External combustion engine with improved piston and crankshaft linkage

An external heat engine has a piston mounted for movement between a first upper position and a second, lower position, a heater for heating a working gas to forcibly move the piston from the upper position to the lower position (power stroke), a crankshaft rotatable about a main axis, the piston and crankshaft being linked so that movement of the piston from the upper position to the lower position during the power stroke is transformed into rotational movement of the crankshaft during a first portion of one rotation of the crankshaft about the main axis. The piston moves from the lower position to the upper position during a second portion of one rotation of the crankshaft (compression stroke). The piston and crankshaft are linked by a disk, a piston rod connected to the piston and a connecting ring for rotatably supporting the disk. The disk is rotatable about its central moveable axis, and is connected to the crankshaft at a point offset from the disk's axis, for rotation about the disk's axis in response to rotation of the crankshaft about its main axis, the axis of the disk being disposed so that when the piston is in the upper position, the axis of the disk is substantially aligned with the main axis of the crankshaft during a third portion of one rotation of the crankshaft about the main axis. With this structure, the piston is maintained in the upper position for substantially 180.degree. of rotation of the crankshaft.

FIELD OF THE INVENTION 
The present invention relates to an external combustion piston-type engine, 
and more particularly, to a piston and its linkage with a crankshaft in an 
external combustion engine. 
BACKGROUND OF THE INVENTION 
In general, in an external combustion engine, such as disclosed in U.S. 
Pat. No. 4,077,221 (to Maeda), combustion takes place outside of a gas 
expansion chamber. A working gas is heated by the combustion, and enters 
the expansion chamber where the gas expands due to the heat and pushes a 
piston downward to deliver a power stroke. Through a linkage between the 
piston and crankshaft, the power stroke causes the crankshaft to rotate. 
After the power stroke, the piston moves upward and the gas is pushed out 
of the expansion chamber through an exhaust. In a closed cycle process, 
the exhausted gas is cooled and recirculated for use in the compression 
chamber, and later is reheated and re-enters the expansion chamber. In an 
open cycle, the gas is simply exhausted. 
To make such an engine as efficient as possible, it is necessary to 
transform as much of the combustion energy as possible into heat energy of 
the gas. The longer the piston remains in the up position, the longer heat 
transfer between the combustion chamber and the gas can occur. It is thus 
desirable to create an external combustion piston-type engine in which the 
piston remains in the up position for a substantial portion of each cycle. 
It is also desirable to have the piston in the up position for a 
substantial amount of the cycle so that combustion can take place more 
thoroughly and therefore burn the fuel more efficiently. 
SUMMARY OF THE INVENTION 
In accordance with the invention, there is provided an improved linkage 
between a piston and a crankshaft of an external combustion piston-type 
engine, having a power stroke and a compression stroke cycle. The linkage 
is such that during the time between completion of the compression stroke 
and the beginning of the power stroke, the piston is maintained in its 
upper position for substantially 180.degree. of the rotation of the 
crankshaft. 
In one embodiment of the invention, the piston is connected to the 
crankshaft via a connecting rod. The connecting rod comprises a ring 
having a central bore. A disk is disposed in the bore so as to be 
rotatable with respect to the ring. The disk has a hole therethrough 
offset from its central axis. 
The crankshaft has a central shaft and a radially extending crank arm. A 
crank pin is fixially attached to the crank arm so that as the central 
shaft rotates, the crank pin rotates orbitally about the axis of the 
crankshaft. The crank pin extends through the hole or aperture in the disk 
and rotatably engages the disk, i.e. the disk is rotatable relative to the 
crank pin. 
Rotation of the crank pin about the crankshaft results in upward and 
downward movement of the piston. In the cycle, the piston moves upwardly 
into its upward position as the crank pin rotates from a position directly 
below the crankshaft, i.e. the 0.degree. position, to a position wherein 
the crank pin is at the same elevation as the crankshaft, i.e. the 
90.degree. position. At this point, the disk and the crankshaft are 
coaxial. The piston remains in its up position as the crank pin rotates 
one-half turn to about its 270.degree. position, movement of the crank pin 
being accommodated by clockwise rotation of the disk relative to the ring. 
As the crank pin rotates downwardly past its 270.degree. position, it 
carries the disk, connecting rod and piston downwardly. As this occurs, 
the disk rotates relative to the crank pin in a counterclockwise position. 
When the crank pin reaches its 0.degree. position directly below the 
connecting rod, the disk, connecting rod and piston are at their lowest 
point. As the crank pin continues to rotate past the 0.degree. position, 
the disk, connecting rod and piston begin to move upwardly, repeating the 
cycle. 
In a further embodiment of the invention, the connecting ring is integrally 
attached to a pivot arm to provide greater stability of the motion of the 
piston, piston rod and connecting ring.

DETAILED DESCRIPTION 
The invention provides an improved linkage between a piston and a 
crankshaft of an external combustion piston-type engine. 
FIG. 1 shows a cross-sectional view of an external combustion engine, 
including a piston 2 and its linkage to a crankshaft 4, and FIG. 1A is a 
cross-sectional view, taken along line 1A--1A of FIG. 1, of details of the 
linkage between piston 2 and crankshaft 4. The piston 2 has a connecting 
rod 5 attached to its bottom end. Connecting rod 5 comprises a connecting 
ring 6, which has a cylindrical bore 8. The bore 8 has a disk 12 rotatably 
disposed (about axis 0) therein. The disk 12 has a hole 14 offset from its 
axis. 
As shown in FIGS. 1 and 1A, crankshaft 4 comprises a segmented central 
shaft 26. Mounted on shaft 26 are radially extending crank arms 20. A 
crank pin 16 is mounted on the crank arm, the axis of the crank pin 16 
being generally parallel with the axis of the shaft 26. Rotation of the 
shaft 26 results in orbital rotation of the crank pin 16 about the shaft 
26. Crank arm 20 comprises a counterweight 21 extending from the shaft 26 
in a direction opposite the crank pin 16. As shown in FIG. 1A, the crank 
pin extends through the hole 14 in the disk 12 so that the disk 12 is 
afforded rotatable movement relative to the crank pin. 
In FIG. 1, the piston is at the beginning of a cycle. The piston 2 is at 
its lowest position. Crank pin 16 is also at its lowest position. The 
position of the crankshaft, at which pin 16 is at its lowest position and 
the piston is at its lowest position, will be referred to as 0.degree. 
(about axis P) for a reference. 
Piston 2 is moveable between an expansion chamber 34 and a compression 
chamber 36. Expansion chamber 34 is largest when piston 2 is at its lowest 
position, and the compression chamber is thus smallest in this position. 
When piston 2 is at its highest or top position, expansion chamber 34 is 
smallest and compression chamber 36 is largest. Piston 2 thus forms a 
moveable border between chambers 34, 36. The piston 2, connecting rod 5 
and disk 12 are mounted in a suitable housing 28, which has a top 28a and 
a shelf 28b which define the upper border of expansion chamber 34 and 
lower border of compression chamber 36, respectively. The engine has a 
heater 40 disposed at top 28a for heating the working gas. At the 
0.degree. position of the crankshaft, the compression stroke of piston 2 
is about to begin. At this point, cool working gas from compression 
chamber 36, which has previously entered through a port 44, has finished 
entering into expansion chamber 34. As crankshaft 4 rotates clockwise in 
FIG. 1, compression begins. Piston 2 moves upwardly due to an upward force 
on connecting ring 6 transmitted from crank pin 16 of crankshaft 4 to disk 
12. Arrow A shows the direction of rotation of pin 16, and arrow B shows 
the counterclockwise rotation of disk 12 in response to rotation of pin 
16. 
In FIG. 2, as in all of the drawings, like reference numerals represent 
like elements. FIG. 2 shows the compression stroke continuing as piston 2 
moves upwardly. The crankshaft 4 has rotated 60.degree. from its position 
in FIG. 1. Piston 2 has traveled about one-half of its total range of 
movement, and cool working gases keep entering compression chamber 36 via 
port 44 and a valve 48. 
In FIG. 3, the compression stroke is completed, as the piston has moved to 
its top position. Crankshaft 4 has rotated 90.degree. from the position of 
FIG. 1. At this point, valve 48 will be closed, as is well known in the 
art, and gas in heater 40 is heating up. In accordance with the invention, 
when piston 2 and connecting ring 6 are in their top positions, disk 12 
has its center axis O coaxial with the fixed axis P of main shaft 26 of 
crankshaft 4. Accordingly, as crankshaft 4 rotates from about 90.degree. 
through about 270.degree. (FIG. 4), disk 12 merely rotates in direction C 
and does not exert any substantial upward or downward force on connecting 
ring 6 other than to hold ring 6 in the top position. Therefore, 
substantially from the 90.degree. position of FIG. 3 to the 270.degree. 
position of the crankshaft 4 shown in FIG. 4, piston 2 remains at its top 
position. The working gas is thus heated very efficiently, as there is an 
increase in the time for heat transfer to take place. It should also be 
noted that, when the crankshaft reaches the 90.degree. position, the disk 
will begin rotating in the clockwise direction as shown by arrow C in FIG. 
3. The disk will continue its clockwise rotation until the 270.degree. 
position. 
FIG. 4 also represents the position where the power stroke is about to 
begin. In FIG. 5, a short while into the power stroke, crankshaft 4 is 
shown at 285.degree.. Valve 48 remains closed, so compression of the cool 
working gases is taking place in chamber 36 while expansion is occurring 
in chamber 34. 
FIG. 6 shows the crankshaft at 315.degree., at which point working gas from 
chamber 34 begins exhausting through an exhaust port 50. The gas enters 
regenerator 52 and then cooler 54. 
FIG. 7 shows crankshaft 4 at a rotation of 330.degree.. At this point in 
the power stroke, hot gas still passes through exhaust port 50, 
regenerator 52 and cooler 54. In addition, cold gas moves from chamber 36 
through passageway 58 into chamber 34. When piston 2 moves to its bottom 
position, crankshaft 4 and piston 2 are back at their positions as shown 
in FIG. 1. The cycle will then repeat. 
From the drawings, it is apparent that the distance (range) of movement of 
the piston is set at twice the distance between the axes of the crank pin 
and the crankshaft. 
As the invention is applied to an external combustion engine, and as it 
maintains the piston at the top of the compression stroke for 
substantially 180.degree. of rotation of the crankshaft, combustion of the 
fuel can take place in a controlled manner and the working gas can be 
efficiently heated, to achieve an efficient engine and thus substantially 
reduce pollution and gas consumption. 
The above described embodiment of the invention is for a closed cycle 
version of the external combustion engine. FIG. 8 shows an open-cycle 
version of the invention. 
In the open-cycle version, the salient differences are that the working gas 
exhausted from chamber 34 by exhaust 62 does not reenter. Rather, fresh 
working gas enters chamber 36 through an intake device 60, which is well 
known in the art. 
FIG. 9 is a further embodiment of the invention, in which piston 102 and 
piston rod 105 are curved. Compression and expansion chambers 134, 136, 
respectively, are curved. The curve of the piston 102, piston rod 105, and 
chambers 134 and 136 have a radius taken at its respective axis and point 
70 approximately equal to that of a pivot arm 68, which is integral with 
connecting ring 106. Pivot arm 68 is mounted on a fixed rod 70 or other 
fixed pivot point. This structure gives more control to the movement of 
piston 102 and other moveable elements of the piston/crankshaft linkage. 
This embodiment otherwise functions the same as the previous embodiments. 
FIGS. 10 and 11 show another embodiment wherein the connecting ring 6 
comprises two spaced-apart legs 150, each having a bore. Disk 12 is 
rotatably mounted in the bores of the connecting ring 6. A supporting ring 
152 is mounted between the legs of the connecting ring 6, in surrounding 
relation to the disk 12. The disk 12 is a afforded rotatable movement 
Within supporting ring 152. Supporting ring 152 is pivotally connected to 
upper and lower pivot arms 156 and 158. The ends of the pivot arms 156 and 
158 remote from the supporting ring 152 are pivotally attached to fixed 
rods 160 and 162 or other fixed pivot points. In this embodiment, the 
supporting ring 152 and pivot arms 156 and 158 prevent lateral movement of 
the disk connecting rod, thus assuring true vertical movement of the 
connecting rod and piston. 
FIG. 12 shows yet another embodiment of the invention wherein a pivot arm 
166 is fixedly attached to the connecting ring 6. Pivot arm 166 is mounted 
on fixed rod 167 or other fixed pivot points. Connecting rod 5 comprises a 
shaft 168 which is pivotally connected at the upper end of piston 102 at 
point 170 and pivotally connected at its lower end to the connecting ring 
6 at point 172. As in the embodiment shown in FIG. 9, this construction 
provides more contact to the movement of piston 102 and other moveable 
elements of piston/crankshaft leakage. 
The above-disclosed embodiments of the invention are exemplary, and are not 
intended to limit the scope of the appended claims which define the 
invention. For example, crankshaft 4 could be formed as one piece, which 
would include the crank arm 20 and pin 16, or it may be formed separately. 
As another example, crank pin 16 may be rotatably mounted on crank arm 20. 
In such an embodiment, crank pin 16 may be fixedly attached or integral 
with disk 12.