Note: Descriptions are shown in the official language in which they were submitted.
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Background and Summary of the Invention
In commonly assigned U.S. Patent No. 4,141,327
a novel and improved carburetion system for an automative
engine is shown to comprise a carburetor having an air-fuel
passage, an air~inlet to the passage, a fuel inlet to the
passage for mixing fuel and air in the passage, and an outlet
from the passage for delivering a mixture of air and vaporized
fuel to the engine. In that improved carburetion system,
a heater means comprising a body of ceramic resistor material
of positive temperature coefficient of resistivity is provided
with a plurality of passages extending through the resistor
body and with means for directing electrical current through
the resistor body and with means for directing electrical
current through the body to heat the body. The heater means
is mounted at the outlet of the carburetor air-fuel passage
for passing the air-fuel mixture through the heater passages
in heat transfer relation to the body, thereby to facilitate
vaporization of the fuel prior to delivery of the air-fuel
mixture to the engine. The heater means is adapted to be
energized upon initiation of engine operation. In this way,
the improved carburetion system of the noted earlier
application is adapted to enhance fuel efficiency during
engine start up and, particularly, where engine start up occurs
in low ambient temperature conditions, is adapted to reduce
the emission of unburned hydrocarbon pollutants and the like
to the atmosphere in the engine exhaust.
However, it has been found that it is difficult
to
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achieve efficient operation of the heater means in such a
systemfrom a 12 volt automotive power supply, that improved
heater efficiency is of particular importance in order to
achieve a desired degree of improvement in fuel vaporization
utilizing the available power, and that it is desirable to
achieve this improved degree of fuel vaporization without
imposing excessive restriction on flow of t~e air-fuel mixture
to the engine.
It is an object of thls invention to provide a novel
and improved high efficiency early fuel evaporation carburetion
system for an automobile engine; to provide such an improved
system which is operable without unduly restricting the flow
of an air-fuel mixture to the engine; to provide such an im-
proved system which is efficiently operable from a 12 volt
automotive power supply; to provide such an improved system
which is adapted to achieve improved fuel efficiency and re-
duction in exhaust gas pollutants in initiating engine operation
from a cold start, an~d to provide such an improved system which
! is of simple, compact, rugged and inexpensive structure.
Briefly described, the novel and improved carburetion
system of this invention includes a conventional carburetor
having an air-fuel passage, an air inlet to the passage, a fuel
inlet to the passage for mixing fuel with air in the air-fuel
passage, and an outlet from the air-fuel passage for delivering
a mixture of air and vaporized fuel to an automotive engine.
A heater means comprising a body of ceramic material of positive
temperature coefficient of resistivity having a plurality of-
passages extending through the body has means for directing
electrical current through the body and is mounted at the outlet
of the carburetor air-fuel passage for passing the air-fuel
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mixture through the heater passages in heat-transfer relation
to the heater body. In accordance with this invention, the
heater passages define a plurality of~s of the resistor material between the
passages so that the air-fuel mixture is passed readily through
the heater passages without unduly impeding the flow of the
air-fuel mixture to the engine. Electrically conductive means
are disposed on the resistor body along the inner walls of
the resistor body passages in ohmic contact with the resistor
body material. The ohmic contacts formed on the walls of
alternate body passages are electrically connected together
at one end of the body, as by a first coating of electrically
conductive material which is formed on that one body end. The
ohmic contacts in the other body passages are electrically -
connected together at the opposite end of the body by a second -
coating of electrically conductive material on that opposite
body end. The resistor body is mounted so that the air-fuel
mixture passes through the heater passages in heat-transfer
relation to the resistor body. Electrical current is
directed through the webs of resistor material to heat the -
resistor body for heating the air-fuel mixture directed
through the heater passages.
The resistor body may be mounted within a housing -
of rigid electrically insulating material which has apertures
on the opposite sides thereof aligned with the heater passages.
The housing may also include mo~mting holes and the like for
mounting the heater between the carburetor and the intake
manifold of the automotive engine. In that case, a pair of
generally wave-shaped annular terminals are mounted within the
housing extending around the resistor body in resilient engage-
ment with the first and second coatings respectively at the
sides of the resistor body, each of the terminals having -
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a portion extending exteriorly of the housing to be connected
in the 12 volt power supply of the automobile. The heater
means is preferably arranged to be energized when operation
~ of the engine is initiated and to be effectively deenergized
:~ 5 thereafter when the engine has warmed up to its optimum oper-
ating temperature.
- In this arrangement, the carburetion system does not
unduly restrict the flow of air-fuel mixture to the engine.
However, the 12 volt power supply of the automobile is effective
- 10 to direct a substantial electrical current through the thin
webs of the resistor body material between ohmic contacts of
different polarity formed within adjacent body passages. In
this way, the heater means of the system efficiently generates
a large amount of heat with the available power for heating
the air-fuel mixture passing through the heater passages to
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provide significantly improved vaporization of the fuel in
the mixture. Further, the heater means used in the system is
compact, rugged and inexpensive and is easily utilized with a
conventional carburetor without excessively increasing the
height of the system over the automobile engine.
Other objects, advantages and details of the improved
high efficiency carburetion system of this invention appear
in the following detailed description of preferred embodiments
of the invention, the detailed description referring to the
drawings in which:
Fig. 1 is a section view along the longitudinal axis
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of the improved carburetion system of this invention;
Fig. 2 is a section view to enlarged scale of the
heater means utilized in the system of Fig. l;
Fig. 3 is an exploded view to relatively smaller
scale of the heater means utilized in the system of Fig. l;
and
Figs 4 and 5 are graphs illustrating performance
characteristics of the system of Fig. 1.
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Description of the ~mbodiments
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Referring to the drawings, 10 in Figs. 1 and 2 indi-
cates the novel and improved high efficiency carburetion system
of this invention which is shown to include a carburetor 12 of
any conventional type having an air-fuel passage 14, having an
air inlet 16 to the air-fuel passage, having a fuel inlet 18
to the air-fuel passage for mixing fuel with air in the air-
fuel passage, and having an outlet 20 from the air-fuel passage
for delivering a mixture of air and vaporized fuel to an auto-
motive engine 22. Such a conventional carburetor typically
includes a body 24 defining the air-fuel passage 14 with a
venturi portion 26 as shown in Fig. 1, choke valve means 28,
throttle plate means 30, and a supply chamber 32 for gasoline
fuel 34 as is diagrammatically shown in Fig. 1. The conven-
tional carburetor also typically includes a flange 36 for use
- in mounting the carburetor relative to the intake manifold 38
of the engine with the air-fuel passage 14 of the carburetor
aligned with an opening or entry 40 to the intake manifold
passage 42 leading to the engine cylinders. In operation of
the convèntional carburetor, a vacuum established in the intake
manifold while the engine is running draws air into the carbur-
etor inlet 16 as indicated by the arrows 44 while the reduced
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pressure established at tlle venturi constriction in the air-
fuel passage also draws fuel through the jet or nozzle inlet
18 as indicated by the arrows 46, thereby to create a mixture
of air and vaporized fuel in the air-fuel passage as indicated
by the arrows 48. The air-fuel mixture 48 is then drawn through
the air-fuel passage outlet 20 into the intake manifold as in-
dicated by the arrows 50 for delivery to the engine as shown
in Figs. 1 and 2. In the conventional carburetor, the throttle
plate is movable through appropriate linkages and controls for
regulating the volume of air-fuel mixture delivered to the
engine and the choke 26 is movable in response to the pull of
the intake manifold vacuum or the like and to thermally respon-
sive spring means for regulating the entry of air into the
carburetor. As the carburetor 12 is of any conventional type
it is not further described herein and it will be understood
that the improved high efficiency carburetion system of this
invention utilizes any single, double or quadruple barrel car-
buretor or other fuel~ supply system or the like which is adapted
to furnish an air-fuel mixture to an automotive engine.
In this regard, when operation of an automobile engine
i5 initiated from a cold start, particularly under low ambient
temperature conditions, the air 44 and fuel 46 drawn into the
carburetor 12 are frequently at too low a temperature to effect
full vaporization of the fuel within the air-fuel passage of
the carburetor. Further, the temperature of the engine 22 is
also too low for a period after startup to effect sufficient
heating of the air-fuel mixture 48 to achieve full vaporization
of the fuel in the mixture. In the conventional carburetor,
the choke 26 is commonly adapted to restrict the entry of air
into the carburetor during the engine start-up or warm-up period,
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thereby to assure that the air-fuel mixture delivered to the
engine is sufficiently rich in fuel to provide smooth engine
starting. As a result, under these starting conditions, the
, air-fuel mixture 48 commonly includes fuel droplets 52 or other
unvaporized fuel as indicated in Fig. 1. Therefore, the engine
achieves only relatively poor fuel efficiency during engine
, ~ start up and, more important, excessive quantities of unburned
hydrocarbon pollutants tend to be emitted to the atmosphere
in the engine exhaust during motor starting.
Accordingly, in the carburetion system 10 of this
invention, heater means 54 are interposed between the carburetor '
12 and the intake manifold 38 for heating the air-fuel mixture
' 48 being delivered to the engine, thereby to provide significantly
improved vaporization of the fuel constituent of the air-fuel
mixture prior to the delivery of the mixture to the engine. In
order to achieve such improved fuel vaporization without unduly
restricting free flow of the air-fuel mixture to,the engine, it
is hecessary to more~efficiently utilize the power available for
this purpose from the 12 volt automotive power supply. Accordingly,
the heater means used in the system 10 of this invention com-
prises a heater body 56 of a ceramic material or the like of
; positive temperature coefficient of resistivity (PTC), the body
having a plurality of passages 58 which extend in a pattern in
spaced side-by-side relation to each other through the body
between opposite ends 56.1 and 56.2 of the body for defining
thin webs 59 of the resistor material between adjacent passages
in the body. Preferably, as shown particularly in Fig. 2,
abutments or parapets 60 of the resistor material are formed
around the margins of the ends of alternate one 58a of the body
passages at one end'56.1 of the body while similar abutments or
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parapets 62 are formed around the ends of the other body
passages 58b at the opposite end 56.2 of the body. Electric-
ally condutive ohmic contacts 64 or other suitable contact means
are attached to the resistor body along the inner walls of each
of the passages 58. The ohmic contacts 64 in said other body
passages 58b are electrically connected to each other at said
one end 56.1 of the resistor body by a coating 66 of electric-
ally conductive material which is deposited on the body end
56.1 extending around the sides of the abutments 60. In this
way, the coating 66 electrically connects the ohmic contacts 64
in the passages 58b but is spaced from the ohmic contacts 64
in the body passages 58a by the tops of the abutments 60. Simi-
larly, the ohmic contacts 64 in said alternate body passages
58a are electrically connected to each other at the opposite
end 56.2 of the resistor body by a coating 68 of electrically
conductive material which extends around the sides of the abut-
ments 62. Preferably, as shown in Fig. 2, each of the coatings
66 and 68 has a portion 66.1 and 68.1 extending circumferentially
around the sides of the resistor body adjacent to a respective
end of the body. Preferably, the coating portions 66.1 and 68.1
are further coated (as indicated at 69 in Fig. 2) with an elec-
trically conductive material characterized by displaying a re-
latively low electrical sheet and surface contact resistance.
Preferably also, a protective coating 71 or electrically in-
sulating material is adhered to the resistor body between the
coating portions 66.1 and 68.1.
Typically, for example, the resistor body 56 is formed
of a lanthanu~-doped barium titanate ceramic resistor material
which has a positive temperature coefficient of resistivity and
which is adapted to display a sharp, anomalous increase in
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resistivity whell heated to a selected temperature. Preferably,
for example, the body is formed of a ceramic titanate having
the empirical formula of Ba 968 Pb.030 La.002 3
a room temperature resistivity of about 36 ohms-centimeters
and a Curie temperature of about 140C. and which is adapted
to display a sharp, anomalous increase in resistivity to about
- 10 ohm-centimeters when heated above its ahomaly temperature
to about 200C.
In the carburetion system 10 of this invention, the
passages 58 in the resistor body 56 are each preferably of square
cross section or the like and are each preferably of relatively
large cross-sectional size on the order of at least about 0.100
inches on a side. The webs 59 of resistor material between the
body passages are also relatively thin on the order of not more
than about 0.060 inches in thickness. Typically, for example,
the passages 58 are each of square cross section of about 0.140
inches on a side and are spaced from the adjacent body passage
by a web 59 of resis~or material of about 0.040 inches thickness,
the body including eight rows of such passages each having
eight passages in the row. Preferably, the resistor body 56
has an overall thickness of about 0.250 inches so that each
passage 58 has a length of about this dimension.
In the carburetion system 10 of this invention, the
resistor body 56 is preferably mounted relative to the carburetor
12 so that the resistor body passages are aligned with the air-
fuel passage 14 to pass the air-fuel mixture 48 through the
passages 58 in heat-transfer relation to the body. With the
construction of the resistor body 56 as above described, the
body is adapted to serve as a highly efficient fluid heater and
is particularly adapted to furnish a large quantity of heat to
the air-fuel mixture 48 even though the heater body is energized
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at a very low voltage such as the 12 volt power supply system
available in an automobile. That is, when the coatings 66 and
68 at the ends of the resistor body are connected to appropriate
terminals, electrical current is directed through each of the
webs 59 of resistor material located between adjacent body
passages 58. This current flows between one group of ohmic
~ contacts 64 of one polarity attached to the coating 66 and the
second group of ohmic contacts of opposite polarity attached
to the coating 68. In this way, the plurality of ohmic contacts
in the body passages cooperate to provide a large effective
; area of ohmic contact to the resistor material. On the other
hand, the thin nature of the webs S9 between the body passages
- permit a relatively large current to be directed through the
thin webs for each unit area of the ohmic contacts even though
a relatively low voltage is applied across the ohmic contacts
of opposite polarity. Further, even if resistivity gradients
should occur within the resistor body between opposite ends
of the body as a result of flow of the air-fuel mixture 48
through the body passages, the occurrence of higher resistivity
in the body adjacent one body end does not tend to restrict
heat generation in other parts of the body. Accordingly, even
though the passages 58 are relatively large to permit flow of
air-fuel mixture through the passages without significant re-
striction, a large amount of heat is efficiently generated by
the resistor body and is transferred to the air-fuel mixture
to effect efficient heating of the air-fuel mixture.
For example, where the resistor body 56 has a thick-
ness of 0.250 inches and has eight rows of eight passages each
extending through the body, each passage being of square cross
section 0.140 inches on a side and being separated from adjacent
passages by webs 59 of about 0.040 inches thickness, the body
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is adapted to pass substantial volumes of air-fuel mixture
through the passages 58 with relatively slight restriction of
the flow of the air-fuel mixture as shown in Fig. 5. That is,
the body passes ~ a substantial volume of the air-fuel
mixture with only a small pressure drop occurring bewteen
opposite ends of the body as indicated by the curve 70 in
Fig. 5. For example, where 5 pounds of air,-fuel mixture per
minute (69.25 cubic feet of air-fuel mixture per minute), as
is typically directed through the primary stage of a two barrel
carburetor in operation of an automotive engine 22, is passed
through the heater body passages, this flow results in a pressure
drop of only 12 centimeters of water (0.15 pounds per square
inch) across the resistor body. I~owever, when energized by a
12 volt automotive power supply, the heater body generates very
substantial quantities of heat as indicated by curve 72 in Fig. 4.
That is, where 5 pounds per minute of the air-fuel mixture is
directed through the body passages, the heater body 56 is adapted
to generate and transfer 400 watts of energy to the air-fuel
' mixture. This heat transfer is effective to raise the temperature
'of air-fuel mixture by about 12F. and to provide significantly
improved vaporization of the fuel constituent of the mixture
particularly when the air and fuel constituents are introduced
to the carburetor 12 at a relatively low temperature. Of course,
the heater body is adapted to start heating the air-fuel mixture
immediately after the initiation of motor operation and is there-
fore adapted to provide its improvement in fuel vaporization
when that improvement is most necessary before the engine itself
has warmed up,to a significant extent. Further, the,positive
temperature coefficient of resistivity of the resistor body
material assures that the heater body is self-regulating. That
is, as the body temperature increases, the resistivity of the
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body also increases to reduce the current level in the body,
whereby the body temperature tends to stabilize at a safe
temperature at which heat generated in the body balances the
heat dissipated from the body.
As fluid heater resistors of the character of the
resistor body 56 as above described are more fully described
in commonly assigned U.S. patent No. 4,107,515, the
resistor body 56 is not further described herein and it will be
understood that the heater means is adapted to achieve highly
efficient heating of the air-fuel mixture 48 from a low voltage
power source without significantly restricting flow of the
air-fuel mixture through the heater body passages.
In the carburetion system 10 of this invention, the
heater means 54 also preferably includes housing means 74 for
permitting convenient mounting bf the resistor body 56 between
the carburetor 12 and the intake manifold 38 without unduly
increasing the height of the carburetion system. Preferably,
- a spacer 76 formed of a rigid electrical insulating material
such as a phenolic resin has a central opening 78 fitted around
the resistor body 56. A pair of generally wave-shaped, annular
terminals 80 of an electrically conductive spring material such
as beryllium copper are fitted around the sides of the resistor
body adjacent respective ends of the body, thereby to resiliently
engage the coating portions 66.1 and 68.1 and the low contact
resistance coatings 69 on the sides of the body. In this
arrangement, the terminals 80 make multiple point pressure
contact with the low resistance coatings 69 as will be under-
stood, and the terminals are separated from each other by the
spacer 76. Each terminal 80 has a terminal portion 80.1
extending laterally therefrom as shown particularly in Fig. 3.
Two outer housing.
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sections 82 and 84 also preferably of a phenolic resin each
; have an aperture 86 and a recess 88 therein and have the recesses
88 fitted over the ends of the resistor body so that the apertures
86 are aligned with the resistor body passages 58. Preferably,
each of the outer housing sections 82 and 84 is cemented or
otherwise secured in sealed relation to one side of the spacer
76 and the housing sections and spacer are provided with mounting
holes 90 for use in mounting the heater means 54 to the carburetor
-. 12 and the intake manifold 38. Each housing section has a
groove 91 for permitting one of the.extending portions 80.1 of
: the terminals to extend exteriorly of the housing 74. Preferably,
a gasket 92 of a compressible material having an opening 54
therein is also enclosed between each housing section and the
- resistor body 56 for securely positioning the ceramic resistor
body within the housing 74 without risk of damage to the ceramic
body when exposed to shock. Preferably, a screen mesh material
.~ 96 of a non-conductive material such as fiberglass is also enclosed
within the housing at the outlet end of the housing 74 between
the resistor body 56 and the housing section 84 for preventing
any chips of the ceramic resistor body from being passed into
the engine 22. Preferably, also, a similar screen mesh 98 is
enclosed in the housing between the resistor body 56 and the
housing section 82 for dispersing fuel droplets 52 entering
the body passages to facilitate vaporization of the droplets.
With this construction of the heater.means 54 as
above described, the heater means is conveniently mounted
between the carburetor 12 and the intake manifold 38 in the.
manner shown by use of mounting screws 99. The terminal por-
tions 80.l of the heater means are also easily connected to
a 12 volt power system or the like of the automobile as is
diagrammatically illustrated in Fig. 1 by the power supply
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terminals 100 and 102. Preferably, as is also diagrammatically
shown in Fig. 1, the heater means 54 is arranged to be energized
when the ignition switch 104 is closed for initiating operation
of the engine 22. Similarly, a control means 106 is interposed
in series with the heater means 54 for deenergizing the heater
means or reducing the output of the heater means a period of
time after the initiation of motor operation when the engine
22 has reached its full operating temperature and when
operation of the heater means 54 is no longer necessary or use-
ful. As has been described in the previously noted U.S. patent
No. 4,141,327, such control means 106 comprise conventional
time delay relay means or the like, thermostat switch means
responsive to the temperature of the engine 22 or other
conventional control means as may be desir~d.
It should be understood that although preferred
embodiments of the carburetion system of this invention have
t been described by way of illustrating this invention, the
invention includes all modifications and equivalents of the
disclosed embodiments falling within the scope of the
appended claims.
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