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Патент USA US2121409

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June 21, 1938.
H. R. RICARDO
2,121,409
TWO-STROKE INTERNAL COMBUSTION ENGINE
Filed Oct. 15. 1935
2 Sheets-Sheet 1
Fig. 1.
D2 D1
“4103
INVENTOR
June 21, 1938.‘
H. R. RICARDO
2,121,409
TWO-STROKE INTERNAL COMBUSTION ENGINE
Filed Oct. 15, 1935
2 Sheets-Sheet 2
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Patented June. 21, 1938
2,121,409
‘ UNlT-EDMSTATES
PATENT OFFICE
2,121,409
'rwo-s'raoxr. INTERNAL-COMBUSTION
'
ENGINE
a
Harry Ralph Ricardo, London, England
Application October 15, 1935, Serial No. 45.158
In Great Britain October 19, 1934
‘6 Claims.
(Cl. 123-65)
This invention relates to two-stroke internal
combustion engines of the kind wherein a single
sleeve valve which may have a combined oscil
lating and reciprocating motion controls the dis
charge of exhaust gases through one or more
exhaust ports or ‘openings in the cylinder wall
adjacent to the cylinder head
while the admis- ‘
sion of scavenging air takes place through one or
more ports or openings in the wall of the sleeve
10 valve towards the‘ end 01' the working chamber
remote from the head.
,
For the sake of convenience the end oi! the
cylinder, ‘sleeve and other parts adjacent to the
cylinder head will be referred to as the upper end.
15
In a two-stroke internal combustion engine or
‘ the kind referred to-according to the present in-‘
vention the exhaust ports .in the cylinder wall
adjacent to the head‘ are controlled by the edge
of the end 01' the sleeve valve‘ so that no ports
are formed in this end portion of the sleeve. No
gas-tight vpart carried ‘by the cylinder head ex
tends into and engages the adjacent end of the
the exhaust ports during the high pressure part
of the cycle than the remaining part of the sleeve,
the thinned part may either be of substantially
constant thickness or tapered, while the remain
ing part of the sleeve may either be of uniform 5
thickness throughout its length or may be thick
ened over that part in which the inlet or, scaveng
ihg ports are formed. This latter arrangement is
convenient, for example, where the thickening
constitutes a strengthening band at the part to 10
which the mechanism for imparting movement
to the sleeve is attached. ‘In any case, the scav
enging ports may be so formed that the charge
entering through them has imparted to it a sub
stantial component in a tangential direction with- 15
in the cylinder. ‘ The obliquity of the inlet ports
for this purpose is determined in accordance with
the degree of “swirl” which it is ‘desired to impart
to the incoming charge as may be requisite ac
cording to whether the invention is applied to an 20
engine‘of the compression ignition type in which ,
bore of the sleeve and the sleeve reciprocates only this swirl is utilized to assist the distribution of
, between the piston and the cylinder wall. The ‘fuel throughout the air or to ‘an engine operating
25
end part or the sleeve which controls or deter with spark ignition in which less swirl is usually
mines the uncovering of the exhaust ports is preferable or, again, to engines of the compresconveniently made thinner than the remaining sion ignition type wherein little or no swirl about
the cylinder axis is required, any organized tur
or main portion of the sleeve or is otherwise. weak
bulence
or the air charge which may be required
30 ened so that this part of the sleeve can expand being e?'ected in some other way, for example by
under the internal gas pressures during operation
forcing the ‘air'charge ‘during the compression
of the engine to assist in maintaining a substan
tially ?uid-tight joint between this part of the stroke from the cylinder bore into a combustion
sleeve which lies above the exhaust ports during chamber through one or more restricted passages.
the compression and ?ring periods‘ and the cylin ' The arrangement is preferably such that at maxi~
35 der wall. ‘Further, the arrangement is conven
mum opening of the exhaust ports the upper edge
iently, such that the part of the sleeve which - of the sleeve does not lie above and is preferably
covers the exhaust ports during the later part of substantially coincident with the lower edge of
‘ the compression stroke and the earlier part of
the exhaust ports.
‘
25
30
35
'
the ?ring stroke of the piston is then shielded by
The invention may be carried into practice in
various ways, but one construction according to
rangement preferably being such that at the end‘
of the piston stroke the uppermost piston ring
lies with its upper edge in or beyond the plane of
the upper edge of the exhaust ports; In this way,
this invention as applied to an engine operating 40
40 the piston from internal gas pressure, the ar
while expansion of the wall of the upper end por-‘
tion of the sleeve under internal gas pressure can
take place to assist in maintaining a substantially
gas-tight joint‘ between this part of the sleeve
and the cylinder wall, the risk of distortion of the
50 wall of the sleeve due to the internal gas pres
‘ sure tending to cause this wall to be forced into
the exhaust ports around it is reduced or elimi
,
nated.
Where, as described above, the sleeve is made
thinner over that end portion which lies above
on the liquid fuel injection compression ignition
system and two modi?cations thereof are illus
trated somewhat diagrammatically by way of ex
ample in the accompanying drawings, in which
Figure 1 is a sectional elevation,
.
45
‘Figure 2 is a section in the plane 2—-2 of Fig
ure 1,
.
‘
Figure 3 ‘is _ a sectional elevation of part ‘of
the upper end ‘of the cylinder and of the cylinder
head showing one modi?cation, and
5
Figure 4 is a sectional elevation showing a mod
cation which may be made to the upper end
of the sleeve valve.
‘
i
In the construction illustrated in Figures 1 and
2 the engine, comprises a crank case A having 55
9,121,400
2
mounted therein a crankshaft B and connected
to a water-cooled cylinder C which may be formed
of an aluminium alloy. To the upper end of the
cylinder C is secured a cylinder head D contain-l
ing a water-cooled combustion chamber Dl of
smaller diameter than the‘ cylinder bore provided
'
with a fuel sprayer D‘, the axis of which lies
substantially parallel to the axis-of the cylinder
and combustion chamber and is displaced from
10 the combustion chamber axis. Formed in the
wail of the cylinder C adjacent to its upper end
are a series of exhaust ports C1, communicating
with exhaust galleries C' provided with outlets
at C8 adapted to be attached to an exhaust pipe.
less'than the bore of the cylinder below the ex
haust ports. The provision of this taper, while
being in some cases desirable’ where an aluminum
alloy or like high expansion‘ cylinder is em
ployed, would in general be unnecessary where a
cast iron cylinder were used.
The thickness of the main part of the wall
of the sleeve- valve E and of the upper part of
reduced diameter may vary, but. in an engine of
15 Also formed in the cylinder at a point adjacent
to the upper end of the crank case is a circum
ierentially arranged inlet or scavenging gallery
0‘ to which scavenging air under pressure is sup
plied, for example in known manner from a
blower.
Mounted within the cylinder is a sleeve valve
E formed, for example, of steel in the wall of
which is formed a series of inlet or scavenging
the compression ignition type such as that shown,
having a sleeve the internal diameter of which
is of the order of ?ve and a half inches, the
thickness of the part of the sleeve which at the
end of its upstroke lies above the exhaust ports,
or at least the upper edge portion of such part, 16
is preferably of the order of one per cent or less
of the sleeve diameter where the sleeve is formed
of steel, this thickness being such that this
upper end part of the sleeve will expand under
the internal pressure towards the end of the 20
ports 1:‘ communicating with‘the inlet gallery
and arranged tangentially with respect to a circle
having for centre the axis of the cylinder so that
the scavenging air passing therethrough from the
inlet gallery C‘ will tend to _ rotate about the
cylinder axis.
80
~ _
The sleeve E is provided at its lower end with
a thickened part E3 rigidly connected to or formed
integral with which is a pin E‘ freely engaging a
bore in a member F the outer surface of which
is part-spherical and is freely mounted in a corre
spondingly internally part-spherical member F1
mounted on the upper end of a coupling rod F2
an intermediate point in which is pivoted to one
end of a link I", the other end of which is piv
oted to the crank case A, while the lower end of
44Tthe rod 1“01 is provided with a strap F‘ engaging
an eccentric F‘ secured tow the crankshaft B. This
mechanism will impart a combined oscillating and
reciprocating motion to the sleeve in known
manner.
‘
'
A piston G reciprocates within the sleeve valve
E and is connected by a connecting rod G1 to a
crank B1 on the crankshaft B in known manner.
The crank B1 and the eccentric F‘ are ap
proximately in phase so that while a combined
50
oscillating and reciprocating motion will be im- ‘
parted to the sleeve E in known manner, the end
of the upward movement of the sleeve will nearly
coincide with the end of the upward or compres
sion stroke of the piston, while the end of the
55 downward movement of the sleeve will coincide
with the end of the downward or firing stroke
of the piston, the upper edge of the sleeve at the
end of its downward movement preferably sub
stantially coinciding with the lower edge of the
exhaustports.
.
The bore of the upper end portion of the sleeve
E, which at the end of the upward movement
of the sleeve lies above the exhaust ports, is
tapered or reduced in thickness as shown at
65 E5, while the upper end of the cylinder bore may
be tapered to a small degree which cannot be
readily illustrated, the smaller diameter of the
taper in the cylinder bore being adjacentto the
upper end of the cylinder, and the taper extend
70 ing downwards to a point adjacent to the upper
edge of the exhaust ports 01. This taper is such
that the bore of the uppervend of the cylinder
has a diameter which, in a cylinder having a bore
of the order of ?ve and a half inches diameter,
is of the order of two thousandths of an inch
compression stroke and during the firing period
to assist in maintaining a ?uid-tight joint be
tween it and the cylinder wall.
A circumferential oil groove 0‘ is formed in the
cylinder wall at a point between the scavenging 25
gallery C4. and the exhaust ports C1, oil being
fed under pressure to this groove through a
The operation of the engine is as follows:
As the piston G moves downwards from its 30
upper dead centre on the firing stroke, the sleeve
E also moves downwards but more slowly, and
the upper edge of the sleeve begins to uncover
the exhaust ports C1, just before the piston G
begins to uncover the scavenging ports E2 in the 35
sleeve ‘valve.’ The exhaust period thus begins
shortly ‘before the admission of scavenging air
through the scavenging ports, so that the waste
gases are driven out and the working chamber
is charged with air in readiness for the next com 40
pression stroke, this air being in a state of rota
tion about the cylinder axis due to the tangential
arrangement of the scavenging ports E’. During
the later part of the compression stroke of the
piston and the early part of the ?ring stroke it 45
will be seen that the part of the wall of the sleeve
E then covering the exhaust ports C1 is shielded
by the piston G from internal gas pressure. Thus,
though the pressure within the working chamber
can then act upon the wall of the sleeve valve 50
lying above the exhaust ports, thereby expanding
this part of the sleeve to assist in maintaining
gas-tight engagement thereof with the adjacent
part of the cylinder wall, the internal pressure,
when at or near its maximum value, cannot act 55
on that part of the sleeve lying immediately over
the exhaust ports C1. The tendency for the wall
of the sleeve valve E to be expanded into the ex
haust ports C1 by the internal gas pressure is
thereby reduced.
‘
60
It will be seen that the exhaust ports are
controlled not by ports in the sleeve valve but
by the adjacent edge of the sleeve valve and that
the tendency for the thin portion of the sleeve
to expand under the internal gas pressure during 65
the compression and firing strokes tends to main
tain a gas-tight ?t between the upper end por
tion of the sleeve and the cylinder, this gas-tight
fit between the upper end of the sleeve valve and
the adjacent part of the cylinder being greatest 70
when the pressure is highest. The necessity for
providing a plug-like cylinder head which projects
into the cylinder, as has hitherto been common
practice, with head rings between the sleeve and
the plug-like head, is thus obviated and the cool 75
9,121,409
ing of the combustion chamber is also facilitated
since this chamber does not have to be formed
' within the plug-like cylinder head and can there
fore be directly accessible. Furthermore, the ab
sence of head rings as are used on plug-like cyl
inder heads ensures that 'di?lculties due to car
boning-up of the head rings, which di?iculty is
more liable to occur in engines of. the two-stroke
10
than in these of the four-stroke type, cannot arise.
It will be appreciated that since there are no
ports in the part of the sleeve valve E adjacent
to the exhaust ports, this part can be made suf
?ciently thin to permit the desired expansion
under the‘action of internal gas pressure, while
15 any possibility of warping occurring due to the
bars or bridges which would be necessary between
adjacent ports if such were provided in the thin
part of the sleeve valve. due to heat flow, is
avoided.
20
,
The lubrication of the lower part of the sleeve
may be effected in some known manner by splash
from the crank case, while the upper part of the
sleeve is lubricated'by oil from the oil groove C5,
1 this 011 being carried to the extreme upper part
25 of the sleeve across the bars 0'' which divide the
exhaust ports (22 in the cylinder, the combined
oscillating and reciprocating movement of the
sleeve tending generally to distribute oil and
maintain adequate lubrication over the whole of
30 the outer surface of the sleeve.
3
part-E6 may be of a high-expansion material such
as an austenitic steel or cast-iron.
It is to be understood that the construction
more particularly described above is given by
way-of example and that details may be modi?ed
without departing from this invention. For ex
ample, the invention may be applied to an engine
in which the cylinder and cylinder head are air
cooled and to engines of the vaporized charge
spark ignition type, while the mechanism for op 10
erating the sleeve and other details‘ of construc
tion may be modi?ed considerably.
Further, the invention may be applied to
double-acting two-stroke engines, in which case
the sleeve would be operated from a point inter 15
mediate in its length and each end thereof would
be formed and arranged to cooperate with ex
haust ports in the manner according to this in—
vention, scavenging ports, of which a single set
may be common to both working chambers, being 20
provided at a point intermediate in the length of
the sleeve.
It is also to be understood that, although in the
present speci?cation and the followi/ng claims
exhaust ports are referred to, this expression is to 25
be interpreted as including a single continuous
exhaust slot undivided by bars engaging the outer
surface of the sleeve.
I claim:~
1. An internal-combustion engine, comprising 30
The bars 07 are conveniently of somewhat
streamline form on their sides remote from the a cylinder with a cylinder head and provided
cylinder bore for ~the purpose of reducing the’ in its wall with exhaust ports adjacent to said
head, the part of the cylinder bore on the side
tendency for carbon to form thereon.
of
the exhaust ports nearest to the cylinder head
35
Figure 3 shows a modi?ed arrangement which
being provided with a slight taper, the smallest 35
in some cases may be desirable, and may be ap
plied to an engine otherwise similar to that shown diameter of which is adjacent to the cylinder
in Figures 1 and 2, wherein the upper end portion head; a piston operable in said cylinder; and a
sleeve valve movable between the piston and the
of the cylinder barrel is constituted by ‘a sepa
10 rate member or liner H having a ?ange H1 cylinder and controlling the exhaust ports with
the edge at one end of the sleeve.
lying between the upper end of the cylinder prop
40
2. A two-stroke internal combustion engine ac
er and the cylinder head D. This liner may be
cording to claim 1, in which the taper of the
particularly convenient where an aluminium cyl
inder is employed, ‘the sleeve being of normal cylinder bore is such that the end of the cylinder ‘
steel, and not only provides the working surface bore adjacent to the cylinder head has a diameter
for the upper end portion of the sleeve which which is of the order of l/émo of the diameter of 45
the cylinder bore less than the diameter of the
serves to seal the exhaust ports, but also pro
vides a member which can readily be replaced part of this bore at that side of the exhaust ports
in the case of wear taking place. In such a case which is remote from the cylinder head.
3. A two-stroke internal combustion engine
the liner H is preferably of cast-iron or other
comprising a cylinder with a cylinder head and
material having about the same expansion co
provided in its wall with exhaust ports adja 50
e?icient as the sleeve.
.
cent
to the said head, a piston operable in said
Fig. 4 shows a modi?cation of the upper end
of'the sleeve which may also be applied to an cylinder and a sleeve valve movable between the
engine similar in other respects to that shown piston and the cylinder wall and controlling the
exhaust ports of the cylinder wall by its edge, 55
in Figures 1 and 2, wherein the upper end por
tion of the sleeve is formed separately from the the end portion of the sleeve which at the end
main part of the sleeve and is constituted by an of its stroke towards the cylinder head lies be
annular part E6 connected to the main part E of yond the exhaust ports being weakened as com
60 the sleeve by a circlip E7 engaging a shoulder on pared with the remaining portion ‘of the sleeve,
the part E5 and a groove in the part E as shown, the thickness of said part of the sleeve being at 60
its edge of the order of not more than one per
the engaging surfaces of the parts E and E6 be-i cent
of the diameter of the cylinder bore.
ing somewhat cut away, as shown at E8, to en
4. A two-stroke internal combustion engine,
sure that there shall be a gas seal between the
comprising a cylinder with a cylinder head and
65 inner edges of these parts and that ‘pressure
provided
in its wall with exhaust ports adjacent 65
within the cylinder will thus tend always to main
‘ tain the part E6 in close contact with the part E. to said head and a scavenging air belt remote
The parts E and E6 in this construction may be from the exhaust ports, the. part of the cylinder
formed of different metals or may be formed of ~ boreon the side of the exhaust ports nearest to
the cylinder head being provided with a slight
the same metal, the arrangement in either case
taper, the smallest diameter of which is adja 70
permitting the part E6 to be renewed in the case cent
to the cylinder head; a piston operable in
of wear thereof taking place. In particular, said cylinder; and a sleeve valve movable be
where the cylinder is of aluminium alloy or other tween
the piston and the cylinder and control
high-expansion material, and the sleeve of car
ling the exhaust ports.
75 hon-steel or other low-expansion‘ material, the
'5. A two-stroke internal combustion engine, 75
4
8,121,409 > '
comprising a cylinder with a cylinder head and
sleeve to such extent that it can expand'under
to said head and scavenging air belt remote from
?uid-tight Joint between it and the cylinder wall.
6. A two-stroke internal combustion engine ac
cording to claim-4. in which the taper oi the
cylinder bore is such that the end 0! the cyl
gas pressure during operation of the en—
provided in its wall with exhaustports adjacent internal
glue ‘and thus tend to maintain a substantially
the exhaust ports, the part oi the cylinder bore
on the side of the exhaust portsnearest to the
cylinder head being provided with a-slight taper,
the smallest diameter of which ‘is adjacent to
the cylinder head; a piston operable in said cyl
inder; and a sleeve valve movable between the
inder bore adjacent to the cylinder head has a
diameter which is of the order of $500 0! the
at the end of its stroke towards the cylinder head
lies beyond the exhaust ports being weakened as
compared with .the remaining portion or the
the exhaust ports which is remote from the cyl
inder head.
diameter of the cylinder bore less than the'di 10
10 piston and the cylinder and controlling the ex
meter of the part of this here at that side or
the
end
portion
oi’
the
sleeve
which
haust ports,
>
HARRY RALPH RICARDO.
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