pipe. The 
present invention relates to the third one of the methods set forth above. 
One of the conventional methods similar to that being introduced herein 
and presently available is such wherein, either a wire mesh, a filter, or 
the like is arranged in place at the outlet of an exhaust pipe. However 
the prior art method is not specifically designed for the purpose of 
effectuating flame-out but is designed for the purpose of preventing 
red-hot sparks of carbon from being scattered around, and the mesh of a 
wire mesh is required to be so formed as to be fine enough. This prior art 
method still involves such a series of inherent defects that the mesh is 
prone to be subjected to clogging, and, in case non-ignited gas mixture 
should be subjected to explosion in a sound deadening apparatus, a quite 
intensive flame is jetted out, which has hitherto made it difficult to 
prevent after-burning in a proper manner. 
SUMMARY OF THE INVENTION 
Now, one purpose of the present invention resides in providing an 
after-burning preventive apparatus of such a new construction as is well 
capable of overcoming the said difficulties involved in the conventional 
after-burning preventive method. More specifically, the present invention 
provides an after-burning preventive apparatus of a new construction which 
includes a flaming-out apparatus that is arranged in place for 
effectuating proper flame-out in the middle of an exhaust system of an 
internal combustion engine for the purpose of preventing an explosion of a 
non-ignited gas mixture from taking place at the time of speed reduction 
or shut down of the internal combustion engine, whereby such a non-ignited 
gas mixture as runs in the wake of passing through the said flaming-out 
apparatus is properly kept free from being subjected to combustion, and 
the pressure of the non-ignited gas mixture is properly checked from 
rising up to such a level as corresponds to the acoustical velocity. 
Another purpose of the present invention resides in providing a sound 
deadening apparatus coupled with an after-burning preventive apparatus of 
such a new construction as is well capable of overcoming the said 
difficulties involved in the conventional after-burning preventive method. 
More specifically the present invention provides a sound deadening 
apparatus of such a new construction that features a narrow and curved 
flow path for an exhaust gas with the flow path being properly formed in 
the interior of the sound deadening apparatus whereby a flame is properly 
prevented from being spread all around. 
In case the flame-out apparatus according to the present invention is not 
employed, (1) a gas mixture that is suctioned by inertia force of an 
engine, when the engine is switched off, is discharged into an exhaust 
system in the state of a live gas, (2) and the gas mixture which is 
exposed to comparatively high temperature in the exhaust system, is then 
subjected to ignition by the heated surface (550.degree. 
C.about.600.degree. C or over) in the interior of an exhaust manifold or a 
thermal reactor which is hard to cool. A flame thus taking shape reaches 
as far as a live gas present inside a main muffler, ignites the live gas 
in the main muffler, and subjects the said live gas to combustion in an 
explosive manner, until the combustion gas having the pressure thereof 
raised by the combustion is thus caused to be jetted out of the outlet of 
the exhaust system at the acoustical velocity. By way of contrast, where 
the flame-out apparatus according to the present invention is employed, 
the live gas present and stagnating in the exhaust manifold or the thermal 
reactor through the flame-out apparatus to be subjected to combustion, the 
pressure of the gas is kept free from rising up to so high a level as to 
be jetted at the velocity of sound, and only stays on such a level as 
simply generates a slight sound of after-burning, whereby an effect of 
preventing an explosion can be attained, especially such a category of 
after-burning as results at the time of cut-off of ignition can be 
prevented in a proper manner. Besides, the flame-out apparatus of this 
invention can achieve a subsidiary effect of proper sound deadening.

DETAILED DESCRIPTION OF THE INVENTION 
The flame-out apparatus 1 shown in FIG. 1 is shaped like a hollow container 
and is provided with an inlet 2 and an outlet 3. A space in the said 
flame-out apparatus is formed by a pair of axially spaced apart porous 
plates 4, 4 with the space being filled with pieces of globules 5 of 
approximately 2mm through approximately 7mm in diameter. The globules 5 
have no oxidative catalytic action on a non-ignited gas mixture and may be 
made of aluminum oxide globules, steel globules, glass globules, and/or 
the like. In this case, for the purpose of forming a path of a flame in 
such a manner as to constitute a maze, at least three layers of the 
globules are required to be arranged in the direction of the flow of the 
flame. The globules 5 are larger in heat capacity than a wire mesh or the 
like, so that the sectional area of the path of a comparatively large 
dimension provides a superb flame-out effect, and such an advantage that 
causes no clogging to take place. Furthermore, for the purpose of ensuring 
the flame-out action by the said globules to be carried out in a secure 
manner, the temperature of the globules before the flame reaches the 
globules is required to be 600.degree. C or less. Therefore, the flame-out 
apparatus is arranged in place in the direction of the down flow 
sufficiently away from an exhaust manifold and a thermal reactor, and is 
subjected to sufficient cooling by the air blowing from the direction of 
movement of a vehicle. Shown in FIG. 2 is an embodiment wherein a 
plurality of porous plates 6, 6 . . . are combined and arranged in place 
in the same space formed in the same manner as in the case of that which 
is shown in FIG. 1, the diameter of each aperture in the plate 6 being 
approximately 1mm through approximately 3mm, the thickness of the porous 
plates 6 being approximately 5mm through approximately 25mm. The apertures 
in the plate 6 are offset from one another to form a maze, and the flame 
is subjected to proper flame-out, while running through the said maze. In 
the embodiment shown in FIG. 3, a flame is subjected to flame-out, while 
the flame runs through a plurality of hollow pipes 7, 7, . . . arranged in 
place in the same space formed in the same manner as in the embodiments 
shown in FIG. 1 and FIG. 2. The said pipes 7 are approximately 1mm through 
3mm in inner diameter, and approximately 100mm through 150mm in length. In 
the embodiment shown in FIG. 4, a plurality of wires, metallic pieces, 
and/or the like fill the space formed in the same manner. In the 
embodiment shown in FIG. 5, the space thus formed is filled with from 
three layers to ten layers of wire meshes of #10 through #100 in mesh. 
When the flame of a gas mixture that as is subjected to spontaneous 
ignition near the exhaust manifold or the thermal reactor reaches the 
flame-out apparatus, the said flame is prone to be further transmitted in 
the direction of the down flow thereof. However, the said flame undergoes 
a quenching action by the said stainless wire mesh layer, thus preventing 
an explosion from taking shape. In this case, when the mesh of the wire 
mesh is #10 or less, a flame is left to pass through the wire mesh. 
Therefore, it is imperative that the mesh of the wire mesh should be finer 
than that. However, a wire mesh of a finer mesh than #100 causes the 
exhaust pressure to rise up and therefore is not recommended for practical 
purposes. Besides, in the case of a wire mesh made of a fine and thin 
wire, the heat capacity thereof is small, and a single layer of such a 
wire mesh is not effective enough for preventing a flame from passing 
through the said wire mesh. Therefore, in case a wire mesh of this 
category is selected, the wire mesh is required to be in as at least three 
layers. Furthermore, for ensuring the flame-out action to be conducted in 
a secure manner, it is imperative that the temperature of the wire mesh 
before the flame reaches the wire mesh should be 600.degree. C or lower. 
To cope with the requirement, it is imperative that the flame-out 
apparatus 1 should be arranged in the direction of the down flow of the 
exhaust manifold or the thermal reactor, and be kept in the state of being 
sufficiently cooled by the air blowing from the running direction, in the 
same manner as is shown in FIG. 1. Shown in FIG. 6 is still another 
embodiment of the invention wherein the exhaust resistance is properly 
caused to be reduced. In this embodiment porous plates 13, 14 have a 
tubular shape, and have globules 15 as are shown in the embodiment of FIG. 
1 which globules are properly selected to fill the space between the said 
porous plates 13 and 14. In the drawing, an arrow designates the direction 
of the flow of an exhaust. 
FIG. 7 through FIG. 9 are schematic drawings specifically illustrating 
several different positions of the flame-out apparatus as is set forth in 
the preceding paragraphs. Shown in FIG. 7 is the arrangement of the 
flame-out apparatus immediately in the rear of the exhaust manifold or the 
thermal reactor 9 in the wake of an engine 8, and a connecting pipe 10 
following the said flame-out apparatus 1 with a sub-muffler 11 and a main 
muffler 12 properly connected therewith. Compared with such a case wherein 
the flame-out apparatus is arranged further downstream, the arrangement 
shown in FIG. 1 has a higher level of atmospheric temperature. Therefore, 
durability is subjected to deterioration, and the cooling capacity of the 
flame-out apparatus is rather inferior. However, since the quantity of the 
gas to be consumed for burning is rather small, the flame-out capacity of 
a low level may suffice. In the arrangement shown in FIG. 8, the flame-out 
apparatus 1 is arranged in place near the inlet of the main muffler 12 
following the sub-muffler 11 through the connecting pipe 10 from the 
exhaust manifold or the thermal reactor 8. In the arrangement of FIG. 8, 
the atmospheric temperature is low, unlike the arrangement shown in FIG. 7 
and the flame-out apparatus is superb in terms of the durability and the 
cooling capacity thereof. However, the quantity of the gas to be consumed 
for burning is higher. Therefore, such a filler for the flame-out 
apparatus as has the gas pressure taken into due account is required. 
Shown in FIG. 9 is an arrangement of the flame-out apparatus at an 
intermediate position between the position shown in FIG. 7 and the 
position of the example shown in FIG. 8, whereby the durability, the 
cooling capacity, and the flame-out capacity of the flame-out apparatus 
are all designed so as to be moderate and reasonable. 
Next, as still other illustrations of the present invention, for example 
wherein the flame-out apparatus is arranged in place in the sound 
deadening apparatus, as in the case of that which is shown in FIG. 8, are 
as shown in FIG. 11 through FIG. 13. Prior to giving a description 
thereof, a sectional view of an example of the conventional sound 
deadening apparatus for a vehicle with an internal combustion engine 
mounted thereon will be shown in FIG. 10. An exhaust gas runs into the 
sound deadening apparatus 12 through an inlet pipe 16, and is exhausted 
out of an outlet pipe 17 through such a route as is generally termed a 
route of the three-path system. To put it in more specific terms, the 
inlet pipe 16 causes a portion of an exhaust to leak out through a 
plurality of apertures formed by drilling through the said inlet pipe 16 
in such a chamber as is formed by separators 19, 19 set in place in the 
interior of the outer body 18 of the sound deadening apparatus 12, while 
most of the outer portion of the exhaust runs into an inner pipe 21 
through a rear chamber 20 in the sound deadening apparatus, as well as 
through an opening of the inlet pipe 16 passing through the said 
separators 19, 19, returns into the front chamber 22 of the sound 
deadening apparatus, and runs through the outlet pipe 17, then is 
discharged to the outside of the sound deadening apparatus. 
The present invention is shown in a sectional view in FIG. 11. The same 
portions as those shown in FIG. 10 will be given the same numerical 
symbols. Such an exhaust as is led into the sound deadening apparatus 12 
through the inlet pipe 16 and is led intact into the rear chamber 20 in 
the sound deadening apparatus, wherefrom the exhaust runs back through the 
sound deadening apparatus, and runs through the flame-out apparatus 23. 
Details of the said flame-out apparatus 23 are as shown in FIG. 13. A 
filling chamber 26 for the filler is formed of porous plates 4, 4 properly 
welded, respectively, with a spacing of 15mm or more, on such an L-shaped 
screen member 25 that is welded on the inner surface of an outer body 18, 
and on another L-shaped screen member 25' that is further welded on the 
said screen member 25. A plurality of globules 5 made of, for example, 
alumina, specifically provided to fill the space in the said filling 
chamber in a close manner. A flow of the exhaust runs through the said 
flame-out apparatus 23, so also does such a flame that results from the 
ignition of a live gas, on the occasion the said flame is transmitted, and 
the said flame is subjected to flame-out in a proper manner in the course 
of running through the flame-out apparatus. After running through the 
flame-out apparatus 23, the flow of the exhaust runs back through a 
central chamber 30 in the sound deadening apparatus and reaches the front 
chamber 22, then is discharged out of the sound deadening apparatus from 
in the outlet pipe 17 provided with a porous section on a part thereof. 
Such portions of the inlet pipe 16, the outlet pipe 17 and the inner pipe 
21 as are shown by a broken line in the drawing, respectively, represent 
the portions having a plurality of apertures properly formed by drilling. 
In the case of the embodiment shown in FIG. 12, the flame-out apparatus 23 
is set in place at a comparatively forward section in the sound deadening 
apparatus, unlike the one shown in FIG. 11, and in this case the exhaust 
is led to the front of the flame-out apparatus by the inlet pipe 16 
through the separator 19. In case a flame is found to have been subjected 
to transmission at this stage, the flame is subjected to flame-out, the 
exhaust following the flame-out is caused to return into the front chamber 
22 from the rear chamber 20 through the inner pipe 21, then runs into the 
outlet pipe 17, and is discharged out of the sound deadening apparatus, 
after passing through the separators 19, 19. Shown in FIG. 13 is a detail 
of the flame-out apparatus. A filling chamber 26 for a filler is formed of 
porous partition plates 4, 4' respectively welded on an L-shaped screen 
member 25 which is welded on the inner surface of the outer body 18 and on 
another L-shaped screen member 25' which is further welded on one side of 
the said screen member 25. The L-shaped screen member 25 is defined by a 
longitudinally extending body portion 25a welded to the inside surface of 
the outer body 18 and a transverse flange portion 25b extending inwardly 
from one end of the body portion 25a. Similarly, the other L-shaped screen 
member 25' is defined by a longitudinally extending body portion 25a' 
welded to the inside surface of the body portion 25a and a transverse 
flange portion 25b' extending radially inwardly from one end of the body 
portion 25a'. The space 26 between the plates 4, 4' s filled with a 
plurality of the said alumina globules 5 of 3mm or less in diameter, 
laminated punched metal sheets 27 provided with a plurality of 
hemispherical projections, metal laths 28, laminated louver plates, 
laminated wire meshes of #10 through #100 in mesh, steel wool, and/or a 
combination thereof, specifically selected as the filler therefor. 
Furthermore, for the purpose of preventing a flame from blazing up between 
the said flame-out apparatus 23 and the outer body 18 of the sound 
deadening apparatus, and for the purpose of preventing a flame from 
blazing up through that portion where the inlet pipe 16, the outlet pipe 
17, and/or the inner pipe 21 run(s) through the flame-out apparatus, as 
well as for the purpose of preventing a container from being subjected to 
a thermal change, the peripheral section of the flame-out apparatus and 
the outer body 18 of the sound deadening apparatus 12 are connected with 
each other by means of screen members 25, 25' each having an L-shaped 
section. With regard to such sections where a pipe is laid through, a 
plate is set in place at the both outer ends of the punched plate, or a 
plate is set in place at the both outer ends of each laminated matter. In 
the case of the filler comprising a plurality of laminated matters, is 
bent to have the shape of an L, or the said L-shaped bent section is 
welded intact on the pipe, or on a strip steel plate welded on the pipe, 
thus preventing a flame from blazing up.