U.S. patent application number 12/252381 was filed with the patent office on 2009-04-30 for fuel system for improved fuel efficiency utilizing glycols in a spark ignition engine.
Invention is credited to Daniel Stedman Connor.
Application Number | 20090107031 12/252381 |
Document ID | / |
Family ID | 40374911 |
Filed Date | 2009-04-30 |
United States Patent
Application |
20090107031 |
Kind Code |
A1 |
Connor; Daniel Stedman |
April 30, 2009 |
Fuel System for Improved Fuel Efficiency Utilizing Glycols in a
Spark Ignition Engine
Abstract
A fuel system for improved fuel efficiency which can be
contained in a single fuel source, such as a fuel tank of a
vehicle, having a gasoline phase comprises gasoline or gasohol; and
an anti-knock phase comprising a glycol anti-knock subagent, water
and one or more of a second anti-knock subagent selected from the
group of methanol, ethanol and mixtures thereof; such that the
anti-knock agent phase is substantially immiscible with the
gasoline phase.
Inventors: |
Connor; Daniel Stedman;
(Cincinnati, OH) |
Correspondence
Address: |
THE PROCTER & GAMBLE COMPANY;Global Legal Department - IP
Sycamore Building - 4th Floor, 299 East Sixth Street
CINCINNATI
OH
45202
US
|
Family ID: |
40374911 |
Appl. No.: |
12/252381 |
Filed: |
October 16, 2008 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
61001177 |
Oct 31, 2007 |
|
|
|
Current U.S.
Class: |
44/302 |
Current CPC
Class: |
C10L 1/125 20130101;
Y02T 10/12 20130101; C10L 1/1824 20130101; Y02T 10/121 20130101;
C10L 1/18 20130101; C10L 1/1826 20130101; C10L 1/103 20130101; F02M
25/14 20130101; C10L 10/10 20130101 |
Class at
Publication: |
44/302 |
International
Class: |
C10L 1/32 20060101
C10L001/32 |
Claims
1. A fuel system comprising: (a) gasoline phase comprises gasoline
or gasohol; and (b) an anti-knock phase comprising an anti-knock
agent comprising a glycol anti-knock subagent, water and one or
more of a second anti-knock subagent selected from the group of
methanol, ethanol and mixtures thereof; wherein the anti-knock
agent phase is substantially immiscible with the gasoline
phase.
2. The system of claim 1 wherein the glycol anti-knock subagent is
selected such that the ratio of oxygen atoms present in the
molecule and carbon atoms present in the molecule is from 0.4 to
1.0.
3. The system of claim 1 wherein the glycol anti-knock subagent is
selected from the group consisting of glycerol, ethylene glycol,
1,2-propylene glycol, 1,3-propylene glycol, isobutylene glycol,
1,2-butanediol, 1,3-butanediol, 2,3-butanediol, 1,4-butanediol,
C.sub.5 diols and mixtures thereof.
4. The system of claim 1 wherein the glycol anti-knock subagent is
selected from glycerol, 1,2-propylene glycol, 1,3-propylene glycol
and mixtures thereof.
5. The system of claim 1 wherein the anti-knock subagent comprises
less than 40% by volume of glycol anti-knock agent by volume of the
anti-knock agent, preferably comprising from about 5% by volume to
about 40% by volume of glycol anti-knock agent by volume of the
anti-knock agent.
6. The system of claim 1 wherein the second anti-knock subagent is
selected as water comprising at least 10% by volume of the
anti-knock agent, preferably from about 10% by volume to about 40%
by volume of the anti-knock agent.
7. The system of claim 1 wherein the second anti-knock subagent is
selected as ethanol.
8. The system of claim 1 wherein the anti-knock agent comprises
glycerol, water and ethanol, preferably water comprising at least
10% by volume of the anti-knock agent, preferably water comprising
from about 10% by volume to about 40% by volume of the anti-knock
agent.
9. The system of claim 1 wherein the anti-knock agent comprises
1,2-propylene glycol, 1,3-propylene glycol and mixtures thereof,
water and ethanol, preferably water comprising at least 10% by
volume of the anti-knock agent, preferably water comprising from
about 10% by volume to about 40% by volume of the anti-knock
agent.
10. The system of claim 1 wherein the anti-knock agent comprises
glycerol, 1,2-propylene glycol, and mixtures thereof, water and
ethanol.
11. The system of claim 1 wherein the glycol anti-knock subagent is
selected from glycols of natural origin, preferably glycols derived
from hydrolysis of fats and oils, made by fermentation of
carbohydrates to give a naturally derived glycol or by partial
hydrogenation of glycols of natural origin.
12. The system of claim 1 wherein the glycol anti-knock subagent is
selected from glycol of petrochemical origin, preferably by the
oxidation and hydration of olefins to give a petrochemical
glycol.
13. The system of claim 1 wherein the anti-knock agent phase is
dispensed into the single fuel source independently of the gasoline
phase.
14. The system of claim 1 wherein the anti-knock agent phase and
the gasoline phase are dispensed into a single fuel source in a
vehicle at the same time.
15. The system of claim 1 wherein the anti-knock agent phase is
injected into an engine cylinder independent of the gasoline
phase.
16. The system of claim 1 wherein the anti-knock agent phase is
injected into an engine cylinder after injection of the gasoline
phase into an engine cylinder.
17. The system of claim 1 wherein the anti-knock agent is injected
into an engine cylinder at about 280 to about 330 degrees crank
angle.
Description
CROSS REFERENCE TO RELATED APPLICATION
[0001] The present application claims priority to provisional U.S.
application Ser. No. 61/001177, filed Oct. 31, 2007.
FIELD OF THE INVENTION
[0002] A fuel system for improved fuel efficiency which can be
contained in a single fuel source, such as a fuel tank of a
vehicle, having a gasoline phase comprises gasoline or gasohol; and
an anti-knock phase comprising an anti-knock agent comprising a
glycol anti-knock subagent, water and one or more of a second
anti-knock subagent selected from the group of methanol, ethanol
and mixtures thereof; such that the anti-knock agent phase is
substantially immiscible with the gasoline phase.
BACKGROUND OF THE INVENTION
[0003] This invention relates to spark ignition gasoline engines
utilizing an antiknock agent which is immiscible with gasoline to
improve engine efficiency while being stored in the same
containment area/volume or tank of a vehicle.
[0004] It is known that the efficiency of gasoline engines can be
increased by high compression ratio operation and particularly by
engine downsizing. The use of techniques to increase engine
efficiency, however, is limited by the onset of engine knock. Knock
is the undesired detonation of fuel and can severely damage an
engine. If knock can be prevented, then engine efficiency may be
increased by up to twenty-five percent.
[0005] Octane number represents the resistance of a fuel to
knocking but the use of higher octane gasoline only modestly
alleviates the tendency to knock. For example, the difference
between regular and premium gasoline (octane number of 95) is
typically six octane numbers. It is known to replace a portion of
gasoline with small amounts of ethanol added at the fuel
distributor blending rack. Ethanol has a blending octane number of
110 (see J. B. Heywood, "Internal Combustion Engine Fundamentals,"
McGraw Hill, 1988, p. 477) and is also attractive because it is a
renewable energy, biomass-derived fuel.
[0006] Using a fuel system to deliver mixed octane fuels which are
kept separated in two tanks or in one tank separated by a diaphragm
and then mixed before injection into an engine is discussed in US
2005/0252489 A1.
[0007] It is known that restricting the use of ethanol to the
relatively small fraction of time in an engine operating cycle,
preferably injecting the ethanol directing into an engine cyclinder
separately from gasoline when it is needed to prevent knock in a
higher load regime and by minimizing ethanol use only at these
times. See US 2006/0102145, US 2006/0102146.
[0008] However, the proposed use of two separate tanks in a vehicle
is a recognized challenge whether consumers will mind filling up
with two fuels in two different fuel tanks. Boston Globe, Apr. 22,
2007, Third Edition, O'Brien, Keith, "Fill 'er up. But with
what?--In the fevered search for the fuel of tomorrow, a team of
MIT scientists has a surprising solution that just might be the
most realistic one of all." Additional proposed solutions include
the use of onboard separation methods of ethanol from a gasoline
such as fractional distillation or membrane separation. See US
2006/0102136.
[0009] Gasoline and anhydrous ethanol are miscible in any ratio,
i.e., they can be mixed without occurrence of a separate liquid
phase. When a certain amount of water is present, however, a
separate liquid layer will occur. The occurrence of a separate
liquid phase in gasohol is perceived as harmful even though the
phase behavior of gasoline-ethanol-water mixtures is totally
different from gasoline-water mixtures. See WO06/137725.
[0010] There still exists a problem of how to deliver two
components to a gasoline engine in a consumer friendly manner that
requires little to no change in customary habits. The present
invention relates to a fuel having a gasoline phase and an
anti-knock phase wherein the two phases are immiscible when held in
a defined volume such as a fuel tank.
SUMMARY OF THE INVENTION
[0011] The present invention relates to a fuel system comprising
gasoline phase comprises gasoline or gasohol; and an anti-knock
phase comprising a glycol anti-knock subagent, water and one or
more of a second anti-knock subagent selected from the group of
methanol, ethanol and mixtures thereof; wherein the anti-knock
agent phase is substantially immiscible with the gasoline
phase.
BRIEF DESCRIPTION OF THE DRAWINGS
[0012] FIG. 1 is a schematic diagram of the fuel management systems
discussed herein.
[0013] FIG. 2 is a graph of an engine cylinder pressure as a
function of crank angle for a three bar manifold pressure.
[0014] FIG. 3 is a graph of charge temperature as a function of
crank angle for a three bar manifold pressure.
DETAILED DESCRIPTION OF THE INVENTION
[0015] The present invention relates to a fuel system for improved
fuel efficiency which can be contained in a single fuel source,
such as a fuel tank of a vehicle, having a gasoline phase comprises
gasoline or gasohol; and an anti-knock phase comprising an
anti-knock phase comprising a glycol anti-knock subagent, water and
one or more of a second anti-knock subagent selected from the group
of methanol, ethanol and mixtures thereof; such that the anti-knock
agent phase is substantially immiscible with the gasoline
phase.
[0016] With reference first to FIG. 1, a fuel management system
(10) includes a gasoline engine (20) having at least one combustion
chamber, such as an engine cylinder, a fuel processor system (30),
a knock sensor (40), a manifold (50) or port area, a combustion
chamber injector (130) and a single fuel source (60). The fuel
processor system (30) controls the direct injection of an antiknock
agent from a combustion chamber injector (130) that is fluidly
connected to a single fuel source (60). The single fuel source (60)
contains gasoline or gasohol (collectively or individually referred
to herein as gasoline). The fuel management system (10) also
affects the delivery of gasoline from the single fuel source (60)
into manifold (50) or a port area. The fuel management system (10)
also communicates with other components of the system (10) as
discussed further below.
[0017] The single fuel source (60) comprises at least two level
detection devices (90, 100) for the gasoline (gasoline phase) and
the anti-knock agent (anti-knock agent phase), the level detection
devices individually indicate the levels (empty, full, or some
fraction) of the gasoline and the anti-knock agent in the single
fuel source (60). The level detection devices (90, 100) are in
communication with the fuel processor system (30) and can
individually transmit information regarding the level of gasoline
and/or anti-knock agent. This information can be used for informing
the vehicle user and may be used to inform other devices such as a
gasoline pump at a gas station. In one embodiment, the anti-knock
agent phase is dispensed into the single fuel source independently
of the gasoline phase. In one embodiment, the anti-knock agent
phase and the gasoline phase are dispensed into the single fuel
source in a vehicle at the same time.
[0018] The single fuel source (60) further comprises at least two
feeds to the gasoline engine (20), the first feed for the gasoline
(gasoline feed [110]) and a second feed for the anti-knock agent
(anti-knock feed [120]). The gasoline feed (110) is located such
that gasoline in a gasoline layer is able to be fluidly conveyed
from the single fuel source (60) into the manifold (50), without
the anti-knock agent being fluidly conveyed by the gasoline feed
(110). The anti-knock feed (120) is located such that the
anti-knock agent in an anti-knock layer is able to be fluidly
conveyed from a single fuel source (60) to the combustion chamber
injector (130) without the gasoline being fluidly conveyed by the
anti-knock feed (120).
[0019] The amount of anti-knock agent injected is dictated either
by a predetermined correlation between octane number enhancement
and fraction of fuel that is provided by anti-knock agent or by a
control system that uses a signal from the knock sensor (40) as an
input to the fuel management system (10). In both situations, the
fuel management system (10) will deliver the amount of anti-knock
agent to a combustion chamber such as an engine cylinder to
preventing knock while minimizing the amount of anti-knock agent
needed. In one embodiment, the anti-knock agent phase is injected
into an engine cylinder independent of the gasoline phase. In one
embodiment, the anti-knock agent phase is injected into an engine
cylinder after injection of the gasoline phase into an engine
cylinder.
[0020] The anti-knock agent is directly injected from the
combustion chamber injector (130) into the gasoline engine (20) via
a combustion chamber such as an engine cylinder. Using a signal
from a knock sensor to determine when and how much anti-knock agent
must be used at various times in a drive cycle to prevent knock,
the fuel management system (10) can be employed to minimize the
amount of anti-knock agent that is consumed over the drive cycle.
If sufficient anti-knock agent is available in the market, the fuel
management system (10) can also be used to employ more anti-knock
agent than would be needed to prevent knock.
[0021] Direct injection substantially increases the benefits of
anti-knock agent addition and decreases the required amount of
anti-knock agent. Recent advances in fuel injector and electronic
control technology allows for tightly controlled amounts of fuel at
high pressures injected directly into an engine cylinder in very
short time frames rather than traditional fuel injection into the
manifold (50). A combustion chamber injector (130) is provided for
direct injection of the anti-knock agent into a combustion chamber,
such as an engine cylinder of the gasoline engine (20) and a fuel
processor system (30) controls injection of the anti-knock agent
into the cylinder to control knock. The injection of the antiknock
agent can be initiated by a signal from a knock sensor (40),
initiated when the engine torque is above a selected value or
fraction of the maximum torque where the value or fraction of the
maximum torque is a function of the engine speed or initiated upon
an increase in pressure on an accelerator pedal of a vehicle or a
rate of change in position of the accelerator pedal of the vehicle.
The combustion chamber injector (130) injects the anti-knock agent
after inlet valve/valves are closed in the combustion chamber, such
as an engine cylinder. In one embodiment the injector (20) injects
the anti-knock agent tangentially into the combustion chamber or
the engine cylinder, preferably at the upper portion of the
combustion chamber or upper portion of the engine cylinder.
[0022] In the case of anti-knock agent direct injection the charge
is directly cooled. It is assumed that the air/fuel mixture is
stoichiometric without exhaust gas recirculation (EGR), and that
gasoline makes up the rest of the fuel. In the embodiment of FIG. 1
gasoline is vaporized in the inlet manifold or port injection and
does not contribute much to cylinder charge cooling. The high heat
of vaporization of the anti-knock agent with its direct injection
late in the cycle gives the desired impact of knock suppression.
The temperature decrease of the air in the cylinder increases with
the amount of oxygen in the anti-knock agent (in terms of the O:C
ratio of the antiknock molecule(s)). It is also useful to compare
ratios of the heat of vaporization to the heat of combustion, a
measure of the potential effects when used as anti-knock agents.
This parameter gives a measure of the amount of evaporative cooling
for a given level of torque.
[0023] Thus when variable anti-knock agent is employed, the fuel
processor system (30) needs to adjust the amounts of air, gasoline
and anti-knock agent such that the air/fuel ratio is stochiometric.
The additional control is needed because, if the air/fuel ratio
determined by the fuel processor system (30) were not corrected
during the injection of anti-knock agent, the mixture would no
longer be stoichiometric. Preferably the fuel processor system (30)
can choose the ratio of the anti-knock agent and gasoline.
[0024] The octane enhancement effect as discussed herein refers
primarily to the decrease in the engine octane requirement rather
than an increase in octane of the fuel itself. Relatively precise
determinations of the actual amount of octane enhancement from
given amounts of direct anti-knock agent injection can be obtained
from laboratory and vehicle tests in addition to detailed
calculations. These correlations can be used by the fuel processor
system (30). Direct injection of gasoline results in approximately
a five octane number decrease in the octane number required by the
engine, as discussed by J. Stokes, T. H. Lake and R. J. Osborne, "A
Gasoline Engine Concept for Improved Fuel Economy--The Lean Boost
System," SAE paper 2000-01-2902. Thus the contribution is about
five octane numbers per 30K drop in charge temperature. Without
being bound by theory, it is believed that the anti-knock agent can
decrease the charge temperature, which decreases the octane number
required by the engine due to the drop in temperature.
[0025] The optimum timing of the injection of anti-knock agent for
best mixing and a near homogeneous charge is soon after the inlet
valve closes, provided that the charge is sufficiently warm for
anti-knock agent vaporization. If, on the other hand, a non-uniform
mixture is desired in order to minimize anti-knock agent
requirements and improve ignition stability, then the injection
should occur later than in the case where the best achievable
mixing is the goal.
[0026] It is important to inject the anti-knock agent relatively
quickly, and at velocities which minimize any cylinder wall
wetting, which as described below could result in the removal of
the lubrication oils from the cylinder liner.
[0027] FIG. 2. shows the pressure (a) and the temperature (b) of
the cylinder charge as a function of crank angle, for a manifold
pressure of 3 bar and a value of .beta.=0.4. For exemplification
only, two values of ethanol fractions are chosen, one that results
in autoignition, and produces engine knock (0.82 ethanol fraction
by fuel energy), and the other one without autoignition, i.e., no
knock (0.83 ethanol fraction). Autoignition is a threshold
phenomenon, and in this case occurs between ethanol fractions of
0.82 and 0.83. The occurrence of knock at a given value of torque
depends upon engine speed. For an ethanol energy fraction of 0.83,
the pressure and temperature rise at 360.degree. (top dead center)
is due largely to the compression of the air/fuel mixture by the
piston. When the ethanol energy fraction is reduced to 0.82, the
temperature and pressure spikes as a result of autoignition.
[0028] Although the autoignition in FIG. 2 occurs substantially
after 360 crank angle degrees, the autoignition timing is very
sensitive to the autoignition temperature (5 crank angle degrees
change in autoignition timing for a change in the initial
temperature of 1 K, or a change in the ethanol energy fraction of
1%). In one embodiment, the anti-knock agent is injected into an
engine cylinder at about 280 to about 330 degrees crank angle.
[0029] Such curves may be compiled via a computer model combining
physical models of the anti-knock agent vaporization effects and
the effects of piston motion of the anti-knock agent/gasoline/air
mixtures with a state of the art calculational code for combustion
kinetics. An example for the calculational code for combustion
kinetics may be the engine module in the CHEMKIN 4.0 code [R. J.
Kee, F. M. Rupley, J. A. Miller, M. E. Coltrin, J. F. Grcar, E.
Meeks, H. K. Moffat, A. E. Lutz, G. Dixon-Lewis, M. D. Smooke, J.
Warnatz, G. H. Evans, R. S. Larson, R. E. Mitchell, L. R. Petzold,
W. C. Reynolds, M. Caracotsios, W. E. Stewart, P. Glarborg, C.
Wang, O. Adigun, W. G. Houf, C. P. Chou, S. F. Miller, P. Ho, and
D. J. Young, CHEMKIN Release 4.0, Reaction Design, Inc., San Diego,
Calif. (2004)]. This model uses chemical rates information based
upon the Primary Reference gasoline Fuel (PRF) mechanism from
Curran et al. [Curran, H. J., Gaffuri, P., Pitz, W. J., and
Westbrook, C. K. "A Comprehensive Modeling Study of iso-Octane
Oxidation," Combustion and Flame 129:253-280 (2002) to represent
onset of autoignition.
[0030] Because of the large heat of vaporization of the anti-knock
agent, there could be enough charge cooling with early injection so
that the rate of vaporization of anti-knock agent is substantially
decreased. By injecting the anti-knock agent into the hot end gases
in the cylinder, which is the case with injection after the inlet
valve has closed, the temperature at the end of full vaporization
of the anti-knock agent is substantially increased with respect to
early injection, increasing the evaporation rate and minimizing
wall wetting.
[0031] Injection after the valve has closed may require that a
modest fraction of the gasoline (e.g. 25%) be port injected in
order to achieve the desired combustion stability. A tumble-like or
swirl motion can be introduced to achieve the desired combustion
stability. Tangential injection is believed to achieve a swirl
motion of the anti-knock agent within the cylinder.
[0032] It is preferred that anti-knock agent be added to those
regions that make up the end-gas and are prone to auto-ignition.
These regions are near the walls of the cylinder. Since the end-gas
contains on the order of 25% of the fuel, substantial decrements in
the required amounts of anti-knock agent can be achieved by
stratifying the end gases and the anti-knock agent. A swirl motion
(from tangential injection) is not affected much by the compression
stroke and thus survives better than tumble-like motion that drives
turbulence towards top-dead-center and then dissipates.
[0033] The instantaneous anti-knock agent injection requirement and
total anti-knock agent consumption over a drive cycle can be
estimated from information about the drive cycle and the increase
in torque (and thus increase in compression ratio, engine power
density, and capability for downsizing) that is desired. A plot of
the amount of operating time spent at various values of torque and
engine speed in FTP and US06 drive cycles can be used. It is
necessary to enhance the octane number at each point in the drive
cycle where the torque is greater than permitted for knock free
operation with gasoline alone. The amount of octane enhancement
that is required is determined by the torque level.
[0034] Gasoline/Gasohol Phase
[0035] As used herein "gasoline" refers to a mixture of
hydrocarbons boiling in the approximate range of 40.degree. C. to
210.degree. C. and that can be used as fuel for internal combustion
engines (e.g., motor gasoline as defined by ASTM Specifications
D-439-89). Gasoline may contain substances of various natures,
which are added in relatively small amounts, to serve a particular
purpose, such as to increase the octane number, biocides,
antifungals, anticorrosion agents or other benefit agents.
[0036] As used herein "gasohol" refers to a mixture of gasoline and
an alcohol, typically ethanol (see ASTM D-4814-91). The ethanol
content is from 1 to 85 volume %. Typically the ethanol content is
from 5 to 10 volume %. Ethanol is typically fermented from grain
(corn, wheat, barley, oats, sugar beets, cane sugar etc.) in a
fermentation process. In the future, ethanol may be produced from
biomass such as switch grass, waste wood, fibers and other
carbohydrates. The ethanol is blended into gasoline in various
quantities. Octane of gasoline or gasohol may be measured according
to ASTM Method D2700.
[0037] Gasoline is utilized in the discussion herein to encompass
both gasoline and gasohol as defined herein for ease in
communication and is not intended to limit the discussion to solely
gasoline.
[0038] As used herein, the term "immiscible" regarding the gasoline
phase and the anti-knock agent phase refers to the amount of one
phase which may be present in the other phase. As used herein, the
term "substantially immiscible" means the gasoline phase comprises
less than 0.1 vol % of the anti-knock agent, preferably less than
0.05 vol % of the anti-knock agent in the gasoline phase.
Similarly, the anti-knock agent phase comprises less than 10 vol %
of gasoline, preferably less than 5 vol % of the gasoline phase in
the anti-knock agent.
[0039] As used herein, the term "fuel" means any combustible
materials including the gasoline, gasohol, anti-knock agents such
as the glycol anti-knock agent and second anti-knock agent.
[0040] The levels discussed herein may be for the anti-knock agent
or the gasoline dispensed into the single fuel source (fuel tank)
or it may be levels for the anti-knock agent or the gasoline before
injected into the engine. As can be seen in the examples of the
present application, as the anti-knock agent is dispensed into the
fuel tank, it mixes with the gasoline before separating into a
distinct phase. However, gasoline may be somewhat soluble in the
anti-knock layer and ethanol may be somewhat soluble in gasoline,
thereby changing the volume percentages stated herein.
[0041] Anti-Knock Phase
[0042] The present invention includes an anti-knock phase
comprising an anti-knock phase comprising a glycol anti-knock
subagent, water and one or more of a second anti-knock subagent
selected from the group of methanol, ethanol and mixtures thereof;
wherein the anti-knock agent phase is substantially immiscible with
the gasoline phase. The anti-knock phase should comprise enough
water so two distinct phases separate rapidly in the vehicle tank
after the gasoline and the anti-knock phase, which mixes during
dispensing through a gasoline pump nozzle.
[0043] Anti-Knock Agent
[0044] The present invention includes an anti-knock phase
comprising an anti-knock agent comprising a glycol anti-knock
subagent, water and one or more of a second anti-knock subagent
selected from the group of methanol, ethanol and mixtures thereof;
wherein the anti-knock agent phase is substantially immiscible with
the gasoline phase. It is preferred that the anti-knock agent have
a heat of vaporization that is at least twice that of gasoline or a
heat of vaporization per unit of combustion energy that is at least
three times that of gasoline.
[0045] Glycol Anti-Knock Subagent
[0046] The large heat of vaporization of the anti-knock agent,
there could be enough charge cooling with early injection so that
the rate of vaporization of anti-knock agent is substantially
decreased. The glycol anti-knock subagent is selected such that the
ratio of oxygen atoms present in the molecule and carbon atoms
present in the molecule is from 0.3 to 1.0, preferably 0.4 to 1.0.
The high heat of vaporization of the anti-knock agent with its
direct injection late in the cycle gives the desired impact of
knock suppression. The temperature decrease of the air in the
cylinder increases with the amount of oxygen in the anti-knock
agent (in terms of the O:C ratio of the anti-knock molecule(s)). It
is also useful to compare ratios of the heat of vaporization to the
heat of combustion, a measure of the potential effects when used as
anti-knock agents. This parameter gives a measure of the amount of
evaporative cooling for a given level of torque.
[0047] The glycol anti-knock subagent may be selected from glycols
of natural origin, preferably glycols derived from hydrolysis of
fats and oils, made by fermentation of carbohydrates to give a
naturally derived glycol or by partial hydrogenation of glycols of
natural origin. Alternatively, the glycol anti-knock subagent may
be selected from glycol of petrochemical origin, preferably by the
oxidation and hydration of olefins to give a petrochemical
glycol.
[0048] The glycol anti-knock subagent is selected from the group
consisting of glycerol (O:C ratio of 1:1), ethylene glycol (O:C
ratio of 1:1 or 1), 1,2-propylene glycol (O:C ratio of 2:3 or
0.67), 1,3-propylene glycol (O:C ratio of 2:3 or 0.67), isobutylene
glycol, 1,2-butanediol (O:C ratio of 1:2 or 0.5), 1,3-butanediol
(O:C ratio of 1:2 or 0.5), 2,3-butanediol (O:C ratio of 1:2 or
0.5), 1,4-butanediol (O:C ratio of 1:2 or 0.5), C.sub.5 diols (O:C
ratio of 2:5 or 0.4) such as 1,2 pentanediol, 1,5-pentanediol,
1,4-pentanediol, 2,3-pentanediol, amylene diols (O:C ratio of 2:5
or 0.4), C.sub.6 diols (O:C ratio of 2:6 or 0.3) such as
1,6-hexanediol, 2,3-hexanediol and mixtures thereof. Preferably the
glycol anti-knock subagent is selected from glycerol, 1,2-propylene
glycol, 1,3-propylene glycol and mixtures thereof.
[0049] The anti-knock agent comprises less than 40% by volume of
glycol anti-knock agent by weight of the anti-knock agent,
preferably comprising from about 5% by volume to about 40% by
volume of glycol anti-knock agent by weight of the anti-knock agent
as dispensed into the single fuel source (fuel tank).
[0050] Water should be present in sufficient amounts in order to
effectively result in the anti-knock agent being in a distinct
layer. Water comprises at least 10% by volume of the anti-knock
agent as dispensed into the single fuel source (fuel tank),
preferably from about 10% by volume to about 40% by volume of the
anti-knock agent as dispensed into the single fuel source (fuel
tank).
[0051] Second Anti-Knock Subagent
[0052] The second anti-knock subagent selected from the group of
methanol, ethanol, water and mixtures thereof. In one embodiment,
the second anti-knock subagent is selected as ethanol.
[0053] Additional Additives
[0054] The fuel system may also comprise additional additives.
These additives may include, but are not limited to anti-knock
agents other than those discussed above, corrosion inhibitors,
surfactants, detergents, metal deactivators, antioxidants, fuel
stabilizers, and anti-freeze components. Examples of anti-knock
agents other than those discussed above include lead alkyls such as
tetraethyl lead and tetramethyl lead; manganese compounds such as
methylcyclopentadienyl manganese tricarbonyl; and iron compounds
such as ferrocene. An example of a corrosion inhibitor is SPEC-AID
8Q103 available from GE Betz, Inc.
EXAMPLES
[0055] All parts by volume--10 mL gasohol (Hex/Tol/EtOH); 5 mL
EtOH/PG/H.sub.2O
[0056] EtOH being ethanol; PG being propylene glycol; H.sub.2O
being water; Hex being hexane; Tol being toluene. Add the mixture
to a stoppered graduated cylinder and shake vigorously for 30
seconds and allow the layers to separate.
TABLE-US-00001 Sec Sec Bottom to to x y Layer clear clear EtOH PG
H.sub.2O x/y (EtOH:H.sub.20) (PG:H.sub.2O) Hex Tol EtOH mL
23.degree. C. 0.degree. C. Visual 52.5 17.5 30 75/25 70:30 70:30 80
10 10 5.5 12 24 Clear (top fast bottom slow) 60 20 20 75/25 80:20
80:20 80 10 10 5.5 11 22 Clear (top fast bottom slow 68.75 21.25 15
75/25 85:15 85:15 80 10 10 6.8 11 14 clear 67.5 22.5 10 75/25 90:10
90 10 80 10 10 6.8 19 14 clear 71.25 23.75 5 75/25 95:5 95:5 80 10
10 6.8 20 28 clear 75 25 0 75/25 100:0 100:0 80 10 10 miscible 40
40 20 50/50 80:20 80:20 80 10 10 6.0 23 26 Top clear Bottom
hazy
[0057] All measurements by volume
[0058] 10 mL gasohol (Hex/Tol/EtOH); 5 mL EtOH/gly/H.sub.2O
[0059] EtOH being ethanol; Gly being glycerol; H.sub.2O being
water; Hex being hexane; Tol being toluene. Add the mixture to a
stoppered graduated cylinder and shake vigorously for 30 seconds
and allow the layers to separate.
TABLE-US-00002 Sec Sec Bottom to to X Y layer sep sep EtOH Gly
H.sub.2O x/y (EtOH:H.sub.2O) (gly:H.sub.2O) Hex Tol EtOH mL
23.degree. C. 0.degree. C. visual 0 80 20 0 100 -- 80:20 80 10 10
6.0 24 -- Not clear water on walls 20 60 20 25/75 80:20 80:20 80 10
10 5.8 25 -- Not clear water on walls 22 68 10 25/75 90:10 90:10 80
10 10 5.8 35 -- Not clear 35 35 30 50/50 70:30 70:30 80 10 10 5.6
14 14 Clear T6 B14 40 40 20 50/50 80:20 80:20 80 10 10 5.9 20 --
Not clear 45 45 10 50/50 90:10 90:10 80 10 10 5.6 35 -- Not clear
60 20 20 75/25 80:20 80:20 80 10 10 5.8 10 10 clear 63.75 21.25 15
75/25 85:15 85:15 80 10 10 5.7 20 -- clear 67.5 22.5 10 75/25 90:10
90:10 80 10 10 5.9 33 -- clear 72 13 15 85/15 85:15 85:15 80 10 10
5.8 30 -- clear 72 8 20 90/10 80:20 80:20 80 10 10 6.0 12 12 clear
81 9 10 90/10 90:10 90:10 80 10 10 6.6 28 -- clear 76 4 20 95/5
80:20 80:20 80 10 10 5.9 10 13 hazy 66.5 3.5 30 95/5 70:30 70:30 80
10 10 5.9 13 T10 Sl B25 hazy 70 0 30 100/0 70:30 -- 80 10 10 5.6 8
17 clear 80 0 20 100/0 80:20 -- 80 10 10 6.4 10 -- Not clear 90 0
10 100/0 90:10 -- 80 10 10 12.0 240 -- Light haze 80 0 20 100/0
80:20 -- 90 10 -- 5.2 6 -- Not clear 90 0 10 100/0 90:10 -- 90 10
-- 5.9 27 -- clear
[0060] The dimensions and values disclosed herein are not to be
understood as being strictly limited to the exact numerical values
recited. Instead, unless otherwise specified, each such dimension
is intended to mean both the recited value and a functionally
equivalent range surrounding that value. For example, a dimension
disclosed as "40 mm" is intended to mean "about 40 mm".
[0061] All documents cited in the Detailed Description of the
Invention are, in relevant part, incorporated herein by reference;
the citation of any document is not to be construed as an admission
that it is prior art with respect to the present invention. To the
extent that any meaning or definition of a term in this document
conflicts with any meaning or definition of the same term in a
document incorporated by reference, the meaning or definition
assigned to that term in this document shall govern.
[0062] While particular embodiments of the present invention have
been illustrated and described, it would be obvious to those
skilled in the art that various other changes and modifications can
be made without departing from the spirit and scope of the
invention. It is therefore intended to cover in the appended claims
all such changes and modifications that are within the scope of
this invention.
* * * * *