Note: Descriptions are shown in the official language in which they were submitted.
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This invention is in the field of internal com-
bustion engines and particularly two-stroke cycle engines.
~ t present, many difEerent desi~ns an~ t~pes ~f
engines are in use, the most com~on being the four-stroke
gasoline engine. OE less significance are the two-stxoke
gasoline engines, rotary engines and both two- and four-
stroke diesel engines. A11 of the above have inherent
disadvantages.
In the four-stroke engine, intake is accomplished
under vacuum conditions which introduces drag on the engine,
particularly under the high vacuum conditions e~isting when
-the engine is throttled. Also, the exhaust stroke is
against a relatively high back pressure and again drag is
placed on the engine. Conventional four-stroke engines in-
clude movable valves for the intake and exhausts and con-
siderable power loss is occasioned by the various elements
necessary to operate the valves. In the case of stratified
charge engines, a further movable valve is provided. In a
four-stroke engine, the piston must complete three prelimi-
nary strokes for each power stroke, each of which consumesengine power through friction losses. While four s-troke
engines can be operated and constructed in a manner to re-
duce polluting emissions, such operation results in lower
efficiency.
In the two-stroke engines the most common type
compresses the fuel and air charge in the crank case and
that charge is introduced into the cylinder by movement of
the piston. The compression of the charge and drawing the
same into the cylinder introduces considerable drag on the
engine with attendant power loss. Such engines effect
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throttli,ng by controlling the air intake under which conditions
incomplete scavenging takes place with attendant loss of power
andan increase in polluting emissions. Customarily, the engine
is lubricated by introducing oil into the fuel charge and that
oil is induced into the cylinder and further increases the pol-
lutants emitted since most of the oil and some of -the fuel is
expelled as unburned hydrocarbons.
Rotary engines are difficul-t to seal and incur
high friction loss in addi-tion to emitting relatively large
amounts of polluting materials.
Diesel engines may operate on ei-ther -two-stroke
or four-stroke cycles, bu-t high shock loads are encountered
during ignition, thus increasing wear. The four-s-troke type
is subject to all of -the disadvantages heretofore enumerated.
The purpose of the present inven-tion is to pro-
vide a more efficient, less complicated and less polluting form
of internal combustion engine.
It is therefore a primary object of this inven-
tion to provide an improved internal combus-tion engine of ex-
tremely simple design and efficient operation.
According to the present invention, there is
provided a -two-stroke cycle internal combus-tion engine having
a cylinder, a piston reciprocable therein and defining there-
with an expansible combustion chamber and exhaust and inlet
ports in a side wall of the cylinder in position to be open to
the combustion chamber only when the piston is adjacent the
end of its expansion stroke wherein the combustion chamber is
of near maximum volume, the improvement comprising an air pump,
the pump having an air intake communicating with ambien-t fresh
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air and pressurized air discharge means co~unicating with -the
inlet ports; a cavity in the upper end of the pis-ton defining
an auxiliary precombus-tion chamber communicating with the
combustion chamber through an opening in an end of the pis-ton,
the pis-ton being provided with a passage through a side thereof
to the cavity and the cylinder side wall being provided with an
air-fuel port aligned with the passage when the piston is a-t
the end of its expansion stroke: charging means comprising a
carburetor and a positive displacement charging pump, the char-
ging pump being arranged to draw a rich air-fuel mixture from
the carburator and deliver a predetermined quan-tity thereof
under pressure to the air-fuel port at each stroke of the pis-
ton; the exhaust, inlet and air-fuel ports being so positioned
that downward movement of the piston firs-t uncovers the exhaust
ports then the inlet port to admit fresh air to scavenge the
combustion chamber and finally align the passage with the
fuel port to admit a predetermined charge of pressurized rich
air-fuel mixture into the cavity.
The present invention eliminates power losses due to
2~ induction vacuum an~l exhaust back ~
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Other objects and advantages wi]l become apparen-t
to those skllled in the art as the descrip-tion proceeds
with reference to the accompanying drawings, which are
illustrative only.
FIGURE 1 is a vertical sectional view -through àn
engine employing the present invention, certain parts being
shown only schematically;
FIGURES 2, 3 and 4 are transverse sectional views
taken on the lines 2-2, 3-3 and 4-4, respectively, of
FIGURE l;
FIGURE 5 is a fragmentary elevational view of a
portion of the interior of the engine cylinder;
FIGURE 6 is a fragmentary sectional view of the
upper part of the engine showing the piston in its upper
position; and
FIGURE 7 is a fragmentary elevational view as
seen on the line 7-7 of FIGURE 1.
Referring first to Figure 1, the engine shown
therein comprises an engine block 2 which may be of cast
aluminum or the like formed to define passages 4 constitut-
ing a cooling jacket surroundiny an inserted cylinder sleeve
6 which will preferably be made of steel or the like. The
upper end of the cylinder 6 and engine block 2 are covered
by a cylinder head structure 8 secured to the engine block
by suitable bolts 10 with intervening gaskets 12. The
cylinder head 8 is provided with coolant jacket passages
14 communicating with the jacket passages 4 through pas-
sages 16. The structure thus far described may be consider-
ed to be more or less conventional. Any suitable coolant
circulating means may be used. Provision is made for
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mounting a spark plu(3 18 on cylinder head 8, as show~, so
that the spark plug projects downwardly into the interior
of the cylinder 6.
A piston 20is slidablein thecylinder 6 in the
usual manner and is connected, by connecting rod 22, to a
crank shaft 24. The engine is also provided with an oil
pan 26 containing a lubricant 28 and it is contempLated
that the lubricant be circulated to all parts of the engine
requiring lubrication in any conventional manner.
The cylinder sleeve 6 is provided with a circ~m-
fexential series of exhaust ports 30, all of which communi-
cate with a manifold channel 32 in the engine block 2. A
fitting 34 connects the manifold channel 32 to an exhaust
pipe 36 which directs the exhaust gases to a turbine driven
supercharger, generally designated at 380 The supercharger
38 is provided with a turbine adapted to be driven by ex-
haust gases from exhaust pipe 36, which are then exhausted
to atmosphere through conduit 40. The supercharger 38 will
not be described in detail since such devices are well-
known in the art.
Referring to Fi.gure 7, however, the supercharger
38 includes a rotary impeller in housing 42 provided with
an air inlet 44 and an air discharge conduit 46. The tur-
bine is housed in housing portion 48. An auxiliary blower
50 driven by electric motor 52 draws ambient fresh air
through a suitable filter 54 and directs the same to the
intake 44 of blower 42. The purpose for this auxiliary
blower will be discussed later, but it is to be noted that
the blower 50 may be stopped and the blower in 42 operated
to draw ambient air freely through blower 50. Also, blower
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50 may supply pressurized air to conduit 46, even though
the blower ln 42 may be stopped.
Pre~surized fresh ai.r delivered by blower ~2 or
blower 50 is conducted to a manifold chamber 56 in engine
block 2, which manifold chamber communicates with a second
series of circumferentially spaced intake por~s 58 in the
cylinder sleeve 6. The ports 58 are positioned below ports
30 and are staggered relative to the ports 30O As shown,
the ports 58 e~tend obliquely through the cylinder sleeve
so that incoming air is directed upwardly within the cylin-
der and between the ports 30.
As depicted in Figure 1, piston 20 is shown at
the bottom of its stroke. In other words, at the end of
its expansion stroke, the top surface of the piston is
slightly above the bottom edge of the inlet ports 58. As
best shown in Figure 3, the periphery of the upper surface
of piston 20 is provided with slanted notches 60, there
being a notch 60 aligned with each inlet port 58 when the
parts are in the position shown. As will be obvious, the
notches 60 assist in deflecting incoming fresh air upwardly
to effect complete and thorough scavenging of the cylinder,
as will be described later, and permit providing large ports
58 to provide for closer timing of intake and exhaust
functions.
As shown in Figure 1, piston 20 is provided with
the usual or customary sealing piston rings 62 adjacent its
upper end and an oil control ring 64 adjacent its lower edge.
The length of the piston 20 is greater than the stroke o~
the piston so that when the piston is in its upper position,
as shown in Figure 6, the oil control ring 64 remains below
33
all ports leading into the cylinder, includlng further
ports to be described~
The piston 20 is further provided wlth a chamber
or cavity 66 communica-ting wi-th the combustion chamber of
the engine through an opening 68 in the upper sur-face of
the piston 20. When -the piStOIl 20 is in i-ts lower position
(Figure 1), lateral openings 70 extending from the cavity
66 to the side of the piston are aligned with fuel ports
72 extending through -the cylinder slee~e 6 and communicat-
ing with further passages 78 in engine block 2. It is tobe noted that opening 68 is axially aligned with the spark
plug 18.
A more or less conventional carburetor 80, con-
trolled by a throttle valve 82, is housed completely within
an air filter housing 84. Thus, any leakage of fuel from
the carburetor body 80 is prevented from reaching ambient
atmosphere and will be drawn into the carburetor intake,
thus eliminating a common source of air pollution. A posi-
tive displacement charge pump device 86 is shown only sche-
matically and is driven from crank sha~t 24 so that itsintake is directly proportional to engine intake. The pump
device 86 has an inlet 88 communicating wi-th the carburetor
80 whereby operation of the pump draws a mixture of air and
fuel through the carburetor to deliver -the same to a mani-
fold 90 from which conduits 92 direct the mixture to pas-
sages 78 pxev:iously described. As also shown in Figure 1,
the exhaust conduit 36 is provided with a throttling valve
94 which may be connected in any suitable manner to throttle
valve 82 for concurrent operation therewith. Broken line
96 schematically indicates such connection.
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When the described engine is ~o he started, ex~
haust gases are not available to operate the turbine pump
38. ~or starting~ -the auxiliary pump 50 is driven by mo-tor
52 to supply compressed fresh air to manifold 56 while a
suitable "starter" causes -the crank shaft 24 to turn slowly
until the engine starts. After the engine has been thus
started, blower 50 is stopped, either manually or automati-
cally, and supercharger 38 takes over.
With the engine running and with the parts in the
relative positions shown in Figure 1 wherein the piston has
completed a power stroke (also to be referred to as its
expansion stroke~, burned gases have started to exit through
ports 30 and fresh pressurized alr is entering through ports
58. The entering fresh air is deflected upwardly to sca-
vange all parts of the expanded combustion chamber of
burned gases. As shown, ports 58 are larger than ports 3~
and more fresh air flows into the engine than is necessary
to fill the combustion chamber. Thus, some of the fresh
air, at each stroke of the piston, enters the exhaust pipe
36. At each stroke, hot exhaust gases entering the exhaust
pipe encounter and mix with the fresh air therein from the
previous stroke and any unburned fuel is burned in the ex-
haust pipe, thus reducing polluting emissions and increas~
ing the power delivered to the supercharger turbine withou-t
taking power :Erom the engine crank shaft.
Whi:Le the above functions are taking place, the
openings 70 axe aligned with ports 72 and a predetermined
charge of a rich fuel-air mixture is caused to enter the
cavity 66. It is to be noted that the circumferential
series of ports 3Q and 58 are interrupted in the region of
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the opening 68 and ports 72 tsee Fi~ure 5). ~hus, there is
no flow of alr or gases directLy over the opening 68 and
little, if any, of the fuel-air mixture is swept out with
the exhaust gases during the described scavenging and
charging functions. The charge of fuel-air mixture is a
predetermined charge controlled by the operation of the posi-
tive displacement pump 86 which preferably operates in timed
relation to the crank shaft 24.
When the piston moves upwardly from its Figure 1
position, on its compression stroke, it covers ports 58,
then ports 30, and moves opening 70 out of registry with
port 72. Continued upward movement ofthepiston compresses
the fresh air in the cylinder and also compresses the fuel-
air mixture in cavity 66.
Figure 6 shows the piston at the upper end of its
compression stroke with the piston somewhat spaced from
cylinder head 8 to define the combustion chamber therebe-
tween. As the piston approaches th~ position of Figure 6,
the lower end of the spark plug 18 enters the opening 68
and the tendency of air to flow into cavity 66 around the
spark plug and the tendency of the spark plug to displace
fuel-air mixture into the combustion chamber results in
turbulence and mixing of fuel and air and the creation of a
very lean fuel-air mixture in the combustion chamber.
At about the top oE the plston stroke, the spark
plug 18 is energized, in any well-known manner, to ignite
the fuel in cavity 66. The piston then moves downwardly
in its power stroke until it again reaches the position of
Figure l and the described cycle is repeatedO The burning
fuel in cavity 66 obviously produces pressure to force fuel
out of cavity 66 into the combustion chamber and into the
air therein for highly efficient combustion, the flame
propagating from cavity 66 throughout the combustion
chamber.
By way of example, assume the compression ra-tio
of the engine to be 8:1, the volume of cavity 66 will be
about 1/5 the volume of the combustion chamber shown in
Figure 6 and about 1/40 the volume of the expanded cham-
ber, as shown in Figure 1. The displacement of the fuel
pump ~6 will be about 1/10 the expanded combustion chamber
volume at full power and throttled to 1/4 this amoun-t at
idle (1/40 of the expanded combustion chamber volume)
(Figure 1) The carburetor 80 should preferably deliver
a mixture having an air-to-fuel ratio of about 1.~7:1;
this would produce an overall air-to-fuel ratio of 17.7:1
at ~ull throttle and 70.8:1 at idle. Thus, at the time
of firing in cavity 66, the air-to-fuel ratio in the cavity
will be about 14.16:1 at idle and about 9.33:1 a~ full
throttle. This range of mixtures is ideal for ignition.
Obviously, the supercharger 38 and/or the blower
50 could be positive displacement blowers or pumps.
While a single specific embodiment o~ the inven-
tion has been shown and described, it will be obvious to
those skilled in the art that other embodiments may be
devised, within the scope of the appended claims.
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