Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
Description
Apparatus_and_Operatin~ Method for
. _
an Internal Combustion E~
Technical Field
The present invention relates generally to
electric ignition, internal combustion engines each
of which functions as an expander during a p~rtion of
a cycle and in particular to a new and improved fuel
system and engine operating method.
10 Background Art
In conventional gasoline engines, particularly
those used in the automotive industry t a carburetor
mounted atop an intake manifold forms the-principal
component of a fuel systemO As is well known,
15 combustion air is drawn through the carburetor. A
controlled amount of gasoline is added to the
incoming air to form a combustible fuel/air mixture,
as the air passes through a venturi throat formed in
the carburetor. The intake manifold, which includes
20 passages that communicate with valve controlled
intake ports in the cylinder head of the engine,
conveys and distributes the fuel/air mixture from the
carburetor to the combustion chambers.
In theory, the liquid gasoline is vaporized
25 prior to entering the combustion chambers. In
practice, however, a major portion of the gasoline
remains unvaporized and in a liquid state even as it
enters the combustion chamber, finally vaporizing
during the combustion process. The presence of un-
30 vaporized fuel in the combustion~chamber, reduces theheat of combustion, thus limiting the power output of
the engine.
It has long been recognized that the efficiency
of the gasoline engine is substantially less than
35 ideal. One ~actor contributing to poor efficiency in
some engines is known as carburetor "double pull".
~.
Since ~he intake port is usually opened well before
the exhaust stroke is completed; gases are forced in
a reverse direction through the carburetor venturi
drawing fuel into this flow. This reverse flow goes
into the air inlet and filter wasting ~uel. Another
10 factor is a substantial portion of the energy
available in each pound of gasoline cons~ed by an
engine, is discharged to the ambient as waste heat
from its cooling and exhaust systems and by way of
radiation from the engine. Automotive designers over
15 the years have proposed methods and apparatus for
recapturing and utilizing at least a portion of this
waste heat.
One proposed apparatus is an exhaust driv~n
supercharger, more commonly called a turbocharger. A
20 turbocharger generally comprises a pair of turbines
mounted to a common shaft. One turbine is a drive
turbine disposed in an exhaust flow path, while the
other turbine is a compressor turbine disposed, at
least in some instances, in the intake flow path
25 between the carburetor and the combustion chambers.
In this configuration, the exhaust gases discharged
by the combustion chambers expand across the exhaust
turbine to rotate it and the intake turbine thereby
compressing gases in the fuel air mixture. This
30 compression permits an increase in the amount of fuel
introduced into each piston cylinder during the
intake stroke of its piston while maintaining a
desired fuel/air ratio, to produce an attendant
increase in the engine's power output.
The addition of a turbocharger has not increased
engine fuel efficiency in normal automotive usage.
In general, the turbocharger allows a smaller engine
with less friction to be used in a given size
vehicle~
With these prior engines under operating
conditions where cylinder intake produces high
vacuum, pressure from the ambient air on the intake
side of the turbocharger may exceed manifold pressure
thus creating a pressure differential across the
compressor side of the turbocharger. When an engine
lO is idling there is little exhaust flow to drive the
turbine and high vacuum manifold conditions exist so
there is a large pressure differential across the
compressor side of the turbocharger. This pressure
differential causes an air flow through the
15 compressor side. This air flow applies rotational
forces to the compressor blade in opposition to the
drive turbine.
Because exhaust flow is low, the air flow
produced forces may be sufficient to cause reverse
20 rotation of the compressor and will in any event
prevent ef~ective turbocharger operation. Thus,
under light load the turbocharger is essentially
inoperative and in fact may run backwards.
Another problem with each prior engine with a
25 turbocharger between its carburetor and its intake
manifold occurs on acceleration. When the throttle
opening is increased, the quantity of liquid fuel
droplets contained in the fuel/air mixture is
increased virtually instantaneously but exhaust flow
30 is notO This additional liquid fuel causes a
significant increase in the load on the compressor
turbine. Indeed in test racing engines the load
increases on occasion, have been great enough to
cause compressor turbine destruction. Since the
35 driving force from exhaust gases is substantially
constant the compressor is slowed by this load
increase and the compressing action of the
turbochager is reduced. In time the increased fuel
produces in~reased exhaust gases, causing the
turbocharger to increase its speed and output. In
sum, prior turbocharged engines have slow response to
demands for power increases and will consume
excessive fuel for a time whenever ~here is a
significant increase in throttle opening. In fact,
this excessive fuel consumption has made it
10 difficul~, if not ;mpossible, for prior turbocharged
engines to meet Environmental Protection Agency (EPA)
standards if the turbocharger in fact operates during
testing.
Other proposals for increasing the fuel
15 efficiency of gasoline engines have included methods
and apparatus or heating the fuel to aid
vaporization Prior proposals have suggested heating
the fuel-air mixture by transferring heat from either
the engine cooling system or the engine exhaust
?0 system. Problems associated with heating a fuel/air
mixture as it travels to a combustion chamber, have
long been recognized.
These problems include an increase in the
temperature of the fuel mixture decreases the mixture
25 density and causes a decrease in the volumetric
efficiency of the engine for it decreases the amount
of fuel drawn into each cylinder during an intake
stroke. In addition, heating the fuel often causes a
vapor lock condition in the fuel system which
30 partially or completely blocks the flow of Euel into
the intake flow path, degrading engine performance.
To avoid vapor lock, many of khe proposed fuel
mixture heaters operate during engine warmup only and
are turned off once the engine reaches its operating
35 temperature. E'urther, prior hot vapor engine
proposals have utilized storage chambers from which
the fuel air mixture is modulated. Such a chamber is
large and can be dangerous.
With prior engines, during engine warmup,
vaporized fuel condensed on the interior walls of the
intake manifold and other surfaces. Manifold and
carburetor heating systems have been proposed to
operate during engine warmup and were intended to
solve or minimize this problem. While such proposals
might improve conditions during warmup, the fuel
10 still experienced as many as four phase changes as it
travelled from the carburetor to the combustion
chambers, even in an engine that had reached its
operating temperature. Specifically, portions of the
fuel entrained in the mixture flow shift between
15 vapor and liquid states as the mixture travels
through the engine intake system. Moreover, these
phase change characteristics in a multi-cylinder
engine are uneven varying from cylinder to cylinder
and furkher varying with engine speed and load.
These phase changes contribute to the reduction
in thermal efficiency in an enyine due to: 1) the
induction of some liquid fuel into the combustion
chambers; 2) the nonuniform nature of the fuel-air
mixture; and, 3) substantial heat energy losses to
25 the intake manifold and other components of the fuel
system. These losses are substantial because
gasoline, like all liquids, has a relatively high
heat of vaporization.
The prior proposals for increasing the thermal
30 efficiency of an engine have not recognized or
addressed this problem. In most of the proposed
systems, the fuel or fuel mixture was merely to be
heated by either fluid from the engine cooling system
or alternately by exhaust gases.
Combining a turbocharger with a fuel mixture
heating apparatus has been proposed in the past. In
one such proposal, the fuel charge would be heated by
exhaust gases during part throttle operating
conditions only. During full throttle conditions,
the exhaust gases would be diverted to a turbocharger
and the fuel mixture would go unllea~ed, so that its
density would be maximized.
It has also been found that many engine
designers are of the opinion that the fuel mixture
should be cooled after leaving a turbocharger or a
10 supercharger. A cooling device commonly called an
"intercooler" is disposed between the outlet of the
supercharger and the combustion chambers. The
purpose of the intercooler is to remove the heat
generated as the mixture is compressed so that the
15 fuel mixture density is increased. These seemingly
conflicting proposals would indicate that confusion
and uncertainty still exist in fuel system design
theory.
The measure of success, however, in increasing
20 the fuel efficiency of an internal combustion engine
does not reside in the complexity or simplicity of
the apparatus or the rigid adherence to long taught
engine design principals, but in the increase in
gasoline mileage and engine performance actually
25 achieved in a given size engine.
Disclosure of Invention
The present invention provides a new and
improved apparatus and method for improving the fuel
efficiency of an electric ignition, internal
30 combustion engine. It is readily adaptable to
existing automobile engines for it does not require
excessive engine retooling and it will decrease the
cost and weight of the vehicle.
According to the invention, a fuel charge
35 forming apparatus is disclosed for combining a
vaporizable fuell such as gasolinel with combustion
air in controlled proportions. The apparatus
utilizes heat normally exhausted by the engine to
condition the fuel mixture. The apparatus prepares
and conditions the fuel/air mixture during its
laminar flow travel to ~he engine combustion chambers
to insure complete fuel vaporization and thorough
fuel/air mixing so that maximum energy output is
realized during the combustion process.
In the preferred embodiment, a fuel mixture
10 flow path is defined that extends between a fuel
mixture introducing device, such as a carburetor and
the engine combustion chambers. The flow path
communicates with each combustion chamber through an
associated valve controlled port. The apparatus
15 further comprises an air heater and fuel/air mixture
vaporizing and heating devices disposed in the flow
path, and a fuel mixture homogenizer located between
the fuel mixture vaporizing and heating devices.
While tests of the present invention have been
20 conducted using a conventional carburetor, it is
believed that the operation of the apparatus does not
depend on the use of a carburetor; alternate methods
for introducing fuel into an air flow path such as
pressure carburetion and manifold injection are also
25 contemplated.
In the preferred embodiment, the fuel mixture
vaporizer includes a chamber disposed in the flow
path intermediate the carburetor and the fuel mixture
homogenizer that is heated by fluid from an engine
30 cooling system. The heat absorbed by the engine
cooling systemr which in the past has been wasted, is
transferred to the incoming fuel mixture as it passes
through the vaporizer chamber thereby enhancing fuel
vaporization and producing an at least partially
35 vaporized mixture.
The mixture is then clirected to the fuel mixture
homogenizer which stirs and further heats the mixture
so that the fuel is fully vaporized to a
"supervaporized" state and the vapor is uniformly
dispersed.
The preferred homogenizer is exhaust driven and
includes a pair of turbines mounted on a common shaft
and rotatably supported in a structure that defines
separate turbine chambers. One turbine is an exhaust
driven turbine and it, in turn, drives the other
10 turbine which is an homogonizing ~urbine disposed in
the fuel mixture flow path. The turbines are sized
to provide both mixing and mixture pressurization at
all throttle openings. Unlike the prior art turbo-
chargers, the homogenizer functions throughout the
15 engine operating range insuring thorough fuel
vaporization and mixing and dispersion of the Euel
uniformly throughout the air of the mixture. One
major reasbn the homogenizer functions throughout the
engines operating range is that the fuel/aix mixture
20 is temperature expanded across the homogenizing
turbine applying rotational force additive to the
exhaust gas produced forces.
In one version of the engine the heated
homogenizer housing defines intake air flow passages
25 which are connected to the carburetor air intake by a
hot air conduitO Air is heated as it passes through
these passages. A temperature responsive valve
closes off an ambient air inlet to the carburetor
whenever air supplied by the hot air conduit is below
30 about 110F and manifold vacuum is above four inches.
An EGR system is provided in the version of the
engine which has preheated air. Unlike prior EGR
systems, the system of the present invention assures
uniform distribution of recirculâted exhaust and
35 vaporization of residual hydrocarbons~ This
uniformity is accomplished by introducing the EGR
fluids to the fuel/air mixture flow path at or ahead
of the entrance to the homogenizer. As these
residuals are passed through the homogenizer they are
thoroughly admixed with the fuel/air mixture assuring
., ~"~
for the first time uniform distribution of the
residuals amony the combustion chambers.
S;nce the fuel/air mixture is preheated before
it is introduced into the homogenizer its specific
density is low and little, if any, unvaporized fuel
10 is present. Thus the fuel air mixture is
comparatively easy to compress and continuous
compression of its output can and does occur at all
engine speeds. In addition the outlet from the
chamber is somewhat restricted to partially isolate
15 the homogenizer's mixing chamber from pressure
differentials between the input and ou~put sides of
the homogenizer which occur during power demand
conditions and prevents a "double pull" on the fuel
supply. This isolation coupled with the low specific
20 density of the fuel/air mixture and the mixtures
thermal expansion permit the homogenizer to function
efficiently during acceleration. Thus, the
homogenizer operates at idle conditions and response
lag is not experienced during accelerating
25 COnditions.
The fuel mixture heater is disposed in the
mixture flow path between the outlet of the
homogenizer and the intake ports of the engine. In
the preferred embodiment, ~he fuel mixture heater
30 includes an exhaust heated chamber through which the
mixture passes on its way to the combustion chamber.
The heater insures that the fuel remains in its
completely vaporized state, preferably at a
temperature twice the vaporization temperature of the
35fuel, prior to entering the combustion chamber.
It is believed that automobile engines presently
being manufactured can be modified or adapted to
utilize the present invention and thereby realize a
substantial gain in fuel efficiency. Some
conventional components are eliminated and those
componellts which are used do not require exotic
materials, extensive engine retooling or complicated
manufacturing processes. In addition, smaller
engines can be standard equipment in present
automobiles to decrease their cost and weight.
According to the exemplary and illustrated
embodiment, the fuel mixture vaporizer comprises a
housing that also serves as a mounting base for the
carburetor. The housing defines an interior chamber
that communicates with the throat of the carburetor
15 and an outlet conduit that conveys the fuel mixture
from the chamber to the homogenizer. Coolant
passages, located in the walls of the housing,
support coolant flow between an inlet and an outlet
forming part of the vaporizer. Suitable conduits
20 communicate the coolant inlet and outlet with the
engine cooling system. A small radiator is coupled
in parallel with the vaporizer. A thermostatically
controlled valve blocks flow to the radiator whenever
coolant temperature is below about 200F.
The fuel mixture heater comprises a housing that
includes passages in the side walls through which
exhaust gases travel and heat the interior walls of
the plenum. According to a feature of this
embodiment~ the chamber includes vertically standing
30 ribs which subdivide the mixture flow into a
plurality of branch flow paths, the number of which
corresponds to the number of cylinders in the engine.
Conduits direct exhaust gases from the combustion
chambers to the passages formed in the walls of the
35 plenum chamber.
The disclosed apparatus recaptures heat normally
wasted from both the engine cooling system and the
engine exhaust system and utilizes this heat to com-
pletely vaporize and thoroughly mix the fuel mixture.
As a result, the size of the vehicle radiator can be
significantly reduced and the need for a radiator fan
is eliminated.
Normally, the coolant radiator is necessary to
provide the means for discharging the waste heat
absorbed by the engine coolant. In the present
10 invention, the waste heat is transferred and absorbed
by the vaporizing fuel. The heat absorbed by the
fuel reduces the coolant temperature and thus
supplants a significant part of the radiator
function.
Additionallyl the coolant system conduits and
pump are sized so that the cQolant flow rate through
the engine is linear with engine output to provide
the requisite amount of heat to the fuel mixture va-
porizer.
According to another feature of the invention,
an isolator is positioned between the carburetor and
the fuel mixture homogenizer. The purpose of the
isolator is to inhibit direct, uncontrolled heat
conductivity along the mix~ure flow path to the base
25 and thence to the bowl of the carburetor. The
isolator minimizes the incidence of vapor lock that
might occur in the carburetor when a "hot" engine is
turned off. The isolator inhibits the transmission
of engine heat to the bowl of the carburetor through
30 the structure that defines the mixture flow path~
In a more specific embodiment, the isolator
comprises an elastomeric, nonconductive coupling
between the outlet of the engine preheater and the
inlet to the homogenizer. In this preferred
35 embodiment, the carburetor and vaporizer are mounted
to the vehicle chassis or body and hence the isolator
prevents not only the transmission of heat to the
carburetor but engine vibration as well. It is
believed the vibration isolation provided by this
isolator construction and carburetor mounting
1~
increases the reliability of the carbure~or, prevents
loss of fuel flow control due to vibration, and
should reduce the incidence of carburetor
readjustment.
The present invention discloses a method for
10 operating an engine in which all the fuel is fully
vaporized before it is introduced into the combustion
chamber and once vaporized remains vaporized as it is
conducted through the engine intake system. ~he ~uel
is not only completely vaporized but is also
lS thoroughly mixed so that a uniform fuel and air
mixture enters the combustion chamber. According to
the method, the fuel, such as gasoline, is entrained
in a flow of atmospheric air. The entrained fuel and
air~ forming a somewhat non-homogenous fuel mixture
20 is preheated by heat derived from the engine, i.e.,
from either the engine cooling or engine exhaust
system. The fuel and atmospheric air is then mixed
by a homogenizer to produce a uniform fuel/air
mixture. The homogenous mixture is then further
25 heated to a temperature well in excess of, preferably
at least twice r the vaporization temperature of the
fuel and then it is introduced, virtually
immediately, into a combustion chamber.
In order to take full advantage of the fuel
30 preparation apparatus and method disclosed above, the
present invention also provides additiona7 method
steps for operating an engine to optimize thè amount
of energy extracted from the fuel charge inducted
into the combustion chamber. This optimizes the
35 power output of the engine and reduces the amount of
heat which must be taken out with a cooling system
thus contributiny to the reduction in radiator size.
According to these additional method steps, the
volume oE the combustion chamber is held
substantially constant during the combustion process
13
until the gases and products of the combustion
reaction subs~antially reach their maximum
~empera~ure and pressure. In order to accomplish
these method steps, the crankshaft stroke and piston
rod length are selected so that the piston remains
10 within 0.001 inches of top-dead-center (TDC~ for at
least 13 of crankshaft rotation.
It is believed that the disclosed fuel charge
forming apparatus used in connection with the engine
operating method disclosed by the present invention
15 provides an enyine that functions as an "expander",
that is, an engine in which all useful expansion
forces generated during combustion are utilized ~3r
producing motion in the piston and to a signi~icant
extent, are not dissipated as heat losses.
20 Maintaining the piston virtually at TDC until, the
combustion temperature and pressure are optimized
assures that the heat energy generated is primarily
dissipated in driving the piston downwardly,
minimizing heat losses to the engine cooling and
25 exhaust systems. Moreover, heat released to these
engine systems is returned to the incoming fuel
mixture via the fuel vaporizing and heating devices
and the homogenizer. In es.sence, the present
invention provides a "hot vapor cycle" engine in
30 which balanced heat loops transfer heat from the
engine to the fuel mixture flow path, the heat trans-
ferred being proporticnal to engine output.
The apparatus and method disclosed by the
present invention has been found to substantially
35 increase the fuel efficiency and power output of a
gasoline automotive engine. Moreover, it was found
that the low rpm torque was also increased while the
tendency towards pre-ignition and detonation were
decreased.
Additional features and a full understanding can
1~
be obtained in reading the following detailed
description made in connection with the accompanying
drawings.
Brief Description of the Drawings
Figure 1 is a schema~ic view of a fuel
10 mixture preparing and conditioning apparatus
constructed in accordance with the preferred
embodiment of the invention,
Figure 2 is a schematic illustration of the
engine coolant circuit that provides heat to a fuel
lS mixture vaporizer constructed in accordance with the
preferred embodiment of the invention;
Figure 3 is an exploded view of the ~uel mixture
preparing and conditioning apparatus;
Figure 4 is a view partly in elevation and
20 partly in section, of fuel mixture homogenizing and
heating devices constructed in accordance with the
preferred embodiment;
Figure 5 is elevational view of the fuel mixture
heater, with parts removed to show interior detail;
Figure 6 is a cross sectional view of the fuel
mixture heater as seen along the plane indicated by
the line 6-6 of Figure 5;
Figure 7 is a sectional view of the fuel mixture
heater as seen from the plane 7-7 of Figure 6;
Figure 8 is a perspective view of the vaporizer
of the engine shown schematically in Figure 1 on an
enlarged scale;
Figure 9 is a sectional view of the vapori~er as
seen from the planes indicated by line 9-9 of
35 Figure 8;
Figure 10 is a graph depicting a measured torque
curve of the engine of this invention;
Figure 11 is a schematic view of a refined
version of the engine of this inven~ion;
Figure 12 is a perspective view of the engine of
Fiqure ll; and
Figure 13 is an enlarged sectional view of the
homogenizer of the engine of Figures ll and 12.
Best_Mode For _ arry_ny Out the Invention
The present invention provides a new and
lO improved apparatus and method or substantially
improving the fuel efficiency of an electric
ignition, internal combustion engine. In accordance
with the invention, engine heat normally discharged
to the ambient by the exhaust and coo~ant systems is
lS captured and utilized to prepare and condition the
incoming fuel mixture so that increased combustion
efficiency is realizedr In particular, the present
invention thoroughly mixes and vaporizes the incoming
fuel charge prior to entry into the engine combustion
20 chambers.
Figure 1 schematically illustrates an apparatus
defining fuel and exhaust flow paths constructed in
accordance with the preferred embodiment of the
invention. Referring also to Figures 3 and 4, the
25 apparatus is connected to an internal combustion
engine 20 which in the illustrated embodiment
includes three cylinders 22, formed in an engine
block 24, each cylinder 22 including an associated
piston 26. The pistons 26 are operatively connected
30 to a crank shaft (an output end 28 of the crank shaft
is shown in Figure 3) by connecting rods in the
conventional manner so that reciprocal movement in
the pistons 26 produces rotary motion in the crank
shaft 28.
A cylinder head 30 is suitably fastened to the
top of the engine block 24 and defines a combustion
chamber 32 in each cylinder 24 ~shown in Figure 4).
A pair of cam driven poppet valves 33 (only one valve
33 is shown~ controls the inflow of the fuel/air
mixture into the combustion chamber 32 and the
4~3
1~
outflow of c~mbustion products. The head 30 includes
integrally formed intake and exhaust passages (only
the intake passage 34 is shown). The intake passages
34 extend from ports 34a formed in the side of the
cylinder head 30 (shown in Figure 3) and the intake
10 valves 33. Coolant passages 36 support coolant 10w
~hrough the head for removing excess heat during
engine operation. The coolant is discharged from the
cylinder head 30 through an outlet port 36a. The
cylinder block 24 also includes coolant passages 38.
Returning to Figure 1, the present invention
provides an apparatus and structure, indicated
senerally by the reference character 37 that defines
a fuel mixture ~low path extending between the
cylinder intake ports 34a and a fuel introducing
20 device 38, preferably a carburetor. According to the
invention, means for thoroughly vaporizing and mixin~
the fuel mixture as it travels from the carburetor 38
to the engine combustion chambers 32 is provided.
Liquid ~uel is delivered to the carburetor 38
25 from a fuel tank 40 by a conventional fuel pump 42
and associated conduits 44. Preferably, the
carburetor 38 operates in a conventional manner and
combines controlled amounts of air and liquid fuel to
form a combustible fuel mixture.
In general, only a portion of the liquid Euel
will be partially vaporized in a throat of the
carburetor as it enters the air flow stream. In
accordance with the invention, a fuel mixture
vaporizer 50 and a fuel mixture heating device 52 are
35 disposed in and preferably form a part of a fuel
mixture flow path 37 to insure complete fuel
vaporiæation and to heat the fuel/air mixture above
the vaporization temperature of the liquid fuel,
preferably to a temperature which is twice the
vaporization temperature of the fuel~ A fuel mixture
17
homogenizer, indicated generally by the reference
character 54 is disposed in the flow path
intermediate the vaporizer 50 and the heating device
52.
In the preferred embodiment the fuel mixture
10 vaporizer 50 heats the fuel mixture with heat from
the engine coolant system. The invention does
contemplate the use of exhaust heat if coolant heat
is unavailable, i.e., in an air-cooled engine. The
engine coolant fluid loop for accomplishing this
15 feature of the invention is illustrated in Figure 2.
The cooling circuit includes a conventional water
pump 60 for pumping coolant into the engine block 24
and the cylinder head 30. The coolant is delivered
to the engine through a supply conduit 62 and is
20 discharged from the head 30 into an outlet conduit 64
through the coolant port 36a formed in the cylinder
head 30 (shown in Figure 3). The outlet conduit 64
has a valve 65 for adjusting the fluid flow through
it~ The outlet conduit 64 delivers coolant to the
25 vaporizer 50. The coolant circulates through the
vaporizer and is subsequently discharged into~a
return conduit 66. The conduit 66 communicates with
the inlet side of the pumpO
A thermostat housing 68 including a conventional
30 thermostat (not shown) is provided for controlling
the fluid commun;cation between the conduit 64 and a
radiator input conduit 70. As long as a coolant
remains below a predetermined temperature (determined
by the thermostat) the thermostat remains closed and
35 the coolant is conveyed to the input of the coolant
pump 60 through the conduit 66. In this operating
mode, the coolant circulation loop includes only the
pump 60, the engine block and head 24, 30 and the
vaporizer 50. Should the coolant temperature exceed
the thermostat setting, the thermostat will open and
13
communicate the conduit 70 and the coolant will
proceed through a radiator 74 and then be returned to
the cooling pump 60 by a radiator return conduit 76.
An electrically driven fan 78, controlled by a
thermostat (not shown) is shown in phantom. In tests
10 the fan has not turned on so it preferably is
eliminated and has for this reason been shown in
phantom. It is shown here only because it was
present, through inoperative, during tests in which
certain data was collected.
The mixture vaporizer S0 preferably mounts and
forms the support base for the carburetor 38. In
accordance with this feature and as seen in Figures
3, 8 and 9, the vaporizer 50 includes a housing 50a
and an integrally formed carburetor mounted flange
20 SOb including vertically extending retaining studs
80. Re~erring in particular to Figures 8 and 9, the
housing 50a defines an interior, heating chamber 82
that communicates with the throat of the carburetor
through a pair of passages 84 that extend downwardly
25 from the top of the carburetor flange 50b and open
into the chamber 82.
A fluid jacket 86 defined by exterior and
interior walls 88, 90 of the housing 50 surround the
chamber 82. Engine coolant is circulated in the
30 fluid passages 86 so that heat from the engine
coolant is transferred to the chamber 82 through the
interior wall 88. The enyine coolant is communicated
to the vaporizer through an inlet nipple 92 formed in
the housing 50a and suitably connected to the outlet
35 conduit 64. The coolant leaves the vaporizer 50
through an outlet nipple 94 (shown in Figure 9) that
is suitably connected to the return conduit 66.
The fuel mixture formed in the throat of the
carburetor 38 enters the heating chamber 82 through
the passages 84. The mixture leaves the chamber 82
~L~8~
19
through a chamber outlet 96 formed in the housing 50a
and preferably extending in a direction orthogonal to
the axes of the passages 84.
Under normal engine operating conditions, it has
been found that a substantial portion of the engine
10 heat absorbed by the engine coolant is released to
the fuel mixture as the mixture passes through the
vaporizer 50. In effec~, the coolant heat discharged
to the vaporizing fuel partially supplants the need
for the coolant radiator 74 and totally supplants the
15 need for the cooling fan 78, thus allowing the use of
fewer and smaller components.
It has been found that the coolant flows in many
conventional automobiles are excessive, resulting in
the loss of large amounts of engine heat to the
20 ambient. This condition is alleviated by the present
invention. According to the invention, the coolant
flow rate through the engine is proportional to the
power output of the engine so that as the engine
output increases, proportionately more heat is
25 carried to the fuel mixture preheater 50 for transfer
to the incoming fuel charge. This "heat balance"
between the coolant flow rate and engine output is
achieved by the sizing of the coolant pump 60 and the
adjustment of the control valve 65. In actual
30 production, the valve 65 is preferably eliminated by
appropriately sizing the various coolant conduits.
Returning to Figure 1, the homoqeni zer 54
operates to thoroughly mix the fuel rnixture received
from the vaporizer 50 and insures that the fuel vapor
35 is uniformly dispersed throughout the fuel/air
mixture. Moreover, the homogenizer operates to
compress the fuel air mixture thereby increasing the
density of the fuel charge entering the combustion
chambers 32.
In the preferred embodiment, the homogenizer 54
2Q
comprises mixing and exhaust driven turbines 102, 104
fixed to a common shaft 106 and mounted for rotation
within a structure that defines separate turbine
chambers or housings 108, 110 associated with the
turbines 102, 104 respectively. The turbine 104 is
10 disposed in the exhaust flow path and is in part
driven by the exhaust gases discharged by the engine
20; the rotation of the turbine 104 produces
attendant rotation in the turbine 102. Further
rotation producing forces are supplied by the mixture
15 flow across the mixing turb;ne which results from
thermal expansion. The rotation of the turbine 102
stirs or homogenizes the fuel mixture passing through
the turbine housing 108 on its way to combustion
chambers.
Referring to Figure 3, the originally preferred
exterior construction of the homogenizer 54 is
illustrated. The turbine housing 108 includes an
axial inlet 12t) through which the fuel mixture from
the vap~rizer 50 is received. The homogenized fuel
25 mix~ure leaves the turbine housing 108 through a
flanged nozzle outlet 122 that extends tangentially
from the turbine housing 108. The exhaust turbine
housing 110 includes a flanged inlet 124, formed
tangentially with respect to the turbine chamber 110.
30 The exhaust gases passing through the housing 110 are
discharged through an axial outlet commun;cating with
an exhaust pipe 126. The pipe 126 includes a flange
126a clamped to the axial outlet by means of studs
128. The studs extend from the side of the exhaust
35 turbine housing 110 and are adapted to receive
suitable threaded fasteners (not shown). The exhaust
gases discharged by engine 20 are conveyed to the
exhaust turbine housing by an exhaust conduit 132
that terminates in a flange 132a~ A similar flange
124a is mounted at the inlet 124 of the housing 110.
21
5 The ~langes 124a, 132 include a plurality of
apertures 125 adapted to receive suitable fasteners
for coupling the flanges 124a, 132a. The turbine 104
is rotatably driven by ~he exhaust gases travelling
from the conduit 132 to the conduit 126 and as
10 discussed above, rotation of the turbine 104~ in
turn, imparts rotation to the mixture turbine 102.
Although the homogenizer 54 bears some physical
similarity to a conventional turbocharger, which
those skilled in the art will recognize as an exhaust
15 driven supercharger, its primary functions are the
homogeniæation of the fuel mixture and the addition
of heat to complete, and assure maintenance of, total
vaporization of the fuel. Thus, while there is
fuel/air mixture compression, as is the case with
20 conventional turbochargers, this is not the primary
function of the homogenizer. In accordance with this
feature of the invention, the turbines 102, 104 are
sized and selected to rotate at 2,000 to 4,000 rpm
with the engine at idle and to rotate under all
25 operating conditions.
The boost pressure provided by the homogenizer
under specific turbine speeds is less than the boost
pressure that would be provided by a similarly sized
turbocharger used with a conventional internal
30 combustion engine. The reason for the reduction in
the boost pressure realized by the present invention
is due to the conditioning of the Euel mixture by the
vaporizer S0. As explained above, the vaporizer 50
adds heat to the incoming uel m^ixture that not only
35 vaporizes the liquid fuel entrained in the fuel
mixture, but it raises the overall temperature and
thus reduces the mixture density. This density
reduction results in reduced boost pressure for a
given steady state turbine speed when compared with
conventional but more importantly results in
~2
5 increased mixing and full vaporization of the
fuel/air mixture. Thls reduction in boost pressure
or a given turbine speed is offset by the increase
in turbine speed which results in achieving desired
boost pressures.
Although the boost pressure is somewhat self
limitinq by the proper selection and sizing of the
turbines 102~ 104, a bypass valve 140 is provided on
the exhaust turbine housing 110 for bypassing exhaust
gas around the housing in the even~ a malfunction is
15 encountered that produces an excessive boost
pressure.
Unlike conventional turbochargers, the output
pressure of the homogenizer 54 increases immediately
upon the initiation of throttle acceleration. As is
20 known in the art, movement of the throttle produces
an immediate injection of fuel via an accelerating
pump and/or other acceleration enrichment devices.
The addition of uel to the intake flow path does not
simultaneously produce a proportionate increase in
25 air flow through the carburetor. The air flow
increases only upon an increase in engine RPM.
In conventional turbocharged engines, the output
of the turbocharger will increase only upon an
increase in engine RPM which produces the necessary
30 increased exhaust flow. In the present invention,
the homogenizer 54 rotates throughout the engine
operating range. As explained above, the mixture
density is reduced by the vaporizer 50. When
acceleration is first initiated, the injected fuel
35 immediately increases the specific density of the
fuel/air mixture. This increased mixture density
immediately increases the pressure in the homogenizer
54, even though the engine RPM has not yet increased.
The homogenized fuel mixture leaves the turbine
housing 108 and enters the fuel mixture heater 52.
23
5 Referring to Figures 3, 5, 6 and 7, the fuel mixture
heater 52 func~ions somewhat as an in~ake manifold
for the cylinder head 30 in that i~ divi~des and dis-
tributes the fuel mixture to the individual cylinders
22.
In the preferred embodiment, the fuel mixture
heater 52 comprises an exhaust heated housing 150
that includes spaced interior and exterior walls
150a, l50b, respectively, between which are defined
passages through which exhaust gases circul.ate to
15 heat an interior chamber 152 defined by the interior
wall 150a and a cover plate 154 .(shown in Figure 3)
fastened to the top of the housing 150 by suitable
fasteners 156. The fuel mixture is communicated to
the chamber 152 through an inlet aperture 158 formed
20 in the side of the housing 150. A plurality of
laterally extending studs 160 extend from the side of
the housing 150 and attach the mounting flange 122a
of the homogenizer outlet 122 to the housing 150.
A pair of vertically standing ribs 162 are
25 disposed in the chamber 152, a spaced distance from
the aperture 158. The ribs 162 subdivide the mixture
flow into a plurality of branch flow paths 152a, each
path communicating with one of the three combustion
chambers 22. Preferably, relatively short,
30 individual conduits 164 extend between the housing
150 and a mounting flange 166 adapted to be attached
to the side of the head 30j as seen in Figure 3.
Each conduit 164 communicates one of the branch flow
passages 152a with one of the cylinder head intake
35 ports 34a. A nipple 170 is also mounted to -the
flange 166 and communicates the coolant discharge
port 36a in the cylinder head with the conduit 64
(shown in Figure 2).
The path of exhaust gas flow to the fuel/air
mixture heater 52 and the homogenizer 54 is shown
24
5 schematically in Figure lo The exhaust conduit 132
extends into fluid communication with a plurality of
exhaust ports (not shown) formed in the cylinder head
30 through three branch conduits 174, terminating in
mounting flanges 174a. The branch conduits have
10 elongated straight sections adjacent the flanges to
minimize back pressure. As seen in Figure 3, the
left end of the conduit 132 is fitted with a couplin~
flange 175. A short nipple 178 and associated flange
178a extend from the side of the conduit 132 about
15 midway between the ends. As also seen in Figures 5
and 6, a pair-of relatively short conduits 180, 182
fitted with mounting flanges 180a, 182a extend
downwardly and laterally from the heater housing lS0,
respectively.
A conduit 184 (shown schematically in Figure 1
communicates exhaust gas from ~he left end of the
conduit 132 to the conduit 180. The outlet 182 is
coupled directly to the flange 178a of the conduit
178 extending from the side of the conduit 132 and
25 forms a return path for the exhaust gases. A pair of
suitable flow control valves 186, 188 are disposed in
the conduits 184, 132 and are used to adjust the
exhaust flow in the respective conduits. The valve
186 controls the amount of exhaust gas that is
30 communicated to the fuel mixture heater 52. By
properly adjusting the respective valves a heat
balance is obtained wherein the exhaust gas conveyed
to the heater 52 will deliver the requisite amount of
heat to the fuel mixture, the heat delivered being a
35 function of the power output of the engine. In
actual mass production of the engine, the valves 186,
188 are preferably eliminated by suitably sizing the
conduits 132, 180, 182 and 184 to achieve the
requisite flow rate of exhaust gas through the fuel
mixture heater 52. While insulation is not shown for
~5
clarity, all of the exhaust gas conduits are
preferably insulated further to minimize heat losses~
Turning now to Figure 4, the profile of the fuel
mixture flow path between the homogenizer 54 and the
combustion chamber 32 is detailed. The geometry of
10 the disclosed flow path minimizes energy losses
because the mixture flow encounters very little path
deviation~ The ~uel mixture leaves the homogenizer
54 along a tangential path defined by the nozzle
outlet 122 and enters the fuel mixture heating
15 chamber 52 along a substantially straight path. The
branch flow paths 152a extend substantially equal
distances to the conduits 164 and flare outwardly
from the axis of the nozzle outlet flow less than 8.
The branch flow paths 152a, the conduits 164, and the
20 cylinder head intake passages 34 define a gradual,
downwardly curving flow path that extends between the
chamber 152 and each combustion chamber 32. In
traversing this flow path, the fuel mixture sustains
very little fric:tional or other energy losses. It is
25 believed that this flow path construction optimizes
the combustion process for the mixture enters the
combustion chamber thoroughly mixed, uniformly
dispersed and completely vaporized. Flow through the
heating chamber is laminar.
According to a feature of the invention, direct,
uncontrolled heat transfer between the t~rbine
housing 108 and the vaporizer 50 is inhibited by a
thermal isolator. In particular, referring to Figure
3, a circular flange 200 including a plurality of
3sapertures 202 and a centrally located nipple 204 is
suitably fastened to the inlet 120 of the turbine
chamber 108. A relatively short conduit 206
constructed f rom a material having a relatively low
thermal conductivity is clamped to and extends
between the vaporizer outlet 96 and the turbine inlet
26
5 nipple 204 by suitable clamps (not shown). Preferably,
the conduit 206 is constructed from an elastomeric
material and provides an added feature of the invention.
Not only does ~he conduit 206 thermally isolate
the vaporizer 50 from the turbine housing 108 it also
10 provides vibration isolation and thereby isolates the
carburetor 38 from engine vibration that would other-
wise be transmitted from the turbine housing 108 to
the vaporizer 50. The heat isolation provided by the
conduit 206 prevents the uncontrolled heat transfer
15 to the bowl of the carburetor 38 that could cause
fuel percolation or vapor lock. Moreover, the vibra-
tion isolation provided by the preferred conduit con-
struction should reduce the need for carburetor re-
adjustment and improve the overall reliability and
20 calibration of the fuel system.
It should now be recognized that the present
invention provides a method for operating an internal
combustion engine that increases the overall efficiency
of the engine by optimizing the combustion process.
25 According to the disclosed method, a controlled amount
of liquid fuel, such as yasoline, is introduced into
the intake system of an engine and mixed with a con-
- trolled amount of air to form a combustible mixture.
The air and entrained fuel are then heated by trans-
30 ferring heat from the engine coolant system, or alter-
nately from the engine exhaust system to encourage
the vaporization of the liquid fuel. The mixture is
then stirred and homogenized so that the vapor is
uniformly distributed throughout.
The homogenized mixture is then further heated
to increase the overall temperature of the fuel mixture
well above the vaporization temperature of liquid
fuel. Preferably, the mixture is heated to at least
twice the vaporization temperature of the liquid fuel
with the fuel air mixture reaching about 400F in the
27
5 mixture heater when the uel is 93 octane unleadedgasoline. Movement of the fuel/air mixture is
important to permit mixture temperatures o~ this
magnitude without reaction. Mixture velocities in
the disclosed engine are such that the temperature
10 shoul~ be kept below ~40F to avoid reaction of the
mixture in the heating chamber. It should be noted
that the average-vaporization temperature o~
currently available gasolines (at sea level) is
approximately 110F. The heating of the fuel mixture
15 not only insures complete fuel vaporization but it
also adds energy to the fuel mixture that would
otherwise be lost to the engine exhaust and cooling
systems. In shortr the fuel~air mixture enters the
combustion chambers with a higher energy content.
20 Since the mixture has a higher energy content, less
fuel is needed to produce the desired temperature and
pressure levels in the combustion chamber.
In order to achieve the optimum energy output
during combustion, the present invention also provides
25 method steps for operating the engine which optimize
the combus~ion process. By optimizing the energy
output, it has been found that the amount of waste
heat discharged through the engine cooling system and
otherwise is reduced thus contributing to the reduction
30 in radiator size and fan elimination.
According to these additional steps, the volume
of the combustion chamber is held substantially constant
at or near its minimum volume during the combustion
process so that the gases and products of the combustion
35 reaction substantially reach their maximum temperature
and pressure. The hot gases generated during this
optimized combustion process are allowed to expand
substantially at a constant volume at a time commencing
before there is any significant drop from the maximum
temperature and pressure. In order to accomplish
combustion optimization, the crank shaft stroke and
~ 8
5 piston rod length are selected so that the piston
remains within 0.001" of top-dead-center (TDC) for
about 13 of crank shaft rotation or longer.
The position of the wrist pin in the piston as
well as the piston radial clearance have been found
10 to affect piston "dwell time" at TDC. In particular,
offsetting the wrist pin position to accommodate a
longer rod length increases piston dwell. Increasing
the piston radial clearance allows the piston to "rock"
and also increases piston dwell.
This "piston dwell" parameter is determined by
directly measuring the piston movement near TDC relative
to crankshaft rotation, with the engine head removed,
i.e., using a dial indicator. It will be recognized
that during engine operation, the actual piston dwell
20 at TDC may be dif~erent than measured becausel with
pressure on top of the piston, relative motions of
the moving parts may be somewhat different. However,
it is believed the difference, i any, is not signifi-
cant and it is certain that top center dwell time is
25 increased over conventional engines. It has been
found through experience and experimentation, that
sizing the piston stroke and rod length to arrive at
the dwell measurements stated above, will produce the
desired increase in combustion eficiency. using
30 this sizing criteria and measurement technique, an
internal combustion engine utilizing gasoline for
fuel and operating at a speed range of between 800
and 4,000 rpm~ fuel efficiency as well as power output
is substantially increased.
Such an engine is more accurately termed an expander
because the piston leaves TDC when pressure is essen-
tially at its maximum so that extraction of power
from the working fluid is maximized due to maximization
of its expansion. It is this expansion which results
in a smooth vibration free operation without counter-
29
weighting used by others to attempt to approach the
smoothness of the engine disclosed here.
An engine and fuel system embodying the present
invention was constructed and installed in a 1980
Buick Skylark. The vehicle weighed 3,005 lbs, two
10 passengers9 full fuel accelera~ed 0-060M.P.H. in 9.4
seconds. The mechanical parameters for the engine
are listed in Table I. A measured torque curve is
illustrated in Figure 10 and indicates a remarkably
level torque output, in excess of 225 ft-lbs, for an
15 opera~ing range of 2000-4400 rpm. Those in the art
will recognize that the discLosed power output for a
three-cylinder engine having a displacement of 125
cubic inches and weighing only 320 lbs. in its operating
mode including clutch and bell housing is substan-
20 tially more than one would expect from an en~ine thissize. Moreover, it was found that the engine was
remarkably vibration free and the radiator with which
the above identified vehicle was originally equipped
was reduced in size and capacity by a~out 50~.
TABLE I
Engine Type: 3 cyl, overhead valve
Displacement: 125 cu. in.
Bore: 3.950 in.
Stroke: 3.4 in.
Rod length 6.5 in.
Horsepower 240 Hp at 4000 ~PM (special
high performance fuel-test
code 20 with 21 pound boost)
Horsepower 190 Hp at 4400 RPM (93 octane
unleaded gasoline with 10
pound b~ost)
Weight 320 lbs.
Fuel economy 48.25 MPG (combined city
and highway)
In order to achieve the earlier discussed "piston
dwell" of 0.001'l piston movement at TDC for 13 degrees
of crankshaft rotation, the wrist pin position is
8~ 3
5 offset approxima~ely .0601l in the direction in which
thrust is applied to the piston from the diametric
center of the piston to accommodate a rod length of
6.5". Additionally, a piston radial clearance of
.006~' was selected to provide a small amount of piston
1~ "rock" which adds to the piston dwell. The combined
effects of the offset and clearance permit thrust
forces to offse~ the piston as the rod connected crank
journal passes over dead center resulting in a closer
spacing of piston top to journal axis than in the
15 case with conventional construction. After the journal
passes dead center the thrust forces are relieved and
the piston centers itself. This centering action has
a movement vector away from the journal and therefore
it assists in maintaining the piston near top-dead-
20 center.
A mileage test for the vehicle was conductedusing a 133 rnile driving loop that included both city
and highway speeds. The vehicle drive train, i.e. r
transmission, differential gearing, etc. was standard
25 and unmodified. Slightly larger diameter, commonly
available, tires were used in the test. With a final
drive ratio of 2.3-1, the engine R.P.M. at 55 M.P.H.
is 2,000. The vehicle speed was maintained within 2
mph of the posted speed limit. One hour and forty
30 minutes of the test was spent in city traffic and an
equal amount of time was spent in highway traffic.
The 133 mile test loop was repeated 10 times and at
the conclusion of the test it was found that the vehicle
averaged 48.25 miles per gallon. The disclosed per-
35 formance gains in both fuel economy and power outputwere obtained without sacrificing driveability.
It was also found that the engine was not prone
to detonation even under high engine loads and low
engine rpm. Moreover, the vehicle could be smoothly
accelerated in high gear, from a road speed of 20
~4g~3
31
5 MPH, under both part and full throttle, without evi-
dence of engine hesitation or flutter. The constant
downshifting to maintain sufficient engine RPM often
required with conventional, small displacement engines
was found to be unnecessary.
It is believed that the apparatus and method
disclosed by this present invention optimizes engine
performance by controlling flame speed during combus-
tion. This control is achieved by the thorough prepara-
tion and mixing of the fuel mixture prior to entry
15 into the combustion chamber so that the mixture inducted
into the chamber is homogenous and burns at a controlled
rate throughout the engine operating range. The heat
energy contained in the engine coolant and exhaust
systems is utilized in the preparation process and is
20 added to the fuel mixture to increase its energy output.
This is achieved by sizing and ad~usting the
coolant and exhaust heat loops to produce a "heat
balancei' wherein the engine heat normally discharged
to the ambient (by the exhaust and coolant systems)
25 is conveyed to the incoming fuel mixture to insure
thorough mixing and vaporization. More importantly,
the heat loops are critically adjusted to produce
heat transfer flow rates that are proportional to the
power output of the engine. Thus as the output in-
30 creases, the amount of heat transferred to the incomingfuel mixture increases proportionately. In short, an
internal combustion engine utilizing the present inven-
tion operates as a "hot vapor cycle" engine. The
apparatus disclosed, not only insures complete fuel
35 vaporization and mixing but also heats the fuel vapor
well above the vaporization temperature of the fuel.
While it is believed the engine which has been
described is, if fine tuned, fully capable of meeting
present and contemplated EPA regulations a test engine
was constructed in which the engine which has been
32
5 described was fitted with mechanisms designed to provide
exhaust gas recirculation (EGR) and intake air heating.
These provisions are designed primarily only to meet
so called "cold start'! test requirements and, again,
can be eliminated by fine tuning of the engine pre-
10 viously described.
A modified homogenizer 210 is provided. Thehomogenizer 210 has an outer housing 212 which defines
an air passage 213 between the homogenizer housing
212 and an exhaust gas and turbine surrounding housing
15 ~14.
The homogenizer housing 212 includes a pair of
air inlet passages 216. The air in~et passages 216
are positioned on opposite sides of homogenizer connec-
tion to the exhaust conduit 132 to entrain ambient
20 air for heating as it passes through the air passage
213.
The homogenizer includes a heated air outlet 218
which is opposite the exhaust conduit 132 so that the
distance from each of the two inlets 216 to the common
25 outlet 218 is equal. Air which has been warmed by
the homogenîzer passes through ~he outlet 218 thence
through a connected air conducting conduit 219 to a
carburetor air intake manifold 220. The carburetor
air intake manifold 220 has an ambient air intake 222
30 through which unheated ambient air can pass to be
delivered to the carburetor.
A temperature responsive air intake control valve
224 modulates the supply of ambient air through the
passage 222. Normally on startup the intake valve
35 224 remains in a closed condition so the only air
supplied to the carburetor is air preheated by passage
through the air heating passage 213. Once this air
reaches that desired temperature of about 110F the
valve will open. If the engine i5 operating in cool
or cold climates the intake valve will modulate to
33
5 maintain intake air temperature of about 110F during
normal operating conditions.
On occasion, as an example during acceleration,
air supplied through the air passage 213 and the air
conduit 219 rnay not be adequate for operating condi~
10 tions. Accordingly the intake valve 224 is also vacuum
sensitive and when engine manifold pressure drops
below 4 inches the intake valve opens to allow addi-
tional ambient air to be entrained into the carburetor
through the intake passage 222 and the carburetor air
lS intake manifold 20.
An EGR conduit 226 is provided, Figure 11. This
EGR 226 conducts exhaust gasses from the outlet side
of the homogenizer to the inlet side of the chamber
in which the compressor turbine 102 is located. This
~0 assures that recirculated exhaust gasses are thoroughly
admixed with the fuel air mixture supplied to the
engine and that such recirculated exhaust gasses are
equally distributed to each of the reaction chambers.
The EGR conduit 22~ is shown only schematically
25 in Figure llo In practice, the connection of the EGR
conduit 226 to the fuel air conducting conduit 206 or
the compressor turbine housing 108 is located such
~hat EGR fluids are directed toward the compressor
charnber. The axis of the EGR inlet is at an angle of
30 less than 45 wlth the axis of the fuel air conduit
206 and the two axes are located in a common plane
which includes the axis of the turbine 102.
The configuration of the compressor turbine housing
and its mating wlth the cornpressor turbine is best
35 illustrated in Figure 11. The housing 108 includes
an outlet opening 208 in a portion of the housing
which fits closely with ~he compressor turbine 102.
The outlet provides a constricting orifice for assisting
in isolating the vaporizer 50 from low manifold pres-
sures. In the test engine used to produce the test
34
S data presented previou~ly, the compressor turbine was
2.2 inches in diameter. The outlet 208 was one inch
in diameter and was followed downstream by housing
walls of a frusto conical shaped contour. These housing
walls flare from the one inch outlet opening 208 to a
10 two inch diameter in an axial length of one inch.
Thereafter the outer side.walls of the two outer flow
paths 152a flare outwardly at 8~ or less within the
interior of fuel mixture heater 152.
Although the invention has been described with a
15 certain degree of particularity, it is understood
that various changes can be made to it by those skilled
in the art without departing from the spirit or scope
of the invention as described and hereinafter claimed.
