U.S. patent number 3,838,673 [Application Number 05/295,029] was granted by the patent office on 1974-10-01 for two-stage cold start and evaporative control system and apparatus for carrying out same.
This patent grant is currently assigned to Chevron Research Company. Invention is credited to Sigmund M. Csicsery, Bernard F. Mulaskey.
United States Patent |
3,838,673 |
Csicsery , et al. |
October 1, 1974 |
TWO-STAGE COLD START AND EVAPORATIVE CONTROL SYSTEM AND APPARATUS
FOR CARRYING OUT SAME
Abstract
As cold start is initiated in a spark-ignition internal
combustion engine, lower molecular weight constituents of a
full-range gasoline are selectively eluted. In accordance with the
present invention, the elution system includes a two-stage
adsorbent bed of adsorbent material, forming first and second
parallel elution zones within a cannister assembly in selective
fluid contact with the full range gasoline under control of a valve
and conduit network. The first zone terminates in fluid contact
with the fuel well of the carburetor of the engine. The second zone
terminates adjacent the air filter of the air intake system. The
valve and conduit network is fitted with an additional valve
metering unit at the second zone to allow only a metered amount of
gasoline to enter, say as a function of temperature. A vapor
emission control system can also be housed within the cannister
assembly and undergo selective operation to prevent escape of vapor
emissions originating from within the carburetor and gasoline
tank.
Inventors: |
Csicsery; Sigmund M.
(Lafayette, CA), Mulaskey; Bernard F. (Fairfax, CA) |
Assignee: |
Chevron Research Company (San
Francisco, CA)
|
Family
ID: |
23135930 |
Appl.
No.: |
05/295,029 |
Filed: |
October 4, 1972 |
Current U.S.
Class: |
123/179.8;
123/179.14; 123/519; 123/3; 123/510 |
Current CPC
Class: |
F02M
1/16 (20130101); F02M 25/0872 (20130101); F02M
2025/0881 (20130101) |
Current International
Class: |
F02M
1/00 (20060101); F02M 1/16 (20060101); F02M
25/08 (20060101); F02m 001/16 (); F02m
027/02 () |
Field of
Search: |
;123/179G,3,18R,187.5R,119E,127,133 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Myhre; Charles J.
Assistant Examiner: Rutledge; W. H.
Attorney, Agent or Firm: Freeland, Jr.; R. L. Messner; H.
D.
Claims
We claim:
1. In a spark-ignition internal combustion engine of the type
having an air intake system, a fuel intake system, and a carburetor
means interconnected therebetween for mixing of full-range fuel
with air to form a combustible mixture for delivery to combustion
chambers of said engine, the improvement for reducing exhaust
pollutants of said engine by dynamically varying the composition of
said full-range fuel during cold starting of said engine (cold
start cycle), comprising;
i. two-stage cannister means selectively connectable between said
carburetor and a reservoir of said full-range fuel and including
separate first and second adsorption beds of adsorbent material
each in flow arrangement with said reservoir means whereby said
full-range fuel dynamically percolates thereover during said cold
starting of said engine to elute first and second cold start fuel
streams,
ii. said first stream being an atomized spray composed essentially
of low molecular weight constituents and being carried into said
carburetor by intake air of said air intake system,
iii. said second stream being composed essentially of low molecular
weight liquid constituents and being conveyed under pressure to a
fuel well of said carburetor, said first and second streams being
mixed together along with air by said carburetor to form a highly
combustible cold start mixture for delivery to said combustion
chambers of said engine,
iv. control means including flow condition means for controlling
flow of said fuel including said cold start fuel streams between
said reservoir means, said cannister means and said carburetor as a
function of at least one of several engine operating parameters to
assure at least substantially simultaneous delivery of said cold
start fuel streams to said carburetor during cold starting of said
engine.
2. The improvement of claim 1 in which said flow condition means of
said control means is further characterized by a first active state
initiated by occurrence of a selected engine parameter indicative
of the start of said cold start cycle whereby said full-range fuel
is allowed to flow in parallel from said reservoir means to each of
said adsorbent beds in said cannister means to initiate elution of
said first and second cold start fuel streams and whereby said
first and second cold start fuel streams are allowed to flow in
parallel from said cannister means to said carburetor to form said
highly combustible cold start fuel-air mixture.
3. The improvement of claim 2 in which said absorbent materials
comprising said first and second adsorbent beds are selected on a
basis of providing efficient retardation of high molecular weight
constituents of said full-range fuel percolating therethrough so
that essentially only low molecular weight constituents are eluted
from each of said beds of said cannister means during cold starting
of said engine.
4. The improvement of claim 3 in which said adsorbent material is
selected from the group consisting of silica gel, alumina, barium
sulfate, calcium carbonate, glass, resins and plastics, quartz,
titanium dioxide, metallic oxides and zeolites, adapted for use in
liquid-liquid partition chromatography.
5. Apparatus for reducing exhaust and inoperative pollutants
produced by a spark-ignition internal combustion engine of the type
including an air intake system, fuel intake system, and a
carburetor interconnected therebetween for mixing full-range fuel
with air to form a combustible mixture for delivery to combustion
chambers of said engine, comprising:
i. a two-stage cannister assembly including first and second
sections each containing a bed of adsorbent material capable of
selectively eluting at cold start first and second parallel cold
start fuel streams each composed essentially of only low molecular
weight constituents, said first stream being composed of low
molecular weight liquid constituents conveyed to a fuel well of
said carburetor said second stream being an atomized spray carried
into said carburetor by intake air of said air intake systems, said
first and second streams being mixed together with air by said
carburetor, said first section also including another bed of
adsorbent material capable of selectively absorbing vapor
constituents of said full-range fuel during an inoperative state of
said engine,
ii. valve and conduit network means attached between said cannister
assembly, a reservoir means for said full-range fuel and said
carburetor for providing selective flow of said fuel including said
cold start fuel between said cannister assembly, said reservoir
means and said carburetor, said network means including a first
plurality of conduit and valve means including first and second
valve means controlling parallel flow relative to each of said
sections of said cannister assembly so as to allow, (a) in a first
operating state flow of said full-range fuel from said reservoir
means to said each section and flow of said first cold start fuel
stream from said cannister assembly to said carburetor to provide
for rapid starting of said engine without producing excessive
exhaust pollutants and (b) in a second operating state, full-range
fuel to flow from said reservoir means to said carburetor bypassing
said cannister assembly after said engine is in a normal running
condition, said network means also including a second plurality of
conduit means including a third valve means operatively connected
between said another bed of said first section of said cannister
assembly said fuel reservoir means and said carburetor for
selectively conveying vapor emissions of said fuel within said fuel
reservoir and/or said carburetor to said another bed when said
engine is in said inoperative state,
iii. control means operatively connected to said first, second and
third valve means of said valve and conduit network for changing
operation states so as to direct fuel flow relative to said
cannister assembly, said reservoir and carburetor as a function of
one or more engine operating parameters.
6. Apparatus of claim 5 in which said carburetor includes a fuel
well and a bore each in selective contact with said first and
second sections of said cannister assembly and said reservoir means
through said first plurality of conduit means including said first
and second valve means, said first valve means being positioned
between said reservoir means and a parallel inlet of each of said
sections of said cannister assembly and having first and second
operating states for controlling flow of full-range fuel between
said reservoir means relative to each of said section and said
second valve means, said second valve means being positioned
between said fuel well and an outlet of said first section and also
having first and second operating states coextensive in time with
said operating state of said first valve means for controlling flow
of said full-range fuel and said cold start fuel stream from said
first sections relative to said fuel well as a function of engine
temperature.
7. The apparatus of claim 6 in which said fuel well and said
reservoir means are placed in selective vapor contact with said
another bed of said first section through said second plurality of
conduit means including said third valve means as a function of a
selective engine parameter indicative of said inoperative state in
said engine whereby evaporative vapor emissions from said
full-range fuel within said fuel well and said reservoir means can
be conveyed to said another bed of said first section for
adsorption therein thereby preventing escape into atmosphere
surrounding said engine.
8. Apparatus of claim 7 in which said first and second adsorbent
beds are formed of a polar adsorbent material while said another
adsorbent bed is formed of a nonpolar adsorbent material.
9. Apparatus of claim 6 in which said first section includes an
elongated tubular means disposed within a forward section of a
shell housing while said second section is disposed within a rear
section of said shell housing with air intake control means
connected to a source of heated gas, so as to allow selective flow
of said heated gas through said first and second sections for
purging both said first, second and another bed of adsorbed fuel
constituents, said purged constituents being carried into and
consumed within said combustion chambers of said engine.
10. Apparatus of claim 9 in which said air intake system includes
an air cleaner assembly having an air intake line and an air
filter, said air intake line including support means for rigidly
supporting said cannister assembly in flow relationship with a bore
of said carburetor.
Description
RELATED APPLICATIONS
Applications filled simultaneously with the subject disclosure
which are assigned to a common assignee and containing common
subject matter but claiming distinct inventions, include: Title
Inventor(s) Serial No. ______________________________________
Single-Stage Cold Start and Evaporative Control Method and
Apparatus for Carrying Out Same Sigmund M. Csicsery 295,028 Cold
Start Method and Apparatus for Carrying Out Same John F. Senger
295,041 Fuel Injection Cold Start and Evaporative Control Method
and Apparatus for Carrying Out Same Sigmund M. Csicsery 295,040
Two-Stage Fuel Injection Cold Start Method and Apparatus for
Carrying Out Same Sigmund M. Csicsery and Bernard F. Mulaskey
295,030 ______________________________________
The present invention relates to cold starting and evaporative
emission control of a spark-ignition internal combustion engine and
has for an object the provision of a simple and effective cold
start and evaporative control system for use in such engine
I. for selectively eluting from a full range fuel flowing to the
engine only the lower molecular weight constituents at cold start
so as to allow quick starting of the engine without excessive
amounts of unburned hydrocarbons appearing at the exhaust as well
as
Ii. for adsorbing evaporative emissions from the gasoline tank and
carburetor bowl when the engine is not operating.
Higher molecular weight constituents adsorbed during cold start
and/or light, evaporative emissions adsorbed during the disabled
cycle of the engine are purged from the system only after the
engine has been warmed and the full range fuel utilized.
During cold start of spark-ignition internal combustion engines,
the fuel-air ratio is generated by the air-fuel intake system, say
a conventional carburetion system. At cold start, the air-fuel
ratio can be varied (enriched) to assure adequate amounts of lower
molecular weight constituents of the fuel at the intake manifold.
By operation of a plurality of interrelated well-known parts, the
higher molecular weight constituents become more easily vaporized
to form combustible vapor-fuel/air ratios to allow starting of the
engine even at low operating temperatures. However, since remaining
higher molecular weight constituents are not oxidized even if the
start is rapid, such remaining constituents contribute to the
formation of unburned hydrocarbons at the exhaust.
Although a more volatile fuel having a lower boiling point, would
permit faster starts and warmup and reduce exhaust pollutants,
including unburned hydrocarbons and carbon monoxide emissions,
experience shows that full range engine performance using the more
volatile fuel would be adversely affected. In this regard, fuel
consumption would be greatly increased over all ranges of
driveability.
In accordance with the present invention, rather than use a more
volatile fuel under a multiplicity of operating conditions of a
spark-ignition internal combustion engine (particularly during cold
start), lower molecular weight constituents of a full-range
gasoline are selectively eluted as cold start is initiated by the
driver. The elution system includes a two-stage adsorbent bed of
adsorbent material, forming first and second parallel elution zones
within a cannister assembly in fluid contact with the full range
gasoline. The adsorbent material--usually in pelletized form--with
the first elution zone is preferably housed within a tubular means
disposed within the cannister assembly, the tubular means being
positioned within a much larger shell housing in fluid contact with
a valve and conduit network. Entry of the gasoline is initiated by
the valve and conduit network under control of a controller
circuit.
Within the second elution zone, the valve and conduit network is
fitted with an additional valve metering unit in parallel with the
first elution zone which allows only a metered amount of gasoline
to enter as a function of temperature. A circumferentially
extending air entryway of approximately the shell housing
dimensions is formed near the rear end of the second elution zone,
the nozzle of the valve metering unit terminating adjacent the air
entryway. As gasoline enters via the nozzle and mixes with the air,
it is quickly carried through the second elution zone as selective
retardation of the higher molecular weight compounds occurs. Due to
the velocity of the accompanying air as well as the presence of
openings within a screen at the remote, exhaust end of the second
elution zone, the lighter low molecular weight constituents are
caused to be broken into a fine atomized spray. The atomized spray
contains both liquid and vapor phases of the lighter constituents,
and is readily flowable through the air filter of the air intake
system of the engine into the carburetor. At the carburetor, the
cold start fuel constituents from both first and second elution
zones are mixed together with air to form a highly combustible cold
start air-fuel mixture.
Construction of the cannister assembly can vary. Preferably the
arrangement within the first elution zone resembles that provided
for a shell-and-tube heat exchanger whereby tube-side
gasoline--during cold start--passes through the tubular means
packed with the adsorbent material (single pass percolation).
Within the second elution zone, the construction of the cannister
assembly includes a housing integrally contacting the shell housing
of the first elution zone, with the aforementioned entryway
disposed therebetween. While the absorbent materal therein can be
similar to that used in the first elution zone, or may be
different, as explained below, it is always retained within the
housing. Selective retardation of the high molecular weight
compounds, vis-a-vis the lighter components occurs so that, during
start up, only the light constituents pass to the carburetor, for
later consumption within the combustion chambers of the engine.
Since the starting cycle of an internal combustion engine is quite
short, say from 1 to 15 seconds and the residence time for the
heavier compounds within the elution zone is 1 to 2 orders longer
say from 1 to 3 minutes, the latter compounds remain selectively
adsorbed with both the first and second parallel elution zones.
Preferably, but not necessarily, the present invention has
additional utility in preventing evaporative emissions originating
within the fuel well of the carburetor and/or within the gasoline
tank from escaping into the atmosphere. In this aspect of the
invention, the escape of large amounts of hydrocarbon fumes and
vapors into the atmosphere from a spark-ignition internal
combustion engine in an inoperative state, is acknowledged as being
a serious environmental problem, especially within large cities. In
this regard, studies indicate that up to 15 percent by volume of
the total vapors admitted into the atmosphere, originate from
evaporative emissions from spark-ignition internal combustion
engines. Governmental bodies are attempting to satisfy emission
regulation in cooperation with industry; for example, California
Motor Vehicle Pollution Control Board has proposed the following
standards for control of evaporative emissions: 2 grams per hot
soak from the carburetor fuel well and 6 grams per day from the
fuel tank under standard operating conditions. In this regard, the
present invention can be selectively, but no necessarily, operative
during such time periods to adsorb such evaporative emissions and
prevent their escape into the atmosphere by arranging the first
elution zone so as to provide space between the tubular means and
the shell housing. Into that space can be inserted an adsorbent
material, preferably of the nonpolar type, which form an adsorptive
capture zone for use in preventing escape of evaporative emissions
into the atmosphere when the engine is in an inoperative state.
The associated valve and conduit network and the controller circuit
can place both the elution and capture zones of the cannister
assembly in fluid contact with other relevant fuel system
components as required; for example, after the engine has started
and warmed up both the elution and capture zones can be purged of
adosrbed constituents (adsorbates) by passing shell-side gases
(either full or partial engine air or manifold exhaust gases)
through these zones. Thus, not only is the present invention able
to rapidly elute low molecular weight fuel constituents at cold
startup, but the other adsorbed fuel components can be
automatically desorbed without formation of excessive amounts of
pollutants at the exhaust.
Although the prior art has suggested both polar and non-polar
adsorbent materials for use in vapor recovery systems, there has
been no suggestion of using adsorbent materials in an elution
system for selectively eluting from a full-range gasoline, only
light, low molecular weight components thereof, to assure a smooth
pollution-free start of a spark-ignition internal combustion
engine.
Further objects, features and attributes of the present invention
will become apparent from a detailed description of several
embodiments to be taken in conjunction with the following drawings
in which:
DESCRIPTION OF THE FIGURES
FIG. 1 is a schematic view of a portion of an engine fuel system
incorporating the present invention illustrating a typical
carburetor and air cleaner assembly interconnected between a cold
start -- evaporative emission system of the present invention, said
cold start evaporative control emission system including a
cannister assembly housed within the air intake line of the air
cleaner assembly under regulation of a valve and conduit networks
controlled by a controller circuit;
FIG. 2 is a partial cutaway of the cannister assembly of FIG.
1;
FIGS. 3 and 4 are section views taken along lines 3--3 and 4--4 of
the cannister assembly of FIG. 2;
FIG. 5 is a schematic view of another embodiment of the present
invention illustrating a typical carburetor and air cleaner
assembly in which the cannister assembly including first and second
parallel elution zones is mounted by means of a platform attached
to the fire wall of the engine compartment;
FIG. 6 is a plan view of the cannister assembly and air cleaner
assembly of FIG. 5 and illustrates the position of a valve metering
unit afixed to an outer housing of the cannister assembly;
FIG. 7 is a fragmentary view of a metering pin of the valve
metering unit of FIG. 6;
FIG. 8 is a partially schematic view illustrating an alternate
embodiment by which air can be heated to an elevated temperature to
better desorb the cannister assembly of FIGS. 1 and 5;
FIG. 9 is a fragmentary view of the valve and conduit network of
FIGS. 1 and 5 illustrating the position of the valve network after
cold start has been achieved and the engine is at running
temperature so that the cannister asembly can be desorbed by
passing gases in heat transfer contact therewith:
FIG. 10 is yet another fragmentary view of the valve and conduit
network of FIGS. 1 and 5 illustrating the position of the valve
network when the engine is in an inoperative state.
Referring now to FIG. 1, there is illustrated an engine fuel system
10 connected to an engine intake manifold 11 of a spark-ignition
internal combustion engine (not shown). Fuel system 10 of the
present invention includes an air intake system 12, a carburetor
13, a fuel intake system 14, that includes cold start-evaporative
control system 15 of the present invention.
To form a combustible air-fuel mixture, air enters by way of air
intake system 12, say by way of air inlet line 16a, and is filtered
at an air filter interior of an air filter housing 16c, before
entry into carburetor 13. Carburetor 13 includes a throttle valve
18, a fuel well 19, and a discharge nozzle 20. Fuel well 19
contains a metered quantity of gasoline to be mixed with air
passing discharge nozzle 20 and to be passed through intake
manifold 11 into the engine combustion chambers (not shown) where
combustion occurs. Supplying fuel well 19 with a metered quantity
of gasoline is by means of fuel intake system 14. Fuel intake
system 14 includes a gas tank 23 containing a reservoir of
full-range fuel (i.e., a full-boiling gasoline), a fuel pump 24 and
cold start-evaporative control system 15 of the present invention.
Cold start-evaporative control system 15 includes a valve and
conduit network 25 in fluid contact with the discharge side of fuel
pump 24 but under operative control of controller circuit 26. A
cannister assembly 27, see FIG. 2, mounted adjacent to the air
intake system 12, say within air inlet line 16a, is likewise an
element of the cold start system 15 as noted below.
It should be noted that carburetor 13 has been modified to exclude
from operation a choke valve so that the enrichment of the fuel-air
ratio is performed solely by the cold start-evaporative control
system 15 of the present invention. Briefly, with reference to FIG.
2, cannister assembly 27 is seen to include two parallel sections:
a forward section resembling a conventional but scaled down
tube-and-shell heat exchanger generally indicated at 27a, and a
rear section 27b including a valve metering unit 90. An elongated
valve gate 91 interior of common housing 22 of the sections
controls internal air flow between the forward and rear sections
27a and 27b, while an air entryway 92 of the same dimensions as and
integral with the common housing 22 control external air flow into
the rear section 27b via a swedged ribbon of openings 95. In the
present aspect of the invention, not only can light low molecular
weight components (liquid phase) be conveyed to the fuel well 19 of
the carburetor 13 through operations of forward section 27a, but
also an atomized spray of such components (both liquid and vapor
phase) can be simultaneously eluted through ports 96 of screen 97
of rear section 27b. As is readily apparent, provision of a
combination of atomized spray and liquid cold start fuel mixed at
the carburetor assures rapid cold start of the engine under a
variety of operating conditions without the formation of pollutants
at the exhaust.
Valve and conduit network 25 of FIG. 1 is seen to include cold
start inlet and exit valves 25a and 25b, respectively controlled
mechanically by relay means 26a of controller circuit 26 through
transducer 26d and electrically through bimetal temperature switch
26b, ignition switch 26c and battery 26f. A second relay 26e of
controller circuit 26 is seen to control operation of evaporative
emissions control valve 25c of valve and conduit network 25 through
mechanical transducer 26g. Transducers 26d and 26g convert
rectilinear travel of the relay means 26a and 26e to the rotational
motion.
COLD-START EVAPORATIVE CONTROL SYSTEM 15.
As indicated with reference to FIG. 1, during cold start of a
spark-ignition internal combustion engine, a full-range fuel, i.e.,
a full-boiling gasoline, having both low and high molecular weight
constituents, is conveyed from gas tank 23 through fuel pump 24
into valve and conduit network 25, and thence to cannister assembly
27, (FIG. 2). Although a full-boiling gasoline enters the cannister
assembly 27, in accordance with present invention, due to selective
retardation of heavier components, only lightweight constituents
are eluted during cold start. Such selective retardation during the
initial one-three minutes of the starting cycle of the internal
combustion engine is achieved based on operational characteristics
of parallel first and second elution zones 28 and 28' formed within
the cannister assembly 27. Since the nature of the elution zones 28
and 28' is based on functional characteristics of adsorbent
materials, in general, and of polar and nonpolar type adsorbent
materials, in particular, a brief discussion of adsorbtion systems
is believed to be in order and is presented below with reference to
FIG. 2.
Essentially, the first and second elution zones 28 and 28' form
parallel columns of parallel frontal analysis chromatagraphs
(solution adsorbtion) as classified in accordance with Kirk-Othmer
Encyclopedia of Chemical Technology, 2nd Ed., Volume 5, page 418.
In accordance with Kirk-Othmer op. cit., such classification is
essentially based on the nature of the mobile phase of the system
percolating through an adsorbent material. In the case at hand,
within the first elution zone 28 full-boiling gasoline enters by
way of inlet conduit 33 and percolates through polar adsorbent
materal 34 packed within the tubular means 31. Note at the outlet
conduit 36, the order of elution is a function of the order of
polarity of the constituents of the full range gasoline since the
individual molecules of the high molecular weight constituents
within the tubular means 31 shuffle at a slower rate between the
mobile and stationary phases than do the lighter constituents.
Within the second elution zone 28', the full-boiling gasoline is
seen to have parallel simultaneous entry into second elution zone
28' by way valve metering unit 90. Adsorbent material 34' retained
within common housing 22, provides at end wall screen 42 an
identical order of eluted products as polar adsorbent 34 with first
elution zone 28. Within the elution zone 28, separation occurs
because of the polarity, nonpolarity groupings of these
constituents whereby different relative velocities are imparted to
the individual molecules of the groupings. The least strongly
adsorb low molecular weight liquid components elute first as a
group followed by a second grouping containing say both the low and
high constituents and so forth until all constituents have
appeared. Within the elution zone 28', separation is apparently
not, primarily, a function of polar interaction since both polar
and non-polar materials can be used to form the adsorbent material
34.
Residence time of the low molecular weight components within the
elution zones 28 and 28' is a function of many factors including
the length of the elution zones as well as the pressure drop during
percolation through the adsorbent materials 34 and 34',
respectively. However, the residence time of the heavier components
is much longer within each zone, usually in a range of 1-3 minutes.
However, care ought be exercised in this regard. The flow rate of
the mobile phase must be slow enough to allow maximum transfer of
the molecules of the heavier constituents into and from the
stationary and mobile phases. Since selective retardation of the
heavier constituents is quite long, say 1-3 minutes, while the
typical starting cycle of a modern engine can be quite short, say
from 1 second up to 15 seconds (except when problems of starting
occurs), the heavier constituents remain adsorbed within the
elution zone 28 and 28' after the engine has started. This
proposition assumes of course that the adsorbent material 34 and
34' are of a compatible polar classification.
CLASSIFICATION OF ADSORBENT MATERIAL 34 AND 34'
As previously mentioned, competition for the high molecular weight
groupings of the full-range fuel has been found in the forward
elution zone 28 to be dependent on its selective interaction with
the adsorptive material 34. I.e., the degree of interaction
(between the material 34 and the more polar heavier constituents of
the full-range fuel) has been found to be directly related to the
magnitude of polarity of the adsorptive material. In accordance
with the present invention adsorptive material 34 should be polar
and preferably selected from following non-exclusive listing of
popular polar adsorptive materials, with silica gel being somewhat
preferred:
Polar Adsorptive Materials Remarks
______________________________________ Silica gel Alumina Activated
Preferred Barium sulfate Calcium carbonate Glass Resins and
plastics Ion-exchange only Quartz Titanium dioxide Metallic oxide
Zeolites (sieves) Sil X Solid Support Material Coated with Liquid
Adsorbers such as chemically bonded liquids. (E.g. Durapak; solids
coated with Octadecyl Silane, Fluoro-ethers, etc.) Commonly used in
Liquid-Liquid Partition ______________________________________
Chromatography
In the case of rearward elution zone 28', competitions for the
higher molecular weight constituents is not so dependent upon
polarity of the adsorption material 34' so that in addition to the
above-listed polar materials the following non-polar materials may
also be used:
Non-Polar Adsorbent Material Remarks
______________________________________ Charcoal Charcoal blacks
Graphite Resins and plastics Organic only Paraffins Stibnite
Sulfides Metallic only Talc
______________________________________
The elution zones 28 and 28' can be formed of adsorbent material in
granular, pellitized or powdered form. Preparation is straight
forward: the adsorbent material should be calcined, acid and base
washed, neutralized, and size graded prior to insertion within the
cannister assembly 27, say along lines set forth in Kirk-Othmer op.
cit., Volume 1 at page 460. Since as previously mentioned, the flow
rate of the full range gasoline within the elution zones 28 and 28'
must be slow enough to allow maximum transfer of the molecules of
the heavier compounds into and from the stationery and mobile
phases, the size of the adsorbent material 34 and 34' should be
such as to minimize the pressure drop across a cannister assembly
27 without adversely affecting its ability to adsorb these
constituents. In this regard, an elution zone having about a
1-liter capacity filled with activated alumina of 8 by 14 mesh has
been found to adsorb from 200-300 ml. of high molecular weight
constituents while yielding about 400 to 500 ml. low molecular
weight constituents in the first initial minutes of the cold
starting operation. In addition to activated alumina, within the
forward zone 28, it has been found that polar gels, such as silica
gel, titania gel, zirconia gel, and alumina gel, Fuller's earth,
bentonite, diatomaceous earth, forisil, attupulgus, and any other
polar adsorptive materials are also useful in carrying out that
aspect of the present invention. However, in some cases, non-polar
materials may be substituted without undue loss in effectiveness.
In this regard, non-polar materials listed hereinbefore are
appropriate.
CANNISTER ASSEMBLY 27.
Construction of the cannister assembly 27 varies with the type of
mounting required to attach the cold start-evaporative control
system 15 adjacent to air intake system 12. In FIG. 2, cannister
assembly 27 is seen to include forward and rear sections 27a and
27b mounted within the intake air line 16a of the air intake system
12. The overall dimensions of the cannister assembly 27 thus must
be minimum so as to allow sufficient air to bypass into the
carburetor 13. To accomodate the required volume of adsorbent
material constituting the elution zones 28 and 28' (FIG. 2), the
common housing 22 may have to be correspondingly ultra-long. Within
the forward section 27a support of tubular means 31 can be brought
about by welding radial supports 37 to the side wall of air line
16a to which cold start conduits 33, 36 as well as evaporative
conduit 38 are attached. Within the rear section 27b, support of
the common housing is by way of inlet conduit 94. Since the forward
and rear sections have essentially individual operational
characteristics, each section will now be discussed in
sequence.
FORWARD SECTION 27a.
Tubular means 31 is seen to be concentric of common shell housing
22 and includes supports 40 and 41 at respective ends thereof. Each
support 40 and 41 has peripheral edges in contact with the shell
housing 22. Each support 40, 41 also includes a central plug zone
in plugging contact with the central tubular means 31 as well as an
intermediate zone 43 (See FIGS. 3 and 4) including a series of
ports 44 in registry with a modified parallelpipedonic spacing
existing between tubular means 31 and the shell housing 22 wherein
adsorbent material 45 is supported. Adsorbent material 45 located
in the aforementioned space constitutes a vapor adsorption zone,
generally indicated at 46 (adsorption capture zone). In this aspect
of the invention, deactivation of ignition switch 26c (of FIG. 1)
deactivates relay 26e causing rotation of the vapor control valve
25c to the position shown in detail in FIG. 10. The fuel well 19
and the gas tank 23 of FIGS. 1 and 5 are thus placed in fluid
contact with the vapor adsorption zone 46. Note that at the shell
side exterior of the central tubular means 31, within zone 46, the
atmosphere is permitted to enter at will but is frustrated to exit
by operation of valve gate 91. During cold start, the shell-side
air is at about the same temperature as the fluid interior of the
tubular means 31, so little heat is transferred between the two
fluids.
REAR SECTION 27b.
Note that tubular section 31 of the forward section 27a of FIG. 2
does not extend into the rear section 27b but terminates well
forward of end wall screen 42. However, the elution zone 28 defined
by adsorbent material 34 within the tubular means 31, is continued
in the rear section 27b. In more detail within the interior of
common housing 22 (preferably of rectangular cross section, see
FIGS. 6, 3 and 4) the rear section 27b is provided with adsorbent
material 34' forming the second elution zone 28'. The adsorbent
material 34' is the preferably of the same polar type as the
absorbent material 34 within tubular means 31 of the forward
section 27a, as previously mentioned but can be different if
desired.
Atop the common housing 22 adjacent rear section 27b, is the valve
metering unit 90. As previously explained, with reference to FIG.
1, the valve metering unit 90 has an inlet conduit 94 connected to
the elution zone 28'.
Valve unit 90 also has features best illustrated with reference to
FIG. 5. As indicated, the valve unit 90 includes conduit 101
connected at T-junction 103 to the conduit 33 in series with cold
start inlet valve 25a of valve and conduit network 25. Thus when
inlet cold start valve 25a is positioned as depicted in FIGS. 1 and
5, not only can full-range fuel enter forward section 27a but also
such fuel simultaneously enters rear section 27b via the T-junction
103, conduit 101 and valve metering unit 90.
The amount of full-range fuel metered into the elution zone 57' by
the valve metering unit 90 is a function of air temperature. Now in
more detail, the valve metering unit 90 is seen to include a
chamber 104 into which is positioned a bimetallic diaphragm 105.
The diaphragm 105 is attached, at its outer edge, to the side walls
of the chamber 104 and has a more central location in engagement
with enlarged head 106 of a metering pin 107. The spring force
provided by the diaphragm 105 is seen to be in opposite direction
to the spring force provided by compressions spring 108.
Compression spring 108 is seen to be mounted about boss 109 at an
end wall of the chamber 104. Boss 109 is also seen to be provided
with an opening 110 into which the metering pin 107 is slideably
mounted. As temperature changes occur as sensed by bimetallic
diaphragm 105, relative movement of the diaphragm causes
corresponding movement of the metering pin 107 relative to the
opening 110.
Intersecting opening 110 at a right angle is passageway 111.
Passageway 111 has an upper inlet port in fluid contact with the
conduit 101 and an exit port in fluid contact with metering pin
107.
FIG. 7 illustrates metering pin 107 in more detail. As indicated,
the pin 107 consists of an elongated shank portion 112 tapered at a
remote end to form a reduced segment 113. At the opposite end, the
shank portion 112 is seen extending into contact with the enlarged
head 106. Reduced segment 113 is seen to be swedged as a function
of length. That is to say, the reduced segment 113 is reduced in
diameter from a beginning section 118 to a mid-portion section 119
and then is allowed to increase in diameter until a maximum is
reached at end section 120. Accordingly, the amount of gas which
can pass into the elution zone 28' is dependent upon whether or not
minimum section 119 or beginning section 118 is in registry with
passageway 111, i.e., when the pin 107 is as depicted in FIG.
5.
Referring again to FIG. 5, as the temperature changes, it is
apparent that the changes in pin location of metering pin 107
relative to passageway 111 meters gasoline into elution zone 57' as
a function of temperature. As the gasoline enters the elution zone
57' in liquid phase, percolation through the elution zone 57' is
initiated. Since the absorbent material 56' is of the same polar
characteristics as the material 34' within the elution zone 28' of
FIG. 2, selected retardation of the aromatic constituents likewise
occurs. In the manner as previously explained, air entryway 92' is
provided with a swedge band of openings 95' positioned not to
interfere with the operation of valve gate 91. Vacuum in the intake
manifold causes air to flow through the radial openings 95' and
thence through the elution zone 57' in the accompaniment of the
percolating full-range fuel. Due to the velocity of the
accompanying air as well as the presence of openings 96' of screen
97' causes the eluding paraffinic constituents at the exit of the
rear section 27b to be broken up into a fine atomized spray
(atomized vapor). The atomzied spray consists essentially of low
molecular weight constituents both in liquid and vapor phases in
the accompaniment of air. The fine atomized spray is then drawn
through the air filter 16b of the air intake system into the
carburetor 13. Due to the velocity of the accompanying air through
the rear section 27b, the resulting atomized spray undergoes very
little condensation.
It should be noted that during cold start, spring-loaded gate 91
between the forward and rear sections 27a and 27b, prevents purging
of the forward and rear sections 27a and 27b, prevents purging of
the forward section 27a. However, as manifold pressure
substantially changes indicating full-load operations have begun,
the spring loaded gate 91 swings from the position indicated in
solid lines in FIGS. 1 and 5 to the positions indicated in phantom
line. In that way, engine air (full or partial) can flow through
the forward and rear sections 27a and 27b to allow a purging of
adsorbed materials.
In FIG. 5, the support of the forward and rear sections 27a and 27b
differs markly from that of FIG. 1. The cannister assembly 27 of
FIG. 5 is seen to be mounted by common shell housing 22 to a
platform 51 which in turn is attached to a firewall (not shown) of
an engine compartment. Additional space afforded by the platform 51
allows for a more complex constructural design of the forward
section 27a. Instead of constructing tubular means 31 of a single
tube as depicted in FIG. 1, a series of upright tubular means 52
can be provided to carry the gasoline entering inlet chamber 53
along a series of sinusoidal passes through the interior of the
forward section 27a, such passageways resembling those provided in
a conventional tube-and-shell heat exchanger. The series of passes
made by the gasoline are indicated by arrows 54 while dotted arrows
54' indicate the direction of gas phase flow. In the depicted
arrangement, tube-side gasoline is conveyed-- during cold starting
within the forward section--through the tubular members 52 via
inlet chamber 53 (multipass percolation) through adsorbent material
56 to intermediate chamber 65 and thence to exhaust chamber 55. Due
to increased total length of the tubular members 52, resulting
elution zone 57 is likewise greatly enlarged over that depicted in
FIG. 2.
The rear section 27b is similar to that depicted in FIG. 1, and
provides the elution zone 57' comprising adsorbent material 56'
similar to material 34 retained with elution zone 28 of FIG. 2.
Retention of the adsorbent material 56' in elution zone 57 is seen
to be provided by screens 42' and 97'.
Further constructural features of the embodiments depicted in FIG.
1 and FIG. 5 are readily apparent. For example, both in FIGS. 1 and
5, the common shell housing 22, is seen to be rectangular in
cross-section whereby the assembly forms a parallelepipedon. As
illustrated in FIG. 6 the shell housing 22 of the forward section
27a is also seen to include end walls 58 and 59. End wall 58
includes a series of ports 60 to allow selective entry of hot,
exhaust gases via conduit 64 into an adsorptive vapor capture zone
generally indicated at 61 exterior of tubular member means 52 but
interior of shell housing 22. Within the vapor capture zone 61,
adsorbent material 62 is supported. At the opposite end, the common
shell housing 22 is also seen to attach by way of fasteners to the
air cleaner housing 16b. Such attachment is oriented such that the
ports 96' are in fluid registry with holes in the air cleaner
housing 16b.
Although the embodiment depicted in FIG. 1 utilizes full or partial
engine air warmed to a high temperature for this purpose, it should
also be noted that embodiment of FIG. 5, contemplates utilization
of gases from the exhaust manifold to purge with the elution and
vapor adsorption zones of adsorbed constitutuents.
After the engine has started and warmed, the cold start exhaust and
inlet valves 25a and 25b return to relaxed positions depicted in
FIG. 9, and the fuel intake system switches over to full
utilization of the full-range gasoline. That is to say, fuel
conveyed from fuel pump 24 passes via conduit 87a to inlet valve
25a and thence from U-shaped conduit 87b and exhaust cold start
valve 25b to the fuel well 19. With the utilization of full-range
gasoline (and corresponding increases in manifold pressure), the
elution zone of the forward section 27a as well as the vapor zones
within the fuel well 19 and gas tank 23 can be placed in fluid
contact with the carburetor 13 by operation of exhaust start valve
25b and evaporative control valve 25c. The elution zone can be
connected via conduits 36, 88a and 88b (connected to respective
ports of valve 25b of FIG. 9) to the carburetor 13; the fuel well
19 via conduit 83 and valve 25c can be also placed in fluid contact
with the conduits 88a and 88b, as can the gas tank 24 via conduit
84 and valve 25c. The elution zone of rear section 27b is always in
fluid contact with the carburetor 13 via the air intake system 12.
In that way, as desorbtion of the adsorbed compounds occurs, say,
as warmed gases are conveyed in heat transfer contact with the
elution zones, and the compounds are swept into the carburetor 13,
there can be a simultaneous conveyance of evaporative emissions if
any, from fuel well 19 and gas tank 24. With the desorption of the
heavier compounds within the first and second elution zones it
should also be pointed out that vapors captured within the adjacent
adsorptive capture zone of the cannister assembly can likewise be
purged. The captured evaporative emissions pass directly into the
air intake system 12 and thence to the carburetor 13, in the manner
of desorbed materials from the elution zone of the rear section
27b.
In FIG. 5, the conveyance of the hot exhaust gases from the exhaust
manifold is under control of additional electrical circuitry (not
shown) of the controller circuit 26. When the temperature of the
exhaust manifold reaches a selected temperature, a relay (not
shown) is tripped to pass the purging gases through the cannister
assembly 27 via conduit 64. The desorbed materials within the
elution and vapor adsorption zones of the cannister assembly 27 are
ultimately consumed within the combustion chambers of the
engine.
Where the aromatic compounds within the elution zone of the
cannister assembly 27 have relatively high boiling points, too high
in fact to be renewed by passing adjacent engine air in heat
transfer contact with the elution zone, the embodiment depicted in
FIG. 5 is especially useful. In this regard, the adsorbent material
56 and 56' of FIG. 5 can be simultaneously renewed using the hot
exhaust gases as the purging agent. If the temperature of such
exhaust gases range from 700.degree. F to about 800.degree. F only
a relatively short desorption time is required. Temperatures of the
adsorbent beds comprising the elution zones can be a range from
400.degree.-500.degree. F with about 450.degree. F being a
satisfactory operating temperature.
Generally desorption time is quite short for such range setting,
say being from about 2-12 minutes in duration. The resulting
desorbed high molecular weight compounds then pass through the air
intake system and carburetor 13 to the combustion chambers where
they are consumed.
Capture of evaporative emissions within vapor adsorption zones of
the cannister assemblies 27 of FIGS. 2 and 5 can also be desorbed
utilizing the purging gases in the manner described above. It
should be noted that the captured adsorbates within the vapor
capture zone are mostly light low molecular weight constituents.
According, the adsorbent material indicated at 45 in FIG. 2 and at
62 in FIG. 66 should be nonpolar. In this regard, the following
non-polar adsorbent materials are preferred in carrying out this
aspect of the present invention.
______________________________________ Non-Polar Adsorbent Material
Remarks ______________________________________ Charcoal Charcoal
blacks Graphite Resins and Plastics Organic only Paraffins Stibnite
Sulfides Metallic only Talc
______________________________________
FIG. 8 illustrates yet another mode for desorbing the elution and
vapor adsorption zones of the cannister assembly of FIGS. 2 and 5.
In accordance with the illustrated embodiment, engine air is heated
by passing the air adjacent to exhaust manifold 70 and thence
through the cannister assembly where desorption occurs.
In more detail, the exhaust manifold 70 is provided with an
exterior hood 71 having lower skirts 72 which snuggly fit adjacent
to the exhaust manifold, yet are open to incoming air. A central
register 73 is also provided with a nozzle 74. Nozzle 74 in turn is
attached by flexible conduit 75 connected at a port 76 say at the
air intake line 16a of the air intake system of the embodiment of
FIG. 2. At the air intake line 16a, a solenoid operator 77 is
positioned so that it is damper 78 is in register with port 76.
Opening the damper 78 allows warmed engine air to enter the
cannister assembly (not shown).
SEQUENCE OF OPERATIONS.
Reference should now be had to the Figures illustrating the method
aspects of the present invention. In more detail, it should be
apparent that the initiation of the cold start cycle automatically
occurs when the driver closes ignition switch 26c of the controller
circuit 26 of FIGS. 1 and 5. Before the driver engages the ignition
switch 26c, however, the valve and conduit network 25 and
particularly the evaporative control valve 25c is in the position
illustrated in FIG. 10 to carry out the vapor adsorption control
function of the present invention. That is to say, the evaporative
3-way control valve 25c is in a relaxed state so that its exhaust
port 80 and inlet ports 81 and 82 are in fluid communication with
fuel well 19 of the carburetor 13, and to the gas tank 23,
respectively, say via conduits 83 and 84. When the engine is in an
inactive state, and evaporation of the fuel occurs, the vapors pass
through conduits 83 and 84, 3-way control valve 25c and conduit 38
to the vapor adsorption zone of the cannister assembly 27 of FIGS.
2 and 5. Adsorption of the vapor prevents its escape into the
atmosphere.
Prior to initiation of cold start, assume the fuel well 19 has been
emptied of full-range fuel. In this regard, consider also the
function of drain conduit 85 of FIGS. 1 and 5 connected between
fuel well 19 and gas tank 23. When the engine is in an inactive
state, fuel within the fuel well 19 (liquid phase) drains therefrom
via conduit 85 to the gas tank 23. As shown, the conduit 85 is
provided with an oriface 86 so as to control the rate of drainage
of the fuel, say at a rate which will allow total removal of all
fuel from the well within a 6-12 hour period. Thus, when the engine
is parked overnight, the drain conduit 85 in cooperation with
oriface 86 provide for total removal of full range fuel from the
fuel well 19. It should also be apparent that if the drainage
conduit 85 is mounted at the side-wall of the fuel well (not at the
bottom wall as shown) not all of the full range fuel will be
drained. Instead, a residual reservoir remains, the amount of which
is a function of the connector position relative to the top wall of
the fuel well, e.g., if the connector to the fuel well and conduit
is at a location say about two-thirds of the way away from the top
wall, the residual fuel would be one-third of the total fuel well
capacity. During initial starting of the engine, the position of
nozzle 20 of the carburetor 13 could be arranged, depthwise, so
that a selected, compatible mixture of the residual and eluted fuel
would enter the carburetor to effect cold start of the engine.
Furthermore, it should also be apparent that the positions of the
drain conduit 85 and fuel well 19 can be arranged such that the
cold start fuel contribution provided by fuel well 19 can be
essentially eliminated. Under such circumstances, the cannister
assembly 27 is modified so that only rear section 27b is operative.
That is, forward section 27a is eliminated from the cold start
operation. Instead, the full-range fuel previously passing thereto
is instead conveyed directly to the fuel well 19. But the positions
of the nozzle 20 and fuel well 19 are arranged during the normal
starting period such that little, of any, full-range fuel flows
from the fuel well 19 via nozzle 20 into the carburetor 13.
As the engine turns over, the fuel pump 24 conveys full-range fuel
through inlet start valve 25a to the cannister assembly 27 of FIGS.
2 or 5. Within the cannister assembly 27, the full-range fuel
percolates simultaneously through the first and second elution
zones culminating in the elution of low molecular weight components
at fuel well 19 and at air intake assembly 12, respectively. High
molecular weight components of the full-range fuel remain absorbed.
A metered amount of the light components is conveyed through the
carburetor 13 into the intake manifold 11 and thence to the
combustion chambers of the engine. After selected rise in the
engine temperature, as measured by bimetal switch 26b of the
controller circuit 26 say positioned at the water jacket or exhaust
manifold of the engine, control relay 26a becomes deactivated,
resulting in the cold start inlet and exhaust valves 25a and 25b
returning to relaxed positions as shown in FIG. 9. The fuel system
thus switches over to full-range fuel, such fuel passing from fuel
pump 24 via conduit 87a to inlet valve 25a and thence from U-shaped
conduit 87b and exhaust valve 25b to the fuel well 19. As
full-range fuel is utilized, the elution zones of the forward
section of the cannister assembly followed by the rear section are
placed in fluid contact with the carburetor.
It should be pointed out that during the operation of the engine,
the evaporative control valve 25c of the valve and conduit network
25 remains an activated state as depicted in FIGS. 1, 5, and 9.
However, when the driver opens the ignition switch 26c of the
controller circuit 26, the evaporative control valve 25c is
likewise deactivated which places it in the position depicted in
FIG. 10 whereby the vapor adsorption zone of the forward section
27a of the cannister assembly 27 is in direct fluid contact with
the fuel well 19 and gasoline tank 23. In that way, as evaporative
emissions are formed within the fuel well 19 or the gasoline tank
23, they are conveyed via conduits 83 and 84 respectively through
inlet ports 81 and 82, exhaust port 80 and conduit 38 to the vapor
adsorption zone.
While certain preferred embodiments of the invention have been
specifically disclosed above, it should be understood that the
invention is not limited thereto as many variations will be readily
apparent to those skilled in the art and thus the invention is to
be given the broadest possible interpretation within the terms of
the following claims.
* * * * *