Note: Descriptions are shown in the official language in which they were submitted.
1056~'3g
1 This application is a divisional application of
Canadian patent application serial number 258,140 filed on
July 30,1976.
BACKGROUND OF THE INVENTION
This invention relates to internal combustion engines,
and more particularly to the improvements in internal combustion
engines for use in automobiles.
During idle running and low-load running of an internal
combustion engine for use in an automobile, the throttle valve
is opened only a small degree and hence the amount of intake air
is small. Accordingly, the rate at which a charge mixture is
introduced through the intake manifold into the cylinder during
the suction stroke is low, resulting in a weak swirl of the charge
; mixture within the cylinder. This also weakens the swirl of the
mixture charge remaining in the cylinder at the time of ignition,
which substantially takes place at the terminal stage of a compres-
sion stroke,resulting in lowered ingitability and combustibility.
In order to insure the stable running of an engine in
such running conditions, a charge mixture whose air-fuel ratio is
lower than that for medium and high-load running must be provided.
However, this causes increased fuel consumption, as well as an
- increase in the quantity of harmful constituents, such as Co and ~-
HC, contained in exhaust gases due to incomplete combustion of
a rich charge mixture.
: Recently, with a view to reducing the quantity of harm-
ful constituents,such as C0 and HC and particularly N0x, contained
~- in exhaust gases from an engine,it has been proposed to burn a
- charge mixture much leaner than the theoretical or stoi-
chiometric air-fuel ratio. Also, with a view to reducing the
amount of N0x, it has been proposed to take a part of the
exhaust gases from the exhaust system and mix it with a charge
mixture for combustion. Both proposals result in lowered
1O 56A~39
1 ignitability as well as lowered combustibility of the charge
mixture, resulting in lowered drivability at idling and low-
load conditions as well as increased fuel consumption.
S~JMMARY OF THE INVE~TION
: . _ _ _ _ _
It is accordingly a primary object of the present
invention to provide an internal combustion engine for use in
an automotive vehicle, wherein the fuel consumption is reduced,
particularly during idle running and low-load running of the
engine.
It is another object of the present invention to
provide an engine for use in an automotive vehicle, which is
compatible with stable burning of a lean charge mixture for
insuring stable idle running and low-load runnin~, although
such has been impossible with an engine of the prior art, whereby
the amount of harmful constituents contained in the exhaust
gases is reduced.
~ .
It is a further object of the present invention to
provide an engine for use in an automotive vehicle, which is
; 20 compatible with stable combustion of a charge mixture containing
a large quantity of recirculated exhaust gases, with the -
assurance of stable idle running and low-load running, although
such has been impossible with an engine of the prior art, whereby
the amount of N0x contained in the exhaust gases is reduced.
It is a still further object of the present invention
to provide an engine for use in an automotive vehicle, which
permits stable combustion of a lean charge mixture or a charge
mixture containing a large amount of recirculated exhaust gases,
without lowering output or drivability, or increasing the fuel
consumption.
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- 1056Z39
1 It is a still further object of the present invention
to provide an engine for use in an automotive vehicle, wherein
........... an amount of harmful constituents contained in the exhaust gases
from an engine in idling running, low-speed, low-load running
. is greatly reduced, as compared with that of prior art engines.
To this end, in one of its aspects, the invention
provides an internal combustion engine comprising a piston, a
cylinder block and a cylinder head together defining a
i: substantially single combustion chamber; an intake port
: 10 and an exhaust port communicating with said combustion chamber;
, "
i` a main intake passage for introducing an air-fuel mixture into
i said intake port; a throttle valve disposed in said main intake
,~ . I
;~;, passage; a spark plug in screw-threaded engagement with a
cylinder head, said spark plug having a spark gap thereof
located at a predetermined position within said combustion
chamber; an injection passage opening into said combustion
chamber; a sub-intake valve in the form of a sub-piston
reciprocable within a cylindrical bore in said cylinder head;
a sub-intake passage opening onto an inner peripheral wall of
said cylindrical bore; and said injection passage communicating
with said cylindrical bore at one end thereof; a gas supply
means for supplying gas to said sub-intake passage; the arrange-
ment being such that, in use, the reciprocation of said sub-
. piston opens and closes communication between said sub-intake
passage and said injection passage, said sub-intake valve
opens at least during a suction stroke of the first-mentioned
piston, and said sub-piston moves towards said one end of the
cylindrical bore during a compression stroke of the first
mentioned piston, whereby a high speed gas is injected with
strong force from said injection passage into said combustion
: ~ 3
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1 chamber during a suction and compression stroke of the first- t
mentioned piston to promote a swirling action and turbulence
i .
to said air and fuel mixture.
Gas which is to be fed to said sub-intake passage
should preferably be air, but may be an air-fuel charge mixture,
or otherwise may be exhaust gas from an engine. In case said gas
is air, atmosphere serves as the gas supply source, and in the
case of a charge mixture, an intake manifold is suitable as a
- gas supply source where an engine is equipped with a carburetor,
10 while in the case of exhaust gases an exhaust manifold serves as
.
a suitable gas supply source. `
According to an engine of the present invention,opening
of a tbrottle valve ie small particularly durlng idllng and low-
,'. ` ~' .
' ~
.
:
- 3a -
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` 1al56Z39
1 load running of the engine, and hence the throttling by the
- throttle valve should be increased so that the speed of intake
air being introduced through the main intake passage into the
combustion chamber is low, with the result that only a small
, .,
amount of intake air is introduced into the combustion chamber.
This creates a high level of vacuum in the combustion chamber
during a suction stroke, so that gas from a gas supply source
will be drawn by the strong vacuum within a combustion chamber
... .
through an injection hole, from which gas is injected into the
combustion chamber in a given direction, thereby creating strong
i swirl or turbulence of a charge mixture within the combustion
chamber, whereby combustion speed is increased, and the limit
of combustion of a lean charge mixture is raised, resulting in
decreased fuel consumption. In addition, since injection streams
of intake air from the injection hole act in the vicinity of a
spark gap of said spark plug, which spark gap is located in the
combustion chamber, scavenging of the burnt gases is facilitated,
whereby ignitability of a mixture charge is improved, and the
limit of combustion of a lean mixture charge is raised as a
result of facilitated scavenging action.
Furthermore, even during idling or low-load running
- of an engine when cylinder-to-cylinder distribution of a charge
mixture is not well performed and combustibility of a charge
mixture are not satifactory because of a low wall temperature
of the combustion chamber, a stable combustion of a lean mixture
charge is ensured, with a minimum lowering of output, a minimum -
increase in fuel consumption, and a maximum reduction of the
quantity of NO contained in the exhaust gases due to a drop of
x
a maximum combustion temperature as a result of an increased air-
fuel ratio.
Use of an exhaust gas recirculating device in combin-
ation with an internal combustion engine of the present invention
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10562~39
1 facilitates reduction in the quantity of NOX contained in the
exhaust gases, without setting the air-fuel ratio, which is
rather painstaking to control, at a high value approximating a
limit of combustion, and the said injection streams serve to
prevent lowering of ignitability and flame propagation speed
caused by exhaust gases from said recirculating device.
, These and other objects and features of the present
. . .
~ invention will be apparent from the ensuing part of the speci-
t fication in conjunction with the drawings, which indicate pre-
; 10 ferred embodiments of the invention. Throughout the drawings,
equivalent components are shown by identical reference numeralF.
BRIEF DESCRIPTION OF THE DRAWINGS
Fig. 1 is a cross sectional view of a first embodiment
of an engine according to the present invention; ~ -
: Fig. 2 is a view as seen along the line A-A of Fig. l;
Fig. 3 is a view as seen in the direction of arrow B
of Fig. l;
- Fig. 4 is a cross sectional view taken along the line
C-C of Fig- l;
Fig. 5 is a plot representing engine output lines for
explaining the operation of the engine of the first embodiment;
Fig. 6 is a cross sectional view of a second embodiment
of an engine according to the present invention;
Fig. 7 is a fragmentary cross sectional view of a
third embodiment;
Fig. 8 is a fragmentary cross sectional view of a
fourth embodiment;
Fig. 9 is a fragmentary cross section~ vuw of a fifth
embodiment;
- ~ . . . . .
;` 1056Z~9
., .
1 Fig. 10 is a fragmentary cross sectional view of a
; sixth embodiment; and
`~!. Fig. 11 is a view for explaining the operation of the
. ~ . .
j sixth embodiment.
'`'','
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
Referring first to Figs. 1 through 4, illustrating a
first embodiment of the present invention, there is shown a body
10 of a gasoline internal combustion engine for use in a motor
vehicle, a cylinder head 12, a cylinder block 14, a piston 16,
i,...................................................................... .
a combustion chamber 18, a spark plug 20, a main intake port
22, an exhaust port 24, a main intake valve 26, an intake manifold
28, a carburetor 30, and an air cleaner 32.
In the cylinder head 12, there is provided an injection
hole 34 open to the combustion chamber 18. The injection hole
34 has an opening directed beneath a spark gap 36 of the spark
plug 20 as well as ~owards the piston 16 at a given angle of,
for example, 30 to 60C with respect to the top face of the
piston 16. The injection hole 34 is connected through the mediary
of a sub-intake valve 38 to a sub-intake passage 40.
Thelmain intake valve 26 and the sub-intake valve are
mushroom valves, which are actuated by a rocker arm 42 common to
these valves,said rocker arm in turn being fitted on a rocker
shaft 44 and adapted to be swung in engaging relation to a cam
48 which in turn is mounted on a cam shaft 46 rotatable in
association with the rotation of a crank shaft (not shown) of the
engine. The rocker arm 42 has forked arm portions on the
opposite side of the engaging surface of said arm with the cam
face 48. Adjusting screws 50 and 52 are threaded in the forked
:
arm portions, respectively, ln a manner that the lower end of one
56Z3~9
. 1 . .
. ad~us~ng screw 50 bears on the top end of a valve stem of the :
- main intake valve 26, while the lower end of the other adjusting
: screw 52 bears on the top end of a valve stem of the sub-intake
valve 38.
Shown at 54 and 56 are valve springs, at 58 and 60
. spring seats, and at 62 a valve guide for the sub-intake valve
. 38. The valves are operative to open the passage between the
injection nozzle 34 and the sub-intake passage 40 during the
. suction stroke of the piston 16.
A venturi 66 and a throttle valve 68 are disposed in
: the main intake passage 64 in a portion corresponding to the
carburetor portion, the main intake passage leading from the air.
cleaner 32, via the carburetor 30 and intake manifold 28 to the
. intake port 22. An idle port 70 and slow port 72 are open from
the inner wall of the intake passage in the vicinity of the
: closed position of the throttle valve 68, said idle port and
slow port supplying fuel when the engine is in the idle running
and low-load running condition, and an adjusting screw 74 is
: threaded in the idle port 70. The venturi 66 has a main nozzle
76 for mainly feeding fuel when the engine is in the medium and
; high-load running conditions.
. An exhaust gas recirculating passage 78 is communicated
.i at one end with an exhaust passage, for example, an exhaust
. manifold (not shown) of the engine and connected at the other
end, through the mediary of a control valve 80 disposed midway
: of said passage, to the trunk portion of the intake manifold 28, ` :- -
said control valve serving to detect varying running conditions
of the engine, thereby controlling a flow rate of exhaust gases
. according to the running condition detected.
30
The sub-intake passage 40 is communicated by way of a
. pipe 82 with the main intake passage 64 upstream of the venturi 66.
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1(~56Z39
:.
, 1 In operation, a major part of air introduced under
suction from the air cleaner 32 intO the main intake passage
6~ is mixed with fuel at a given air-fuel ratio in the carburetor
~ 30, and the charge mixture thus produced is introduced under
;
suction through the intake port into the combustion chamber 18.
A portion of the air introduced in the main intake passage is
introduced through the pipe 82 and then through the sub-intake
passage 40 into the injection hole 34, being injected into the
combustion chamber 18.
The amount of air injected from the injection hole 34
and the force of the injection stream depend upon the degree of
opening of the throttle valve 68, i.e. the load of the engine. -
Specifically, when in the idle running or low-load running
condition, with the throttle valve being opened to a small extent,
the amount of charge mixture being fed through the main intake
,: .
passage 64 into the combustion chamber is small, thus creating
;- a high level vacuum in the combustion chamber 18 during the
- suction stroke. Meanwhile, the portion of the main intake passage
. 64, which is upstream of the venturi 66, is maintained substan-
tially at atmospheric pressure so that, due to a pressure
difference between the intake passage and the combustion chamber,
a large amount of air is injected with a strong force from the
. injection hole 34 into the combustion chamber 18. consequently,
injection streams of air from the injection hole create a strong
. swirl or turbulence of the charge mixture which has been introduced
into the combustion chamber 18, and at the same time, air from the
injection hole is mixed with the charge mixture, whereby the
latter is stratified or spottedly dispersed under uneven distri-
bution of concentration.
Since the injection streams of air run past the vicinity
of the spark gap 36 of the spark plug 20 beneath the spark gap,
- ~OS6Z39
.
1 combustion gases residual in the vicinity of the spark gap 36
are scavenged under the guidance of injection streams of air,
and in turn a fresh charge mixture will be introducea into the
vicinity of the spark gap. Thus, it is understood that at the
time of ignition of a charge mixture, which is to be effected
in the latter half stage of a compression stroke, there still
exists a strong swir] or turbulence of air and charge mixture
stratified or unevenly distributed in a combustion chamber, and
the charge mixture introduced in the combustion chamber runs in
the vicinity of the spark gap 36. It has been proven through
tests that the speed of flame propagation as well as the limit
of misfiring are amazingly increased and fuel consumption is
lowered, as compared with that in engines of the prior art, and
that use of a lean charge mixture does not cause a considerable
lowering of outputs any more, assuring improved drivability of
an engine.
In this embodiment, it is so designed that an inner
- diameter of the injection hole 34 is on the order of 3 mm and
an inner diameter of the sub-intake passage 40 is on the order
20 of 5 mm, so that in a low-load running zone, the amount of ~ -
intake air being fed through the sub-intake passage 40 may be
in the range of 10 to 20% of the amount of intake air being fed
through the main intake passage 64. The carburetor 30 is so
adjusted that the total air-fuel ratio of intake air from the
main intake passage 64 and from the sub-intake passage 40 is
given in Fig. 5.
Fig. 5 plots engine-output lines, wherein the output of
an engine is represented on the ordinate and the rpm of the
engine is represented on an abscissa. A solid line A represents
an output line when the throttle valve 68 assumes a fully open
.
` ~056Z3'3
" .
1 position, and a solid line s represents an output line when the
throttle valve assumes an opening for idle running, while a solid
line C represents a curve when an automobile runs on a level
road. Single dotted lines represent iso-vacuum lines of the
intake manifold vacuum which is produced in the intake manifold
28, and double dotted lines represent iso-throttle-opening lines,
while broken lines represent iso-air-fuel ratio lines.
The numerals on the broken lines represent an air-fuel
ratio. A cross hatched area D represents a low-load urban running ;
; 10 zone. In the low-load running zone represented by the hatched
area D, an air-fuel ratio is adjusted to a range of 15 to 17
which is higher than the air-fuel ratio in the same running zone
of an ordinary engine.
The amount of exhaust gases being introduced under
suction through the exhaust gas recirculating in passage 78 to
- the intake manifold 28 is controlled by the control valve 80.
The amount of recirculating exhaust gas is adjusted so as to hold
~;; down the quantity of NOx contained in exhaust gases to a given
value.
' 20 On the other hand, in a high-load running zone, in
.! which an opening of the throttle valve is large, a large amount
of charge mixture is introduced under suction through the main
intake passage 64 into the combustion chamber 18. Accordingly,
the amount of air being injected through the sub-intake passage
40 and the force of injection streams of air becomes lowered,
with the result of the lowered swirl-creating effect of injection
streams of air. In this case, however, charging efficiency is
high, a strong swirl or turbulence of the charge mixture is
produced when introduced from the intake port 22 into the com-
bustion chamber 18, and the inner wall temperature of the com-
bustion chamber 18 rises. These factors are effective enough to
-- 10 --
1056Z~9
1 increase the flame propagation speed and improve combustibility,
without resorting to injection streams of air from the injection
hole 34 for creation of a strong swirl or turbulence.
The engine of this embodiment yields the below-mentioned
various results. In a low-load running zone of the engine in
which the combustion conditions are not satisfactory because of
a comparatively low inner wall temperature in the combustion
chamber 18 and low charging effeciency, a stable combustion of
charge mixture is insured not only when the charge mixture is
i1 obtained by mixing the air, which is flown into the combustion
chamber 18 through the injection port 34, to a charge mixture
~s
containing some exhaust gases and having a total air-fuel ratio
in the range of 11 to 14, but also when the lean charge mlxture
has a total air-fuel ratio in the range of 15 to 21. Strong
injection streams of air from the injection hole 34 contribute ~-
to treating strong swirl or turbulence of a charge mixture in a
combustion chamber, and air thus injected is mixed to a charge
mixture sucked through the main intake passage, in a proper
stratified form or under uneven distribution of concentration,
whereby a combustion speed is increased with shortened combustion
time, without incurring an increase in the quantity of N0x con-
tained in the exhaust gases. Furthermore, fuel consumption is
reduced, drivability is improved, and quantity of unburnt gases
such as HC, C0 contained in exhaust gases is reduced.
In the embodiment of this invention shown in Figs.l - 4,
since the main intake valve 26 and the sub-intake valve 38 are
actuated by the single rocker arm, these valves are opened at
substantially the same time. Ho~7ever, it may be possible to
provide one rocker arm for each of these valves to set the openinq
timing of the sub-intake valve 38 within the open period of the
main intake valve 26.
.
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1056Z~9
1 A second embodiment shown in Fig. 6 is so arranged
that a change-over valve 84 is disposed midway of the pipe 82
communicating with the sub-intake passage 40. The changeover
valve is switched to allow the passing of air or exhaust gases
therethrough. A valve body 86 of the changeover valve 84 is
connected through the mediàry ol a valve rod 88 to the central
portion of a diaphragm 92 of a diaphragm device. The diaphragm
92 defines two chambers, one chamber 94 being open to atmosphere,
while the other chamber 96 is communicated through a pipe 98
with the intake manifold 28. A spring 100 which, normally acts
to urge the diaphragm 92 upwards as viewed in Fig. 6, is housed
r~,`, in chamber 96. The chamber 102 housing therein the valve body
86 has a top opening communicating with one end of the pipe 82
leading to the intake passage 64 and a side opening communicating
; with the other portion of the pipe 82 which is communicated with
the sub-intake passage 40. The chamber 102 communicates with a
chamber 108 via a through-hole 106 provided in a partitioning
wall 104. The valve rod 88 extends vertically through the hole
106. The chamber 108 has a side opening, which communicates with
one opening of a branch pipe 110 stemed from the exhaust gas
recirculating passage 78.
The valve body 86 is displaced vertically in response
to the movement of the diaphragm 92, so that the valve body 86
closes the opening of the pipe 82 when moved upwards, and closes
the through-hole 106 when moved downwards.
A check valve 112, which is disposed midway of the
pipe 82, allows air flow only in the direction from the main
intake passage 64 toward the chamber 102. The diaphragm device
90 is so designed that when a vacuum level of more than a given
level, for example, 300 mmHg, is established in the chamber 96j
the diaphragm 92 is moved downwards against a force of the spring
100 into the lowest position.
- 12 - t
~ - f
1056Z~9
1 In operation, in the idling or low-load running zone
of an engine, the opening o~ the throttle valve 68 is small and
; the intake manifold vacuum is raised to more than a given vacuum
level. The diaphragm 92 is deflected downwards, whereby the valve
body 86 closes the through-hole 106. As a result, air in the
main intake passage 64, upstream of the venturi 66, will be fed
to the injection hole 34. When the intake manifold vacuum drops
to less than a given vacuum level, such as during the high-load
` running zone of the engine when the opening of the throttle
valve 68 is large, the diaphragm 92 is moved upwards, whereby
the valve body 86 closes the opening of the pipe 82. Consequently,
exhaust gases in the exhaust gas recirculating passage 78 are
introduced by way of the branch pipe 110, chamber 108, through-
~, hole 106, chamber 102, pipe 82 near to the sub-intake passage,
and sub-intake passage 40, into the injection hole 34. Thus,
when the engine i5 run in the low-load running zone, a strong
injection stream of air is injected from the injection hole 34
into the combustion chamber 18, thereby rendering the mixture
charge leaner under uneven distribution of concentration and at
the same time creating a strong swirl or turbulence of the mixture
charge, whereby there are obtained the same results as in the
first embodiment. On the other hand, in the high-load running
zone of the engine during which the injection stream of air from
the injection hole 34 is weak, exhaust gases in the exhaust gas
recirculating passage 78 are recirculated through the main intake
passage 64 as well as being introduced into the injection hole 34,
so as to increase an amount of exhaust gases being recirculated.
This greatly contributes to reducing the quantity of NOX contained
in the exhaust gases.
A third embodiment shown in Fig. 7 is so constructed
that the pipe 82 connected to the main intake passage 64 upstream
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1056Z39
of the venturi 66 is connected midway of a passage 116 for second-
, .
ary air, which is fed from an air pump 114 to an exhaust system
in an exhaust gas purifying device (not shown), such as a thermal
reactor, catalytic converter or the like, provided in the exhaust
system of the engine, with a view to oxidation of unburnt gases
contained in exhaust gases. The injection hole 34' is of a larger
diameter, equal to the diameter of a bore in the valve seat portion
;.
of the sub-intake valve 38, although, in the first embodiment,
~ the diameter of the injection hole 34 is as small as 3 mm. In
.,.,. 10
this embodiment, a pressure difference between the injection
pressure from the air pump and the vacuum level in the combustion
chamber during a suction stroke is large and a large amount of air
.
is injected into a combustion chamber because of the injection
hole 34' having a large diameter. Thus, the engine of this
embodiment is particularly useful where injection of a large a~t
of air is needed.
A fourth embodiment shown in Fig. 8 is a modification
of the first embodiment. In this embodiment, the pipe 82 is
communicated with a portion of the main intake passage 64 between
the venturi 66 and the throttle valve 68. In a low-load running
zone of an engine, during which the opening of the throttle valve
68 is small and fuel is essentially fed through a slow system
consisting of the idle port 70 and the slow port 72, while only
a small amount of fuel is fed from the main nozzle, an extremely
lean charge mixture containing a very small amount of fuel
; supplied from the main nozzle 76 is injected through the injection
hole 34 into the combustion chamber 18. On the other hand, when
in a high-load running zone, a charge mixture whose air-fuel
ratio is substantially equal to that of a charge mixture introduced
under suction through the main intake passage 64 is injected from
the injection hole 34 into the combustion chamber.
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1 Since, in this embodiment, a charge mixture having the
above-described air-fuel ratio is injected through the injection
hole 34 into the combustion chamber 18, there are created strong
swirls or turbulences of a charge mixture within the combustion
chamber 18, thereby increasing the combustion speed. In addition,
if the injection hole 34 is disposed, with its opening directed
to the vicinity of the spark gap 36 of the spark plug 30 for
scavenging of burnt gases dwelling in the vicinity of the spark
. .
gap, then improved combustibility results.
In a fifth embodiment of the present invention shown
in Fig. 9, the sub-intake valve 38 and the mechanism for actuating
the valve in the first embodiment are omitted, and in turn, a
check valve 118 is provided as a sub-intake valve in the sub-
intake passage 40, the check valve being opened in response to
a vacuum created in the combustion chamber 18. The check valve
118 is inserted in a threaded hole 120 in which the pipe 82 is
threaded, and consists of a valve body 122 and a spring 124
which normally urges the valve body 122 in the valve-closing
direction. A cooling water passage 126 for cooling the check
valve is provided in the cylinder head in the vicinity of the
check valve 118. In this embodiment, the injection hole 34 is
disposed, with its openin~ directed to the vicinity of a spark
gap in the spark plug 20.
When a vacuum is created in the combustion chamber 18
during a suction stroke, then the check valve 122 is opened,
whereby air is injected by way of the pipe 82, sub-intake passage
40 and through the injection hole 34 into the combustion chamber
18, thereby scavenging a residual mixture charge existing in the
vicinity of the spark gap 36 in the spark plug 20, and at the
same time, creating a strong swirl or turbulence of a charge
mixture within the combustion chamber 18.
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1~)56Z39
1A sixth embodiment shown in Fig. 10 is so arranged
` that a cylindrical injection chamber 128 is provided in the
cylinder head 12 above the combustion chamber 18, the cylindrical
injection chamber being communicated by way of the injection
;
hole 34, open from the bottom thereof, with the combustion chamber
18. Within the injection chamber 128 there is fitted a sub-piston
130, which is adapted to verticallY move within the injection
chamber 128 by means of a valve-actuating mechanism which is
operated by rotation of the cam shaft 46. The sub-intake passage
40 in this embodiment is such that one end thereof leads to the
atmosphere through the mediary of an air cleaner 132 solely
serviceable for this passage, and the other end thereof leads to
the inner peripheral wall of the injection chamber 128, so that
-opening of the sub-intake passage 40 at the other end may be
opened or closed by the peripheral surface of the sub-piston
::
130 when the sub-piston moves vertically. Also shown is a
rocker arm 134 for actuating the sub-piston 130, a spring seat
136, a return spring 138, and a cam 140 mounted on the cam shaft
46. The cam 140 is given a profile suited for displacing the
sub-piston 130 in the manner shown by a curve in Fig. 11.
In Fig. 11, the time X represents a duration for which
the sub-intake passage 40 is maintained in communication with
the injection chamber 128, and the time Y represents a duration
for which the sub-piston 130 effects a compression stroke to
compress air within the injection chamber 128. The sub-intake
passage 40 and the injection hole 34 are maintained in communica-
tion with each other during the suction stroke of the main piston
(if it is desirable, the initial stage of a compression stroke
may be included).
30According to this embodiment, air will be injected from
the injection hole 34 into t~he combustion chamber 18 according to
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$~. 1 a vacuum level within the combustion chamber during the period
of time X, and during the period of time Y, injection of air is
, continued under the compression of the sub-intake 130, so that
the injection pressure of streams of air from the injection hole
is increased to a greater extent, as compared with those in the
preceding embodiments thus intesifying a function of creating -
swirl or turbulence of a charge mixture.
Also in this embodiment, if streams of air being injected
from the injection hole 34 are directed towards the spark gap 36
in the spark plug 20, then scavenging is promoted by injection
streams of air immediately before ignition, resulting in an
; amazingly raised limit of combustion of a lean mixture charge.
Throughout the embodiments described, an optimum amount
of intake air being fed through the sub-intake passage into the
combustion chamber largely depends upon the type of engine used,
but should preferably be set to a range of 5 to 30~ by weight of
the amount of intake fuel-air mixture being fed through the main
intake passage 64, when the engine is in the low-load running zone.
Although the disclosure describes and illustrates a
preferred embodiment of the invention, it is to be understood
the invention is not restricted to this particular embodiment.
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