Classification: - international: F01B7/00;
F01B9/02; F02B75/24; F01B7/00; F01B9/00; F02B75/00; (IPC1-7):
F02B75/24 - European: F01B9/02B; F01B9/02R;
Also published as : JP9504587 // EP0746679 // EP0746679 //
An improved engine (1) uses a dwelling
scotch yoke (42) and a journalled flywheel (20) which provides
for stalling the translatory movement of oppositely paired
pistons (10) during the power stroke so as to achieve a clean
exhaust and an energy efficient engine. The yoke (42) is made up
from a U-shaped cam member (43) to which the piston rods (12)
are connected at junction (114). The cam member (43) defines an
involuted cam (44) which contacts the cam follower (32) carried
by the flywheel (20).
SUMMARY OF THE INVENTION
This invention relates to an improved engine, and will have
special application, but not necessarily so limited, to
internal combustion engines which can be used in lawn mowers
to diesel electricity generators.
The engine embodied in this invention utilizes a dwelling
scotch yoke and a journalled flywheel in a unique
combination for stalling the translatory movement of
oppositely paired pistons during the detonation of lean fuel
mixture. A fixed volume is thus maintained above the piston
during detonation, in which a complete chemical reaction of
the fuel molecules and the rich air can occur. Consequently,
the fuel mixture can be disassociated into its purer
elements to achieve a very clean exhaust and a highly energy
An additional feature of this engine is that it is compact
and efficient in size and maintenance. The journalled
flywheel obviates the use of a crankshaft and throws
typically used in two and four cylinder engines. Further,
the flywheel functions as an oil pump for supplying
lubrication to the pistons. Each of the pistons have flared
skirts to allow for better engine lubrication and to reduce
heat warping, thus reducing wear.
The engine also utilizes cylinders with sealed end walls.
The cylinder bore by being enclosed at its lower end is
separated from the crankcase internal chamber where the
journalled flywheel and oil bath is located. The presence of
the cylinder end wall functions to provide a barrier between
the cylinder bore and the oil bath and also to allow for an
increase in the density of the fuel mixture during piston
movement. By increasing the density of the fuel mixture, it
is more efficiently burned during the detonation process.
Still another feature of the cylinder is the location and
size of its exhaust ports. The exhaust ports are located
such that the exhaust gases generated within the cylinder
are not released until the piston completes its inward or
power stroke. Thus, a longer power stroke is achieved
resulting in increased horsepower than can be gained using
Accordingly, an object of this invention is to provide an
energy efficient engine.
Another object of this invention is to provide an engine
that produces environmentally favorable exhaust.
Still another object of this invention is to provide an
engine that can operate by burning various forms of fuels.
Still another object is to provide an engine that is
compact, lightweight, durable, easily assembled, and
Other objects will become apparent upon a reading of the
BRIEF DESCRIPTION OF THE
A preferred embodiment of the invention has been depicted
for illustrative purposes only wherein:
FIG. 1 is a
perspective view of the invention.
FIG. 2 is a
longitudinal-sectional view taken along line 2--2 of FIG. 1
showing the invention from the side.
FIG. 3 is a
longitudinal-sectional view taken along line 3--3 of FIG. 2
showing the invention from the top.
FIG. 4 is a
longitudinal-sectional view like FIG. 3, but showing the
engine configuration in another operative position.
FIG. 5 is a
cross-sectional view of a cylinder and piston taken along
line 5--5 of FIG. 4.
FIG. 6 is a
perspective view of the piston, saddle and yoke components
of the invention showing the piston in partial sectionalized
form for illustrative purposes.
FIG. 7 is a
sectional view of a cylinder with the piston at its top and
the cam follower at zero degrees or top dead center.
FIG. 8 is a
sectional view showing the cam follower at 30.degree..
FIG. 9 is a
sectional view showing the cam follower at 150.degree.,
illustrating that the cam follower travels 120.degree.
between the opposing involuted cams or dwell cups during the
power stroke of the piston.
FIG. 10 is a
sectional view of the fuel being drawn into the cylinder as
the piston begins its upward movement while compressing the
fuel mixture already above the cylinder.
FIG. 11 is a
sectional view of the piston at the top of the cylinder and
the fuel mixture compressed prior to detonation.
FIG. 12 is a
sectional view of the fuel mixture detonated forcing the
piston downward, opening the exhaust port to allow the
exhaust gases to escape while also forcing the fuel mixture
below the piston into the transfer ports.
FIG. 13 is a
sectional view of the piston at the bottom of the cylinder
and the transfer port opened to release the fuel mixture
into the upper cylinder chamber, and expel any remaining
exhaust gases out the exhaust port.
FIG. 14 is an
exploded perspective view of the cylinder head and neck,
illustrating the exhaust ports, the transfer ports, the
inlet port, the spark plug hole in the cylinder bore of the
cylinder head and the through hole for the connecting rod in
the cylinder neck.
DESCRIPTION OF THE
The preferred embodiment herein described is not intended to
be exhaustive or to limit the invention to the precise form
disclosed. It is chosen and described to explain the
principles of the invention and its application and
practical use to enable others skilled in the art to utilize
The preferred embodiment of the invention is a
four-cylinder, two-stroke engine. The concepts that exist in
this invention are applicable to other types of engines such
as multiple-cylinder, four-stroke engines.
Referring now to the drawings, FIG. 1 illustrates the
preferred embodiment of the twin-opposing four--cylinder,
two-stroke internal combustion engine 1. For descriptive
purposes, engine I can be referred to as having similar
halves sharing a flywheel 20. Thus, only one such engine
half will be described in detail with similar reference
numerals being used for like functioning components of both
Each engine half la, lb includes a pair of oppositely
located pistons 10, a cylinder 26 for each piston 10, and a
portion of a crankcase 50 supporting a journalled flywheel
20 therein. Each crankcase half 50a, 50b includes an outer
part 52 and an inner part 54 forming in conjunction with the
other crankcase half a central chamber 102 for the internal
components of engine 1. Outer part 52 and inner part 54 are
fastened to other crankcase half by screws 94. Crankcase 50
supports a journalled flywheel 20 in central chamber 102 by
a bearing 104. Bearing 104 is seated in the cavity defined
by inner parts 54 so as to support flywheel 20 and allow it
to rotate about an axis perpendicular to the piston
movement. Crankcase 50 has a side opening 21 for a sectored
portion of flywheel 20 to mesh with a suitable power input
gear (not shown). Additionally, outer part 52 and inner part
54 form in conjunction the openings 53 for interfitting
cylinder neck parts 28, as shown in FIG. 2.
As shown in FIG. 14, each cylinder 26 includes a head part
27 and a neck part 28. Each head part 27 includes top
opening 31 for an interfitting spark plug 24, a lower
annular lip 25 for interfitting with neck part 28 and which
defines an opening 33 which is part of the cylinder bore 4,
two exhaust ports 46 for allowing the discharge of the
exhaust gases out of cylinder bore 4, diametrically located
transfer ports 16 for allowing the passage of the fuel
mixture from below the piston to above the piston and
cooling flanges 30 for dissipating the heat generated within
the head part, all as shown in FIG. 14. Each neck part 28
has an annular recess 29 for accepting head part lip 25, an
inlet port 14 for allowing the passage of the fuel mixture
into the cylinder bore 4 below the piston, and necked collar
part 100 for fitting into crankcase opening 53.
Each cylinder 26 contains a piston 10 located in bore 4.
Each piston 10 includes a skirt 76 with opposing slots 74
and circumferential grooves 40, as shown in FIG. 6. Slots 74
are for reducing the effects of heat warping upon each
piston 10 and to allow skirt 76 to flare outwardly into
contact with cylinder bore 4 so as to achieve a greater
vacuum below the piston during engine operation. Rings 41
are carried in grooves 40. The length of each piston 10 is
preferably longer than the length of transfer ports 16.
The pair of pistons 10 are coaxially interconnected by a
yoke 42. Each piston 10 includes opposing lugs 75 which
extend from the piston top wall 11 spacedly along the
interior of skirt wall 76, as shown in FIG. 6. Lugs 75 have
aligned holes 78. As shown in FIG. 5, a hollow retainer pin
79 extends into each hole 78. Retainer pin 79 is held within
piston 10 by a pair of washers 81 each placed over one end
of the pin and is secured by a retainer screw 83 which
extends through the hollow pin. A saddle 62 is pivotally
carried between lugs 75 by retainer pin 79 inserted with
clearance through the saddle piston hole 66. Saddle 62 has
aligned wrist pin holes 70. Wrist pin 82 extends into each
hole 70 and is held by a screw connection. A rod 12 is
pivotally carried between the saddle walls 68 by wrist pins
82 inserted with clearance through the rod wrist pin hole
72. The end of rod 12 abuts against the saddle seat 64 for
ensuring no longitudinal loading is experienced by wrist pin
82 or skirt 76 during the power stroke of pistons 10.
Clearance exists between rod 12 and saddle walls 68 for
allowing lateral movement of piston 10 relative to rod 12 so
as to achieve uniform piston wear. The oppositely aligned
ends of rods 12 coaxially join a U-shaped cam member 43 to
form yoke 42. Cam member 43 is located in internal chamber
102. Each rod 12 extends from internal chamber 102 through
the lower end wall 140, in which a hole 106 is provided in
each neck part 28, and into cylinder bore 4.
Each cam member 43 includes two side walls 110 and a back
wall 112. Each side wall 110 defines an involuted cam or
dwell cup 44, as shown in FIG. 6, herein described later.
The center of each dwell cup 44 is referred to as either top
dead center 44a or bottom dead center 44b. This nomenclature
is relative to the position of each individual piston 10.
For some applications of engine 1, dwell cups 44 can have
varying curvatures as required to gain the desired engine
efficiency during fuel detonation. This may be achieved by
using an insert a shoe (not shown) in cam member 43 that has
the desired shape of dwell cups 44. In this preferred
embodiment dwell cups 44 have symmetrical curvatures. Back
wall 112 of cam member 43 can be adapted for imparting
auxiliary motion to a second machine through a suitable
capped opening 130 in crank case 50.
Each yoke 42 is connected to flywheel 20 through a cam
follower 32, as shown in FIG. 2. Cam followers 32 form a
part of flywheel 20 and are diametrically located on
opposite sides of the flywheel within chamber 102. The
contact surface of each cam follower 32 is in the form of a
bearing 35. Each cam follower 32 fits with rolling clearance
between side walls 110 of cam member 43.
Lubricating oil is placed in chamber 102 for reducing
friction wear of the engine components during operation. An
oil passage 47 is provided in each inner part 54, connected
to neck part 27 and head part 27. Passage begins at an inlet
port 49 within internal chamber 102 and terminating in an
outlet port 45 located in each cylinder bore 4, as shown in
FIG. 4. Each outlet port 45 is located so piston rings 41
are lubricated as piston 10 reaches the bottom of its
stroke, as shown in FIG. 3. During the operation of engine
1, the movement of the internal components located in
crankcase 50 act as a pump forcing the oil in chamber 102
into inlet port 49, along passage 47, out each port 45 and
onto rings 41. Negative pressure created from piston 10
movement aids in drawing the oil onto rings 41. The flaring
of piston skirt 76 serves to obstruct the release of oil
into bore 4 when rings 41 are not in contact with inlet port
Each yoke rod 12 is necked at the cam member junction 114
for preventing oil in chamber 102 from being injected into
cylinder bore 4 through opening 106 during engine 1
operation. A seal 107 is located at opening 106 of each neck
28 and extends about rod 12 to also assists in obstructing
oil from being pumped into cylinder bore 4. Cylinder bore 4
is also sealed at its innermost end by its neck part 28.
In the operation of engine 1, pistons 10 act in concert to
rotate flywheel 20 by means of yokes 42. Each yoke 42 serves
to translate the longitudinal coaxial motion of each pair of
opposed pistons 10 into rotational movement of flywheel 20.
This occurs when a piston 10 moves down cylinder bore 4
thereby pushing yoke 42 along its longitudinal axis. As each
yoke 42 is moved it carries with it the connected cam
follower 32, thus causing flywheel 20 to rotate. Flywheel 20
will rotate 360.degree. about its axis as each yoke 42 is
pushed down and back.
Piston 10 movement occurs upon the detonation of a fuel
mixture 120 in cylinder 26. Fuel mixture 120 cycles through
each cylinder bore 4 in the following manner. The first
outward stroke of each piston 10 causes a negative pressure
below the piston to draw fuel mixture 120 from inlet port 14
into cylinder bore 4, as shown in FIG. 10. The following
inward stroke of piston 10 forces fuel mixture 120 from
below the piston into transfer ports 16, as shown in FIG.
12. When piston 10 reaches the bottom of cylinder bore 4,
transfer ports 16 open above the piston and allows the
pressurized fuel mixture 120 to flow into the area above the
piston, as shown in FIG. 13. The succeeding outward stroke
of piston 10 further compresses fuel mixture 120 above the
piston, as shown in FIG. 11. When piston 10 reaches the top
of cylinder bore 4, fuel mixture 120 is detonated by a spark
from sparkplug 24. The subsequent explosion causes piston 10
to move inwardly; this motion is commonly referred to as the
power stroke. As piston 10 reaches the bottom of cylinder
bore 4 during its power stroke, exhaust ports 46 open to
allow the burnt or exhaust gases 122 to expand and flow out
of cylinder bore 4 through exhaust ports 46, clearing it to
receive nearly simultaneously a fresh charge of fuel mixture
120, as shown in FIG. 13. The cycle is then repeated.
The presence of dwell cups 44 in yokes 42 increases the
engine's horsepower by regulating the movement of pistons
10. The outward movement of each piston 10 is substantially
stopped when its associated cam follower 32 travels along
the concave surface of dwell cup 44 during the power stroke
of its oppositely located, paired piston. By stopping piston
movement at the top its compression/detonation stroke, fuel
mixture 120 is compressed into a fixed volume and can
experience a substantively complete burn before the piston
moves and enters its power or inward stroke. Further,
hydrocarbons or nitrous oxides are reduced and sometimes
even eliminated from exhaust gases 122, because the fuel
mixture 120 is more thoroughly consumed. Thus, contamination
of subsequent fresh charges fuel mixture 120 entering into
cylinder bore 4 by unburned hydrocarbons will be reduced and
perhaps even eliminated.
This process begins when each cam follower 32 reaches the
cam or concave surface of its associated top dwell cup 44a
at -30.degree. There, fuel mixture 120 is ignited. For
60.degree. of rotation, cam follower 32 travels along the
dwell cup surface which is curved to match the radial
sectored movement of the cam follower, stopping the movement
of piston 10 while fuel mixture 120 is consumed. At
+30.degree., piston 10 begins its power stroke, as shown in
FIG. 8. The expansive forces created from the detonation of
fuel mixture 120 moves piston 10 inward, pushing yoke 42
against cam follower 32 which turns flywheel 20. When cam
follower 32 reaches 150.degree., it begins to travel along
the bottom dwell cup 44b, as shown in FIG. 9. Piston 10 will
again be substantially stopped in movement for 60.degree.
until cam follower 32 reaches 210.degree.. This allows the
detonation process to occur in the opposite cylinder 26.
Piston 10 then begins its succeeding outward stroke once cam
follower 32 reaches 210.degree. and is forced out along
cylinder bore 4 into its compression/detonation stroke by
the connected opposite paired piston 10 which is being
forced inward during its own power stroke.
Each pair of pistons 10 has two power strokes (one for each
piston) per revolution of flywheel 20. Each piston pair
operate in synchronous translation and 180.degree. out of
phase with the other pair of pistons. Thus, fuel mixture
detonation occurs at each piston 10 in its outermost
position simultaneously. Hence, the outermost piston 10 of
one piston pair will be in its power stroke as the offset
oppositely located outward piston 10 of the other piston
pair is also in its power stroke, and in concert, the two
pistons will function to rotate flywheel 20.
The presence of cylinder end wall 140 also serves to
maximize engine's 1 creatable horsepower by increasing the
density of fuel mixture 120. Because cylinder bore is
enclosed at its lower end and thus separated from internal
chamber 102, fuel mixture 120 achieves a greater density
when being compressed into transfer ports 16 than
conventional engines. Thus, when fuel mixture 120 is
consumed, the increase in density equates to an increase in
generated power. The thickness of cylinder end wall 140
thickness can be varied by installing specially machined
neck parts 28 so as to alter the fuel mixture density as
The location and size of exhaust ports 46 serves to maximize
the amount of horsepower piston 10 can generate during its
power stroke. Exhaust ports 46 are positioned to open when
the opposite paired piston 10 begins detonation. Thus, a
longer power stroke is achieved resulting in increased
horsepower than can be gained using conventional cylinders.
During operation of engine 1, noise generated by yoke 42
impacting against cam follower 32 is reduced because of the
presence of dwell cups 44. Also during the operation of
engine 1, yoke 42 may have a tendency to rotate about the
longitudinal axis during translation. An I-beam 5 is
fastened to each crankcase cover 6 so as to prevent such
It is understood that the above description does not limit
the invention to the details given, but may be modified
within the scope of the following claims.