A two-stroke piston engine and method in which oil-free air is mixed prior to ignition with oil-free fuel, by means of a venturi. The engine is lubricated by utilizing the pressure which the piston exerts in the crankcase to draw an air-oil mix into the crankcase and then to push the air and oil out while filtering the air with a rotary filter, to return the oil to a suitable reservoir, the oil-free air being sent to the venturi. Fuel enrichment, as for cold starting, is caused by placing air pressure on a fuel-containing bowl ahead of the venturi so as to increase the flow of fuel into the venturi, rather than by reducing the amount of air as is done with a conventional choke plate.

BACKGROUND OF THE INVENTION 
This invention relates to an improved two-stroke piston engine and to an 
improved internal combustion method. 
Current conventional two-stroke engines mix the fuel with a substantial 
proportion of lubricant and carburet the fuel-oil mixture and air before 
sending the air-fuel-oil mixture to a venturi. To be more specific, air is 
usually moved by atmospheric pressure past a choke plate and through the 
venturi, where fuel and oil are induced into the air stream; then this 
mixture of air, fuel, and oil is sent around a throttle plate, past reed 
check valves, and into the crankcase, from which the mixture is taken into 
the cylinder when the piston approaches its limit of travel farthest from 
the cylinder head. The purpose of this procedure, aside from refueling the 
cylinder, is to provide the needed lubrication of parts in the crankcase 
and of the parts of the cylinder and piston that come into contact with 
each other. However, as a result of this procedure a substantial amount of 
lubricant is consumed by the engine during operation and is expelled with 
the exhaust gases. In fact, the main objection usually raised about such 
two-stroke engines is the large amount of expensive lubricating oil used 
by these engines, necessitating the inconvenience of mixing the fuel with 
oil and leading to harmful pollution of the environment. 
I have found that by providing an engine operating according to a 
completely different procedure, I can reduce the consumption of 
lubricating oil to an amount like that consumed in four-cycle engines. At 
the same time, I can improve the operation of the engine. 
Thus, an important object of this invention is to provide a two-stroke 
piston engine which is more economical to operate than previous two-stroke 
piston engines. 
A further important object of the invention is to provide a two-stroke 
piston engine in which very little lubricant is consumed during operation. 
Another object of the invention is to provide a two-stroke piston engine 
that is less polluting in its operation and can meet higher standards set 
by environmental protection agencies. 
Another object is to provide a two-stroke piston engine having lower 
manufacturing costs than heretofore. 
Another object is to provide a two-stroke piston engine that is competitive 
economically with four-stroke piston engines, for many uses. 
A further object is to provide an improved method of operation for a 
two-cycle engine. 
SUMMARY OF THE INVENTION 
A two-stroke engine of this invention has a cylinder with a head, an open 
end, one or more intake ports, and one or more exhaust ports generally 
closer to the head than the intake port or ports. A compact crankcase lies 
adjacent to and opens into the open end of the cylinder. A rotatable shaft 
in (and extending outside) the crankcase has a flywheel on one end outside 
the crankcase, a power output on the other end outside the crankcase, and 
a crank in the crankcase. A connecting rod joins the crank to a piston in 
the cylinder, and the crank has a throw greater, and the piston a stroke 
greater, than the distance between two of the piston's oil-sealing and 
compression rings. Moreover, the piston rings most distant from the 
cylinder head never move across the intake ports or exhaust ports. The 
volume of the crankcase is kept small, so that the piston will have a 
significant pressure effect on air within the crankcase. 
An intake manifold enclosing the intake port or ports has a venturi at its 
entry. A fuel system has a fuel intake line, a bowl normally exposed to 
atmospheric pressure, and a fuel supply line having a check valve therein 
leading from the bowl to the venturi. 
An air inlet is provided with an air cleaner, a throttle plate, and reed 
check valves to admit air into the crankcase when the piston is moving 
toward the cylinder head and thereby reducing the pressure in the 
crankcase. Below the crankcase, but not open to it, is an oil reservoir 
having a metering valve for metering oil into the incoming airstream as it 
flows into the crankcase. The metered oil is mixed with the air, 
preferably by atomizing it into the air, and is carried into the crankcase 
and from there, into the adjacent portion of the cylinder, so that it 
lubricates between the cylinder and the piston, as well as lubricating 
other moving parts. When the piston moves away from the cylinder head, the 
crankcase pressure forces air-oil mist out from the crankcase, and at the 
same time the pressure in and from the crankcase closes the reed check 
valves at the air inlet. 
The air-oil mist leaving the crankcase is forced to pass through a filter 
that removes the oil for return to the reservoir. The filtered air is 
oil-free. Oil is returned to the reservoir by a drainage line in the 
bottom of the crankcase and a line from the filter's cover. 
The filtration is preferably accomplished by a rotary filter mounted on the 
crankshaft near the boundary of the crankcase. The filter operates 
centrifugally and also contains a filter medium for aiding in separating 
the oil from the air. The filter's inlet for the oil-air mixture 
preferably lies all around its outer periphery, and its outlet for the 
oil-free air is at its inner periphery. The crankcase is kept small in 
volume, being reduced in volume enough to compensate for the volume of the 
filter and adjacent areas, so that there is adequate pressure variation in 
the crankcase and filter as the piston reciprocates. The oil-return 
conduit includes a check valve passing air into the oil reservoir but not 
out therefrom, so that as the piston moves away from the cylinder head, 
pressure is built up inside the oil reservir, as it is inside the 
crankcase. Then, when the piston moves toward the cylinder head, the 
crankcase pressure drops while the pressure within the oil reservoir 
remains high. As a result, the pressure within the oil reservoir forces 
oil through the metering valve and into the air that is then being drawn 
into the crankcase. 
The filtered oil-free air is sent through the venturi, drawing in and 
mixing with the oil-free fuel from the fuel supply line. As a result, a 
mixture of oil-free fuel and oil-free air flows to each intake port at the 
time the piston opens the intake ports. Hence, there is very little 
consumption of lubricant, for the lubricant is used only to lubricate 
within the crankcase. 
A fuel enrichment system accomplishes what is, in other engines, 
accomplished by a choke. For this purpose, there is a check valve in the 
fuel intake line, and a branch air conduit conducts some of the oil-free 
air on its way to the venturi, into an air space directly above the 
surface of the liquid in the fuel bowl. This branch air conduit has a 
normally closed valve, which can be opened manually to place air under 
crankcase pressure above the fuel in the bowl. When the bowl is thus 
pressurized, more fuel than normal is forced through the fuel supply line 
to the venturi, enriching the oil-free fuel-air mixture fed to the intake 
port manifold. When the need for enrichment is over, the normally closed 
valve in the branch air conduit is closed, and the fuel bowl is returned 
to its normal operation, exposed to air under atmospheric pressure. 
The main similarities between the method of operation of the present 
two-stroke piston engine and that of conventional ones, are that both use 
crankcase pressure to recharge the cylinder with a fresh supply of fuel 
and air, that the supply of the fuel-air mixture passes through intake 
ports at the lower end of the piston stroke, and that, in both, the 
compressed gases are fired each time the piston reaches or approaches its 
upper limit of travel. In most other ways, the present invention operates 
differently from conventional two-stroke piston engines. Unlike them, the 
engine of this invention mixes no oil with the gasoline, and the air is 
handled in a completely different manner, nearly opposite to carburetion 
systems of current two-stroke piston engines. 
In the method of the present invention, the incoming air, at the very 
beginning, passes around a throttle plate and then through a check valve, 
such as a reed valve, and from there goes into the crankcase, without 
mixing with any fuel. However, after passing the reed valves, the air, in 
an amount selected by the throttle plate, preferably flows through the 
rotary filter from the center outward and then through a port or ports 
that enters into the crankcase. As the air enters the crankcase, a small 
amount of oil is injected into it, creating a mixture to lubricate the 
crankcase and all of the moving parts therein. 
When the piston begins its downward travel, air is then forced to flow back 
by the same path from which it had entered the crankcase, again passing 
through the filter but this time, from the outside in. The compression of 
the air within the crankcase closes the reed valves, and they remain 
closed until the piston travels downward far enough to open the intake 
ports in the cylinder wall. Thus, as soon as decompression of the cylinder 
through the exhaust ports has taken place, the air trapped inside the 
crankcase is forced via the filter through the intake manifold to the 
lower pressure area inside the cylinder. To reach the intake manifold, the 
air leaving the crankcase must first pass through the rotary filter, which 
removes all of the oil from it, and only then does the air flow toward and 
through the venturi, which creates a low pressure area in the air stream, 
so that a metered amount of fuel is drawn in and is mixed with the air 
without using any carburetor per se. 
Thus, whereas a conventional carburetion system blends a mixture of 
gasoline and oil with air before the air enters the crankcase, in the 
present invention unblended fuel without oil is mixed with the air but 
only after the air has first entered the crankcase, lubricated the engine, 
and has been filtered free from the oil. Fuel is mixed with the air after 
the air leaves the crankcase. This is substantially the opposite of 
prior-art systems. 
The throttle plate, which restricts the amount of air entering the 
crankcase, also, therefore, restricts the amount of air that passes 
through the venturi and, in turn, determines the degree of vacuum to be 
developed in the venturi. Thus, the intake manifold is separate from the 
crankcase, and yet it is linked to the crankcase by way of the rotary 
filter which removes the entrained oil. 
In the present system, carburetion is accomplished in the venturi itself, 
but a fuel bowl like that in a conventional carburetor may be used, and in 
fact a conventional carburetor mechanism may, if desired, be used, having 
a fuel bowl and float assembly; the venturi draws fuel from the fuel bowl 
into the air which mixes with the fuel in the venturi (i.e., atmospheric 
pressure within the bowl forces the fuel into the low pressure area within 
the venturi), but in this invention no mixture takes place inside such a 
conventional "carburetor" mechanism. 
The method of operation is also novel in its fuel enrichment system, which 
is different from the typical choke that enriches the fuel-air mixture by 
reducing the size of the air passage and thereby reduces air flow and 
draws in more fuel relative to the air. In the present invention, the fuel 
enrichment used at the time that choking would normally be used, as in 
starting a cold engine, employs a valve that switches from atmospheric 
pressure on the fuel in the bowl to crankcase pressure, by inducing air 
under pressure into the space above the fuel in the bowl. The more highly 
pressurized fuel bowl then sends more fuel to the venturi to provide a 
richer mixture with the air. The normally closed valve is open only at 
times when fuel enrichment is necessary, primarily for starting the cold 
engine. Once the engine has been started, the fuel enrichment selector is 
rotated, so that the valve is closed, and atmospheric pressure again 
operates to pressurize the fuel in the bowl from then on. 
To enable this type of operation in which crankcase pressure pressurizes 
the bowl, it is necessary to have a check valve in the fuel line, so that 
the fuel can pass from the tank to the bowl, but not back. With this 
arrangement, crankcase pressure cannot backfeed the fuel toward the tank. 
Another check valve is also necessary in the fuel line leading from the 
fuel bowl to a needle valve assembly near the venturi, to stop any flow of 
fuel from the needle valve back to the fuel bowl and float assembly when 
the piston is on its downstroke, compressing air in the engine crankcase 
and manifold system. 
It should be stressed that fuel is not mixed with the air until the air has 
lubricated the crankcase, has left the crankcase, and has been freed of 
oil content. Only when the air is moved toward the cylinder and after the 
intake ports are opened by the piston's being displaced below the intake 
ports, is air mixed with the fuel, and this mixture occurs in the venturi, 
at the entrance to the intake manifold, rather than in a carburetor per 
se. 
Other objects and advantages of the invention will appear from the 
following description of a preferred embodiment thereof.

DESCRIPTION OF A PREFERRED EMBODIMENT 
The engine 10: cylinder 12, piston 20, and crankcase 25 
An engine 10, shown partially exploded in FIG. 1 and in section in FIGS. 2, 
3, 6, and 7, includes a casing 11 providing a cylinder 12 (FIGS. 2 and 3) 
having a head 13 at which a spark plug 14 may be located. The cylinder 12 
is provided with one or more exhaust ports 15 and one or more intake ports 
16, and the intake ports 16 are provided with an intake manifold 17. For 
an air-cooled engine 10, cooling fins 18 may be provided; a water-cooled 
engine may use a conventional water-cooling system. 
A piston 20 moves in the cylinder 12 and is provided with piston rings, for 
example, four rings 21, 22, 23, and 24. The extreme piston rings 21 and 24 
are relatively close to the ends of the piston 20, and it will be noted 
from a comparison of FIGS. 2 and 3 that the lower piston rings 23 and 24 
never go above the intake ports 16 or the exhaust ports 15. It will also 
be noticed in the comparison of FIGS. 2 and 3 that at the bottom of the 
stroke the upper piston rings 21 and 22 both lie below the position 
occupied by the piston rings 23 and 24 at the top of the stroke. An 
air-oil mixture is used to lubricate the engine 10 from within a crankcase 
25, as a mist. This mist is able to accomplish proper lubrication of the 
moving parts, including the rings 21, 22, 23, and 24, without sending any 
of the air-oil mist into or out through any of the ports 15 or 16; yet, 
full lubrication of all the piston rings 21, 22, 23, and 24 is achieved. 
A shaft 26 rotates inside the crankcase 25, being supported on suitable 
bearings 26a (FIG. 7) with oil seals 26b. The shaft 26 extends beyond the 
crankcase 25 at both ends, with a flywheel 27 (FIG. 7) on one end portion 
28 and a power take-off arrangement (not shown) on the other end portion 
29. Since a one-cylinder engine 10 is being described, by way of example, 
the shaft 26 carries a single crank 30, supporting a thrown shaft 31 
(FIGS. 2, 3, and 7) and a connecting rod 32 (FIG. 2) connects the piston 
20 to the thrown shaft 31 by means of suitable bearings 33. The shaft 26 
also carries normal counterweights 34. The crankcase 25 is enclosed in the 
casing 11 with the aid of a closure plate 35, in which are provided 
conduits 36 and 62 (FIG. 7). As can be seen in FIGS. 1 and 7, a portion 38 
of the plate 35 closes off a generally semicircular portion of a circular 
opening 39 through the casing 11, which has ports 37 therethrough that are 
connected to the conduits 62. 
The air entry and flow into the crankcase 25; the separator 50 
Air enters the engine 10 via an air cleaner 40 and a conduit 41 having a 
throttle plate 42 (FIG. 1), and reed check valves 43 having an 
air-distributing casing 44 connected to the conduit 41. As best shown in 
FIGS. 1 and 7 (and diagrammatically in FIG. 8), the air flows from the 
check valves 43 into a main air conduit 45. As will be seen, air from 
outside enters the conduit 45 only when the crankcase 25 is dropping below 
atmospheric pressure, due to the piston 20 moving upwardly from its FIG. 3 
position to its FIG. 2 position. Air then flows from the conduit 45 into 
the conduit 36 between closure plate 35 and casing 11 and from there, by 
way of a semicircular port 46 (matching the semicircular partition 38) 
into a space 47 enclosed by a stationary filter casing 48 that is bolted 
to the casing 11. 
Inside the stationary filter casing 48 is a rotary filter unit 50, 
comprising a pair of discs 51 and 52 secured together with a porous filter 
medium 53, such as steel wool, between them. The outer disc 51 is mounted 
on a sleeve 54, which is attached to the shaft 26, as by a set screw 55. 
The casing 48 has a rotary shaft seal 56 which engages the sleeve 54. The 
inner disc 52 is spaced away from the shaft 26 to provide an inner 
peripheral port 57 and has a flange 58 that is in rotary sealing 
engagement with a rotary shaft seal 59 mounted in the closure plate 35. 
The outer periphery 60 of the filter unit 50 is open and is spaced 
somewhat in from the inner periphery 61 of the casing 48 to provide for 
air passage to one or more conduits 62 leading to conduits 37 and thereby 
into the crankcase 25. Crankcase volume is kept small, by so casting the 
casing 11 to reduce volume, to compensate for the volume inside the filter 
casing 48, so that the piston 20 varies the pressure in the crankcase 25 
adequately below and above atmospheric. 
The air from the conduit 36 thus flows via the port 46 into the port 57 at 
the inner periphery of the filter 50, then outward through the filter 
medium 53, leaves the outer periphery 60, and then flows via the conduits 
62 and 37 into the crankcase 25. 
The oil reservoir 65 
An oil reservoir 65 (See FIGS. 3-5) is conveniently located beneath the 
crankcase 25, though partitioned off from it. The reservoir 65 is placed 
under pressure by means of a conduit 66 having a check valve 67 and 
leading via a passage 68 into an air space 69 at the upper end of the 
reservoir 65, from a drainage cup 70 formed by a part of the filter casing 
48. The check valve 67 is preferably of a magnetic type to ensure quick 
action. Oil which collects at the bottom of the crankcase 25 flows via a 
sump 71 and a conduit 72 into the drainage cup 70, and then into the 
conduit 66. Oil which is filtered out from the air, flows from the 
drainage cup 70 into the conduit 66. Both the sump 71 and the drainage cup 
70 are at crankcase pressure. The check valve 67 prevents backflow from 
the reservoir 65 to the crankcase 25; so air that enters at more than 
atmospheric pressure, thereby pressurizing the reservoir 65 relative to 
the crankcase 25 and holding the pressure in the reservoir 65 when the 
crankcase pressure begins dropping below atmospheric. 
As can be seen by FIGS. 3, 4, 5, and 8, oil is fed from a low level of the 
reservoir 65 through an opening 73 into the interior of a sleeve 74 whence 
it can enter an opening 75 in a tube 76. A branch conduit 68a for air 
under pressure leads from the passage 68 into the upper end of the sleeve 
74. The tube 76 has a check valve 77, and oil flows upwardly through a 
needle valve 78, from which it is injected via a conduit 79 into the 
conduit 37 through which the air stream enters the crankcase 25. 
Air flow in and out of the crankcase 25 and concomitant oil flow 
As stated, air flow is generated, and its direction determined by, the 
movement of the piston 20 in the cylinder 12, which determines the 
crankcase pressure. When the piston 20 is moving upwardly (from its FIG. 3 
position to its FIG. 2 position) air is drawn into the crankcase 25, and 
when the piston 20 is moving down from its FIG. 2 position to its FIG. 3 
position, air is being expelled from the crankcase 25. At the time when 
air is being drawn into the crankcase 25, the air pressure in the 
reservoir 65, being higher than the pressure in the crankcase 25, forces 
some oil through the needle valve 78 and into the air stream. The air 
therefore carries this oil as a mist throughout the entire interior of the 
crankcase 25 and lubricates all the bearings. The mist is also carried 
into the lower portion of the cylinder 12. The air-oil mist is not 
permitted to flow into the combustion chamber 80 of the engine 10 nor into 
the ports 15 or 16. 
Air flow from the crankcase 25 to the intake manifold 17 
Downward movement of the piston 20 forces a predetermined amount of air-oil 
mist to flow out from the crankcase 25 through the ports 37 and 62 and to 
the outer periphery 60 of the filter 50. The air flows through the filter 
50, and in doing so the air is centrifugally freed from oil, aided by the 
filter medium 53. The filtered oil passes back into the reservoir 65 
through the conduit 66, and oil from the oil sump 71 at the bottom of the 
crankcase 25 collects by condensation and gravitation and is drained into 
the conduit 66 via the drainage cup 70 and conduit 72. The air is freed 
from oil as it flows through the separator or filter 50 and passes out 
from the inner periphery 57, whence it flows via the port 46 and conduit 
36 back to the conduit 45. 
The air, after leaving the crankcase 25 and passing through the filter 50, 
is oil-free and is ready to be mixed with fuel for use in the combustion 
chamber 80 of the engine 10. Since the air contains no oil, no oil is 
consumed in the combustion chamber 80 of the engine 10. The air passes 
from the conduit 45 to a conduit portion 81 leading to a venturi 82 and 
from the venturi 82 flows to the intake manifold 17 and from there, 
through the intake ports 16 and into the cylinder 12. 
Fuel flow 
Fuel comes into the engine 10 from a tank 83 (FIG. 1) via a fuel line 84 
having therein a check valve 85. The fuel flows into a bowl 86, which may 
be a carburetor bowl with a float valve, although no carburetion is truly 
performed in the assembly 87 which includes this bowl. From the bowl 86, a 
fuel supply line 88 having a check valve 89 leads the fuel through a 
metering valve 90, which may be a needle valve, into the venturi 82. There 
it is drawn into the air, due to the low pressure created by the venturi 
82 after exhaust has taken place and the intake ports 16 are open. Mixture 
is accomplished in the expansion portion of the venturi 82 at the entrance 
to the intake manifold 17. Thus carburetion is performed in a different 
manner from the usual method, taking place after the air has left the 
crankcase 25 and within the venturi 82, which is part of the intake 
manifold 17 and is separated from the assembly 87. No oil, it must be 
stressed, is introduced into the fuel, nor is any present in the fuel-air 
mixture. 
Fuel enrichment is obtained without the use of a choke by means of placing 
air under crankcase pressure into a subordinate conduit 91 connected to 
and midway between the conduit 45 and the conduit 81. A valve 92 has two 
positions. In the normal position, the valve 92 admits air from the 
atmosphere via a conduit 93 into a conduit 94 that conducts it into the 
assembly 87, where it assures that the bowl 86 is under atmospheric 
pressure. In other words, the space 95 above the fuel in the bowl 86 is 
normally under atmospheric pressure. However, when fuel enrichment is 
desired, the valve 92 is moved to close off the conduit 93 and open the 
conduit 94 to the conduit 91. In this position, air under crankcase 
pressure is conducted from midway between the conduit 45 and the conduit 
81 into the space 95 over the surface of the fuel in the bowl 86. This air 
more highly pressurizes the fuel in the bowl 86, which is normally held 
under atmospheric pressure. During this fuel enrichment operation, the 
fuel in the bowl 86 is thus subjected to additional pressure. The 
additional pressure causes more fuel to pass through the needle valve 90 
and to enter the venturi 82. Operation of the fuel enrichment system is 
done in the normal manner, with what appears like a choke lever 96 
operating the valve 92. 
Some comments on the rotary filter 50 
The rotary filter 50 is one of the key components of the engine 10. Without 
it, the engine 10 would consume oil. The rotary filter 50 is a spinning 
wheel with filtering media 53 through which the air can pass from outside 
the engine 10 into the crankcase 25, and then from the crankcase 25 to the 
intake manifold 17. The sole purpose of the rotary filter 50 is to remove 
oil from the air when the air passes from the crankcase 25 toward the 
venturi 82, at the times when the piston 20 is moving from its FIG. 2 
position to its FIG. 3 position. The filtering is accomplished primarily 
by centrifuging, that is, by centrifugal force, and partly by the 
filtering medium 53. As noted before, when air is introduced into the 
crankcase 25 from the outside atmosphere, it enters the rotary filter 50 
at the inner periphery 57, near the shaft 26, i.e., at the center or hub 
of the spinning wheel 50. The rotary filter 50 is traveling at the same 
r.p.m. as the engine crankshaft 26, and this is a high rate of speed. The 
air flowing toward the crankcase 25 thus passes from near the center of 
the spinning wheel 50 outwardly to the outer periphery 60 and thence into 
the crankcase 25. 
When the piston 20 is moving downwardly, it begins to compress air within 
the crankcase 25. The air then leaves the crankcase 25, taking the same 
path back from which it came. The difference is that this time the air is 
going from the outer periphery 60 of the spinning wheel 50 toward the 
center of the spinning wheel 50. The air, with the slight oil mist in it, 
must pass through the rotary filter 50 in order to get to the intake 
manifold 17 and the venturi 82. As it does this, oil accumulates on the 
filter medium 53 and is immediately cast out by centrifugal force. The 
cubic inch displacement of the piston 20 does not have the capacity to 
force the oil inwardly against the centrifugal force, but air can pass 
inwardly through the rotary filter 50, for air can be compressed while the 
liquid oil cannot. As a result, oil inevitably collects on the filtering 
medium 53 of the spinning wheel 50, and the high centrifugal force of the 
spinning wheel 50 does not allow any liquid, in this case oil, to pass 
through it inwardly, but at the same time it does not restrict the air 
flow. The rotary filter 50 is used as a cleaning or isolating part of the 
engine 10 to isolate the oil reservoir 65 and the crankcase 25 from the 
intake manifold 17, so far as the lubrication system is concerned. It, 
however, does let the air pass through, and it assures that the air 
entering the venturi 82 is substantially free from oil. 
The volume of the rotary filter 50 can be changed to meet the oiling needs 
of a specific engine. The cubic inch capacity of the rotary filter may be 
less, equal to, or greater than, the cubic inch capacity of the piston 20. 
The crankcase volume is, as said, kept small. 
It is important to remember that just as much air passes through the 
filtering medium 53 from the center out as passes from the perimeter 
toward the center. In other words, just as much air tries to cleanse the 
filtering medium 53 of oil while entering, as there is air trying to put 
oil into the filtering medium 53 when air is flowing out of the crankcase 
25. As a result, there is a canceling effect, except as affected by 
gravitation, oil creepage, and so on. 
If the air entering into the crankcase 25 be considered a positive factor, 
being clean air, and the air that has the oil mist blended with it leaving 
the crankcase 25, be considered as a negative factor, then since they are 
equal in amount, they substantially cancel each other out. The spinning 
wheel 50 makes certain that they do cancel each other out. The clean air 
entering the spinning wheel 50 from the center of the hub and moving 
outward and the oily air entering at the periphery 60 and working inward, 
are moving in opposite directions and doing so at different times. The 
spinning wheel 50 removes the oil from the air charge that is forced 
toward the venturi 82. 
A novel effect of the rotary filter 50 is its blower effect. Like any other 
spinning object that enables air to flow from the center outward, it tends 
to act as a blower, which in no way affects the performance of the engine 
10, due to the equilibrium factor discussed earlier. The blower effect is 
always into the crankcase 25. Centrifugal force is the only force that is 
always present and uncanceled, always moving the liquid out and away from 
the center to the outer periphery 60. In effect, the rotary filter 50 is a 
two-way port between the engine crankcase 25 and the intake manifold 17, 
and it keeps the oil mist on one side and the clean air on the other. 
Lubrication within the crankcase 25 
As the air enters the engine crankcase 25 on the crankcase side of the 
rotary filter 50, it passes through the openings 62 and 37. As the piston 
20 moves up and draws a fresh charge of air into the crankcase 25, the air 
passes through these ports 62 and 37, and as it does so, minute droplets 
of oil are formed on the end of the oil line 79 leading from the oil 
reservoir 65. The air passes very quickly through the portals 62, 37 and 
blends with the oil to form a slight mist of light density. This air-oil 
mist moves throughout the crankcase 25 and lubricates the moving parts 
within the crankcase 25. 
Then, as the piston 20 begins its downward stroke, the air-oil mist is 
forced into the rotary filter 50, where the oil is cast-off, collecting on 
the walls of the stationary filter casing 48. Gravitation then moves the 
oil to the drainage cup 70 at the bottom of the casing 48. Oil that 
condenses and drops down in the crankcase 25 collects in the sump 71 and 
flows by gravitation to the drainage cup 70 via a conduit 72. 
The entire oiling system is operated by air pressure changes. As the oil 
collects in the drainage cup 70, it is returned to the oil reservoir 65 by 
an air stream sending it through the conduit 66. The entire oiling system, 
including the engine crankcase 25 and the oil reservoir 65 is isolated 
from the rest of the engine 10 by the rotary filter 50 and is, in basic 
effect, a closed system. Thus, when the piston 20 begins its downward 
stroke, the oil reservoir 65 and the interior of the sleeve 74 are 
pressurized with the same pressure that exists throughout the crankcase 
25. When the piston 20 begins its upward travel, the crankcase 25 then 
becomes a low pressure area, but the high pressure remains trapped in the 
oil reservoir 65 due to the check valve 67. The high pressure in the oil 
reservoir 65 forces oil through the oil line 79, going past the check 
valve 77 and through the oil metering needle valve 78. The high pressure 
then moves the oil into the incoming air stream. As long as the oil 
reservoir 65 air pressure is high and the crankcase 25 pressure low, that 
is, when the piston 20 is traveling upwardly, the oil continues to move 
toward the low pressure area. 
It is important to note that the oil is metered precisely by the needle 
valve 78, the setting of which can be changed, if desired. The action of 
feeding oil out through the conduit 79, bleeds off some of the pressure 
from the oil reservoir 65 into the crankcase 25, but when the piston 20 
begins its next downward stroke, it again creates a high pressure in the 
crankcase 25. The crankcase pressure is then higher than the pressure in 
the oil reservoir 65. The oil reservoir 65 has been isolated from the 
crankcase 25 by the one-directional check valve 67 in the oil return line 
66. While oil is being spun off the rotary filter 50 and collected in the 
drainage cup 70, the high pressure of the descending piston 20 has created 
a higher pressure in the crankcase 25 than in the oil reservoir 65, so 
that the oil accumulated in the drainage cup 70 is moved past the check 
valve 67 and back to the oil reservoir 65. If there is no oil in the 
drainage cup 70, the air from the high pressure within the crankcase 25 
merely increases the pressure in the oil reservoir 65. Any oil that is 
collected in the line 66 is moved along with the air pressure. 
Thus, the entire isolated oiling system works by pressure changes in the 
oil reservoir 65 and in the engine crankcase 25. To summarize, when the 
crankcase pressure is high, oil is returned to the reservoir 65, and when 
the crankcase pressure is low, a metered amount of oil is sent into the 
incoming air stream. Reservoir pressure is high only when the piston 20 is 
moving upward. It is also important to note that the density of the oil 
mist is very light, just enough to create an oil film over the moving 
parts within the crankcase 25. This includes the piston 20 and cylinder 
12, and it also includes the bearings for the shaft 26, the bearings for 
the wrist pin and the bearings 33 for the connecting rod 32. 
Some oil is cast-off the engine's moving parts and is not moved toward the 
rotary filter 50 by the airstream. Such oil collects, by means of 
gravitation, in the sump 71, at the bottom of the engine's crankcase 25, 
which drains down to the drainage cup 70 at the bottom of the rotary 
filter casing 48. The drainage cup 70 is the lowest point of any 
gravitation-returned oil, and once oil is in the drainage cup 70 air 
pressure moves this oil, along with the oil cast-off from the rotary 
filter 50, back to the oil reservoir 65. The cycle continues as long as 
the varying air pressures between the crankcase 25 and the oil reservoir 
65 continue, and this continues as long as the engine 10 runs. 
As mentioned before, it is important for the isolated oiling system, that 
there be a sufficient number of operative piston rings 21, 22, 23, 24, and 
the piston rings 23, 24 at the bottom of the piston 20 prevent the oil 
from creeping up the cylinder wall 12 and into the exhaust and intake 
ports 15 and 16. These rings 21, 22, 23, 24 are wiping and compression 
rings that keep the cylinder 12 clean and prevent oil consumption. Rings 
23 and 24 never expose the intake or exhaust ports 15 and 16 to crankcase 
oil mist. Since the upper rings 21, 22 always travel further down the 
cylinder wall 12 than the highest upward travel of the lower rings 23, 24 
adequate lubrication is given to them. 
To those skilled in the art to which this invention relates, many changes 
in construction and widely differing embodiments and applications of the 
invention will suggest themselves without departing from the spirit and 
scope of the invention. The disclosures and the descriptions herein are 
purely illustrative and are not intended to be in any sense limiting.