Note: Descriptions are shown in the official language in which they were submitted.
IMPROVE~ INTE~AL CO~USTIO~ ENGINE
This invention relates to a method o deriving mech-
anical worl: from combustion gas in an internal combustion
engine by ~eans of a new thermodynamic working cycle and to
reciprocating internal combustion engines for carrying out
the ~ethod~
~ BAC~GROI~D nF T~E~TION
_
I~ is well ~nown that as the expan6ion ratio of an
internal co~ustion engine i.s in~reased, more energy 1
extracted from the combustion gases and the thermodynamic
ef~iciency increase~. It is further wnderstood that increas-
ing rom~ression increases both power and fuel economy due to
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further thermodynamic im~rovements. The objectives for an
efficient engine are to ~rovide high compression, begin com-
bustion at maximum compression and then expand the gases
as far as possible against a piston.
Conventional engines have the same compression and
expansion ratios, the former being limi~ed by the octane
rating of the fuel. Furthermore, since in these engines the
exploded gases can only be expanded to their initiaL volume,
there is usually a pressure of 70-100 psi against the piston
at the time the exhaust valve opens with the resultant loss
of energy.
Many attemnts have been made to ex~end ~he expansion
process in internal combustion engines to increase their
thermodynamic efficiency. An early design was described in
the Brayton Cycle engine of 1872 (U.S. Patent No. 125,166).
This engine expanded the combustion gases ~o their initial
pressure but lacked the means of transferring and igniting
the charge while maintaining maximum compression. The
A~kinson cycle engine was devised ~o extend the expansion
process, but this engine was limited by its mechanical co~-
plexity to a one-cylinder configuration.
A notable attemp~ was more recently revealed in the
Wishart engine, disclosed in U.S. Patent No. 3,408,811, in
which a large piston co~pressed the charge into a smaller
~5 cylinder which further compressed the charge and then trans-
ferred it into another small "firing" cylinder where the
charge was ignited and expanded to the full volume of the
smaller cylinder. It then passed the burlled gases through
ports uncovered by the piston into a larger cylinder where it
was expanded further. This required four cylinders with
pistons which made two working strokes for each power strol;e,
hence it is an eight-stroke cycle engine ~itn all of the
mechanical and fluid friction inherent in such a working
cycle. The mechanical com~lexity of this engine makes it
costly to manufacture.
In another attempt (Vivian, U.S. Patent No.
4,174,6~3~, the induction valve in the working cylind~r of the
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engine is kept open during part of the compression stroke
and thereafter closing the valve and compressing only a
fraction of a full charge which is then ignited and expanded
a~ainst the piston to the full volume of the cylinder. This
process is very complex requiring means for both changing
the point of axis of the crankshaft and for altering the
intalce valve timing according to load demands. Furthermore,
no means of increasing compression or charge ~urbulence is
provided. This concept continues to opera~e with the fric-
tion in'nerent in the four~stroke cycle engine. In addition,the operation of this engine at full load is the same as for
a conventional engine so that it offers improved character-
istics at part load only.
~hers have attempted to extract more shaft work
from combustion gases using similar systems of conducting the
burned gases into other cylinders after firing for additional
expansion, also with similar results. Some have tried burning
charges in one-half the cylinders of a multi-cylinder engine
and then ducting the exhaust from ~he firing cylinders into
the remaining half of the cylinders for the extraction of
additional shaft work. To date none of these atte~pts have
been successful and emissions were generally increased over
conventional engines.
Rotary engines have also been patellted which strive
to gain the same advantages. Gne such is the new l-'ankel
engine, U.S. Patent No. 3J688l749 issued in 1972, in which a
charge is compressed in one chamber of the rotor of a four-
lobed rotor engine where the charge is ignited and expanded
first in the initial cham~er and then through a duct into the
next down-stream chaml~er. ~ome of the problems with this
concept are that the second expansion chamber is already half
filled with recompressed exhausted gases from the previous
firing and there are extensive throttling losses in trans-
férring the charges.
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BRIEF D~SCRIPTION OF THE''TNVENTION
The present invention provides a reciprocating
internal combustion engine comprising a compressor chamber for
compressing an air charge, ~ower chambers in which combustion
gas is ignited and expanded~ a piston operable in each chamber
and connected to a crankshaft by connecting link means for
rotating ~he crankshaft in respcnse to reciprocation of each
piston, a transfer manifold communicating said compressor
chamber with said power chambers through which manifold the
compressed charge is transferred to enter the power chambers,
an admission valve controlling admission of air to said com-
pressor chamber or compression therein, an outlet valve con-
trolling admission of the compressed charge from the compressor
chamber to the transfer manifold, an intake valve controlling
admission of the compressed charge from the transfer manifold
to said power chambers, and an exhaust valve controllin~ dis-
charge of the exhaust gases from said power chambers, said
valves being timed to operate such that ~he air charge is
maintained within the transfer manifold and introduced into
the power chamber without any appreciable drop in cha,rge
pressure sc that ignition can commence at substantially maxi-
mum compression, means being provided ~or causing fuel to be
mixed with the air charge to produce a combustibl~ gas, means
being proviZed for ignition of the combustible gas, and wherein
said compressor chamber and the combustion chambers of said
power chambers are si~ed ~ith respect to the displaced volume
of said power chamber such t'~at the exploded combustion gas
can be expanded substantially beyond its initial volume.
~ le chief advantages of the present concept over
existing internal combustion engines are: the compression
ratio for spark ip,nited engines can be increased without ~he
attendant problem of combustion detonation, the expansion
ratio for both spar~ ignited and compression ignited engines
is greatly increased, and a much greater charge ~urbulence is
produced in the combust,ion ch~mber of both.
-5~ 3~
The higher compression, the more extensive
expansion process and the incre2sed charge turbulence will
greatly increase the thermal efficiency of an internal com-
bustion engine according to this invention at all loads,
whilst a.t the same time providing a cleaner e~haust These
features are enhanced by extra power strol;es produced per
revolution of the engine crankshaft ~50% more in the 4- and
8-cylinder arrangements and 337 greater in the 3- and 6-
cylinder configuration, as described in detail herein) which
operating at higher compression, will assure approximately
the s~me power-to-weight ratio as that of a conventional engine
of the same power ratir.g even though charge weight is reduced.
Experimental data indicate that a change in compression ratio
does not appreciably change the mechanical efficiency or the
volumetric efficiency of the engine. Therefore, any increase
in thermal efficiency resulting from an increase in compression
ratio will be revealed by a corresponding increase in torque
or mean effective pressure (mep); this power increase bein8
an added bonus to the actual efficiency increase~
The extra po~Jer strol;es per revolution of crank-
shaft translates into a nominal 2-~/3 strol;e cycle engine in
the 4- or 8-cylincler design and produces a nominal 3-stroke
cycle engine in the 3- or 6-cylinder design for reduced
friction and greater~mechanical efficiency.
BRIEF D~SCRIP~ION OF DRA~INGS
_
Embodiments of internal combustion engines according
to the invention will now be described, by way of example,
with reference to the acco~..panying drawings, in ~ich:
Figure 1 is a Perspec~ive view of ~he cylinder bloclc
of a four-cylinder internal com~ustion engine according to the
invention;
Figure ~ is a part sectional view through the com-
pressor cylinder of the engine shown in Figure l;
Figure 3 is a part sectional view through one power
cylinder of the engine at the intalce valve;
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Figure 4 is a part sectional view through one
power cylinder of the en~ine at the exhaus~ valve;
Figure 5 is a diagram showing suggested valve tim-
ing for the engine shown,
Figure 6 is a transverse sectional view ~hrough an
alternate embodiment for a power cylinder showing a sliding
valve;
Figure 7 is a schematic plan view of a similar
four cylinder engine modified to allow quiclc compression
build-u~;
Figure 8 is a schematic transverse sectional view
of the cylinder block of a modified four cylinder engine;
Figure 9 is a schematic transverse section o a 6-
cylinder engine having ~wo compressor cylinders and ~our power
cylinders;
Figure 10 is a schematic transverse section of a 6-
cylinder engine having six powPr cylinders supplied wi~h a
compressed air charge by a separated compressor;
Figure 11 is a schema~ic ~ransverse sectional view
~O through a 6-cylinder engine adapted for use with an economizer
device comprising an air retarder brake;
Figure 12 is a part sectional view through one power
cylinder of t`he engine at the intake valve in which a projec
ti~n is affixed to the crown of the piston;
Figure 13 is an expanded view of ~he projection on
the piston and com~ustion chamber of Figure 12; and
Figure 14 is a diagram showing suggested valve tim-
ing for an engine with a power cylinder as shown in Figure 12.
DESC~IPTION OF DRA~INGS
Referring to the drawings, Figure 1 shows a four
cylinder reciprocating internal com~ustion engine for gaso-
line, diesel, gas or hybrid dual-fuel operation and having
four cylinders 2-5 in which ~istons 6-9 respectively are
arranged to reciprocate. Pistons 6-9 are connected to a
common crankshaft 10 in conven~ional manner by means of
connecting rods 11-14, respectively. Engine 1 is adapted to
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-7- ~ 3~
operate in a 2-strol;e cycle so as to produce three power
strokes per revolution of the crankshaft 10. To this end
one cylinder 5, f~nctions as a compressor, so that during
operation of the engine, compressor cylinder 5 takes in an
air charge at a~mospheric pressure, or alternatively an air
charge which previously has been subjected to supercharging
to a higher pressure, via an admission control valve 'a',
through an intake conduit 15. During operation of the
engine 1, the air charge is compressed within the compressor
cylinder 5 by its associated piston 9, and the compressed
charge is forced through outlet valve 'b' into a high-pressure
~ransfer manifold 16. Manifold 16 is constructed and arranged
to distribute the compressed charge by means of branch con-
duits 17, 18 and 19 and intake valves 'i' to ~he three remain-
ing (expander3 cylinders 2, 3 and 4 respectively which producethe power of the engine.
The volume of the combustion chamber of each expander
cylinder 2, 3 and 4 is preferably sized to be no larger than
one third that of a conventional engine having a similar
compression ratio. This is because the total ~olume of the
combustion chambers should not exceed th~ volume of charge
compressed by the compressor piston and therefore no expansion
of the gases will occur before combustion takes place.
Engine 1 has a camshaft 20 which is arran~ed to be
driven at the same speed as the crankshaft in order to supply
one working s~rolce per revolution for both power and com-
pressor pistons, as described hereinafter.
~he operation of the engine is as follows:
The intake valve li' of each po~er cylinder is timed
to allow the charge to begin entering at approxirla~ely 4~
before top dead center (BTDC) (see Fig. 5) and the exhaust
valve is timed to close at approximat ly thP same crank an~le.
A compressed air charge in transfer nanifold 16 enters the
combustion chamber of the cy~inder which is to be fired ~ith-
out any appreciable Pressure drop occurring and at a highvelocity during which fuel may be injected simul~aneously.
The fuel may be injectPd after intake valve closure on spark
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ignited engines. At about 10 BTDC (see Fig. 5) the intake
valve is closed and the fuel is ignited either by spark plug
or by means of auto ignition. Hence, the charge is ignited
at maximum compression and the gases expanded against ~he
working cylinder beyond their initial volume,
At the time the intake valve opens, at about 40
BTDC, ~he piston has completed about 90.5% of its exhaust
stroke leaving only 9.5~/O of îts displacement volume, plus the
diminutive combustion chamber volume unoccupied. The air
charge will have a velocity similar to tha~ of the rising pis-
~on and virtually no expansion of the charge will take plac~
before the piston reaches top dead center (TDC). The advanc-
ing piston prevents admission of a charge volume greater than
the volume of the combustion chamber (whose pressure equili-
brates with the manifold-reservoir pressure) at the time of
the closing of the intake valve 'i', at about 10 BTDC. Com-
bustion will begin before top dead center (BTDC) for the utmost
in efficiency, As stated, in this particular arrangement if
the compression ratio is 16:1 the expansion ra~io will be
48:1. Therefore, the gases are expanded to three times their
initial volume, Alternatively, one s~age of compression,
could b~ done in the compressor cylinder 5 and the slightly
larger volume of charge could be received in the expander
cylinders 2, 3 and 4 and a second stage of compression could
then be accomplished in the expander cylinders, the compression
ratio being established by the volume of the three combustion
chamber in relation to the total displaced volume of the single
compressor cylinder.
The exhaust gases are discharged via an exhaust
manifold 21 and the scavenging would be extremely efficient.
In a conventional 4.2 liter ~ cylinder automobile engine each
piston displaces about 89.4% of its to~al cylinder volume in
the exhaust stroke (displaced volume/total volume). Similar
scavenging efficiencies can be realized in the engine accord-
ing to this invention, For example, if the intake valve 'i'opened at 40 BTDC and the exllaust valve closed at 40 BTDC
the stroke of the piston would be 90.54% com~lete. TherefGre,
3~
90.54% Qf the displacement volume of 522.3 cc (same 4.2 liter
engine) is 472.9 cc. This a~ount divided by the total volume
of the cylinder of the engine of this invention is 87.8% of
volume displaced (and scavenged).
Referring now to Figure 12, there is shown a similar
engine arrangement to that illustrated in Figure 3 iIl which
like parts are designated like reference numerals with the
addi~ion of suffix 'b' and in which a projection 150, Figure 12,
affixed to the crown of expander cylinder piston 6b, closes
the opening of the combustion chamber 151 at somewhere near
40 degre~s before top dead center (BTDC) as piston 6b rises
in its exhaust stroke. This arrangement facilitates exhaust
scavengin~ by allowing the exhaust valve to remain open past
TDC and by virtually displacing all of the burned gases while
preventing the charge, which is passing the intake valve into
the combustion chamber, from entering the cylinder proper. The
projection 150 may be fi~ted with a compression ring 152
residing inside the opening o the combustion chamber as shown
in Figure 13.
Figure 14 is a diagram for suggested valve timing
and can be used with the arrangement shown in Figure 12 for
improved scavengingfor all of the designs of ~his invention.
The suggested operation is in this manner. In the expander
cylinder (Fig. 12) the exhaust valve opens near bottom dead
center (BDC) and as the piston 6b ~ises, it expresses the
burned gases through the exhaust valve 'e' (not shown).
about 40 degrees before top dead center (BTDC), the intake
valve opens, at approximately the same time the projection 150
on top of the piston occludes the outlet of the combustion
chamber 151 effectively sealing it. At this tim (40 degrees
BTDC) the piston has completed 90% of its scavenging, therefore,
it only has lOV/o of further travel. If ~he pis~on stroke is
four inches9 then the amount of stroke remaining would be
4/10 inch. Therefore, the projection on the piston would n2ed
be only 4/lOths inch high to seal the combustion opening as
the intake valve opens at 40 degrees BTDC, As illustrated in
Fi~ure 14, ~he exhaust valve remains open as much as 30
degrees pas~ TDC.
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Th~ diagram in Figure 14 illustrates valve timing
ln which at 40 degrees BTDC the projection 150 on piston 6b
closes combustion chamber port 151 and a~ the same time
fresh charge begins to enter intake valve 'i'. The piscon
continues to rise until there is practically zero clearance
with the face of the engine head, expelling virtually all of
the exhausted gases. During the 40 degrees of crank rotation
the intake valve is opened, pressure equilibrium is established
between the combustion ehamber 151 and the manifold 16b.
At 5-10 degrees before top dead center, the in~a~e valve
closes and fuel is injected and ignited at maximum compres-
sion for greatest eficiency. Shortly after top dead center
(TDC) the exahust valve 'e' closes. The pressure of the
burning gases is expanded against first the piston valve
crown 150 and then into the cylinder and against the entire
piston ~rown after the crank angle is 40 degrees past top dead
center. The charge is expanded against the piston for the full
length of the expansion stroke.
The compression ratio is established by the total
volume o all of the combustion chambers which are supplied
by a single compression cylinder, divided into the displaced
volume of the single compressor cylinder. For a 2 liter four
cylinder engine, this would be 500 cc divided by 31.25 for a
compression ratio of 16:1. The combustion chamber volume of
this engine would be only 10.4 cc per cylinder or the 31.25 cc
for the thrQe firing cylinders.
Although the intake manifold 16 ~ust withstand high
pressures this will not add to the weight of the enginer because
the volume of air charge flowing through it should not be more
than l/16th to l/8~h of the volume passing ~hrough the mani-
fold of a conventional engine ~s the charge is alreadypartially, or preferably7 completely compressed. This small
volume of charge allows ~he manifold to have a small inside
diameter. The manifold 16 should be small enough or the
heavier charge to have suficient velocity to charge the
expander cylinders 2, 3 and ~ bu~c nevertheless should have
enough volume so that ~here would be no appreciable pressure
drop when an expander cylinder is charged. When the intake
3t~
valves 'i' to the power cylinders open the pres.sures in
the combustion chamber and in the manifold equilibrate.
With the small volume of air charge introduced into
the combustion chambers the intake valves 'i' of the engine 1
can be smaller and lighter (requiring lighter springs) and
indeed may be shrouded with no loss of volumetric efficiency.
Other mPans besides shrouding for providing a tangential
charge direction can also be ~sed.
Although the in~ake valve wîll be open for a short
time only (such as 30 or 40), this will be about the l/8th of
the time (or crank angle) that a conventional Otto cycle
engine in~a~e valve is normally open. Yet, the volume of
charge passing the intake valve, assuming a 16:1 compression
ratio, is only l/48th (one-third of the normal charge already
compressed) of ~he volume passing the intake valve of the Otto
cycle engine. In the three or six cylinder engine the volume
entering the combus~ion chamber will be only 1/32 that passing
the intake valve of a conventional engine,
Fuel may be injected directly into each of the expander
cylinders 2, 3 and 4 or into the individual inlet ports. The
quantity of fuel may be proportionate to the engine operating
conditions by varying the effective stroke of a fuel pump;
by varying the opening time of a uel injection nozzle fed
from a constant pressure main or by varying the rate of flow
through the injection nozzle.
Alternatively, a carburetor may be placed in front
on the compressor cylinder 5 and used for maintaining the
ratio of fuel to air in the region of the stoichiometric ratio.
In the gas or spark ignited version or mode the
engine may be throttled near the a~mospheri.c intal~e conduit 15
by means of a butterfly valve (not shown) in order ~o prevent
the engine wasting work by having to compress more air than
needed to maintain the s~oichiometric fuel to air ratio. A
means is described later for reducing or eliminating requir~d
throttling in the spark ignited version or mode.
So far as compression ignition operation is con-
c~rned the speed could alternati~ely be controlled by the fuel
- 12 -
rate alone. Thus automatic fuel air ratio control would not
be required and throttle valves could be eliminated.
Figure 2 shows one means of utilizing automatic one-
way valves in the compression cylinder 5. ~ile reed type
valves 30 (admissi.on), 31 (outlet) are illustrat~d on the
compressor cylinder 5, other valve types> such as sliding
valves or sleeve valves could be used.
Figures 3 and 12 of the dr~wings illustrate one means
of operating the intake valves 'i' o~ the power cylinders of
the engine with reference to cylinder 2. The speed of the
camshaft 20 is arranged to be the same as tha~ of the crank-
shaft 10 and is driven from the crankshaft by a gear 22 on
the crankshaft and sprocket drive 23 shown in Figure 1.
Large cam 24 or 246 opera~es push-rod 25 or ~5b and rockerarm
26 or 26b to activate in~ake valve 'i' which opens at about 40
BTDC and closes at about 10 BTDC.
Figure 4 shows how cam 27 operates push-rod 28 and
rockerarm 29 to activate exhaust valve 'e' which opens a~
approximately bottom dead center ~BTDC) and closes at 40 -
35BTDC in the first design. In the alternate design, theexhaust valve may be held open past top dead center for better
scavenging if desired as illustrated in Figures 1~ and 14.
To facilitate starting the englne, quick compression
build-up could be achieved if necessary, by mo~entarily block-
ing the intake to the expander cylinders (Fig. 7). Theintake valves of the expander cylinders 2, 3 and 4 could`be
deactivated (there are several methods of doing this in the
art, some of which are described la~er). For example, one
way blocking valves 32~ 33 and 34 (Fig. 7) could be placed
~n each branch of the transfer manifold 16 and closed.
Alternatively, sliding valves could be placed between
the transfer manifold and the inlet ports of the cylinders
and closed. Moreover, or.e way valves 35, 36 and 37 can
be placed between each expander piston and thP associated
intake valves ~o allow each expander pis~on to pull in
atmospheric a~r unrestricted while the engine manifold was
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3~
being charged. Furthermore, a bypass line 38 with a one
way valve 39 and a blocking valve 40 could be placed in the
exhaust manifold 21 in order to direct the pumped air into
the manifold 16 for quiclcer build-up of compression.
A second means ~o facilitate fast starting would
be to open a valve leading from a compressed air reservoir
to the cylinders. This would supply compressed air for
instan~ firing of the cylinders or could be used to rotate
the engine for starting, as described later. The air reser-
voir could be supplied by an air-compressor retarder brake
described with reference to Figure 11 or by any o~her method.
In order to produce fast burning efficient combus
tion, velocities of the compressed air in each manifold branch
conduit 17, 18 and 19 should be high and charge veloci~ies in
the combustion chamber up to sonic velociti~s may be achieved.
Tremendous swirl can be produced in the combustion chamber by
controlling the angle of the inlet port with respect to the
cylinder radius or by the use of a shrouded intake valve.
The resulting turbulence helps promote combustion
by inte~mixing burned and unburned gases at the flame front
as i~ progresses across the combustion chamber. This feature
alone should make N0x and HC emissions negligible and virtually
eliminate CO emissions. The extra burning time of the extended
expansion process should then further reduce HC emissions to
only a trace.
Referring now to Figure ~ of the drawings, there is
shown a similar 4-cylinder engine 42, in which like par~s are
designated like reference numerals with the addition of
suffix 'a', and in which additional mid-cylinder exhaust ports
43, 44 and 45 are provided in the walls of the expander
cylinders 2a, 3a and 4a respectively, in order to improve the
scavenging efficiency. Such ports 43-45 would be uncovered
by their associated pistons 6a-8a respectively at the lowest
point of the piston s~roke. As the exhaust ports 43-45 are
35 uncovered, the pressure in the cylinders could expel much of
the exhausted gases to the atmosphere.
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Alternatively, a step-up gear set 46 can be placed
on the crankshaE~ lOa and geared to drive a scavenging type
blower 47 in order to inject fresh air into the ports 43-45
as they are uncovered by their associated pistons 6a-8a,
respectively In this arrangement, the associated exhaust
valves of each power cylinder 2a-4a would be opened at approx-
imately the same time as the ports 43-~5 were uncovered.
In this invention, the exhaust valves are open from
before BDC until about 40-45 BTDC and the piston itself dis-
places (scavenges) 907O of the burnt gases through the exhaustval~es. Therefore, if ~he blower system 46-47 is added, only
a small amount of fresh air need be supplied in order to drive
some of thP burnt gases through the exhaust valve and to
dilute the remainder of the gases which are then scavenged by
the stroke of the associated piston.
These arrangements would provide for cooler exhaust
valves and allow the exhaust valves to be closed earlier. In
~his way, the intake valves could be opened earlier and it
is envisaged ~ha~ ~he expander cylinder could be used for
additional compression of the charge if desired. For example,
the compression could take place partly in ~he compressor
cylinder 5a, whereafter this slightly larger charge could be
further compressed by the expander cylinders 2a-4a.
In a further arrangement of either of the four-
cylinder engines the single compressor cylinder could bedouble acting (not shown) althou~h the basic operation of
the engine would remain the same. In this arrangement, the
compressor cylinder would compress an air charge to a volume
sufficient to supply ~he three power cylinders wi~h one-half
to two-thirds of the normal volume of charge depending on
the expansion ratio required.
It is also envisag~d that a 5-cylinder engine in
which one of the cylinders comprised a dou~le acting compressor
cylinder would supply four expander (power) cylinders whose
combustion chambers are half the volume of a conventional
engine. This arrangement will produce four power strokes per
revolution with the expansion ratio being twice the compression
ratio.
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Furthermore, in an 8-cylinder reciprocating engine
any of the 4-cylinder constructions described above could be
doubled or alternatively three compressor cylinders could cc.n-
press the air charge for five power cylinders. The former
S would produce six power strokes per revolution and the latter
would produce five. In the latter case the combustion chambers
could be from 50% to 60~/o of normal volume according to the
expansion ratio desired.
In any of the engine constructions described herein
~he engines may be fueled by means of gasoline, gas or diesel
or indeed the engine can be constructed for hybrid operation
as a multi-fuel engine. In any event ~he smaller charge
exploded would permit a lighter construction for the compression
ignition engine arrangement and will also provide quieter opera-
tion for compression ignition (CI~ engines.
Referring now to Figure 9 of the drawings, there is
shown a schematic transverse sectional view through a six
cylinder internal combustion engine having two compressor
cylinders 68 and 69 and four expander (power) cylinders 70,
71, 72 and 73 and associated pistons 103, 10~, 105, 106, 107
and 108 all connected to a common crankshaft 74 by means of
connec~ing rods 75-80 respective~y.
The operation of an engine constructed according to
this arrangement is similar to that previously described in
that air at atmospheric pressure or supercharged ~o a higher
pressure is supplied to the compressor cylinders 68 and 69
~ia an inlet conduit 81 through admission control valve 113
and 114 and the air is compressed by way of outlet valves 84
and 85 into a high pressure transfer manifold 82 which supplies
the compressed charge to the expander cylinders 70 to 73
through intake valves 109-112. Therefore, each of ~he com-
pressor cylinders 6S and 59 supplies ~wo expander cylinders.
The combustion chambers of the expander cylinders
are preferably dimensioned to be no more than one-half the
volume of tha~ of a conventional engine at a s~milar com-
pression ratio and therefore the expansion ratio of the
engine is at least double that of a conventional engine. For
3~
example, at a compression ratio of 16:1 the combustion cham-
ber would be about one-quarter the volume (one-half the
normal charge compressed to the higher ratio) of an ordinary
engine and the expansion ratio would be 32:1.
Each cylinder is a two-stroke cylinder and is
scavenged by displacing the burn~ gases during the exhaust
stroke of the piston. Hence, virtually no air is used in
scavenging. The working ~iston rises displacing the exhaust
gases via an exhaust manifold 83, the associated intake valves
(109-112) open so that the charge begins to flow at about 40
BTDC and the associated exhaust valves (115-118) close at
about 40 BTDC. The enhanced scavenging system illustrated
in Figures 12 and 14,and described more fully in the descrip-
tion of the engine of Figure 1, would allow the exhaust valves
lS to remain open past top dead center without allowing the mixing
of incoming charge and exhaust gases. The inta~e valve can
have a shroud on one side which directs air charge flow into
a very turbulent swirl as previously described. Fuel is
injected at the time the intake is in progress or as soon as
the intake valve is closed at about 10 BTDC. When the inta~e
valve closes the charge is ignited by spark plug or by means
of auto ignition. The volume of the entering air charge in
~he preferred embodiment, is no greater than 1/32nd of that
passing through the intake`valve of a conventional engine and
therefore a good volumetric efficiency is achieved. This
gives each of the expander cy'linders 70 to 73 one power stroke
per revolutioTI so that a ~otal of four power strokes per
revolu~ion is produced by the 5iX cylinder engine which, of
course, is equal to ~he number of power strokes of a conven-
tional our-stroke eight-cylinder engine.
The valves of the power cylinders could be operated
as shown in Figures l, 3 and 6 or in the system illustrated
in Figures 12 and 14. ~lhe compressor cylinders could be
arranged as shown in Figure 2. Prefera'bly ~,he manifold 82
would be insulated for compression ignition operation.
The air charge could be completely compressed by
the com~ressor cylinders 68 and 69 or, it is also envisaged
that the compression could take place partly in the compressor
- 17 -
~ 3 ~
cylinders 68 and h9 and then this charge could be further
compressed by the expander cylinders 70 to 73.
A three cylinder engine arranged to operate in a simi-
lar manner to the six cylinder engine just described is also
envisaged. In this event only one compressor cylinder would
be provided which would supply a co~pressed air charge to two
expander cylinders thus producing two power strokes per revolu-
tion to equal the smoothness of a four-cylinder four-stroke
cycle engine. This arrangement would be the same as shown in
Figure 1 with one power cylinder removed and the volume of the
combustion chambers would ideally be no grea~er ~han one-half
tha~ of a conventional enginer at a similar compression ratio.
Either of the two schemes of Figures 4 and 5 or Figures 12 and
14 may be used for scavenging.
Reduced throttling can be achleved in any spark ig-
nited engine o~ this invention which has a plurality of compres-
sor cylinders in the following manner. At any time the atmos-
pherie air intake manifold pressure dropped appreciably below
ambient pressure, for example near half throttle, the outlet
fr~m one or more of the compressor cylinders could be closed
by a shut-off valve. Work done in compressing this captive charge
is recovered as the charge expands on the back stroke of the
piston with zero net induction pumping done by that cylinder.
Throttlin~ may be eliminated completely in spark ig-
nited engines as illustrated in Fig. l by providing late fuel
injection into the combustion chamber and allowing combustion
to begin in the injected s~ray. The violentswirling motions
of the gases will insure that very lean mixtures will burn com-
pletely.
Pumping work created by throttling would be greatly
r~duced thereby and intake manifold 81 pressure will remain
more nearly constant at all output loads, particularly over
the range including idel and one-third of maximum power out-
put where most engine loading occurs during typical automotive
operation. '~liS method could be used with any multlple of
the four cyl~nder or three cylinder arrangemen~.
Referring now to Figure lO of the drawings there is
shown a six-cylinder reciprocating internal co~ustion engine
3~
in which all ~he cylinders 86-91 and associated pistons 119-
124 operate on a two-stroke cycle and all cylinders are used
for producing power ~o a common cranlcshaft 98 via connecting
rods 92-97 respectively.
This engine is characterized by a more extensive ex-
pansion of the burned gases and a greater charge turbulencewith combustion beginning a tmaximum compression. In the case
of ~asoline operation ~he engine can operate at a higher compres-
sion ratio than is usual.
` In this two stroke design the cylinders are scavenged
by positive displacement with vir~ually no loss of air charge
or fuel in the scavenging process. The greater expansion ratio,
higher compression ratio and increased charge turbulence pro-
duces a more fuel-efficient engine while providing greater
power to weight ratio than that of the Otto cycle engine.
The engine is constructed much the same as a four-
stroke cycle internal combustion engine but with a number of
significant differences. The combus~ion chamber of each cy-
linder is preferably made no greater than one-half to one-third
the usual size for the compression ratio desired and according
~0 to the expansion ratio decided upon. The cam shaft (not shown~
is geared to turn at ~he same speed as the crankshaft in order
to open and close the inlet (125-130) and exhaust (131-136)
valves once during each revolution of the crankshaft. Compres-
sion takes place in one or more stages before the air charge
is admitted to the combustion chambers of the cylinders and
the intake manifold becomes a high pressure manifold reservoir.
Fuel injectors are used to inject fuel directly into the combus-
tion chambers except for natural gas or propane operation which
can be mixed in an EMPCO type carbueretor. An efficient high
compression air compressor 99 is placed between the air intake
15 and the working cylinders.
It is also envisaged that any extenral source of com-
pressed air can replace the compressor 99 and therefore the en-
gine can operate on waste compressed air for further fuel economy.
The pressure ratio can be increased at will until
the pressure ratio ~nominal compress~on ratio) is equal to or
surpasses the expansion ratio for greater power as the load
. . . . . .
-19-
demands. This could be accomplished simply by increasing
the speed of the compressor,
One of the most important el2ments needed for
success in this design is to provide a compressor which will
produce both the pressures and ~he quanti~y o~ air charge
needed for efficient operation and any suitable compressor
is within the scope of this invention, It is envisioned
that three stages of radial compression would be economical
and ideal for compression ignited engines.
The operation and function of the six-cylinder engine
depicted in Figure 10 of the drawings is as follows: the
compressor 99 aspirates air and compresses it into the manifold-
reservoir 100. A check valve at 101 may be used if compressor
pressure pulsations are great. The manifold reservoir 100 con-
tains such a volume that there is no appreciable drop in over-
all pressure as the cylinders 86-91 are charged sequentially.
As the engine is cranlced the working piston ascends to about
40 BTDC (see valve timing schemes shown in Figures 5 and 14)
which displaces the gases when its travel is almost to the
end of its associated cylinder. 1~is expels 90% of the
burnt gases through the exhaust valve (into the exhaust mani-
fold 137) which opens as the piston begins its exhaust stroke.
The piston is then at about 40 BTDC. The intake valve then
opens and an increment of the compresed air charge enters
through a valve (can be shrouded) as the piston continues
its strolce which is 90~/O complete. Fuel can be injected at
the same time (or as soon as the intake valve is closed3. The
high pressure air, the persistency of flow and the small
volume of the charge ~about 1/32nd to 1/48th of the volume
which normally passes an intake of a conventional engine)
assures a high volumetric efficiency. The intake valve ~hen
closes at about 10 BTDC and the mixture is ignited. In
~his manner combustion begins at maximum compression but ~he
air charge has at least two to three times the expansion of
an equi~alent Otto cycle engine. It will be appreciated that
if the combustion chamber is made half thP normal vol~me the
expansion ratio will be ~wice the compression ratio and a one-
-20-
3~
third normal volume combustion chamber will triple the expan-
stion ratio. IE the compression ratio is 16:1, the expansion
ratio can be either 32:1 or 48:1, respectively. Enhanced
scavenging may be achieved if desired by use of the scavenging
-system shown in Figures 12 and 14. In this scheme the mouth
of the combustion chamber is blocked at about 40 BTDC and
the exhaust valve is held open pas~ top dead center, and
the intake valve is opened at the time the com~ustion is
blocked. This sche~e is better descri7~ed in the description
of the engine of Figure 1.
Although less air charge is used, a correspondingly
smaller increment of fu~l is used. The farther the gases
expand against a piston the more work is done on the piston
and the more complete is the combustion and the cooler is the
exhaust gases. In a convention diesel engine approximately
100% excess air is aspirated at full load but the lack of
turbulence and time hinders complete mixing of the oxygen
and fuel. In the present engine design the tangential
entrance of the high velocity air as previously referred to
permits complete mixing of the fuel air charge which together
with the more extensive expansion gives more complete combus-
tion and, of course, ~he density of the air can be increased
at any level deemed efficient.
Alternatively, as in other designs one s~age of
compression say ~:1 could be done in the compressor 99 and
the charge received and furt'ner compressed in the expander
cylinders.
It is further envisaged that a reciprocating internal
combustion engine according to any of the designs of this
invention may have only one compressor cylinder for use in
charging a single expander (power) cylinder, i.e., a two-
cylinder Pngine In this case, the expander cylinder would
be of greater volume than the co~lpressor cylinder.
Higher ~han n~rmai compression ra~ios can be u~
ized in the gasoline engines of ~his invention for the
following reasons. The charge being co~.pressed outside the
hot firing cylinder will be cooler to begin with (it also will
3~
require less power to compress this cooler charge) which causes
a corresponding decrease in temperature of the end-gas at peak
pressure. Extreme cahrge turbulence causes mixing of the burned
and unburned gases at the flame front greatly increasing ~he
flame speed and allows the flame front to reach any end-gas
before the pressure waive arrives. The much smaller combustion
chamber (1/4 to 1/6 normal size) presents a much shorter flame
path from the spark plug to the end gas, further assuring arri-
val of the falme front ahead of the pressure wave. Furthermore,
the grea~er expansion of the gases produces a cooler exhaust
valve which is in the region of the end-gas which again reduces
the chance of detonation. This also reduces the peak pressure
temperature. The nominal time between start of compression and
peak pressure is much less since compression is done outslde the
firing cylinder which fact gives less residence time for pre-
~.nock conditions to occur. The air charge will have such ra-
pid swirl that burning of the fuel can take place as injection
proceeds leaving no fuel in the end-gas. In addition the en~
tire charge could be afker-cooled for large supercharge boost
when utmost power is required as for example during an aborted
landing by an aircraftO
Preignition will not be a problem in the engine of
these designs because the residence time of the fuel is less
than that required for preignition to occur.
The power of compression ignition engines operating
in this working cycle can be greatly increased by supercharging.
The inlet pressure can be boosted from a slight boost up until
the theoretical compression ratio equals the expansion ratio.
Some locomotives operate with a supercharge boost of ~hree
atmospheres which, with a eompression ratio of 12:1, produces
a theoretical compression ratio of b8:1. Some intercooling or
aftercooling would likely be required with very high pressure
boosts in order to lessen NOX emissions in C~ engines.
The power of spark ignition engines can also be
greatly increased by similarly boosting the inle~ air pressure.
Although tl~e characteristics of this working ycle
provides for very high compression without detonation, some
aftercooling would be required as the co~pression ratio
figures approached those of ~he expansion ratioO
.. . . . . ... . . . . . ..
-22~
This working cycle may under certain conditions,
such as when us~d in a compression ignition engine at very
light loads, result in the combustion gases expanding to
pressures less than atmospherie, At such conditions the nominal
compression ratio can be increased until it is equal to the
expansion ratio by increasing supercharge boost or by closing
off one or more of the expander cylinders, The latter can be
done by deactivating ~heir intake and exhaust valves along
with their respective fuel injector~s).
In the system suggested for a four-cylinder engine
in which the ~xpansion ratio is three times the compression
ratio, one expander cylinder could be closed to increase the
compression ratio ~o one half the expansion ratio. If, under
very light loads ~he pressure at the exhaust valve was still
negative, a second expander cylinder could be closed to produce
a compression ratio equal to the expansion ratio. l~ith an
eight-cylinder engine, one cylinder could b~ closed at a time
for finer control of th~ compression ratio,
With the system suggested for the six-cylinder
engine, the expansion ratio is double the compression ratio.
Under very light loads in the compression ignition engine,
one expander cylinder could be closed to increase the com-
pression ratio to two--~hirds the expansion ratio. Two could
be closed to produce equal compression and expansion ratios.
Aftercooling would not likely be required because now the
lightly loaded engine would be usin~ much less fuel and
grams N0x emissions per mile should not exceed limits.
There are several sys~ems described in the art for
deactiva~ing the poppet valves of a cylinder. The 189g Daimler
auto engine provided such a means by removing an extra member
from between the cam follower and the valve l.ifter push rod,
This allowed the valve spring to hold the valve closed until
such time as the spring loaded intermediate member was released,
An electroni system of valve control is manufactured
by Eaton Corporation and has bPen used in several automotive
engines, This latter system allows the releasing of ~he rocker
arm pivot support in order to deactivate the valve, This
-23- ~ 3~
system provides electronic controls which can sense exhaust
manifold pressure and cut out the necessary number of
expander cylinders at such a time the exhaust manifold
pressure drops to or below ambient pressure~
When the valves of a cylinder are closed the energy
of compression is returned to the shaft during expansion of
the same gas, Even if some of the gas contained in the
closed cylinder leaks out, there will be an equilibrlum
establis`hed in which the pressure of the contained gas and
the ambient atmospheric pressure will interact in such a
~anner that there will be no net loss of energy. No "flow
work" will be done during the time the cylinder(s) are closed.
Alternatively in any engine in which ~he gases could
expand to a pressure less th~n atmospheric further economy
could be achieved in the following manner. A pressure sensor,
102 in Figure 9, could be placed in the exhaust manifold and
monitored~ The fuel ra~e could then be adjusted so that there
would always be a slight positive pressure in the e~haust
manifold, This system would work well in a constant load,
constant speed engine in particular.
Referring now to Figure 11 of the drawings, addi-
tional fuel savings can be achieved in the engines described
hereinbefore by use of an economizer constructed as an air
compressor retarder brake. This six-cylinder engine is
similar to the engine shown in Figure 9 in which like parts
are designated by like reference numerals with the addition
of the suffix 'a'. The air retarder brake illustrated has a
compressor 13~ operatively connected to thP drive shaft of
vehicle or geared to the engine and stores energy produced
durin~ braking or downhill travel which is utilized to supply
compressed air to the engine power cylinders via the transfer
manifold of 82a, Such an economizer would be coupled with an
air reservoir 139 and during the time in which the economizer
reservoir air pressure was sufficiently high for use in the
power cylinders of the engine, the engine compressor coul.d
be clutchably disengaged so that no compression work would be
required of the compressor. A relief valve 140 prevents
-24-
excess build up of pressure in the air reservoir One way
valve 141 allows air from the reservoir to be transferred
to the manifold when the pressure in the reservoir 139 is
higher than in the transfer manifold 82a. In the case of
engine constructions having compression cylinders each com-
pression cylinder of the engine could also be deactivated
during this reserve air operation time by shutting off the
admission valve so that no net work would be done by the com-
pressor(s) until the manifold-reservoir pressure dropped
below operating levels. Several systems of deactivating
cylinder valves are described in the art and have ~een men-
tioned previously.
Operating the engine on this reserve air supply
would improve the net mean effective pressure (~EP) of
the engine for greater power and efficiency per unit of fuel
used.
This feature would produce additional savings in energy
especially in heavy traffic or in hilly country. For example,
an engine producing 100 horsepower uses 12.7 pounds of air
per minute. Therefore, if all energy of braking were stored
in the compressed air in the economizer reservoir, a ten,
twen~y or even thirty minute supply of compressed air can
be accumulated and stored during sto~s`and doT~^m hill travel.
When the reservoir pressure drops below the desired level for
efficient operation, a solenoid will reactivate the compression
cylinder valves and they (with the supercharger, when needed)
will begin to compress the air charge needed by the engine.
This economizer or alternatively any o~her suitable
type of air pump may also be used to prevent excessive mani~
fold pressure fluctuation in any of the designs of this
invention, i it is found desirable.
Using this air reservoir, the engine needs no com-
pression build-up for starting and as soon as the shaft is
ro~ated far enough to open one inta~e valve ~he compressed
air and fuel would enter and be ignited for "instant" starting.
Fur~hermore, the compressed air could be used to rotate
the engine for starting by opening simple valves a~ the top
.. . . .. . . .
-25 ~ 3 ~
of the cylinder as is common in large diesel engines, thus
eliminating the need for a starter motor.
~ n additional means, to those already suggested, of
facilitating cranking of the engine i5 to hold the intake valve
'i' or the bypass valves 35, 36 and 37 open during the full
downstroke of the associated piston thereafter closing the
intake valves, holding the exhaust valves closed and then
beginning the upstroke of the piston, adding the fuel (if
not premixed) and igniting it near the completion of the
upstroke, the next downstroke becoming the power stroke.
