Power plants – Combustion products used as motive fluid – Rotating combustion products generator and turbine
Reexamination Certificate
1999-03-31
2001-10-02
Casaregola, Louis J. (Department: 3746)
Power plants
Combustion products used as motive fluid
Rotating combustion products generator and turbine
Reexamination Certificate
active
06295802
ABSTRACT:
FIELD AND BACKGROUND
The present invention relates to rotary engines, and more particularly, to an engine whose power is provided by rocket motors orbiting a central power shaft.
Through the Twentieth Century, the efficiencies and power to weight ratios of engines have improved steadily. Modern powerful aerospace gas turbine engines attain thermal efficiencies of 35% and a power to weight ratio of 3 to 4 kW per kg at a cost of $250 per kg. This high cost excludes these engines from the low power (under 500 kW) aircraft vehicular and industrial applications. For example, small airplanes and helicopters are powered only by prison engines to this day. The main factor contributing to this high cost is the complexity of a rotating turbine operating at high speed and high temperature. The main factor contributing to the low efficiency of low power turbine engines is the small dimension of the rotating compressors and turbines.
A major limitation of a rotating turbine is the creep characteristics of the turbine blade material. At present, the temperature limit at the turbine inlet of a gas turbine engine is 1500° C. because of creep, although the combustion temperature is much higher (around 2500° C.). This prevents turbine engines, especially small turbine engines, from approaching their theoretical thermodynamic efficiencies.
Thus, there is a widely recognized need for, and it would be highly advantageous to have, a low power rotary engine that would overcome these disadvantages of present known turbine engines.
SUMMARY OF THE INVENTION
According to the present invention there is provided an engine for driving a load shaft, comprising: (a) a power shaft; and (b) a plurality of combustion chambers, each of the chambers being substantially equidistant from the power shaft and rigidly connected to the power shaft, each of the chambers being provided with a nozzle oriented so that exhaust gases exit the chamber therethrough in a direction substantially tangential to a circle concentric with the power shaft.
The earliest known reaction motor is the device shown in
FIG. 1
, invented more than 2000 years ago by Hero of Alexandria for sprinkling water of purification on worshippers in a pagan temple. A spherical boiler
10
is provided with two tangential nozzles
12
at opposite sides of boiler
10
and pointing in opposite directions. Boiler
10
is mounted on a stand
16
so that boiler
10
is free to rotate about an axis perpendicular to the plane defined by nozzles
12
. Boiler
10
is partially filled with water and fire
18
is placed under boiler
10
to boil the water. Water and steam
14
emerging from nozzles
12
causes boiler
10
to rotate. Hero's device was intended to provide a spray of water, not to provide power. An ordinary garden water sprinkler functions similarly, also to provide a spray of water rather than providing power. The device of the present invention uses reaction motors, disposed circumferentially like nozzles
12
of Hero's device, to provide power to a central shaft.
About fifty year ago, a system similar to Hero's was tried for helicopter propulsion. In this system, hot gases were forced radially through the blades of the helicopter and exhausted circumferentially from the blade tips. The idea was to rotate the blades using the reaction force of the circumferentially exhausted gas. This system was unable to give sufficient propulsive power at a reasonable efficiency, because the blades could not withstand the high temperature of the hot gases needed for the desired performance. That system differs from the present invention in that that system uses hot gases generated elsewhere to drive the rotation of the blades, whereas the present invention drives a central shaft using reaction motors deployed around a circle concentric with the central shaft.
FIG. 2
shows the conceptually simplest, albeit least preferred, embodiment of the present invention. Two reaction motors, shown in
FIG. 2
as solid fuel rocket motors
10
, are connected rigidly by struts
22
to a power shaft
24
. Rocket motors
20
are on opposite sides of shaft
24
, and point in opposite directions. As is well known in the art, the bodies of rocket motor
20
serve as combustion chambers
26
for the solid fuel (actually a fuel-oxidizer mixture) contained therein. The exhaust gases produced by burning the solid fuel exit combustion chambers
26
via nozzles
28
. All four struts
22
are of equal length, so that the exhaust gases emerge from nozzles
28
in opposite directions substantially tangent to a circle
30
concentric with shaft
24
. Shaft
24
is supported by bearings (not shown) that allow shaft
24
to rotate about the longitudinal axis thereof, but allow no other motion, so that the reactive forces associated with the emergence of exhaust gases from nozzles
28
apply a torque to shaft
24
, causing shaft
24
to rotate about the longitudinal axis thereof.
The embodiment of
FIG. 2
illustrates the principle of the present invention, but suffers from several practical deficiencies. The embodiment of
FIG. 2
operates only as long as the solid fuel in rocket motors
20
lasts. Furthermore, it is difficult if not impossible to regulate the power output from this embodiment. Therefore, preferred embodiments of the device of the present invention provide continuous, easily regulated flows of fluid fuel and oxidizer to circumferentially mounted combustion chambers. The preferred oxidizer is air, compressed by one or more centrifugal compressors coaxial with shaft
24
and driven by shaft
24
.
REFERENCES:
patent: 2465856 (1949-03-01), Emigh
patent: 2499863 (1950-03-01), Hart
patent: 2594629 (1952-04-01), Exner
patent: 3200588 (1965-08-01), Math
patent: 3557551 (1971-01-01), Campbell
patent: 3699771 (1972-10-01), Chelminski
patent: 61-16252 (1986-01-01), None
Levy Yeshayahu
Lior David
Casaregola Louis J.
Freidman Mark M.
Lior David
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