U.S. patent number 3,768,787 [Application Number 05/157,087] was granted by the patent office on 1973-10-30 for high velocity carburetor.
This patent grant is currently assigned to Ethyl Corporation. Invention is credited to Frederick J. Marsee.
United States Patent |
3,768,787 |
Marsee |
October 30, 1973 |
**Please see images for:
( Certificate of Correction ) ** |
HIGH VELOCITY CARBURETOR
Abstract
A multibarrel, high velocity carburetor comprising at least one
primary barrel having a conventional secondary construction and at
least one venturi barrel which has a cross-sectional area greater
than that of the primary barrel and which has means for varying
this cross sectional area in response to engine demand; and its use
in a low exhaust emission, spark ignition internal combustion
engine system of the lean reactor type, to effect improved
driveability. A preferred carburetor has one primary barrel and two
variable secondary barrels.
Inventors: |
Marsee; Frederick J. (Clawson,
MI) |
Assignee: |
Ethyl Corporation (Richmond,
VA)
|
Family
ID: |
22562288 |
Appl.
No.: |
05/157,087 |
Filed: |
June 28, 1971 |
Current U.S.
Class: |
261/23.2;
261/44.4; 123/568.12 |
Current CPC
Class: |
F02M
11/02 (20130101); F02M 26/30 (20160201); F02M
7/17 (20130101); F02M 26/13 (20160201) |
Current International
Class: |
F02M
7/00 (20060101); F02M 25/07 (20060101); F02M
11/02 (20060101); F02M 11/00 (20060101); F02M
7/17 (20060101); F02m 009/06 () |
Field of
Search: |
;261/44R,23A
;123/119A |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Miles; Tim R.
Claims
I claim:
1. A multibarrel, multistage carburetor for a spark ignition
internal combustion engine which comprises
a. at least one primary barrel which includes
1. a first mixing conduit having a venturi,
2. a fuel nozzle situated in said venturi to deliver fuel to said
first conduit,
3. a first throttle means mounted in said conduit downstream of
said fuel nozzle, said throttle means being manually moveable
between opened and closed position,
4. choke means situated in said first conduit upstream of said
nozzle, said choke means being mounted in said conduit to permit
manual movement between closed and opened positions,
5. a vacuum modulated throttle by-pass which provides required
enrichment of fuel/air mixture during engine deceleration, and
b. at least one secondary barrel, having no choke means, which
includes
6. a second mixing conduit having a cross-sectional area larger
than said first mixing conduit,
7. a second throttle means rotatably mounted in said second conduit
to permit manual movement between closed and opened positions, said
second throttle means being directly linked to said first throttle
means so that said second throttle means begins to open when said
first throttle means reaches a pre-determined open position,
8. slidably adjustable means situated above said second throttle
means, and being positioned to move across the short axis of and
into said second conduit, said slidably adjustable means having a
needle axially attached to the end which enters said conduit and
being attached to a vacuum operator at the opposite end, said
vacuum operator being responsive to a vacuum signal obtained at a
point in said second conduit just above said second throttle
means,
9. a fuel orifice for providing fuel to said second conduit,
situated in said second conduit upstream of said second throttle
means and opposite said slidably adjustable means, the extent of
said fuel orifice opening being controlled by the movement of said
needle into and out of said orifice as said slidably adjustable
means responds to said vacuum operator,
10. a fuel/air mixture enrichment means which comprises a vane
situated in and substantially parallel to the long axis of said
second conduit, said vane being responsive to manifold vacuum and
acting to reduce the cross-section area of said second conduit in
the region of the slidably adjustable means at high engine
loads,
said primary barrel providing fuel/air mixture to said engine at
idle and relatively low engine loads and combining with said second
barrel to provide fuel/air mixture to said engine at higher engine
load.
2. The carburetor of claim 1 wherein said choke means is attached
to and is responsive to an ambient temperature sensor element.
3. The carburetor of claim 1 having one primary barrel and two
secondary barrels.
4. The carburetor of claim 1 wherein said vane in said enrichment
means has a lip on its leading edge.
5. The carburetor of claim 1 wherein said first barrel additionally
includes a conventional power system and accelerating pump.
6. The carburetor of claim 1 wherein said primary barrel has no
separate idle system and said first throttle means is
perforated.
7. The carburetor of claim 6 having one primary and two secondary
barrels.
8. The carburetor of claim 6 wherein said vane in said enrichment
means has a lip on its leading edge.
9. The carburetor of claim 7 wherein said vane in each secondary
barrel has a lip on its leading edge.
Description
BACKGROUND OF THE INVENTION
Ordinary spark-ignition internal combustion engines utilize a
carburetor/intake manifold combination as part of their fuel
system. In the carburetor, air and fuel are blended and fed into
the intake manifold for distribution to the cylinder or cylinders.
In order to ensure good engine operation, the air:fuel mixture is
kept near and usually slightly higher than the stoichiometric
ratio. The use of such rich fuel:air mixtures contributes to
undesirable unburned hydrocarbon and carbon monoxide exhaust
emissions. Operating an engine using air:fuel mixtures greater than
stoichiometric, commonly called a lean mixture, will result in
reduction of exhaust hydrocarbon emissions. The ordinary
carburetor, however, although capable of providing lean mixtures,
is inadequate because (1) it cannot provide these lean mixtures for
all engine operating conditions, (2) its fuel/air mixing capability
is relatively poor for lean mixtures, and (3) it is ordinarily
limited to providing fuel/air ratios down to only about 1:15.5.
There are carburetors available, (e.g., Delco-Rochester's "Quadra
Jet;" also, see U. S. Pat. No. 3,310,045, to E. Bartholomew) which
do effect good air/fuel mixing at relatively lean air/fuel ratios.
However, such carburetors are somewhat limited in their capacity to
provide sufficient air/fuel mixture for high engine demand; these
carburetors are relatively complex in structure; and finally, their
air/fuel blending characteristics for lean mixtures, for example,
air/fuel of 18:1 and higher, may not be adequate for good engine
performance. These carburetor limitations in general have an
adverse effect on the driveability of an automobile -- especially
where the engine is equipped with other exhaust emission reducing
modifications such as catalytic converters, thermal reactors,
etc.
The present invention provides a carburetor of novel design and
relatively simple construction featuring a combination of at least
one primary barrel of conventional venturi construction and at
least one secondary barrel having a cross-sectional area larger
than the first barrel and having means whereby the cross sectional
area can be varied in response to engine demand. This carburetor
affects excellent air/fuel mixing over a wide range of air:fuel
ratios, especially in the leaner air:fuel ratios, i.e., 16:1 -
18:1. The variable cross sectional area secondary barrel feature
provides sufficient capacity for the carburetor to ensure adequate
air:fuel supply to be provided to an engine even at high engine
demand. Use of the carburetor of the present invention on a
conventional internal combustion engine improves the efficiency of
such an engine and reduces undesirable exhaust emissions,
especially the hydrocarbons and carbon monoxide. Furthermore, when
the present carburetor is used in place of currently available
carburetors, with an engine which is modified to further decrease
exhaust emissions, for example, with a catalytic converter or a
lean reactor system, the driveability of an automobile powered with
this new combination is significantly improved.
SUMMARY OF THE INVENTION
A multibarrel carburetor comprising at least one primary barrel
having conventional venturi construction and at least one secondary
barrel which has a cross-sectional area greater than that of the
primary barrel and which has slidable means for adjusting this
cross-sectional area, said adjustment being responsive to engine
demand via a vacuum signal, whereby improved fuel/air blending,
especially at leaner than stoichiometric fuel/air ratios is
effected. In the variable cross-sectional area barrel, the
improvement which consists of an enrichment means to provide
additional fuel required at rapid acceleration.
A low exhaust emission, lean reactor engine system having improved
driveability characteristics.
DESCRIPTION OF THE DRAWINGS
FIG. 1 is a partial section through a schematic illustration of the
carburetor of the present invention.
FIG. 2 is a top view of a partial section of a carburetor
illustrated in FIG. 1, but having one primary barrel and two
secondary barrels.
FIG. 3 is an expanded view of the fuel orifice portion of FIG. 1,
seconary barrel, at full throttle.
FIG. 3A is a top view through a section of the FIG. 3
illustration.
FIG. 4 is an expanded view of the fuel orifice portion of FIG. 1,
secondary barrel, at part throttle.
FIG. 5 is a schematic illustration showing a temperature responsive
means for controlling opening of the secondary barrel before
warm-up.
FIG. 6 is a schematic illustration, in partial section, of a
preferred internal combustion engine system which utilizes the
carburetor of FIG. 3.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
A preferred embodiment of this invention is a multibarrel,
multistage carburetor for a spark ignition internal combustion
engine which comprises
a. at least one primary barrel which includes
1. a first mixing conduit having a venturi,
2. a fuel nozzle situated in said venturi to deliver fuel to said
first conduit,
3. a first throttle means mounted in said conduit downstream of
said fuel nozzle, said throttle means being manually moveable
between opened and closed positions,
4. choke means situated in said first conduit upstream of said
nozzle, said choke means being mounted in said conduit to permit
manual movement between closed and opened positions,
5. a vacuum modulated throttle by-pass which provides required
enrichment of and increase in amount of mixture during engine
deceleration, and
b. at least one secondary barrel, having no choke means, which
includes
6. a second mixing conduit having a cross-sectional area larger
than said first mixing conduit,
7. a second throttle means rotatably mounted in said second conduit
to permit manual movement between closed and opened positions, said
second throttle means being directly linked to said first throttle
means so that said second throttle means begins to open when said
first throttle means reaches a pre-determined open position,
8. slidably adjustable means situated above said second throttle
means, and being positioned to move across the short axis of and
into said second conduit, said slidably adjustable means (1) having
a needle axially attached to the end of said slidably adjustable
means which enters said conduit, and (2) being attached to a vacuum
operator at the end opposite said needle, said vacuum operator
being responsive to a vacuum signal obtained at a point in said
second conduit just above said second throttle means,
9. a fuel orifice for providing fuel to said second conduit,
situated in said second conduit upstream of said second throttle
means and opposite said slidably adjustable means, the extent of
said fuel orifice opening being controlled by the movement of said
needle into and out of said orifice as said slidably adjustable
means responds to said vacuum oerator,
10. a fuel/air mixture enrichment means which comprises a vane
situated in and substantially parallel to the long axis of said
second conduit, said vane being responsive to manifold vacuum and
acting to reduce the cross-section area of said second conduit in
the region of the slidably adjustable means at high engine loads,
or at any engine operating mode where the intake manifold vacuum is
low,
said primary barrel providing fuel/air mixture to said engine at
idle and relatively low engine loads and combining with said second
barrel to provide fuel/air mixture to said engine at higher engine
load. A carburetor having one primary and two secondary barrels is
a more preferred embodiment.
Another embodiment of this invention is an improved "lean reactor"
engine system having enhanced driveability characteristics
featuring the use of a three-barrel carburetor of the present
invention. By lean reactor is meant an engine system which utilizes
lean air/fuel mixture and exhaust heat conservation means to reduce
undesirable exhaust emissions.
Construction and operation of the present carburetor and engine
system will be better understood by considering the device as
illustrated in the accompanying FIGS. 1-6. The same number is used
to designate the same elements in all of the drawings. FIG. 1 is a
schematic illustration of the carburetor of the present invention.
The primary barrel 1 is of conventional venturi configuration, but
of relatively small diameter. It has a conventional choke means 2
above the fuel nozzle 4 and a throttle plate 3 below said nozzle 4.
The choke means can be of conventional design with the conventional
bimetal coil thermostatic control. The choke means may additionally
be ambient temperature modulated by means such as described in U.S.
Pat. No. 2,970,825; or in my copending application Ser. No. 80,106,
filed Oct. 12, 1970. The nozzle 4 may be of any conventional
design; the illustration shows a nozzle having a step design of the
type described in U.S. Pat. No. 3,472,495. Such a nozzle permits
better fuel/air mixing as well as improved flow under idle
conditions. The throttle plate 3 may be of conventional design, but
is preferably perforated. A perforated throttle plate also improves
fuel/air mixing and permits operation of the engine at idle without
necessitating a separate idle fuel system. Conduit 7 and control
valve means 7b and 7a comprise a conventional throttle by-pass
system. The conventional control valve 7b is responsive to a
manifold vacuum signal and in turn controls valve 7a which permits
air/fuel mixture to by-pass throttle 3 while said throttle 3 is
closed or is being closed, during idle and/or deceleration. This
by-pass system reduces the necessity for excess air/fuel enrichment
which occurs with ordinary carburetor idle systems during idle and
deceleration engine modes. Although the dimensions are not
critical, the cross section of the primary barrel venturi conduit 1
is preferably small enough to effect relatively high air velocities
of 60- 400 feet per second (fps) with air velocities of about
between 60 and 80 fps and higher being especially desirable. By
maintaining such air velocity in the primary barrel, sufficient
suction is obtained in the fuel nozzle 4 area so that it (the
nozzle) meters fuel from fuel bowl 5 via fuel conduit 6 during idle
operation Thus, only the primary barrel 1 provides fuel during idle
and low engine demand modes of operation. Some exhaust can be
recycled into the intake manifold along with the air/fuel mixture
from the primary barrel. FIG. 6, which is discussed below,
illustrates a suitable exhaust recycle arrangement. This recycling
of exhaust reduces nitrogen oxide levels in emitted exhaust.
The secondary barrel conduit 8 has a cross section which is larger
than that of the primary barrel 1. Extending into the secondary
barrel (or conduit) 8 is a slidably adjustable means 9 for varying
the secondary barrel cross section. FIG. 1 illustrates this
slidably adjustable means 9 to be a cylinder. This is not meant to
limit this slidably adjustable means. Such means might be a plate,
hemicylinder, or a movable element of any other configuration,
provided it has sufficient rigidity to withstand deflection which
might be caused by the high velocity air moving through said
secondary conduit 8. One end of said slidably adjustable means 9 is
attached via structural member 16 to a diaphragm 15. A spring 16a
is set inside slidably adjustable means 9 and against stop 16b. To
the other end of slidably adjustable means 9 there is attached a
needle valve 10. The needle valve 10 is positioned in the secondary
barrel 8 so that it moves in and out of fuel orifice 11 in order to
meter fuel into said secondary barrel 8. The slidably adjustable
means 9 responds to a vacuum signal obtained through an opening 13a
just above throttle 12, which signal is conducted into the chamber
16c, via conduit 13. The portion 14 is open to the atmosphere to
vent the space 14a in front of the diaphragm 15. The signal thus
obtained acts on the diaphragm 15 which in turn moves the slidably
adjustable means 9 out of said secondary barrel 8. The spring 16a
operates to return said slidably adjustable means 9 as the vacuum
in chamber 16c decreases. In operation, when the throttle 12 is
closed, there is no vacuum signal and the slidably adjustable means
9 and needle valve 10 are urged forward by the spring 16a, thus
closing the fuel orifice 11. As the throttle 12 is opened, a vacuum
signal is obtained and acts on the diaphargm 15. The spring 16a
which maintains the slidably adjustable means 9 in a closed
position when throttle 12 is closed, may be set to maintain any
desired vacuum in chamber 16c; a setting conveniently used is one
which provides a vacuum or pressure drop of 1.3 to 1.6 inches of
mercury. Consequently, the air velocity in the secondary barrel 8
is kept relatively constant and generally at about 300 feet per
second, when this barrel is in operation.
The needle valve 10 in the secondary barrel 8 moves into and out of
the fuel orifice 11 as engine demand requires, that is, as the
throttle 12 in the secondary barrel is opened. This neelde valve 10
is necessarily tapered in order to effect good fuel metering
control. The secondary barrel can operate with no other elements
than these already described. However, in order to improve the
performance characteristics of an engine which utilizes the present
carburetor, a fuel enrichment means embodied in the vane 18 and its
attendant control system elements 19, 19a, 19b, and 19c is
provided. This vane 18 is situated in the secondary barrel 8 in
position to span the area around fuel orifice 11. It has an opening
through which the needle valve 10 extends into the fuel orifice 11.
A detailed explanation of the structure and operation of this
enrichment vane will be presented below when discussing FIGS. 3,
3a, and 3b. The throttle 3 and primary barrel 1 and throttle 12 and
secondary barrel 8 are mechanically linked (linkage not
illustrated) so that the primary throttle is opened first to
provide fuel/air mixture at idle and low power demand while the
second throttle 12 is kept closed; and then when the first throttle
3 is opened about 40.degree./o, the linkage actuates the second
throttle 12 which then begins to open to supply the additional
air/fuel required for higher engine power demand. This mechanical
linkage is ao arranged that the rate of opening of said second
throttle 12 is gradually reduced from initial opening to full open.
Although FIG. 1 schematically illustrates one primary barrel and
one secondary barrel, combinations involving one or more primary
barrels and more than one secondary barrel come within the scope of
this invention.
FIG. 2 is a top view in partial section of a carburetor of the
present invention having two secondary barrels 8 and 8' and one
primary barrel 1. The secondary barrels 8 and 8' are in parallel.
The slidably adjustable means 9 and 9' in each of these barrels are
illustrated with the needle valves 10 and 10' partially inserted
into the fuel orifices 11 and 11', respectively. Each of the two
secondary barrels has an enrichment vane 18 and 18'. Each slidably
adjustable means 9 and 9' is attached to a separate diaphragm; but
only one vacuum chamber (enclosed in housing 20 and controlled via
a vacuum signal through an externally mounted conduit 13) serves to
control both slidably adjustable means. The conduit 13 by which the
vacuum signal is transmitted to the vacuum chamber is shown to be
external of the carburetor housing. Although not shown, a common
enrichment vane control system (shown as 19, 19a, 19b, and 19c in
FIG. 1) is used to control both enrichment vanes 18 and 18'.
Individual vacuum chamber and individual enrichment vane control
systems could be utilized if desired; but since both secondary
barrels operate simultaneously, the common vacuum chamber and
enrichment vane control system is simpler, more efficient and
preferred. This three-barrel arrangement is also a preferred
embodiment of the present invention.
FIG. 3 is an enlarged view of the fuel orifice portion of the
secondary barrel illustrated in Example 1, showing the enrichment
vane 18 and the control elements 19, 19a, 19b, and 19c, at full
throttle. In the absence of manifold vacuum the piston 19c is urged
up by spring 19b. This movement of the piston 19c upward causes the
control arm 19a to push lever arm 19 attached to vane 18 at point
21 up, thus urging the bottom edge of the enrichment vane 18
inwardly, to rest against the barrel 8 surface on attachment point
21, causing the leading edge of vane 18 to move out into the
secondary barrel conduit 8. This efficiently reduces the
cross-sectional area through which air passes between the slidably
adjustable means 9 and the enrichment vane 18, thereby causing an
increase in the vacuum signal which control said slidably
adjustable means 9. In response to this increased vacuum signal,
the needle valve 10 attached to the slidably adjustable means 9
moves further out of the fuel orifice 11, thereby causing
additional fuel to flow into the secondary barrel 8, thus enriching
the air/fuel mixture passing through said secondary barrel 8. This
means of enriching the air/fuel mixture corrects for the lag in
response of the secondary barrel slidably adjustable means which is
called for when there is a sudden demand placed on the secondary
barrel, such as, for example, when the accelerator pedal is rapidly
and/or fully depressed. This enrichment device thus provides the
additional fuel which is called for by a rapid acceleration demand
and significantly improves the engine driveability. Without such an
enrichment device, there is a noticeable response lag when rapid
acceleration demand is made and consequent impairment in the
driving quality of a vehicle driven by an engine using the present
carburetor. The leading edge of vane 18 is illustrated as having a
lip 18a. This configuration of the leading edge of the vane 18
reduces the tendency to cause laminar flow and thereby prevents the
fuel out of orifice 11 from running down against the barrel wall at
8a. A vane having no lip or equivalent protrusion at its leading
edge can be used, if desired. However, the lipped configuration is
preferred since it improves fuel flow, increases turbulence and
improves fuel/air mixing.
FIG. 3A is a top view of FIG. 3 section through B, B'. This view
shows that vane 18 rests on two points of attachment 21 and 21' and
slightly away from the wall of the barrel 8. This provides a narrow
opening 22 which allows air to pass through and vaporize any fuel
which might run down from the orifice 11 along the barrel 8a
wall.
FIG. 4 is an enlarged view of the same portion of the secondary
barrel as illustrated in FIG. 3, except that the manifold vacuum
has been increased, as under part throttle conditions, and the
control piston 19c has now been pulled downward, compressing spring
19b. The lower edge of the enrichment vane is thus positioned away
from the barrel 8 wall and the leading edge of said vane 18 is
moved back towards the barrel 8 wall. This is normaly the position
that the vane 18 will be in when there is no rapid acceleration
demand.
FIG. 5 illustrates a temperature responsive bleed valve for
controlling the vacuum in the vacuum chamber which controls the
secondary barrel(s) cross-section area of the present carburetor
while the engine is being warmed up. The FIG. 5 illustration shows
the bleed valve 26 connected via conduit 23 to the vacuum chamber
housing 20 of a three-barrel carburetor of the type illustrated in
FIG. 2, mounted in an engine intake manifold 30. The temperature
control bleed valve means comprises a simple chamber 24 having an
opening 25 in which a valve 26 is situated. The valve is in turn
attached to a bimetal element 27 which responds to the air
temperature inside the air cleaner housing 28. When the air in the
housing 28 is below the normal engine operating temperature, the
valve 26 is opened and bleeds vacuum from the carburetor vacuum
chamber. This tends to prevent excess fuel being metered into the
secondary barrel while the engine is warming up. Once the air in
the air cleaner 28 reaches normal engine operating temperature, the
bimetal element 27 moves the valve 26 to close the orifice 25, thus
sealing the bleed valve. When the bleed valve 27 is closed, the
carburetor functions in the manner set out above. FIG. 5 shows the
temperature control bleed valve mounted in the air cleaner. This is
a convenient and preferred position for this element. The bimetal
control means, however, can be mounted anywhere that it can sense
and respond to the engine operating temperature.
FIG. 6 schematically illustrates a preferred engine system using a
three-barrel carburetor of the present invention. The basic system
is described in U.S. Pat. No. 3,577,727, to F. Marsee and J. A.
Warren; and the system has been and is herein referred to as the
lean reactor system. The carburetor 29 is of the three-barrel type
illustrated in FIG. 2. It is conventionally mounted on the intake
manifold 30. Air/fuel mixture is fed through the carburetor 29 into
the intake manifold 30 which in turn supplies the air/fuel mixture
through intake port 31 to the combustion chamber 32. On being
ignited, the air/fuel mixture provides energy and forms exhaust
products, or simply, exhaust. This exhaust passes through the
exhaust port 33 into the exhaust manifold 34, then into the exhaust
pipe 35 and finally out into the atmosphere. The exhaust port 33 is
insulated by means of a metal liner 36 which forms an insulating
air space 37. The exhaust manifold 34 is also insulated by means of
a metal shroud 38 which defines an insulating air space 39. This
air space 39, if desired, can contain other insulating material,
e.g., asbestos, metal foam, fiberglas insulation and the like. A
portion of the exhaust is recycled via conduit 40 to a point 41 in
the intake manifold 30 just below the primary barrel 1 of
carburetor 29. It is preferred to obtain the exhaust for recycle at
a point in the exhaust system beyond the exhaust manifold 34.
However, exhaust for recycle can be obtained at any other desired
point in the exhaust portion of the system. The quantity of exhaust
which is recycled is controlled by valve means 42. Although this
valve means 41 may be controlled mechanically or electrically,
valve means responsive to a manifold vacuum signal is preferred. A
most preferred exhaust recycle control system is described in my
concurrently filed application herewith. By recycling exhaust in
this manner, a substantial reduction in total nitrogen oxides in
the exit exhaust is achieved. A heat exchange means 43 is also
provided to cool the recycle exhaust before it is introduced into
the intake manifold 30. Any suitable heat exchange device or
construction can be used. Although not shown in FIG. 6, a catalytic
converter and/or a back pressure control valve may also be provided
in the engine exhaust system if desired.
The multistage, multibarrel carburetor of the present invention can
be used with a conventional internal combustion engine having a
conventional induction system and exhaust system. Use of the
carburetor in such a system will effect improved air/fuel mixture
uniformity, especially with lean mixtures, that is, mixtures in
which the amount of air is greater than the stoichiometric amount
of air required for complete combustion of the fuel (e.g., air:fuel
ratios of 16:1 and greater), and distribution of this air/fuel
mixture uniformly to all the cylinders in a multicylinder engine
will be facilitated. Because of the improved air/fuel blending, the
combustion efficiency of the engine is improved and unburned
hydrocarbons and carbon monoxide emitted in the exhaust are
reduced. Although other multibarrel carburetors and especially
three-barrel carburetors, will provide good lean air/fuel mixtures
(see U.S. Pat. No. 3,310,045, to E. Bartholomew), the present
carburetor, especially the preferred three-barrel embodiment,
significantly improves the driveability of an automobile powered by
an engine which uses the present carburetor.
The carburetor of the present invention can also be used in a
system of the type described in U.S. Pat. No. 3,577,727. This
patent describes a system for reducing exhaust emissions from an
internal combustion engine which comprises combination of (1) a
fuel induction system to provide a lean air/fuel mixture, (2) means
of conserving the exhaust heat, and (3) a back pressure control
valve. Use of a three-barrel carburetor of the present type, in the
fuel induction portion of the combination described above, either
with or without the back pressure element (3) enhances the overall
efficiency of the aforesaid system; and substantially improves the
driveability of an automobile which utilizes such an engine system.
To illustrate the effectiveness of this latter combination (that
is, without the back pressure control valve) in maintaining low
hydrocarbon, carbon monoxide emissions, the following emission
ranges can be maintained by a standard V8 engine equipped with (a)
the present three-barrel carburetor/intake manifold induction
system and (b) some of the elements for conserving exhaust heat
described in U.S. Pat. No. 3,577,727 (and illustrated in FIG.
6).
exhaust Emissions Test Method Hydro- Carbon Nitrogen carbons
monoxide oxides California 7-Mode Cycle Test <30 ppm
<0.4.degree./o <300 ppm Federal Vehicle Exhaust Test
Procedure, 0.6-1 6-10 1-2 Subpart H (1) gram/mile gram/mile
gram/mile (1) Described in Federal Register, Volume 35, No. 219,
Nov. 10, 1970
More importantly, the driveability of a standard automobile
equipped with such an engine system is excellent. This has been
verified by extensive road testing and rating of such an automobile
by qualified personnel. By standard automobile is meant a current
model of a regular production automobile.
The present invention is embodied in (a) a multistage, multibarrel
carburetor which comprises a high velocity primary section and an
essentially constant and high velocity, variable venturi secondary
section; (b) air/fuel mixture enrichment means in the secondary
section for improved fuel control; and (c) a combination using the
present engine carburetor with elements of an exhaust emission
reducing system (described in U.S. Pat. No. 3,577,727) which
improves driveability of an automobile. These embodiments have been
described in detail and illustrated in the drawings. Claims to the
invention follow.
* * * * *