Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
~041b~
BACKG~OUND OP T~ ENTION
The present invention relates ~enerally to an lnternal
combustion en~lne~ and more partlcularly to an en~ine
havin~ a main ar,d an auxiliary combustion chamber, as uell
as an intake valve to control the supply of air-fuel ~ixture
into the main and auxiliary combustion chambers.
For the purpose of reducin~ the amount of harmful
exhaust gas from internal combustion en~ines, particularly
rrom car englnes, there have been pro~osed diverse types of
improvements of the lnternal combustion engines. One
resultin~ lnternal combustlon en~lne is of the type in
which a main and an auxiliary combustlon chamber are dlsposed
ln each c~linder so that a stratified combustion of an air- -
ruel mlxture takes place ln each cylinder of the internal
combustlon engine. l~ith the internal combustion en~ine
having maln and auxiliary combustion chambers, there have
been proposed di~ferent types o~ arrangements for carrying
out the supply of the air-fuel mixture lnto the ~ain and
.T ' auxiliary combustion chambers. Among these different
arrangements, one has been proposed by the present inventors,
-~ ~ in whlch arran~ement the alr-fuel mixture ls introduced
lnto the maln and auxillary combustion chambers through a
common intake port and, therefore, a sin~le intake valve
-j provlded in the common intake port operates to control the
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~ - 25 duratlon o~ the suppl~ o~ the air-~uel mixture to both
t : :
chambers. This type of air-~uel mixture supply arran~e~ent~
i ha~ brought about a practical advantage that the structure
, ~ ,. .
~ and the assembly Or an internal combustlon en~ine-can be -~
:. , .
ery simp1e.
~ 3 The lnternal combustlon englne lncludin~ the air-ruel
r. ~ ~ 2 ~
'
5~
mixture supply arrangement of the type described above is
c~aracterized in that t~e auxiliary com~ustion chamber is
formed with a suction aperture through which the auxiliary
combustion c~amber receives the air-fuel mixture supplied via
the intake port during the intake stroke, and a discharge
aperture throug~ which residual gas in the auxiliary combus-
tion chamber is discharged or exhausted. Thus, positive
exhaustion of the residual gas from the auxiliary combustion
cham~er as well as ~illing of a fresh air-fuel mixture into
the entire space of the auxiliary combustion chamber are
aiways attained.
The internal combustion engine o~ the type described
~`f above is also c~aracterized in that the engine ma~ have such
a modified arrangement that the afore-mentioned auxiliary
, combustion chamber is furnished with an air-fuel mixture
richer than that for the main combustion chamber as necessary.
T~e moaified arrangement may be realized by providing the
internal combustion engine with a separate passage~ay for
~ enabling the introduction of the richer air-fuel mixture into
; 20 the auxiliary combustion chamber. In this case, the separate
passageway will be arranged so as to also open into the intake
~ port provided for lean air-fuel mixture or air to be intro-;~ duced into the main combustion chamber. The modified arrange-
ment may also be realized by providing the internal combustion
engine with a fuel injection nozzle installed in the intake
port.
~ The internal combustion engines of the type des-
.~
cribed above are disclosed in, for example, Canadian Patents
016,434 and 997,639. However, it should be noted that in the
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1041856
internal combustion engines of the type described above,
the volume of each auxiliary c~mbustion chamber and the
areas of the suction and diseharge apertures must appro-
priately be selected so that stabilized combustion of the
air-fuel mixture is achieved. Particularly, the sizes or
areas of the above-mentioned suction and discharge apertures
of the auxiliary combustion chamber must be such that the
exhaustion of the residual gases from the auxiliary combustion
chamber is promoted during the intake stroke of the engines.
This is because the completeness of the exhaustion of the
residual gas rom the auxiliary combustion chamber has a
large influence of the stability of the operation of internal
combustion engines. In other words, it should be ;understood
that when the exhaustion from the auxiliary combustion
chamber i8 incomplete, failure of ignition of the rich air-
fuel mixture within the auxiliary combustion chamber will
often occur with the result that the operation of the
internal combustion engine becomes unstable. -~
SUMMARY OF THE INVENTION
The principal ob~ect of the present invention is to ~ -
eliminate the drawback encounteret with the already proposed ~
internal combustion engines with the air-fuel mixture ~ --
supply arrangement of the type described above. -
~ Another ob~ect of the present invention is to provide --
`~ annlnternal combustion engine in which stable combustion of -- -
a lean-air-fuel mixture is achieved, thereby efficiently
realizing clean exhaust gas from the internal combustion
engine.
~ ~ A further ob~ect of the present invention is to
c~ s 30 provlte an lnternal combustlon engine in which the choice
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of the volume of the above-mentioned auxiliary combustion
chamber, and the sizes of the suction and discharge apertures
provided for the auxiliary combustion chamber is based on
experiments conducted on the operation o an example of an
internal combustion engine.
The prior art discloses a torch ignition type
internal combustion engine, in which the volume of the
auxiliary combustion chamber and the size of the torch
aperture are chosen to be within specified values. However,
t 10 the choice of the volume of the auxiliary combustion chamber
"~ and of the size of the torch aperture in the publicly dis-closed torch ignition type internal combustion engine are
intended only for enhancement of the so-called torch effect.
Thus, the torch ignition type internal combustion engine
should be distinguished from the internal combustion engine
embodying the present i~vention.
In accordance with a preferred embodiment of the`
present invention, there is provided an internal combustion
engine including: a main combustion chamber which is defined
~ 20 by a cylinder, a piston movably fitted in the cylinder, and a
; ~ cylinder head with an intake port mounted on the cylinder; a
trap chamber intercommunicating with the main combustion
J chamber and having a limited volume of space separated from
said main combustion chamber, the trap chamber being provided
; with at least a suction aperture through which an air-fuelmixture is supplied into the space of said trap chamber, and
at least a discharge aperture for discharging residual gas
~ from 8aid trap chamber into said main combustion chamber;
i ~S an ignition plug having electrodes exposed to said trap
~ 30 chamber, and; an intake valve for closing and opening said
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104185ti
intake port through which both said main combustion and
said trap chambers-are supplied with the air-fuel mixture,
wherein said limited volume of space of said trap chamber
is selected so as to be within a range between 0.03 and
0.13 times the total volume of said limited volume of said
trap chamber and the volume of said main combustion chamber
when said piston is at the top dead center; said suction
aperture of said trap chamber is provided with an opening
area whose size is selected so as to be within a range
between 0.03 and 0.15 square centimeters per each cubic
centimeter of said volume of said trap chamber, and; said
, discharge aperture of said trap chamber is provided with an
opening area whose size is selected so as to be within a
range between 0.024 and 0.12 square centimeters per each
, cubic centimeter of said volume of said trap chamber.
The present invention will be understood from the
;~ ensuing description and claims taken in connection with the
accompanying drawings, forming a part of this application,
in which:
Fig. 1 is a cross-sectional elevation view of an
internal combustion engine embodying the present invention;
Fig. 2 is a partial cross-sectional view taken
along the line II-II of Fig. l;
~ Fig. 3 is a cross-sectional elevation view of
.J another internal combustion engine embodying the present
invention;
Fig. 4 is a cross-sectional elevation view of a
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104~8S~
further internal combustion engine embodying the present
invention, and;
Figs. 5 through 7 are diagrams illustrating
results of experiments with respect to the internal combustion
engine of the present invention, respectively.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
Referring to Figs. 1 and 2 showing an internal
combustion engine according to one embodiment of the present
` invention, the engine is provided with a main combustion
chamber l~and an auxlliary combustion chamber 2 which is
usually referred to as trap chamber. An ignition plug 3
; is mounted on the en8ine so that electrodes 3a of the
ignition plug 3 are exposed to the trap chamber 2. The
main combustion chamber 1 is defined by?a cylinder 4 a
piston 5 slidably fitted in the cylinder 4, and a cylinder
head 6 located at the top of the cylinder 4. The trap
chamber 2 is defined within a hollow cup element 7 which is
~- mounted on the cylinter head 6. The cup element 7 is
`' pro~ected into the main combustion chamber 1 and is provided
with a suction aperture 8 and a discharge aperture 9 formed
- in the pro~ecting part of the cup element 7. The suct~on
`~ aperture 8, whlch permits an air-fuel mixture supplied
during the suction stroke of the piston 5 to pass into the
-~ trap chamber 2, opens in the main combustion chamber 1
; ~toward an intake port 10 which opens in the inner surface
of the cylinder head 6. The discharge aperture 9 which
serves to discharge resldual gas fr~m the trap chamber 2,
op~ns ln the main combustlon chamber 2 toward the top
surface of the plston 5. It should be understood that
durlng the co~bustlon stroke ofCthe engine, both suction
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1041856
and discharge apertures 8 and 9 act as torch apertures. In
the trap chamber 2, a separating wall 11 is formed as a
partition between the apertures 8 and 9. A suction pas-
sageway 12, which is formed in the cylinder head 6, is
curved downwardly toward the main combustion chamber 2 at
its downstream portion. The suction aperture 8 of the trap
chamber 2 is located on an inward extension of an outer
radial inner surface of the curved portion of the suction
passageway. The inner end of the suction passageway 12 is
connected to the intake port 10 where an intake valve 13, ~ -
. .
;~ comprising a valve member 13a and a valve stem 13b, is -
positioned so as to open and close the intake port 10. The
suction passageway 12 allows the supply of an air-fuel -
mixture into the~main combustion chamber 1 and the suction
aperture 8 of the trap chamber 2, respectively, through the
opened intake port 10 during the suction stro~e of the
piston 5. It should be appreciated that while the air-fuel
mixture flows through the suction passageway 12~ the mixture ':A
`~ undergoes centrifugal action at the downwardly curved
.~ 20 portion of the suction passageway 12. As a result, a rich
air-fuel ~ixture component is urged to the upper part of
3 tbe flow of the air-fuel mixture within the suction passage-
way 12. Thus, the rich air-fuel mixture, flowing along the
upper part of the inner wall of the downwardly curved
portion of the suction p~ssageway 12, is then supplied into
the suction sperture 8 of the trap chamber 2. The outer
end of the suction passageway 12 is connedted to an intake
~ ~ manifold 14 to which a carburetor 15 is connected.
; In the engine having the construction as described
f 30 above~ the air~fuel mixture produced by the single carburetor -
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104~856
15 is sucked into the main combustion chamber 1 and the
trap chamber 2 of each cylinder 4 through the single suction
passageway 12 during the suction stroke of the engine. The
duration of the supply of the air-fuel mixture to both
chambers l and 2 is controlled by the intake valve 13.
That is, in response to the opening and closing operation
of the single intake valve 13, an intermittent supply of
the air-fuel mixture to the main combustion chamber 1 and
the trap chamber 2 is carried out. Further, as previously
described, the air-fuel mixture is separated into a richer
air-fuel mixture component and a leaner air-fuel mixture
component under the centrifugal aetion which the air-fuel
mixture undergoes when it flows past the curved suction
passageway 12. Thus, the rich air-fuel mixture component
is sucked into the trap ehamber 2, while the~lean air-fuel
mixture component is sucked into the main combustion chamber
1. While each mixture component is being sucked into the
~;l corresponding chamber, residual gas is discharged from the
trap chamber 2 through the discharge aperture 9 owing to
the pumping action exerted by the~piston 5 moving downwardly
in the cylinder 4 during the intake stroke. As a result, a
fresh and rich air-fuel mixture sucked through the suction -~
aperture 8, flows into the trap chamber 2. It should be
J understood that the flow of the rich air-fuel mixture is
substantially guided by the separating wall ll into the -
region ad~acent to the electrotes 3a of the ignition plug
j 3. Thu8 the trap chamber 2 is completely scavenged and
then filled with the fresh and rich air-fuel mixture with
certainty. The air-fuel mlxture, which is subsequently
compressed by the compression stroke of the piston 5, is
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104185~
lgnlted by a spark of the lgnltion plug 3 withln the trap
chamber 2, whereby torch ~ets are spurted through both
apertures 8 and 9 into the maln combustlon chamber 1 so
that the combustlon Or the lean alr-fuel mlxture withln
sald maln combustlon chamber 1 can be deflnltely attalned.
Thus, ln each cyllnder 4, a stable combustion Or the lean
alr-~uel mixture takes place by vlrtue Or the torch lgnltlon
so that clean exhaust emission ~rom the lnternal combustlon
engine ls achleved.
A description of the arrangement o~ an lnternal
combustlon englne accordlng to another embodlment o~ the
present lnventlon wlll be herelnbelow presented wlth reference ~-
to Flg. 3. It should be noted that ln the englne of Flg.
3, llke elements or parts as those of the englne of Flgs. 1
and 2 are deslgnated by the same reference numerals. In
' the englne o~ Flg. 3, a maln carburetor 15A, whlch ls
"~ intercommunicated wlth the suction passageway 12, produces
a lean air-~uel mixture to be supplled lnto the main com-
bustlon chamber 1 of each cyllnder 4 through the suctlon
passageway 12 and the intake port 10. A secondary carburetor
l~B, whlch ls lntercommunicated wlth a secondary passageway
~, 20, produces an alr-fuel mixture rlcher than that produced
by the maln carburetor 15A, and supplles the rlch-alr-fuel
, mlxture lnto the passageway 20.~ The secondary passageway -
20, ~ormed ln the cyllnder head 6 ad~acent to the suction - ~
passageway 12, has its one end opening 20a located ad~acent ~.
to the lntake port 10. Thus, the rlch alr-fuel mlxture
8upplied lnto the secondary passageway 20 is suckea into ,
' the trap chamber 2 through the openlng 20a, the lntake port
~ 30 10, and the suctlon aperture 8 when the lntake port 10 ls
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opened by the lntake valve 13. It wlll be seen from Plg, 3
that the suction aperture 8 ls located adJacent to and
~aces the openlng 20a of the secondary passageway 20 ror
the rlch alr-ruel mlxture. It wlll also be under~tood from
Fig. 3 that the discharge aperture 9 opens toward the top
sur~ace of the plston 5. It should now be appreclated that
the constructlon o~ the englne descrlbed above ensure~ the
~uctlon of the rich air-~uel mixture lnto the trap chamber
-~ 2. As a result, sure lgnltlon of the lean alr-fuel mlxture
wlthin the maln combustlon chamber 1, owlng to the torch
Jets spurted from the trap chamber 2 throu~h both apertures
; 8 and 9, ls guaranteed.
A descrlption of the lnternal combustion engine
according to the thlrd embodiment of the present inventlon
will now be presented wlth reference to Flg. 4.
As ls seen ~rom Flg. 4, the constructlon o~ the
. .
englne of the thlrd embodiment is very slmilar to that Or
the englne o~ the flrst embodlment shown ln Flgs. 1 and 2
. i~ . . .
Thus, llke elements or parts are deslgnated by the same
~ 20 rererence numerals. However, the important dlfference rrom
`~ the ~irst embodiment resldes ln the fact that a fuel inJectlon
~ . ..
nozzle 30 ls lnstalled in the suctlon passageway 12 through
whlch alr or a lean alr-fuel mlxture ls dellvered lnto the -
maln combustlon chamber 1. The fuel lnJection nozzle 30 ~ -
.
ln~ects a rlch alr-fuel mlxture toward the suctlon aperture
8 Or the trap chamber 2 durlng the suctlon stroke Or the
pl8ton 5. The ruel In~ectlon nozzle 30 shown ln Flg. 4 ls -
the electro-magnetlcally operated type by whlch fuel is
lntermlttently inJected. However, a contlnuously lnJectlng
ty~e o~ the inJectlon nozzle may be employed and wlll
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10418S~
result ln the same operatlon as the above-mentioned inter-
mlttently inJectlng fuel in~ection nozzle 30.
The ~oregoing descriptlons were directed to the
three arrangements of the lnternal combustion englne embodylng
the present invention. Wlth respect to these arrangements,
the volume of the trap chamber is an important factor ln
causlng an optlnum combustlon withln the main combustion
chamber 1. Also, the slzes o~ both suction and discharge
apertures 8 and 9 Or the trap chamber 2, which produce
torch ~ets from the trap chamber 2 into the maln combustlon
chamber 1, are important ~actors to acquire a proper torch
ef~ect and stable combustion within the main combustion ~ -
chamber 1. Thererore, determination or choice of the
extent Or the volume o~ the trap chamber 2 and of the slzes
Or the suction and discharge apertures 8 and 9 must be such
that an optinum and stable combustion Or the alr-fuel
mixture wlthin the main combustlon chamber 1 will take
place. Purther, lt is necessary to take into consideration
not only the size Or the discharge aperture ~ but also the -
.1 . .. .
'. 20 slze o~ the suction aperture 8 in achieving comp~ete scaveng- -
lng Or the trap chamber 2. In additlon, the ratio between
the area Or the suction aperture 8 and the area of the
dlscharge aperture 9 has a great effect on the completeness
the scavenging Or the trap chamber 2. Thus, said ratlo
must be selected on the basis Or experiments so as to be ~-
~; wlthln a properly determined range. The results Or the :
~ éxperlments perrormed are shown ln the diagrams Or Flgs. 5,
s 6 and 7. ~ ,
;~ The example o~ the internal combustion engine used
, 30 ~or perrormlng the experiments was of the type in which the
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lO~l~S6
number of cylinders ls four and the total plston dis-
placement ls 2000 cublc centlmeters. Each cyllnder was
provlded with the lnternal arrangement as shown ln Flg. 3.
Further, the operatlng condltlons of the engine durlng the
experlments were as follows.
The number of rotatlons of the engine = 2,000
(r.p.m.)
The degree of the lntake vacuum s 240 millmeter
Hg
The average air-fuel ratlo of the air-fuel
ratios of the maln combustlon and the trap chamber
18
~he quality of the experlmental results was ascertalned
~ based on the general evaluation of the measured results Or:
- 15 ~1) the amount of generation of harmful components contained
wlthln the exhaust gas, such as nitrogen oxides, carbon
monoxide, and hydrocarbon; (11) the fuel consumption, and;
~lil) the rate Or change in combustlon which is an analogous ---
factor to the rate Or change in torque o~ the englne and 18
lndlcative Or the degree of stability of the operation of
, an lnternal combustlon engine.
In Flgs. 5 through 7, the circle mark " O" lndicates
- that the engine operation is Or the best quality where the
amount of generatlon of harmful exhau~t components is quite
8mall, the ~uel consumptlon ls superior, and the rate of
change ln combustlon ls small. The triangle mark "~"
lndlcates that the englne operation is of a good and accept-
able quallty, whlle the cross mark ~IX~ lndicates that the
eng~ne operatlon i8 of an lnferlor and unacceptable quallty.
Plg. 5 lndlcates the results o~ the experiments when the
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10~18S~6
relatlonship between the volume (Va) Or the trap chamber 2
and the area (Sln) of the suction aperture 8 Or the trap
chamber 2 was changed, whlle the area (Sd) of the d$~charge
aperture 9 and the volume (Va) were maintalned at a constant
relatlonship as shown by the equation Sd=o~o6 va. The
abscissa of Flg. 5 shows the volume of the trap chamber 2,
and the ordlnate of Fig. 5 shows the area of the suction
aperture 8 as viewed from the dlrectlon corresponding to
the rlowing direction of the alr-fuel mixture lnto the trap
chamber 2. Flg. 6 similarly shows the results of the
experiments when the relationship between the volume (Va)
of the trap chamber 2 and the area (Sd) of the discharge
aperture 9 was changed, while the area (Sin) of the suction :aperture 8 and the volume Or the trap chamber 2 were main-
talned at a constant relatlonship lndicated by the equation
Slns0.06-Va. Further, Fig. 7 lndlcates the results Or the
experlments when the relatlonship between the area ~Sinj of
.
the suctlon aperture 8 and the area (Sd) of the discharge ~ :
aperture 9 was changed, while the volume of the trap chamber
- 20 2 18 maintalned at a given extent. In Flg. 7, it should be
noted that the scales Or the abscissa and the ordinate show
the values Or Sin/Va and Sd/Va, respectively. From the --
results shown ln Figs. 5 through 7, it will be understood
that the volume (Va) Or the trap chamber 2 should pre-
~erably be wlthin the range of two cublc centimeter through -
elght cubic centimeter, the area (Sin) of the suction ~ -
~ aperture 8 should preferably be within the range Or 0.03 Va
-1~ through 0.15 Vaj and the area (Sd) Or the discharge aperture
9 should prererably be within the range o~ 0.024 Va through
0.12 Va. It wlll also be understood that the ratio Sin/Sd
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109~1856
should be within the range between 0.8 and 2.2, and that
the area (Sin) should preferably be sllghtly larger than
the area (Sd). In addition, it is necessary that the
relatlve relationship between the volume of the trap chamber
2 and the volume of the main combustion chamber 1 be taken
lnto conslderation. In the actual comparlson, the ratios
of the above-mentloned varlous volumes of the trap chamber
2 to the total volume of the main combustion 1 and the trap
chambers 2, which is deflned when the piston 5 ls at lts
top dead center (TDC), ranged between 0.03 and 0.13.
Consequently, lt was understood that the ratio of the
volume of the trap chamber 2 to the volume Or the main
combustion chamber 1 should desirably be within the range
of 0.03 and 0.13 for every engine embodying the present
inventlon. ~-
It was also conf'lrmed that the results of the above-
mentloned experlments are appllcable to lnternal combustion
englnes of the present lnventlon which have a dlfferent
internal arrangement from that of the engine used for the
above-mentioned experiments.
It should be understood that due to the above- -
~ mentloned determination of the volumes-of the main combustion
.` and trap chambers and of the sizes of the suction and -
discharge apertures, cleaning of the exhaust gases from
lnternal combustion englnes as well as enhancement of the
t, ~uel consumptlon and stable combustlon of the lean alr-fuel --
mlxture can be achleved. In some internal combustion
~- englnes embodying the present lnvention, a plural number of
suctlon and discharge apertures may be provided ~or the
trap chamber 2. In thls case, the entire area of the
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plural suction apertures and the entlre area Or the pluraldischarge apertures should meet the condltions obtained
from the above-explalned experlments.
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