TWO CYCLE INTERNAL COMBUSTION ENGINE

MOTEUR A COMBUSTION INTERNE EN DEUX TEMPS

English Abstract

-26-
HIGH TORQUE TWO-STROKE DIESEL ENGINE
ABSTRACT OF THE DISCLOSURE
A two-stroke engine includes an intake-and-scavenge
valve in the cylinder head together with a fuel injection
system, a recirculating type pressure lubricating system, and
a blower or turbo charger assisting in charging the cylinder
with air and also assisting in scavenging the exhaust gases.
The piston head is domed with one side curving downwardly to-
wards the exhaust port formed through the wall of the cylin-
der above the bottom dead centre position of the piston head.
The exhaust port slopes outwardly and downwardly following
generally the slope of the piston to facilitate the flow of
exhaust gases therethrough assisted by the scavenging air
entering through the inlet-and-scavenger valve. The valve
is operated by a cam mounted on a cam shaft upon the cylin-
der head which in turn is operatively connected to the crank
shaft. The width of the cam lobe is such that the opening,
closing and duration of opening of the valve is controlled
with the valve being opened approximately 140° and with the
piston controlling the opening of the exhaust port through
approximately 130° so that there is approximately a 5° over-
lap at either end of the exhaust port opening. It should be
noted that the oil scraper ring remains below the exhaust

-27-
port at all times to prevent lubricating oil from escaping
through the exhaust port.

Claims

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CLAIMS:
(1) A two-stroke supercharged multi-cylinder in-
ternal combustion engine, with inline or V-type configura-
tion and including a pressure lubrication system; compris-
ing in combination a cylinder block having cylinder bores
formed therein, a cylinder head on the upper end of the cy-
lindrical bores and closing same and defining a combustion
chamber at the upper end of each cylindrical bore, a pis-
ton assembly in each of said bores including a piston hav-
ing a domed head and a connecting rod operatively connected
to said piston for reciprocating same between top dead cen-
tre and bottom dead centre, a crankshaft mounted for rota-
tion at the base of said block, said connecting rods being
operatively connected to said crankshaft and an oil pan en-
closing the lower end of the cylinder bores and said crank-
shaft, said cylinder head including a cam shaft mounted for
rotation thereon and being operatively connected to said
crankshaft, at least one inlet-and-scavenger valve mounted
on said cylinder head and being operatively connected with
said combustion chamber of each of said cylindrical bores,
a rocker arm operatively mounted on said cylinder head and
operatively engaging said inlet-and-scavenger valve by one
end thereof, a cam lobe for each rocker arm formed on said
cam shaft operatively connected with the other end of said

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rocker arm, said cam lobes having a relatively wide area of
contact with said rocker arm to control the opening, closing
and duration of opening of said inlet-and-scavenger valve
and exhaust port located in the lower side of the cylinder
walls of the cylinder bores inclining downwardly and out-
wardly through the cylinder walls and being covered and un-
covered by the reciprocating piston passing thereby.
(2) The invention according to Claim 1 in which
said cam lobe opens said inlet-and-scavenger valve at ap-
proximately 110° after top dead centre and closing said in-
let-and-scavenger valve at approximately 70° after bottom
dead centre thereby maintaining said inlet-and-scavenger
valve open through approximately 140°.
(3) The invention according to Claim 1 in which
said piston uncovers said exhaust port approximately 115 °
after top dead centre and closes said exhaust port approx-
imately 65° after bottom dead centre whereby said exhaust
port is opened through approximately 130°
(4) The invention according to Claim 2 in which
said piston uncovers said exhaust port approximately 115°
after top dead centre and closes said exhaust port approx
imately 65° after bottom dead centre whereby said exhaust
port is opened through approximately 130°.
(5) The invention according to Claim 4 whereby

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the overlap between said inlet-and-scavenger valve and said
exhaust port is approximately 10° with the inlet-and-scaven-
ger valve opening approximately 5° before the exhaust port
opens and closes approximately 5° after said exhaust port
closes.
(6) The device according to Claim 1 in which said
piston assembly includes means to control and reduce the es-
cape of lubricating oil therepast, said means including said
piston assembly having a domed piston head crown, a piston
skirt extending therefrom, wrist pin bosses formed in said
skirt below said domed head, sealing caps installed in adja-
cent the outer end of each of said wrist pin bosses, to pre-
vent the escape of oil therepast, a wrist pin mounted in said
wrist pin bosses and operatively connecting said connecting
rod to said piston, at least two compression piston rings
situated in spaced and parallel grooves in the head of said
piston above said wrist pin bosses and at least one oil scra-
per ring mounted within an annular groove around the skirt of
said piston below said wrist pin bosses, drain holes extend-
ing from said groove through said skirt to reduce the escape
of lubricating oil through said exhaust port, said oil scra-
per ring always remaining below the lowermost edge of said
exhaust port when said piston at top dead centre.
(7) The device according to Claim 2 in which said

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piston assembly includes means to control and reduce the es-
cape of lubricating oil therepast, said means including said
piston assembly having a domed piston head crown, a piston
skirt extending therefrom, wrist pin bosses formed in said
skirt below said domed head, sealing caps installed in adja-
cent the outer end of each of said wrist pin bosses, to pre-
vent the escape of oil therepast, a wrist pin mounted in said
wrist pin bosses and operatively connecting said connecting
rod to said piston, at least two compression piston rings
situated in spaced and parallel grooves in the head of said
piston above said wrist pin bosses and at least one oil scra-
per ring mounted within an annular groove around the skirt of
said piston below said wrist pin bosses, drain holes extend-
ing from said groove through said skirt to reduce the escape
of lubricating oil through said exhaust port, said oil scra-
per ring always remaining below the lowermost edge of said
exhaust port when said piston is at top dead centre.
(8) The device according to Claim 3 in which said
piston assembly includes means to control and reduce the es-
cape of lubricating oil therepast,said means including said
piston assembly having a domed piston head crown, a piston
skirt extending therefrom, wrist pin bosses formed in said

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skirt below said domed head, sealing caps installed in adja-
cent the outer end of each of said wrist pin bosses, to pre-
vent the escape of oil therepast, a wrist pin mounted in said
wrist pin bosses and operatively connecting said connecting
rod to said piston, at least two compression piston rings
situated in spaced and parallel grooves in the head of said
piston above said wrist pin bosses and at least one oil scra-
per ring mounted within an annular groove around the skirt of
said piston below said wrist pin bosses, drain holes extend-
ing from said groove through said skirt to reduce the escape
of lubricating oil through said exhaust port, said oil scra-
per ring always remaining below the lowermost edge of said
exhaust port when said piston is at top dead centre.
(9) The device according to Claim 4 in which said
piston assembly includes means to control and reduce the es-
cape of lubricating oil therepast, said means including said
piston assembly having a domed piston head crown, a piston
skirt extending therefrom, wrist pin bosses formed in said
skirt below said domed head, sealing caps installed in adja-
cent the outer end of each of said wrist pin bosses, to pre-
vent the escape of oil therepast, a wrist pin mounted in said
wrist pin bosses and operatively connecting said connecting
rod to said piston, at least two compression piston rings
situated in spaced and parâllel grooves in the head of said

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piston above said wrist pin bosses and at least one oil scra-
per ring mounted within an annular groove around the skirt of
said piston below said wrist pin bosses, drain holes extend-
ing from said groove through said skirk to reduce the escape
of lubricating oil through said exhaust port, said oil scra-
per ring always remaining below the lowermost edge of said
exhaust port when said piston is at top dead centre.
(10) The device according to Claim 5 in which said
piston assembly includes means to control and reduce the es-
cape of lubricating oil therepast, said means including said
piston assembly having a domed piston head crown, a piston
skirt extending therefrom, wrist pin bosses formed in said
skirt below said domed head, sealing caps installed in adja-
cent the outer end of each of said wrist pin bosses, to pre-
vent the escape of oil therepast, a wrist pin mounted in said
wrist pin bosses and operatively connecting said connecting
rod to said piston, at least two compression piston rings
situated in spaced and parallel grooves in: the head of said
piston above said wrist pin bosses and at least one oil scra-
perring mounted within an annular groove around the skirt of
said piston below said wrist pin bosses, drain holes extend-
ing from said groove through said skirt to reduce the escape
of lubricating oil through said exhaust port,said oil scra-
per ring always remaining below the lowermost edge of said

-23-
exhaust port when said piston is at top dead centre.
(11) The invention according to Claim 1 in which
said exhaust port is provided with a rectangular configura-
tion and inclines downwardly and outwardly upon the lower
side of said cylinder wall, said exhaust port being cover-
ed and uncovered by said piston as it moves between top dead
centre and bottom dead centre within said cylindrical bore.
(12) The invention according to Claims 1, 2 or 3
which includes an air blower component operatively connected
to said engine and having an air intake opening and an air
outlet, said air outlet being operatively connected to said
inlet-and-scavenger valve to supply air in sufficient volume
to charge and scavenge said cylinder.
13) The invention according to Claims 1, 2 or 3
which includes a turbo charger and an air blower connected
in series thereto, said air blower being operated by the ex-
haust gases of said engine, said turbo charger and air blow-
er being operatively connected to said inlet-and-scavenger
valves to supply air sufficient to charge and scavenge said
cylinders.
(14) me invention according to Claims 6, 7 or 8
in which said wrist pin is hollow and is bearingly engaged
within said wrist pin bosses, a retainer pin secured to bet-
ween said sealing caps, said retainer pin extending freely

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through said hollow wrist pin, said retainer pin securely
retaining said end caps in position spaced slightly inboard
from the outer ends of said wrist pin bosses.
(15) The invention according to Claims 9 or 10
in which said wrist pin is hollow and is bearingly engaged
within said wrist pin bosses, a retainer pin secured to bet-
ween said sealing caps, said retainer pin extending freely
through said hollow wrist pin, said retainer pin securely
retaining said end caps in position spaced slightly inboard
from the outer ends of said wrist pin bosses.
(16) The invention according to Claim l which in-
cludes a recirculating type pressure lubrication system and
in which lubricating oil is stored in the oil pan and being
supplied to all the vital moving parts by means of the pres-
sure lubricating pump which is driven by the crankshaft by
means of gears, said lubrication system using a micronic oil
filter to ensure that clean oil is supplied at all times to
the critical moving parts.
(17) The invention according to Claim l in which
said cam lobe includes a peripheral contact surface portion
engageable with said inlet-and-scavenger valve and extend-
m g through approximately 140° of rotation thereby control-
ling the opening and closing of said valve and the duration
of the opening and closing thereof in relation to the degree

- 25 -
of piston travel when the exhaust port is covered and uncover-
ediby said piston, said exhaust port being uncovered for ap-
proximately 130° and covered for approximately 230° of crank
shaft rotation.

Description

~%~6~%
-- 1 --
TWO CYCLE INTERNAL COMBUSTION EN&INE
BA~KGROUND OF THE INVENTION
This invention relates to a new and improved method
of operating a two-stroke or two cycle high torque and high
speed gas or diesel ~ueled multi-cylinder internal combustion
engine utilizing an air blower or turbo charger combination
connected in series, and having a new and improved design of
the internal moving parts, more specifically to the design of
the scavenging valves which are opened and closed by the re-
latively wide area of cam lobes of a cam shaft and related
mechanisms all assembled in the cylinder head. Also of impor-
tance is the piston assembly having a novel feature of design.
A recirculating type pressure lubrication system is used to
lubricate all the vital and critical moving parts, making this
invention an efficient device. The design and location also
of the exhaust ports in each of the cylinders provides the~most
efficient operatlon of this machine.
SUMMARY OF THE INVENTION
.., . . , . . _ :
~ It is an object of this invention therefore to
dlsclose its design, ltS novel~featuresj its advant~ages, ltS
efficiency and method of operation.
Among the objects of this invention is how to eli-
minate the many disadvantages, l~imitations,~difflculties and
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inefficient operations of most two-stroke engines specially
when pressure lubrication is used.
Another object of this invention is to disclose
and provide a device of the character herewithin described
in which a new and improved design of the scavenging valves
which are opened and closed by cam lobes of special design
having relatively wide area of contact for longer duration
of valve opening period. The valves and related mechanisms
are assembled and installed in the cylindex head.
Still another object of this invention is to dis-
close and provid~ a device of the character herewithin des-
cribed in which a new and improved design of the piston as-
sembly, having novel features that reduces and controls
pressure lubrication problems,
Still another object of this invention i9 to dis-
close a new and improved design of the pi~ton assembly, the
design of the scavenging valves and related mechanisms and
the design and location of the exhaust port openings in each
~cylinder an~d the application of an alr blower which together
leads to ~his~relatLvely cleaner exhaust~gas emisslon cha-
racteristic.
Still another object of this invèntion~is to pro-
vide an engine capable o~f produci~ng high~torque and high~re-
volution per minute because o less~mo~ing parts and compact

. ~2~ 2
assembly.
Still another object of this invention is to
provide a device of the character herewithin described
which may include the design of the air blower assembly
having a scoop~type impeller and a compressor rotor that
are bolted together to a common shaft supported with ball
bearings that can be driven by means of a gear or by a
belt pulley.
Still another object of this invention is to
provide a device of the character herewithin described
which is compact in design, economical in manufacture and
otherwise well suited to the purpose for which it is de-
signed~
` In accordance with the inven~ion there is provi-
ded a two-stroke supercharged multi-cylinder internal com-
bustion engine, with inline or V-type configuration and~in-~
cluding a pressure lubrication~system; compriaing in combi-
nation a cylinder block having~cy1inder bores formed there-
in, a cylinder:head on the~upper end of the oyl1ndrica1 bores
: 20 and closing same and defining~a combustion chamber~at:the up-
per e~nd of each cylindrical~ bore, a~p1ston assemb1y in each
of said bores includ1ng a piston~havlng a domed~head and
connecting rod operatively connected~o said piston~for re-
ciprocating same between~top dead~centre~and bottom~dead cen-
: ~
.. :: : :

tre, a crankshaft mounted for rotation at the base of said
block, said connecting rods being operatively connected to
said crankshaft and an oil pan enclosing the lower end of
the cylinder bores and said crankshaft, said cylinder head
including a cam shaft mounted for rotation thereon and be-
ing operatively connected to said crankshaft, at least one
inlet-and scavenger valve mounked on said cylinder head and
being operatively connected with said combustion chamber of
each of said cylindrical bores, a rocker arm operatively
mounted on said cylinder head and operatively engaging said
inlet-and-scavenger valve by one end thereof, a cam lobe
for eaoh xocker arm formed on said cam shaft operatively
connected with the other end of said rocker arm, said cam
lobes having a xelatively wide axea of contact with said
: rocker arm to control the openingj closing~and duration of:
opening of said inlet-and-~cavenger~valve and exhaust port
located in the lower side of~the cylinder walls of the cy~
llnder bores inclining downwardly and outwardly through the~
: :~ cyllnder:walls and being covered~and~uncovered b~ the~recl-
procating piston passing thereby. :
With the for~goin~in view,~ and other:advantages
as will become apparent to those~ killed~;in~the art~to which
this:lnvention relates as this~specification prooeeds~, the
invention is herein des~cribed~by:referen~e to the àcco~pany-~

::~20~
ing drawin~s forming a part hereof, which includes a desorip-
tion of the best msde known to the applicant and of ~he pre-
ferred typical embodiment of the principles of the present
invention, in which:
DESCRIPTI~N OF THE DRAWINGS
Figure 1 is a schematic partially sectioned side
elevation of one cylinder and a piston assembly showing the
piston position in the latter part of the power stroke with
the scavenging valv~ or intake valve already partly opened.
Figure 2 is a view similar to Figure 1 but showing
the piston position at bottom dead centre with the intake
valve fully opened.
Figure 3 is a view similar to Figure 1 but showing
the exhaust port covered by the piston at the beginning of
the compression stroke with the intake valve still partly
opened.
~igure 4 is a view similar to Fiyure 1 but showing
the piston pssition at top dead centre of its compression
stroke.
2Q Figure 5 is a fragmentary cross sectional view of
the piston and connectiny rod assembly ~ se.
Figure 6 is a schematlc side elevation partially
sectioned showing a turbo charger connected to the engine.
Figure 7 is~a view similar to Figure 6 but showing
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~L2~
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a V-type configuxation.
Figure 8 is a fragmentary cross sectional view of
the preferred air blower construction.
Figure 9 is a view from the left hand side of
Figure 8.
Figure 10 is an example of the valve and port dia-
gram of the engine.
In the drawings like characters of r~ference indi-
ca~e corresponding parts in the diff~rent figuxes.
DETAILED DESCRIPTION
.... . .. _
Proceeding therefore to describe the invention in
detail, reference should first be made to Figures 1 to 4 in
which reference character 10 illustrates generally a cylin-
der including a cylinder wall ll, wa~er cooling passages 12
formed ther~ln and a cylinder head assem~ly 13 secured~to
the upper side of the cylinder by conventional means tnot
; illustrat~d).
A valve ~asing 14 surmounts the;cylinder head and
is once again connected by conventlona~l~means;~not shown~
A pis~on assembly is xecipro~al within said~`cylin-
der, said piston assembly being gen0rally~designa~ed by re-
ference character l5 and including a piston collectively de-
signated 16 and a connecting~rod oollectively designated 17,
details of which will hereinaftex be described~
: ~ :
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: : :

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. 7
An exhaust port 18 is formed through the wall of
the cylinder 11 on one side thereof, said exhaust port pre-
ferably being of rectangular configuration and inclining
downwardly and outwardly through the wall as clearly shown
in Figures 1 to 4.
An exhaust conduit 19 leading to an exhaust mani-
fold 20 (see Figure 6~ is secur~d to the exhaust port on
the outer side thereof by means of flange 21 and bolts 22
and this exhaust conduit 19 extends outwardly and downward-
ly at an inclined angle similar to the inclined angle of the
exhaust port through the cylinder wall 11 to facilitate the
exit of exhaust gases as will hereinafter be described~
At least one and preferably two or more air intakeand scavenging valves 23 are provided within the cylinder
head 13 normally seated on valve seats 24 and being retain-
ed therein by means of valve springs 25 on the upper ends
26 of the valve stems which engage through ~alve guides 27
: within the head 13 in a conventional manner.
These valves are preferably operated by an over-
2~ head cam shaft 28 supported for rotation in a csnventional
manner (not illustrated) and being opera iveIy connected to
the crankshaft (not illustrated~ which is also conventional.
Howev~r, the cam lobes 29 of the cam shaft areshaped with a relatively wide contact area:30A to control
::

the duration of the opening of the air intake valves 33
and also the time that they are opened and closed.
The cam lobes 29 engage rocker arms 30 pivoted by
one end thereof to rocker arm bearings 31 and engaging the
upper ends 26 of the valve stems by the other ends 32A in
a conventional manner.
In Figures 1 to 4, an air blower assembly collec-
tively designated 32 is provided and is operati~ely connec-
ted to the engine in a conventional manner ts supply air un-
10der superatmospheric pressure ts the air inlet valve 23 via
passages 33 which may be connected to an intake manifold if~
a plurality of pistons and cylinders are utilized.
Details of the preerred embodiment o the air
blower assembly are shown in Figures 8 and 9 and com~rises
a cylindrical casing 34 within which a fan blade assembIy~
collectively designated 35 is supported for rotation upon
~a shaft 36~supported with bearings 37 and drlven rom ~he~
engine by means of gear~ 38~or gear bel~(not illustrated)~
~either o whlch is operatlvely;connected~to the~cam~shat
20in a conventional manner~ by~means~o~a gear chaln~or~cog~
belt.
The blower~includes;the~aforementioned~combination
an~assemb1y 35 with an~outer~se~t;~of~impeller blades 3~9~and
an inner set of~ screw~or~compréssor blades 40. Rotation ~f
.

` " ~2~
g
the fan assembly in the direction of arrow 41, draws airthrough the central intake 42 in the centre o the front
wall of the casing, compresses same and ejects it from the
discharge end 43 which is operatively connected to the air
intake valves 23 as hereinafter described.
Reference should be made to the piston assembly
illustrated in detail in Figure 5. The piston is prefer-
ably formed from aluminum alloy and includes a piston head
44, a piston head crown 45 and a surrounding cylindrical
skirt portion 46.
The piston crown 45 is domed as illustrated by
refer2nce character 47 and is convexly curved with ~he side
of the crown 48 towards the exhaust port 18 curving down to
a point 48 which is lower than ~he junction of the crown to
the head on the opposite side as illustrated by reference
character 50 50 that the apex 51 of the dome is offset from
the vertical centre line of the piston, towards the side 50
which is diametrically opposite to the lower side 49 on the
exhaust port side of the cylinder when assembled.
This facilitates the flow of exhaust gases from
the combustion chamber 52 assisted by the ~ir entering ~ia
the blower a~sembly 32.
,
A pair of opposed piston boss~es 53 axe formed with-
in the wall of the piston in a conventional manner and a
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` ~2~6~L~2
-- 10
wrlst.pin 54 bearingly engages these bosses and also bear-
ingly engages the wrist pin end 55 of the connecting rod 17.
It is desira~le to seal the outer ends of the boss-
es 53 to prevent lubrica~ing oil ~rom bein~ discharged there-
through and in this connection a tie rod or pin 56 ex~ends
freely through the wrist pin 54 which is hollow, and is se-
cured as by brazing to tw~ concave ~eallng end caps 57 , one
being situated slightly within each outex end 58 of the wrist
pin bosses of the piston as clearly shown.
A pair or more of compression piston rings 59 are
seated within the piston ring grooves 60 around the piston
adjacent the upper end of the head thereof and an oil scra-
per ring 61 is installed within an annular groove 62 adja-
cent the base of the skirt o~ the piston with oil return
apertures 63 being fsrmed through the skirk at the base of~
the groove in a conventional manner. : ::
O~ importance i~ khe fact that the oil scraper~ ~
: ring always remains below the lower side 18A of the exhaust
port:when the piston is in the top dead centre posi~ion as
20 illustrated in Figure 4.
The exhaust port 18 design lS such that lt incli-~
nes downwardly and outwardIy on the~walls of the cylinder:
and ~he attaching èxhaust~conduit is preferably~rectangular
in configura~lon and may be provided with one or more verti-
:
: :

~ 6~
-- 11 --
cal bars 64 to guide the compression rings past the exhaust
port and to prevent them catching on the edges of the walls
defining the port.
In operation to this point, reference should be
made to Figures l to 4.
In Figure l, the piston 15 is approaching the low-
er end of the power stroke and the scavenging valve is just
beginning to open. In Figure 2~ ~he piston is at the lower
end of the power stroke with the exhaust port 18 being un-
covered and air passing through the now fully opened scaven-
ging or inlet valve, being supplied in sufficient volume by
the blower assembly 32, to complete scavenge the exhaust
gases through the exhaust port facilitated by the common
angle of the piston head crown at this point and downwardly
inclining exhaust port 18 and exhaust conduit l9.
In this position, the plston is at the bottom dead
centre and in Figure 3 it is commenc:ing to mo oe upwardly on
~: ~ the compre~sion~stroke having covered the:~exhaust port 18
although the scavenging valve is still~slightly open to en-
: 20 : ~sure that a full charge o~ air is:~supplied within: he:combus-
tion chamber 52.
. The æcavenging or intake valve~23 now closes~as
~: the plston contlnues to move upwardly~on the compression~ :
stroka to the top:dead centre position as shown in;Figurè 4.
.

~Z[)6~
12
With the piston at this position, it will be noted that
the aforementioned oil scraper ring ~1 always remains be-
low the lower edge 18A of the exhaust port so that the lu-
bricating oil cannot escape through this port.
Within a few degreees of the piston reaching the
top dead centre of its travel as shown in Figure 4, an atom-
ized spray of fuel is injected via a conventional fuel in-
jector assembly 65 which ignites due ~o ~he highly compres-
sed air ~etween the crown of domed piston head and the com-
bustion chamber of the cylinder head, in a conventional man-
ner with the scavenging valve 23 being completely closed at
this point. The ignited fuel and highly compressed air mix-
ture expands and pushes the moving piston downwardly perform-
iny the power or expansion stroke to the posltion shown in
Figure 1 and the cycle of operation is repeated again and
again.
It is to be noted that the scavenging valves 23
are of relatively large diameter to ensure that the air~sup-
plied to cylinders 52 is sufficient to~completely scavenge
and charge its cylinders every time the piston reaches the
bottom of its stroke.
It is also to be noted~further that the~sc~venging
valves 23 are opened and closed at the correct timing~in ~
relatio~ to the piston degrees of~travel.~ In~order to achieve
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this, cam lobes 29 of the cam shaft 28 have a relatively
wide area of contact 30A and is designed to correctly time
the duration of opening and closing of its scavenging valves
23 in relation to the piston degrees of travel. The sca-
venging valves 23, the rockers 30 and c~m lobes 2g of the
cam shaft 28 are mechanically contacting one another and
are all assembled upon the cylinder head. The cam shaft
28 is mechanically driven by the cranks~af~ by means of
gears and chain or cogged belt in a conventional mannerO
Reference should be made to the novel design of
the piston assembly illustrated in detail in Figure 5.
The piston is preferably formed from alumin~n alloy and in-
cludes a piston head 44, a piston head crown and a surround-
ing cylindrical skirt portion 46.
As discussed previously,` another very important
point to be rnoved is the piston assembly shown in a;frag- ;
mentary form as in Figure S, having a novel desLgn features
that controls and reduces lubricating~ oil problems;:especial-
ly if a pressure lubrication~system is utilized"in a two
: 20 cycle engine. The novel design features of~the piston~as-~:
sembly are: the head ~45 is~dome shaped:to facilitate the
flow o~ the scavenging exhaust gases, a pair of compression
rings 59 and a pair of ~sealing caps:~57~installed ~t~both
: ends of the piston bo~sess` For~safety ~f operation these

~zo~
- 14
sealing caps 57 are secured by brazing a pin 56 that ex-
tends freely through the wrist pin 54 which is hollow.
The sealing caps 57 are installed at each outer end of
the piston bosses 58 to prevent any amount of th~ lubri-
cating oil from being discharged therethrough.
Another important feature of the piston assembly
to be noted is the oil scraper ring 61 which is installed
close to the base of the piston skir~ with oil return holes
6 3, the function of which is to prevent any amount of lubri-
cating oil from being discharged to the exhaust ports 18 and
that said oil scraper 61 always remains below the lower side
18A of the exhaust port when the piston is in the top dead
centre position of its stroke.
The exhaust port 18 is located in the side of the
cylinder wall adjacent the bottom dead centre position of
the piston, the design of which is incllning downwardly and
outwaxdly and is covered and ~ncovered by the piston, the
design of which is to facilitate the flow of exhaust gases
more freely into the atmosphere.
::
As mentioned previously, this invention is suit-
able for use with slngle or mu1ti-cylinders~ either inline
or V-type configuration being shown schematically in Figu-
res 6 and 7 xespectively.
It will also be appreclated that the air blower
~: ~

~2(~6~
assembly 32 can be used with all configurations or alterna-
tively, a turbo charger and aix blower combination connect-
ed 1n s~ries can be utilized as shown schematically in Figure
7 collectively designated 66.
Final~y, reference should be made to Figure 10
which shows a valve and port diagram.
The width of the cam lobe 30A is such that the in-
let and scavenger valve opens approximately 105 to 110 af-
ter top dead centre and closes approximately 70 after bot-
tom dead centre so that it remains open through approxima-
tely 140.
The position of the exhaust port relative to the
piston is such that the piston uncovers the exhaust port
at approximately 115 after ~op dead centre and covers or
closes the exhaust port at approximately 65 after bottom
dead centre so that the ~xhaust port remains uncovered
through approximately 130o The relationship between the
exhaust port opening and the inlet-and-scavenger valve
o~ening is such that there is approximately a 5 overlap
:: : : :
at either end in which the inlet-and-scavenger valve is
open approximately ~ before the exhaust port i~ uncovered
and remaina open approximately 5 after~the exhaust port
is covered or clo~es. : : :
~ This provides the necessary:control for the open-

ing, closing and duration of opening of the inlet-and-sca-
venger valve with the pis~on ~nd position of the exhaust
port controlling the opening, closing and duration of open-
ing o the exhaust port.
Since various modifications can be made in my in~-
vention as hereinabove described, and many apparently wide-
ly different embodiments of same made within the spirit and
scope of the claims without departing frGm such spirit and
scope, it is intended that all matter contained in the ac-
companying specification shall be interpreted as illustra-
tive only and not in a limiting sense.
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