Note: Descriptions are shown in the official language in which they were submitted.
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TITLE: OPTIMIZED LINEAR ENGINE
CROSS-REFERENCE TO RELATED APPLICATIONS:
This application claims the benefit of PPA Ser. Nr. 60/437,875, filed 2003
January 3
FEDERALLY SPONSORED RESEARCH: Not Applicable
SEQUENCE LISTING: Not Applicable
FIELD OF THE INVENTION
[001] This invention relates to combustion engines primarily; and to pumps,
compressors, and fluid driven motors secondarily.
BACKGROUND OF THE INVENTION - THE PRIOR ART
[002] Internal combustion engines are used in enormous numbers as a means of
converting combustible fuel energy into rotary mechanical motion useful for a
multitude of
industrial and transportation tasks. These have become almost universally
standardized as
one or more units of a piston reciprocating in a cylinder where combustion
takes place, the
reciprocating motion of the piston being converted to rotary output motion by
means of a
connecting rod and crankshaft. In the earliest days, before 1900, this system
was well
adapted as a replacement for stationary steam engines, after which it was
patterned, being
slow, heavy, and easily repairable by local blacksmiths.
[003] After 1900 came the advent of the mass-produced automobile and
motorcycle
and the new sports of racing these. With these incentives, and through
monumental amounts
of both trial and error and modern technology, the crankshaft engine has
gradually developed
surprising reliability, efficiency, and light weight. Yet, it is clear that it
is still NOT an
optimum arrangement, especially as single cylinder units and fox tvpo-stroke
use. Standard
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connecting rod crankshaft engines suffer from numerous disadvantages and
limitations:
[004] (a) Standard engines have excessive vibration, especially as single
cylinder
units. The piston as it accelerates and decelerates creates reciprocating
inertia forces, which
cannot be balanced by the rotary motion of crankshaft counterweights. Such
counterweights
normally balance near 50% of reciprocating weight, but add vibration in other
directions.
Vibration of small engines contributes to operator fatigue, noise levels,
short life span, and
various and often unpredictable maintenance problems. Due to vibration
problems, drive
engines often are isolated from the load they drive, meaning a larger and less
efficient system
than integral construction would be.
[005] (b) Heavy inertia-storage flywheels are added to smooth out vibrations
and
allow smooth running at lower speeds, especially in the case of Diesel
(compression ignition)
types. Also crankshafts are often built with added weight for flywheel effect
and torsional
stiffness, but as energy storage varies as the square of the distance from
center of rotation,
this added weight near the center of rotation is far from the optimum
location, as the rim of a
flywheel would be. Together these add to engine weight, inefficient use of
this weight, cost,
size, and complexity.
[006] (c) In spite of the fact that a large diameter tubular shaft is the most
efficient
for rigidity and power transmission, crankshaft engines due to their
configuration transmit
power out of a closed crankcase by a sealed small diameter shaft, and then
must attach a
larger diameter power output hub. This entails splines, keyways, threaded
shafts, etc.
Generally another separate component is also attached for fan, ignition,
starter mechanism,
accessory drive, etc. The results are added weight and specialized machining,
with oil seals
and added parts at both ends of the crankshaft.
[007] (d) Especially in crankshaft engines operating with a vertical output
shaft,
vibration due to inherent unbalance is transmitted horizontally, adding to
machine operator
discomfort and maintenance problems, including lubricating oil leakage.
[008] (e) Cranl~shaft engines for industrial use with a single cylinder seldom
produce
more than 15 horsepower, due to vibration problems as size increases. Yet
efficient multi-
cylinder engines of 50 or even over 100 horsepower per cylinder are common,
showing that
with less vibration larger single cylinder engines would be viable, with great
advantages of
simplicity and economy over small muti-cylinder units.
[009] (f) Where smooth operation is a concern multiple cylinders - three or
more -
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are added to try to balance out and thus partially solve this vibration
problem, at an expense
and complexity uneconomical for small power needs. Also, adding additional
cylinders
contributes to additional harmonic vibrations which can lead to fatigue
failure and must be
carefully tested and analyzed, leading to longer development times and
sometimes operating
restrictions, as in the case of aircraft engines.
[010] (g) Crankshaft engine piston speed variations are inappropriate. With
the
connecting rod and crankshaft system piston speed varies between top and
bottom phases of
the stroke, and is actually fastest near the top, when a slower speed would be
advantageous to
allow time for more complete combustion and higher effective expansion ratios.
Conversely,
piston speed is slowest near the bottom of the stroke, with no useful effect.
The Bourke two-
stroke engine of the 1950's overcame these drawbacks with the use of a scotch
yoke drive to
the crankshaft, but could never solve vibration problems. Other methods have
been proposed,
but all involve additional complexity, weight, and manufacturing cost.
[011 ] (h) The connecting rod-crankshaft system has lugh friction due to side
thrust
on the piston during most of the stroke. This causes heat and wear, reducing
efficiency and
the useful life of the lubricating oil and the engine itself. Also, the piston
skirt needed to
carry this thrust adds to piston weight and engine height.
[012] (i) Crankshaft engines have developed into high-speed machines, giving
more
power to weight with smaller sizes. This, though, requires more gearing to
reduce these
speeds to those usable in practice, especially in transportation. At the same
time some speeds
are set within narrow limits, such as lawn mower blade speeds, and that of
generators to give
the necessary output frequencies, etc. To use lighter, higher-speed engines a
reduction drive
would be necessary for such uses, at a cost not compatible with the small
engine market.
Thus, despite many advances in high-speed mufti-cylinder engines, the
technology of small
engines is virtually stagnant due to speed as well as cost restrictions.
[013] (j) Crankshaft four-stroke engines require a separate camshaft operating
at half
crankshaft speed to drive valve gear. This requires two precision cut gears or
toothed pulleys
and belts, and entails extra parts, bearings, weight, and attention to timing
and alignment
during assembly and repair.
[014] (k) Crankshaft four-stroke engines depend on a lubrication system that
requires a pressure pump and stable horizontal orientation. This limits or
denies their use in
inclined and inverted operation, as in chain saws and other power tools, and
requires added
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systems and complexity to allow use in aerobatic airplanes.
[015] (1) Crankshaft four-stroke engines require a volume of oil for adequate
lubrication, cooling, and consumption, which adds to engine weight with no
mechanical
benefit, putting them at a weight disadvantage compared to two-stroke engines.
Additionally,
if water-cooled these engines require a separate and complex system including
radiator,
pump, external hoses, etc. with weight penalties, maintenance problems, and no
mechanical
advantage.
[016] (m) Crankshaft engines are very unsymmetrical, especially the four-
stroke
types, leading to high costs in engineering and manufacture. Due to offset
components such
as the camshaft and its gearing, the oil pump, cylinder placement at ninety
degrees to
crankshaft axis, etc., the cross-sectional area is large, leading to high drag
in aeronautical
applications, and limiting use in circular spaces. Due to lack of axial
symmetry, the majority
of engine components must be intricate castings or forgings, and thus they do
not lend
themselves to rapid or easily automated manufacture from extrusions or flat
stock
components. This also makes the setup for manufacture, and model changes
later, both slow
and costly, restricting both the size and location of engine manufacturers to
generally large
ones in developed countries. At the same time repair parts tend to be
specialized and costly.
This has led to high repair costs, trade deficits, and lack of self
sufficiency in smaller and
poorer countries.
[017] (n) In crankshaft two-stroke cycle engines the combined volume of both
crankcase and variable under-piston volume is used as a pump to ingest the
intake mixture of
air, fuel, and oil. The varying movement of the connecting rod would make
sealing the area
below the piston from the rest of the crankcase cavity very difficult. If this
were practical it
could be used to advantage for simple supercharging in both two and four-stoke
engines, air
compression, direct drive to reciprocating pumps, etc.
[018] (o) In crankshaft two-stroke engines the use of the crankcase for intake
pumping precludes the use of more reliable oil-lubricated power output
bearings in a separate
cavity.
[019] (p) Crankshaft two-stoke engines generally suffer from the fact that
intake
transfer and exhaust ports are timed only by piston movement, allowing fuel
mixture to exit
through open exhaust ports, exhaust gases to be intermixed with incoming fuel
nnixture
causing rough idle, etc. This causes high rates of fuel consumption and air
pollution. A few
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attempts have been made at varying exhaust port timing, but with additional
complexity and
cost. The addition of bulky and expensive "tuned" expansion chamber exhaust
systems has
been used to partially offset this problem. However they are effective only
during a small
range at high rpm, increasing power but not reducing pollution at other speeds
or rough idle.
More stringent air pollution controls and higher fuel prices will increasingly
limit the use of
standard two-stroke engines.
[020] With modern materials, computed aided design and manufacturing, and fuel
use and air pollution concerns, viable alternatives to the crankshaft engine
should be
investigated. Many other types of engines have been proposed, some tested, and
in a few rare
cases put into production, such as the Wankel rotary and the cam track
DynacamTM engine.
However even these have not been optimum, especially in the areas of exhaust
emissions and
economy of manufacture and have had generally limited success.
[021 ] While clearly much different in operation, the small, light, and low-
vibration
Wankel could be used in virtually every application now using piston engines.
It has
disadvantages, though, including:
[022] (q) Wankel rotary engine cost of manufacture is high. The necessary
optimum
clearances and large flat combustion chamber areas to seal require higher cost
production
processes and materials. Thus, in real terns it has not been able to compete
successfully with
standard piston engines.
[023] (r) Wankel rotary engine air pollution is more of a problem due to
varying
combustion chamber temperatures and sealing problems. Techniques used to
control
enussions in standard crankshaft engines are often not directly applicable to
the Wankel
rotary engine. These appear to worsen more with age than with standard
engines.
[024] (s) Wankel rotary engine repair services and parts are more costly and
are not
widely available due to few mechanics and parts manufacturers being familiar
with the very
different technology used.
[025] An alternate method to the connecting rod-crank shaft and rotary engine
systems of power output is the use of a reciprocating piston driving a rotary
output shaft
through a sinusoidal cam track driven mechanism. U.S. patent 1,052,763 (Stone
& Scott,
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1913) is one of many early examples of cam track single-cylinder engines. The
most
successful modern example is the DynacamTM Type Certified mufti-cylinder
aircraft engine,
shown in U.S. patent 4,492,188 (Palmer et a1,1985). Past patents for this type
of engine have
described various arrangements whereby this motion transfer has been tried,
and different
component arrangements, but clearly they all have had disadvantages,
including:
[026] (t) Previous cam track engines have excessive vibration as single piston
engines, caused by an innbalance of parts, even more than the connecting rod-
crankshaft
system with counterweights. Some patents show a second piston in line with the
first for
balance, examples being U.S. patents 1,613,136 (Schieffelin, 1927), 1,629,686
(Dreisbach
1927), 1,876,506 (Lee, 1932). These involve excessive added complexity,
especially in the
arrangement for power output, often necessitating multiple cam tracks,
undesirable shaft
through a combustion chamber,etc. Again in the interest of balanced operation,
many
patents show additional pistons added in an array around the shaft, as in the
DynacamTM, an
early example being 1,065,604 (Gray,1913). Like mufti-cylinder conventional
engines, these
also are too complex and expensive for small power needs.
[027] (u) Previous cam track engines have cooling complications. Some patents
for
single cylinder versions show a cam system within the piston itself, with no
means of cooling
the bearings as in U.S. patent 1,052,763 (Stone & Scott, 1913). As these would
be exposed
to heat from the piston, such a system would necessitate a large flow of oil
for cooling and
lubrication, necessitating a high capacity and power consuming oil pump, oil
cooling
radiator, etc., not economically practical for small engines, and never shown
in the patent
drawings. When multiple cylinders are used around a central shaft, space
restrictions
generally do not allow for air-cooling of the cylinders, and thus also require
a liquid coolant
pump, radiator, etc.
[028] (v) In previous cam track engines, lubrication is either a major problem
or
requires a complex system. In configurations showing a spinning bearing
assembly, lubricant
would clearly be thrown from the bearings by centrifugal force and would need
to be
constantly replenished by a pump-supplied pressure lubrication system.
Reciprocating
components may be difficult to supply or direct lubricant to, especially if
using sleeve-type
bearings needing internal oil pressure to operate. As mentioned, if adjacent
to the hot piston
or cylinder assembly, additional systems for cooling of the lubricant would
also have to be
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provided.
[029] (w) In previous cam track engines sizing of bearings is definitely
problematic
if these are within the diameter of the piston or cylinder, as shown in
several patents. The
high inertia and pressure loading on the piston assembly to be transferred to
the output cam
track require relatively large bearings, not possible in the space
restrictions often shown.
[030] (x) In previous patents of cam track engines, one or more single output
rollers
in a single cam track is usually shown. These are clearly subject to constant
and undesirable
abrupt rotation reversals, a major problem. Some show two output rollers at
each location to
avoid this, still with a single cam track, but need added length and
complexity to achieve this,
with no other advantage.
[031 ~ (y) In previous cam track engines, output is still generally by a small
diameter
shaft and a lower case equivalent to a crankcase is still needed, as well as
the shaft machining
and additional components mentioned above. With mufti-cylinder systems complex
castings
and machinings are needed.
[032] (z) In previous cam track engines, as with crankshaft engines, heavy
inertia
storage flywheels were often added to smooth out vibrations and allow smooth
running at
lower speeds. Alternately, the output shaft or sinusoidal cam may be made
oversize and
overweight for a similar effect, but as with a crankshaft its small radius is
still not an efficient
location for inertia storage.
BACKGROUND OF THE INVENTION - OBJECTS AND ADVANTAGES
Accordingly several objects and advantages of the present invention include:
[033] (a) to provide a single-cylinder engine which is of low vibration, with
100%
balanced reciprocating forces, minimal operator fatigue, low noise levels,
long life span,
minimal maintenance problems, and especially adaptable to direct or integral
drive of loads.
[034] (b) to provide an engine without the necessity of added flywheel inertia
for
low vibration or for operation using the Diesel cycle;
[035] (c) to provide an engine with a lightweight and rigid power output
attachment,
without need of separate parts or machining operations;
[036] (d) to provide a vertical-shaft engine without horizontal transmission
of
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vibration, operator discomfort, excessive maintenance problems, and leakage of
lubricant.
[037] (e) to provide an engine capable of smoothly producing large amounts of
power in a single cylinder, thus replacing mufti-cylinder engines in many
uses.
[038] (f) to provide an engine which does not require the complexity of adding
cylinders to achieve smooth operation;
[039] (g) to provide an engine with a balanced piston speed for optimum
combustion;
[040] (h) to provide an engine without piston side thrust;
[041] (i) to provide an engine with inherent speed reduction for high piston
speed
and low weight, adaptable to modern advances in high speed engines;
[042] (j) to provide a four-stroke engine that does not require a separate
camshaft
and its drive mechanisms;
[043] (k) to provide an engine without a gravity feed oil pump and which can
thus
be operated in inclined and inverted positions;
[044] (1) to provide an engine with an effective oil lubrication system that
acts as a
flywheel and thus minimizes weightin both four-stroke and two-stroke versions,
also
adaptable as a liquid cooling system with no water, radiator, or external
hosing.
[045] (m) to provide an engine with symmetrical components of minimal axial
cross-section especially suited to use in aeronautical applications and use in
tubular spaces,
and of easily automated and economical manufacture from stock extruded and
rolled
materials;
[046] (n) to provide an engine whose under-piston volume is usable for
effective
supercharging or other useful work;
[047] (o) to provide a two-stroke engine with oil-lubricated output bearings
sealed
from the airlfuel intake system;
[048] (p) to provide a two-stroke engine with smooth running, minimized fuel
use,
and reduced harmful emissions by simple timed closing of the exhaust port;
[049] (q) to provide an engine of simple manufacture which can compete with
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standard crankshaft engines in cost;
[050] (r) to provide an engine which uses standard cylinder, piston, and valve
technology for even temperatures, optimum sealing, and long life; and thus can
easily and
effectively use emissions control methods of standard crankshaft engines;
[051 ] (s) to provide an engine which uses well-proven and available piston
engine
technology and components for low cost manufacture, parts supply, and repair
services;
[052] (t) to provide a single-cylinder cam track engine with simple 100%
balancing
of piston assembly reciprocating weight for minimum vibration;
[053] (u) to provide a cam track engine which has simple and effective oil
cooling of
internal components, and does not require additional liquid cooling or cooling
radiators;
[054) (v) to provide a cam track engine which has a simple and effective
pressure oil
lubrication system, without an oil pump;
[055] (w) to provide a cam track engine with ample space for high capacity
power
output bearings;
[056] (x) to provide a cam track engine with double output rollers to avoid
rotation
reversals, on the same axis, allowing double cams for increased diameter and
thus flywheel
effect, without increasing length.
[057] (y) to provide a cam track engine without separate and complex
stationary
output bearing covers and rotary output means;
[058] (z) to provide a cam track engine which uses the rotating cam track and
existing lubricating oil most effectively as flywheel energy storage.
[059] Further objects and advantages are to provide an improved technology for
engines which are simple, smooth-rurming, economical, of low pollution, easily
manufactured including in developing countries, especially adaptable to use of
supercharging
and compound operation cycles, and which allow new opportunities for fiuther
advances
applicable to many other related uses such as air and refrigerant compressors,
pumps, fluid
driven motors and the like, at a cost competitive with present machines. Still
further objects
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and advantages will become apparent from a consideration of the following
drawings and
description.
SUMMARY
[060] In accordance with the present invention, an external rotary drum
(rotor)
system replaces the connecting rod, crankcase, and crankshaft of a
conventional piston
engine. This converts the reciprocating motion of the piston or pistons to
rotary motion of
the rotor, and incorporates multiple improvements over the prior art. An
integral lubrication
and cooling system captures the dynamic pressure of lubricant spinning with
the rotor,
providing a source of pressurized lubricant andlor coolant, enhanced flywheel
effect, and
operational advantages. To eliminate vibration of single cylinder versions, a
balancer of
weight equal to the piston assembly reciprocates on the same axis as the
piston assembly, in
opposite directions.
DRAWINGS - DESCRIPTION OF FIGURES
In the drawings, closely related figures have the same number but different
alphabetic
suffixes.
[061 ] Fig 1 is an isometric view of the preferred embodiment of the invention
as
adapted to propeller aircraft use.
[062] Fig 2 is an isometric view showing the main stationary and reciprocating
components of the engine.
[063] Figs 3A to 3C are isometric views showing the piston and balancer
assemblies
and their manner of assembly.
[064] Fig 4 is an isometric view showing the main rotary components.
[065] Fig 5 is a graphical representation of the cam track output means of Fig
4.
[066] Fig 6A is a side cross-sectional view of the rotor assembly 50 of Fig 2.
[467] Fig 6B is a side cross-sectional view of the stator 44 of Fig 2.
[068] Fig 6G is an end cross-sectional view of the assembled rotor and stator
of Fig
1.
[069] Fig 7A is a partial side cross-sectional view of the assembled rotor and
stator
of Fig l, showing details of the lubrication system.
[070] Fig 7B is an end cross-sectional view of the assembled rotor and stator
of Fig
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1, showing details of the lubrication system.
[071 ] Fig 7C is a partial side cross-sectional view of the stator 44 of Fig
6B,
showing details of the lubrication system.
[072] Fig 8 is an alternate embodiment using a second piston in the same
cylinder.
[073] Fig 9 is a schematic representation ofthe operation of a compound four-
stroke
cycle engine using the alternate embodiment of Fig 8.
[074] Fig 10 is an alternate embodiment using a second piston in a second
cylinder.
[075] Fig 11 is an alternate embodiment bearing arrangement to reduce
diameter.
[076] Fig 12 is an alternate embodiment showing an exhaust port shield for two-
stroke engines.
[077] Fig 13 is an alternate embodiment showing a multiple cylinder version.
DRAWINGS - REFERENCE NUMERALS
20 cylinder assembly 22 cylinder
23 muffler 24 valve cover
25 camshaft 25A intake valve cam
~7Bu~ou~iubaese cam ~~~ mm~foe ower box
p
28B exhaust 29 exhaust porr shield
30 piston/balancer assembly 32 piston
33 balancer 34 cross tube
35 cross member 36 piston tube
37 dynamic oil pickup 39 bearing retainer
40 stator assembly 42 cylinder mount studs
43 stator drive slots 44 stator
46 thrust plate 49 thrust plate bolts
50 rotor assembly 51 rotor shaft
52 inner cam plate 53 outer cam plate
54 bearing surface 55 drum
56 end plate 57 inspection plug
58 ignition magnets 59 rotor bolts
63 balancer bearing 64 stator drive slot
sleeve bearing
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65 cam plate bearing 65A inner cam plate bearing
65B outer cam plate bearing 73 oil passage in piston/balancer
74 oil passages in stator 75 oil orifice to rotor bearing
76 oil orifice to cam plate bearings 77 lubricating oil
84 ignition coil 88 spark plug
90 engine mount 92 engine mount bolts
95 propeller 98 spinner
99 propeller bolts
PREFERRED EMBODIMENT DESCRIPTION AND OPERATION - FIGS 1-7C
[077] Fig 1 depicts the preferred embodiment ofthe present invention, an
aircraft
engine. A cylinder assembly 20 is assembled to a stator 44, supported on an
engine mount 90
by means of engine mount bolts 92. A rotor assembly 50 spins coaxially with
the
longitudinal axis of the cylinder assembly, imparting rotary motion to a
propeller 95, over the
central portion of which is mounted a streamlined spinner 98.
[078] Fig 2 shows the engine in partially exploded form, with stationary and
reciprocating components clarified. The cylinder assembly (20 of Fig 1)
comprises a cylinder
22 with a valve cover 24, and an intake 28A and exhaust 28B, to which may be
attached prior
art carburetion and exhaust systems (not shown). A cam follower box 26 houses
prior art
valve actuation means, which drive prior art intake and exhaust valves through
pushrods
housed in pushrod tubes 27. Ignition is provided by an ignition coil 84
excited by rotating
ignition magnets 58 on the rotor assembly 50, supplying energy to a spark plug
88. A
piston/balancer assembly 30 is further described in Figs 3A to 3C. G~linder
mount scuds 42
attach the cylinder 22 to the stator 44, which incorporates drive slots 43. A
thrust plate 46
attaches to the stator 44 by means of thrust plate bolts 49. The thrust plate
46 includes
dynamic oil pickups 37, in the form of drilled passages. The thrust plate 46
is assembled
between components of the rotor assembly 50, thus locating the rotor assembly
in position to
rotate upon the stator 44. The propeller 95 attaches to the rotor 50 and is
covered by the
spinner 98.
[079] Fig 3A shows a piston 32 mounted upon a piston tube 36, integral with a
cross
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tube 34, upon each end of which mount a stator drive slot bearing 64, an inner
cam plate
bearing 65A, and an outer cam plate bearing 65B, secured by bearing retainers
39. A
dynamic oil pickup 37 protrudes from the bearing retainer 39 on each end of
the cross tube
34, and serves to capture lubricating oil under pressure which is led to the
interior of the cross
tube 34 for distribution as suitable to lubricate and cool the various
mechanical components,
as will be better understood by reference to Fig 7B. Fig 3B shows a balancer
33 which in
operation is of essentially the same weight as the piston 32 of Fig 3A. The
balancer 33
includes a balancer bearing sleeve 63 which is free to reciprocate upon the
piston tube 36 of
Fig 3A. The balancer includes stator drive slot bearings 64 and inner and
outer cam plate
bearings 65A and 65B in the same positions as on the piston cross tube, and
may also include
dynamic oil pickups 37 as shown. As shown in Fig 3C, the piston/balancer
assembly 30
consists of the slideable joining of the two assemblies of Figs 3A and 3B.
[080] Fig 4 shows the engine in exploded form with the main rotating
components
clarified. The streamlined spinner 98 covers the attachment area of the
propeller 95, where it
is attached to an end plate 56 by means of propeller bolts 99. Rotor bolts 59
are used to
rigidly assemble an inner cam plate S2, a drum 55, and an outer cam plate 53
to the end prate
56 to form a torsionally rigid unit. On assembly the thrust plate 46 is
sandwiched between
the end plate S6 and the outer cam plate 53 with a small clearance altowing
rotation, and is
rigidly attached by the thrust plate bolts 49 to the stator assembly 40, thus
fixing the
longitudinal position of the rotor assembly (SO of Fig 1 ) and carrying rotor
end loads. The
thrust plate 46 may include notches as the four shown to build dynamic
pressure for entry of
lubricating oil into passages within the thrust plate 46, as further seen in
Fig 7C.
[081 ] One or more inspection plugs S7 allow inspection of bearings, changing
of
oil, etc. Indexing notches or pins (not shown) positively locate the drum 55
in position on the
cam plates 52 and 53, with oil retained by rubber O-ring or similar means. On
assembly the
cam plates 52 and 53 form an open bearing groove of sinusoidal shape, as will
be graphically
described in Fig 5 and seen in Fig 6A. On assembly the bearings of the
piston/balancer
assembly 30 protruding from the stator assembly 40 fit within the groove
formed between the
cam plates 52 and 53, thus locating the piston and balancer and controlling
their relative
reciprocal motion. Cam plates 52 and 53 include a bearing surface 54, allowing
their rotation
on the stator assembly 40 with minimum friction.
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[082] On the inner cam plate 52 is located an intake cam 25A and an exhaust
cam
25B which drive the intake and exhaust valves through a pushrod system, these
being of
standard prior art design, through prior art roller tappets (not shown).
halves may be adjusted
automatically by hydraulic lifters operating from the pressure oil system, or
manually if so
designed. It will be noted that the pushrod tube (27 of Fig 2) for the exhaust
valve is raised
slightly to align with the exhaust cam 25B. These combined features allow the
flexibility
and advantages of using an off the-shelf aircraft cylinder 20 in most aircraft
applications.
When using purpose-built cylinders, it will be appreciated that a single cam
will often suffice,
with the tappets and pushrods located near 110 degrees rotation apart for
correct valve
timing. Also, using this general arrangement with or without rocker arms, four
valves per
cylinder, true hemispherical combustion chambers with exhaust on one side and
intake on the
other, L-head ("flathead") or other variations can easily be accommodated.
[083] Fig 5 is a graphical representation of the movements imparted to the
piston
and balancer bearings 65A and 65B of Figs 3A and 3B by the inner and outer cam
plates,
shown over 360 degrees of rotation. These resemble a mathematical or
electrical sine wave.
Alternately, it can be understood to represent the pattern cut into the inner
and outer cam
plates 52 and 53 of Fig 4, as if the cylindrical form of these were
"unrolled". When the upper
curve 52-52 of Fig 4 represents the inner cam plate 52 and the lower curve53-
53 represents
the outer cam plate 53, it can be seen that the piston bearings 65A and 65B of
Fig 3A would
operate at 180 degrees apart on the graph, with the vertical variations of the
centerline each
90 degrees representing the stroke of the piston, four strokes per 360 degree
rotation. The
counterpart bearings for the balancer of Fig 3B would also operate at 180
degrees apart on the
graph, at a 90 degree lateral angular distance from those of the piston,
assuring a reciprocal
movement exactly equal and opposite that of the piston, with fully balanced
reciprocal forces.
[084] Fig 6A shows the rotor assembly 50 of Fig 2 in cross-section, whereby
the
assembly of the four components inner cam plate 52, drum 55, outer cam plate
53, and end
plate 56, by means of the rotor bolts 59 (one shown) can be seen. Also shown
are the
propeller mount bolts 99 (one shown) which attach the propeller (95 of Fig 1 )
to the end
plate 56. On assembly as shown, it can be seen that a groove is provided
between outer cam
plate 53 and end plate 56, wherein the thrust plate (46 of Fig 2) is to be
located.
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[085] Fig 6B shows in its upper portion the stator 44 in side cross-sectional
view
where the locations of the stator drive slots 43 may be seen. 'The thr~.ist
plate 46 is shown in
its location on the stator 44, to be attached by thrust plate bolts 49 (one
shown). Cylinder
mount studs 42 are shown, as well as the alternating locations (dotted lines)
of an outer cam
plate bearing 65 protruding beyond the stator drive slot at top and bottom of
its stroke.
[086] Fig 6C shows the components of Figs 6A and 6B assembled with those of
Fig
3C in end cross-sectional view, as referred to in Fig 1. The piston rod 36 by
means of the
cross tube 34 and the balancer 33 include sets of bearings 64, 65A, and 65B.
Dynamic oil
pickups 37 are provided, which operation will be better understood by
reference to Fig 7B.
The stator 44 shows in cross-section the arrangement whereby the stator drive
slot bearings
64 are located and output torque is thus transmitted to the stator. The
assembly of outer cam
plate 53, inner cam plate 52, and drum 55 rotates as a unit upon the stator
44, while the piston
and balancer and assembled bearings reciprocate but do not rotate. The
location of the inner
cam plate 52 is shown for better understanding of its relative position,
though it would not
actually be visible if looking toward the propeller end of the engine.
[087] From Figs 6A and 6B it cau be seen that the drive slot bearing 64 is
subject to
a relatively low speed alternating rotation. The cam plate bearings 65A and
65B are subject
to high speed rotation, and align with the inner and outer cam plates 52 and
53 at different
radial distances from the center axis, providing two separate but coaxial cam
surfaces for
bearing contact, thus eliminating bearing rotation reversals with reversing
reciprocal forces
on the bearings as in most prior art patents. The orientation of the balancer
bearings at an
angular spacing of 90 degrees from those of the piston bearings assures a
reciprocal
movement exactly opposite that of the piston, as shown graphically in Fig
S,thus fully
balancing the reciprocal inertia forces of the piston for smoothness of
operation.
[088] Fig 7A shows the assembled components of Figs 6A through 6C in partial
cross-sectional view, and includes details of the lubrication system. The
operating location of
the piston and balancer 30 is more clearly shown, with the outer cam plate
bearing 65B at the
top of its stroke, at which time the piston (32 of Fig 3A) is at the bottom of
its stroke. The
assembled location of the thrust plate 46 and its thrust plate bolts 49 are
shown. It will be
noted that the assembled companents including the inner cam plate 52, drum 55,
outer cam
plate 53, and end plate 56 form a hollow chamber, which revolves on the stator
44 in the
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direction shown by the downward pointing arrow. In operation this formed
chamber holds a
volume of lubricating oil 77, which rotates or spins with the assembly. The
dynamic oil
pickups 37, which here reciprocate but do not revolve, thus capture
pressurized oil from the
volume of spinning lubricating oil 77, from which it is conducted by dynamic
pressure to
within the piston or balancer assembly 30 to be distributed where needed, as
for example by
an oil passage in the piston or balancer 73.
[089] Fig 7B shows the assembled rotor and stator cross-section of Fig 6C, and
includes added details of the lubrication system. Here lubricating oil 77
spins clockwise as
shown by the external arrow together will the drum 55, and is captured by the
dynamic oil
pickups 37, from which it is conducted inward by oil passages in the
piston/balancer 73,
being available at any point to lubricate bearings, piston, etc.
[090] Fig 7C shows other details of the lubrication system, where a partial
cut-away
of the assembled stator 44 with thrust plate 46 attached by thrust plate bolts
49 shows by
dotted lines oil passages in stator 74 which supply pressurized oil for oil
orfices to rotor
bearings ? S, or any other need for oil, as for example to valve components,
oil pressure gauge
sender, external oil filter, etc. The periphery of thrust plate 46 may be
notched as visible in
Fig 4 or on either side (not shown) to create positive dynamic pressure at the
dynamic oil
pickups 37.
ALTERNATE EMBODIMENTS DESCRIPTION AND OPERATION - FIGS 8-12
[091) Fig 8 is an alternate embodiment of the assembled piston/balancer 30 of
Fig
3C, where the balancer 33 includes a secondary piston 101 which operates
coaxially in the
same cylinder as the first or combustion piston 32. It will be noted that the
effective stroke of
the cylinder volume between the two pistons 32 and 32 is twice the stroke of
the preferred
embodiment, and can be achieved by simply extending the cylinder bore of the
cylinder (22
of Fig 2) further into the stator (44 of Fig 2), with a minor increase in
engine length and with
little added complexity.
[092] This embodiment can be used to supercharge the intake transferred to the
combustion chamber above piston 32, for substantially increased power output
or, as in
aircraft, full rated power up to high altitudes. Also by this means in both
two stroke and four
stroke engines the rotor assembly and its bearings are permitted to operate in
a permanent oil-
lubricated environment with a very minimum of dilution or contamination from
combustion
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gases blown by the piston rings.
[093] Given the location of the rotating inner cam plate (52 of Fig 4)
adjacent to the
second piston, a rotary valve system similar to that used on many two-stroke
cycle engines
may be integral with, attached to, or driven directly by the cam plate. This
could control flow
into and from the resulting inter-piston chamber and allow its transfer into
the combustion
chamber at the appropriate time. Also a prior art reed valve system could be
used. For two-
stroke cycle use a theoretical 100°l° (twice combustion chamber
volume per cycle)
supercharging is thus provided, and for four-stroke use a theoretical 300%
(four times
combustion chamber volume per cycle) supercharge is provided. Actual effect
will be less,
and a four-stroke system would include a charge storage chamber, doubling as
intercooler, to
hold that charge compressed during the power stoke of the combustion piston,
the total
charge to be transferred on the intake stroke of the combustion piston.
[094] Fig 9 is a schematic representation ofhow the embodiment ofFig 8 can be
applied to the operation of a compound four-stroke cycle engine. Using the
beginning of air
inlet into the engine at bottom center of the piston 32 as 0 degrees, both
pistons are shown at
a mid-position of their four strokes, at the different stages of 45,135, 225,
and 315 degrees Qf
rotor rotation past bottom center. The combustion piston 32 is mounted on
piston tube 36, by
which it is driven from the cam means best illustrated in Fig 7A. A secondary
piston 101, as
also shown in Fig 8, reciprocates in the same cylinder 22 with equal and
opposite movement
imparted by balancer 33, to which it is attached. A combustion chamber above
the piston 32
is filled by an intake 28A and emptied by an exhaust 28B, through conventional
valves. A
primary intake 102 is the first inlet for air or airlfuel mix. A secondary
exhaust 104 serves as
the final outlet for burnt gases. The four manifolds or passages shown in the
four schematic
representations are timed in their interconnection with an inter-piston port
106 by means of a
rotary valve 108, driven from or attached to the innex cam plate 52 of Fig 4.
By this port 106
or multiple similar ones the inter-piston volume is both filled and emptied as
the pistons 32
and 101 move apart and together. An intercooler 110 and associated manifold
serves to cool
and store pressurised charge for the coming intake into the combustion
chamber.
[095] At 45 degrees past bottom center, the gases above piston 32 are being
compressed, while a fresh volume of gases is being admitted through the port
106, as timed
by the rotary valve 108. At 135 degrees, ignition (or injection of compression
ignition
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versions) has occurred and the piston 32 is traveling downward, producing
power. A portion
of the power produced is used directly by piston 32 and indirectly by piston
101 to compress
the new volume of intake 2:1 and force it to the intercooler 110 and
associated manifold for
storage and cooling. The use of power at this time helps to smooth out the
output torque
fluctuations experienced by a conventional engine. At 225 degrees, the burnt
gases above the
piston 32 are being admitted into the inter-piston space where they undergo an
additional 1:2
expansion for higher e~ciency, expansive cooling, and additional power output.
At 31 S
degrees the fresh intake at near 2:1 preliminary compression is being admitted
into the
combustion chamber, where they help to force the expanded exhaust gases out
the secondary
exhaust 104. It will be seen that power is transferred to the rotor on three
of the four strokes:
at 135 degrees by combustion above piston 32, at 225 degrees by expansion
between pistons
32 and 101, and at 315 degrees by admission of the pressurized charge stored
in the
intercooler 110.
[096] From this explanation of the generally prior art compound engine, it can
be
appreciated that a very advantageous arrangement is provided by the present
invention for the
simple and efficient functioning of a compound four-stroke engine. It should
be noted that
due to the near-total absence of side forces on the piston 32, and the fact
that the piston can
be easily cooled by any desired internal flow of cooling oil as provided in
Fig 7B, this
alternate embodiment holds the most promise of any engine design to date to
allow the
practical use of an unlubricated ceramic or low friction coated piston (32)
and achieve for the
first time a simple and efficient compound four-stroke engine. Also it is
noteworthy that
because of the lower internal pressures acting upon the lower portion of the
cylinder 22 in
which piston 1 O l operates, it is conducive to the enlargement of the
diameter of this piston
for additional supercharge and /or expansion effect, beyond the 2:1 and 1:2
mentioned, likely
near a 3:1 ratio being optimum.
[097] Fig 10 shows a second piston embodiment wherein the secondary piston 101
is
attached to the balancer 33 to operate in a second cylinder (not shown) at the
opposite end of
the engine from the first piston 32, attached to its piston tube 36. It can be
appreciated that
under some situations this embodiment can be advantageous, as for example
where the
secondary piston 101 is used directly as an air compressor, or where a small
diameter high
pressure pump piston replaces the secondary piston 101.
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[098] Several other combination arrangements and embodiments not shown are
possible. For example extension of both the piston rod 36- with attached
piston 32 - and the
balancer 33 - with attached piston 101- in both directions, can give a
supercharged two-stroke
or four stroke, or compound four-stroke, engine driving a compound compressor
or double-
acting pump at the end opposite the combustion chamber, without increasing the
number of
moving parts. Also, by varying the relative diameters between pistons 32 and
101 any
desired compound ratios may be obtained.
[099] The mechanism described can also be used as a single or double-ended
simple
or compound compressor or pump driven by an outside power source (electrical
or by belts),
with three moving parts plus bearings. When the secondary piston 141 is not
desired, for
simplicity a cylindrical cross pin of weight equal to the piston can replace
the balancers
shown, and operate with clearance in a slot in a single or two-ended piston
assembly, of a
stretched letter "O" shape. Clearly an electrical generator or motor rotor can
be incorporated
integral with the rotor for compact low-vibration generator or compressor
units, integral
engine driven or electric powered. Further, a combination of both a generator
rotor and
compressor pistons can be driven integral with the same engine (gasoline,
Diesel, two stoke,
fourystroke, compownd or supercharged) for a universal field power system,
with great
economy of size, weight, cost and practicality.
[100] Fig 11 shows an alternate embodiment to reduce rotor diameter and
eliminate
the stator drive slot bearings (64 of Fig 3A). This is shown as a twin piston
version with
combustion piston 32 and secondary piston 1 O1. In this embodiment cam plate
bearings 65
are spaced longitudinally on an extended balancer 33, and a cross member 35,
which replaces
the cross tube 34 of Fig 3A. These extended generally flat surfaces
reciprocate in slots in the
stator relatively narrower than the bearings 65, thus allowing a large flat
sliding bearing area
and a smaller diameter stator as compared to the preferred embodiment, without
losing
strength. The bearings 65 in operation operate upon the two surfaces of a
single cam track
projecting internally from the rotor, as can best be appreciated by reference
to Fig 13, a multi-
cylinder version which also uses a single cam track (53 of Fig 13) projecting
inward from a
drum (55 of Fig I3).
[ 101 ] It will be seen that for the same rotational speed of the bearings 65,
the smaller
diameter allowed by the embodiment of Fig 11 will allow higher revolutions of
the rotor.
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This higher speed will compensate for the reduced flywheel effect of the
reduced diameter.
The reduced diameters will be conducive to more economical fabrication and to
output
speeds closer to those of conventional small two-stroke engines, while keeping
most of the
advantages of the invention, such as permanent oiling of the bearings,
inherent reduction,
supercharging, etc. Due to more relative stress left in the wall of the
stator, the slots can
be extended to the end of the stator for ease of assembly, then fixed by the
thrust plate, etc.
Further variations for ease of manufacture yet with similar operation are
possible.
[I02) Fig 12 shows one alternate embodiment using an exhaust port shield for a
two-
stroke engine. Piston, balancer, and bearing components are here omitted.
Engine mounts 90
supports a cylinder assembly 20 for vertical operation. A rotor assembly 50
includes an inner
cam plate 52, to which is attached an exhaust port shield 29. On assembly the
port shield 29
aligns with the exhaust 28B. As the rotor 50 rotates the cutouts in the port
shield 29 align
with the exhaust to cover it at a time when the internal ports (not shown) are
still uncovered
by the piston (32 of Fig 3A). As shown the shield 29 operates in a slot in the
muffler 23. The
exhaust 28B opens internally by means of prior art piston timed ports soon
enough to allow
efficient expelling of burnt gases, yet closes externally by the shield 29
soon enough to keep
the fresh charge of air and fuel from exiting out the muffler 23, thus
increasing power and
fuel economy, and reducing pollution due to unburnt gases. Alternately the
shield may be
external to the muffler, operate horizontally or at an angle, be only a
portion of a cylinder or
disk, or be driven indirectly from the cam plate 52.
[103) In Fig 13, the main features of my invention are applied to a multiple
cylinder
version. Here a cylinder assembly 20 is supported by motor mounts 90 and
carries multiple
double-ended pistons 32 reciprocating parallel to a rotor 50. A camshaft 25
carries the rotor,
supported by a bearing surface54, with axial thrust carried by a thrust plate
46, here with an
integral cam for valve operation and covered by a valve cover 24. The pistons
32 are
elongated and double-ended to include a lower compression chamber opposite the
combustion chamber shown at the top. By means of two cam plate bearings each,
the pistons
engage an outer cam plate 53, whose working surface contour is shown by hidden
lines. A
drum 55 supports the eam plate 53 and encloses a supply of lubricating oil 77,
which spins
with the assembly of drum 55, cam plate 53, and cam shaft 25.
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[104] Using a minimum of three pistons, the embodiment shown eliminates the
need
for a balancer (33 of figure 3B). Four pistons is likely optimum, leaving room
for manifolds
for intake and transfer to and from the bottom of the piston, prior art rotary
or reed valviug
means for this, etc. Unlike the embodiments of Figs 8 through 11 there is not
an enhanced
supercharge effect from an additional secondary piston (101 of Fig 8)
operating coaxial with
the piston 32, but for two stoke use a higher ratio than standard engines is
still achieved, and
for four-stroke cycle a 100% supercharge is still obtained. A larger diameter
of the lower
(supercharge) portion of the piston 32 can give a greater supercharge if
desired. Side thrust
from torque is carried by sides of the piston to the cylinder assembly 20, and
from there as
torque to the engine mounts 90. As the bearing 54 is of the relatively small
diameter of the
camshaft 25, fictional losses are minimized and manufacture, assembly, and
maintenance are
simplified. Lubricating and cooling oil is captured by a dynamic oil pickup 37
and thereby
conducted by an oil passage in the stator 74 to be used where necessary. With
multiple
cylinders, multiple such dynamic oil pickups 37 are allowed and may be located
between the
cylinders, including in positions higher than that shown.
[105] It can be seen that using multiple pistons as shown here and in the
prior art ,
such as US Patent 2,983,264 ( Herrmann 1961), air-cooling is problematic due
to space
limitations, and water-cooling is thus normally proposed. It would be
advantageous to use
the lubricating oil for cooling also and eliminate a water cooling system, but
as the heat
conduction properties of oil are about half that of water this becomes bulky,
heavy, and
impractical with the prior art. With the embodiment of Fig 13, the drum 55 is
a large external
rotating surface which can be easily cooled by forced air flow, which effect
is enhanced by
the addition of cooling fins integral with the drum as shown. Using this
system an oil-based
cooling system is provided which is integral with the engine, needs no
external hosing or
radiators, does not need to be pressurized or subject to leaks or added
maintenance, and
which uses am expanded system of dynamic oil pickups 37 to eliminate the need
for a
mechanical coolant pump.
[106] The camshaft may include an integral extension in the form of rotor
shaft 51 to
locate or drive external components, while large diameter components, as the
generator/motor for a hybrid gasolineJelectric automobile may be mounted
directly and
independently to the rotor assembly 50. For automobile use the engine can be
easily canted at
an angle if desired for lower height, with belt-driven accessories driven by
an extension of the
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camshaft. °Thus both the independent and combined features of the
present invention greatly
aid the practicality, simplicity, and viability of multiple-cylinder cam track
engines.
CONCLUSION, RAMIFICATIONS, AND SCOPE
From the description above, the many advantages of my optimized linear engine
become evident, including:
[107] (a) It is a simple engine achieving a built in reduction, cam drive,
power
output attachment, and pressure lubrication and cooling system with no
additional parts.
[108] (b) It is an efficient engine by reducing or eliminating friction losses
and
improving combustion conditions.
[109] (c) It is a lightweight engine due to optimum location and use of
components.
[l 10] (d) It is a powerful engine due to built-in supercharging and inherent
high
speed.
[111 ] (e) It is an easily manufactured engine due to simple generally
cylindrical
components.
[112] (fj It is of low vibration due to full dynamic balancing ofreciprocating
parts.
[113] (g) It has a low risk of exhaust emission or maintenance problems due to
the
use of proven cylinder and valve technologies.
[114] Although the description and operation above contains many
specifications,
these should not be construed as limiting the scope or applications of the
invention but as
merely providing illustrations of some of the present preferred embodiments of
this
invention. Many other variations are possible. For example, other reduction
ratios of piston
to rotor movement may be easily obtained by varying the number of curves in
the cam track,
variations of the cam track curvature may allow enhanced combustion
properties, and
additional features may be added which enhance operation and were difficult or
impossible
with the prior art. Also some features of the prior art may be retained in
combination with the
present invention, for example lubrication of the bearings with a gasoline/oil
mixture as in
prior art two-stroke cycle engines, whereby the spinning oil supply is
eliminated yet the other
advantages are retained. Thus the scope of the invention should be determined
not only by
the examples given, but by the appended claims and their legal equivalents.
