U.S. patent application number 16/091572 was filed with the patent office on 2019-04-25 for oil-replacement additive for reducing emissions from two-stroke engines.
The applicant listed for this patent is Triboron International AB. Invention is credited to Kristina NILSSON, Magnus UNDEN.
Application Number | 20190119589 16/091572 |
Document ID | / |
Family ID | 60001334 |
Filed Date | 2019-04-25 |
United States Patent
Application |
20190119589 |
Kind Code |
A1 |
UNDEN; Magnus ; et
al. |
April 25, 2019 |
OIL-REPLACEMENT ADDITIVE FOR REDUCING EMISSIONS FROM TWO-STROKE
ENGINES
Abstract
An oil-replacement additive for two-stroke engine fuel capable
of reducing fuel consumption, enhancing combustion and reducing
emissions comprises boron and a carrier, wherein the boron
concentration in said additive is in the interval of 100 to 600
ppm, the carrier comprises an alcohol, the amount of oil in the
additive is less than 10% (w/w), and the balance is a fuel. Most
preferably said additive is substantially oil-free. A two-stroke
fuel comprising said additive, and a significantly reduced amount
of oil, or substantially no oil, said fuel having a boron
concentration in the interval of about 1 to 12 ppm.
Inventors: |
UNDEN; Magnus; (Lidingo,
SE) ; NILSSON; Kristina; (Lidingo, SE) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Triboron International AB |
Saltsjo-boo |
|
SE |
|
|
Family ID: |
60001334 |
Appl. No.: |
16/091572 |
Filed: |
April 7, 2017 |
PCT Filed: |
April 7, 2017 |
PCT NO: |
PCT/SE2017/050345 |
371 Date: |
October 5, 2018 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
C10L 1/1291 20130101;
C10L 10/02 20130101; C10L 1/1824 20130101; C10L 10/08 20130101;
C10L 2230/22 20130101; C10L 2270/08 20130101; C10L 2270/023
20130101; C10L 1/12 20130101; C10L 1/1616 20130101; C10L 1/10
20130101 |
International
Class: |
C10L 1/12 20060101
C10L001/12; C10L 10/08 20060101 C10L010/08; C10L 10/02 20060101
C10L010/02 |
Foreign Application Data
Date |
Code |
Application Number |
Apr 8, 2016 |
SE |
1650481-3 |
Claims
1. An oil-replacement additive for two-stroke engine fuel, said
additive comprising boron and a carrier, wherein the boron
concentration in said additive is in the interval of 1 to 600 ppm,
the carrier comprises an alcohol, the amount of oil in the additive
is less than 10% (w/w), and the balance is a fuel.
2. The additive according to claim 1, wherein the amount of oil in
the additive is less than 8% (w/w).
3. The additive according to claim 1, wherein the amount of oil in
the additive is less than 1% (w/w).
4. The additive according to claim 1, wherein said alcohol is
chosen from methanol, ethanol, propanol, and butanol, and said
balance of fuel is a fuel having a flash point similar to that of
the two-stroke fuel to which the additive is intended to be
added.
5. The additive according to claim 1, wherein the concentration of
boron is in the interval of 10 to 600 ppm.
6. The additive according to claim 1, wherein the concentration of
boron is in the interval of 100 to 300 ppm.
7. The additive according to claim 1, wherein the boron is added in
the form of a stable boron solution prepared by dissolving a boron
compound in an alcohol, followed by vigorous mixing and exclusion
of particles larger than 100 nm.
8. A two-stroke engine fuel comprising an additive according to
claim 1, wherein the boron concentration in the fuel is in the
interval of 1 to 12 ppm.
9. The two-stroke engine fuel according to claim 8, wherein the
boron concentration is in the interval of 1 to 6 ppm.
10. The two-stroke engine fuel according to claim 8, wherein the
boron concentration is about 2 to 3 ppm.
11. The two-stroke engine fuel according to claim 8, wherein the
fuel contains less than 1% oil (w/w).
12. A method for reducing the emissions from a two-stroke engine,
wherein an additive comprising boron dissolved in an alcohol, less
than 10% oil (w/w), the balance being a fuel and the concentration
of boron in said additive is the interval of 1 to 600 ppm, is added
to the fuel.
13. The method according to claim 12, wherein said additive is
mixed into the fuel at a proportion of about 1 part additive to 100
parts fuel.
14. The method according to claim 12, wherein said additive is
injected into the cylinder together with fuel at a proportion or
about 1 parts additive to 50 parts fuel.
15. The method according to claim 12, wherein the additive is added
in an amount resulting in reduced emissions of total hydrocarbons,
CO and CO.sub.2 with maintained lubrication of the engine.
16. The additive according to claim 1, wherein the amount of oil in
the additive is less than 6%(w/w).
17. The additive according to claim 1, wherein the amount of oil in
the additive is less than 2%(w/w).
18. The additive according to claim 1, wherein the additive is
substantially oil-free.
19. The additive according to claim 1, wherein the concentration of
boron is in the interval of 100 to 600 ppm.
20. The method of claim 12, wherein said additive is the interval
of 100 to 600 ppm.
Description
TECHNICAL FIELD
[0001] The present disclosure relates generally to fuel additives
for improving the function and reducing the emissions from
two-stroke engines as well as fuel mixtures containing such
additives. The disclosure relates in particular to oil-replacement
additives.
BACKGROUND
[0002] A two-stroke engine is a type of internal combustion engine
which completes a power cycle with only two strokes (up and down
movements) of the piston during one crankshaft revolution. In
comparison, a "four-stroke engine", requires four strokes of the
piston to complete a power cycle. In a two-stroke engine, the end
of the combustion stroke and the beginning of the compression
stroke happen simultaneously, with the intake and exhaust functions
occurring at the same time.
[0003] Two-stroke engines have been in commercial use for over a
century, and remain very popular still today as they usually have a
high power-to-weight ratio, a greatly reduced number of moving
parts, can be more compact and therefore also significantly lighter
than four-stroke engines.
[0004] Spark ignition versions of two-stroke engines, i.e.
two-stroke engines using gasoline or similar volatile fuel, are
particularly useful in lightweight applications such as
motorcycles, three-wheelers, snowmobiles, outboard motors, and the
like, and preferably in handheld high-power applications such as
chain saws, trimmers etc. In these and similar applications, the
two-stroke engine has offered an affordable and flexible source of
power. In developing countries, two-stroke engines have become
extremely popular in small vehicles such as motorcycles, scooters,
three-wheelers, tuk-tuks and the like, providing affordable and
flexible means of transport.
[0005] In four-stroke engines, lubrication is achieved by oil held
in an oil sump. The oil is distributed through the engine by splash
lubrication or a pressurized lubrication system, including an oil
pump. Unlike a four-stroke engine, which is a more advanced
construction, two-stroke engines use a total-loss lubrication
system where fuel and oil are combined to provide both energy and
lubrication. In an oil-injected two-stroke engine, the oil is
injected directly into the engine, where it mixes with the fuel.
Many two-stroke engines however require a pre-mixed fuel-oil
mixture.
[0006] Crankcase-compression two-stroke engines, such as the common
small gasoline-powered two-stroke engines, create more exhaust
emissions than four-stroke engines because lubricating oil is mixed
with the fuel, and burned in the engine. The tell-tale blue smoke
is typical for two-stroke engines. The lack of strict emission
regulations in many parts of the world and the high number of
motorized light vehicles results in high emissions. In many cities
two-stroke engines are among the main sources of urban air
pollution.
[0007] The main pollutants in exhaust fumes from two-stroke
engines, of course depending on several factors, such as the fuel
used, are particulate matter (PM), total hydrocarbons (THC),
volatile organic compounds (VOCs), and nitrogen oxides (NOx).
Carbon dioxide (CO.sub.2) and carbon monoxide (CO) formed in the
combustion of organic fuels are also noteworthy emissions, as they
contribute to the greenhouse effect and climate change.
[0008] There are many health and environmental issues related to
air pollution from combustion engines. High levels of air pollution
are linked to respiratory problems, for example allergies, asthma,
and acute respiratory infections. Emissions of particulate matter
are linked to an increased risk for cardiovascular diseases.
Needless to say, CO.sub.2 contributes to the greenhouse effect and
climate change.
[0009] In U.S. Pat. Ser. No. 6,783,561, Ali Erdemir presents a
method for providing enhanced lubricity in fuels and lubricants
wherein a boron compound is added to said fuel or lubricant.
Erdemir is focused on reducing or eliminating sulfur in the fuel,
and has investigated the anti-wear properties of low-sulfur fuel
with different additions of boron. Erdemir suggests boron
concentrations from about 30 ppm to about 3000 ppm, about 200 to
about 2000 ppm, alternatively from about 50 to about 1000 ppm, or
from about 100 ppm to about 500 ppm.
[0010] An international patent application, WO 2005/083042,
presents an additive for two-stroke engines where the amount of oil
is reduced and a lubricating effect is achieved by an addition of
boron. It is suggested that 10-90% of the oil is replaced by fuel
or a hydrocarbon carrier, for example an alcohol. However,
according to a preferred embodiment, only 10-60% of the oil is
replaced, and the boron content of the additive is in the range
1500-2500 ppm. The application contains no examples.
[0011] Problems with the stability of boron solutions i.e. a
tendency of aggregation and sedimentation, has however hampered the
large scale use of boron containing additives.
[0012] Later, Tommy Lindblom and Magnus Unden developed a method
for producing stable boric solutions, disclosed in international
patent application WO 2010/134872 and patented for example in U.S.
Pat. No. 9,222,045. The method addresses the difficulties in
producing a stable boric solution, i.e. avoiding aggregation and
precipitation during storage. The method results in a boron
solution with desired particle size, and which is stable over time.
According to their findings, the finished fuel, after adding the
additive produced by their method, should reach a boron
concentration within the range 10-10 000 ppm, preferably within the
range 20-30 ppm. A higher concentration, up to 10 000 ppm pertains
primarily to use in more solid lubricants.
[0013] The Safety Data Sheet concerning an early product, the
"Triboron Fuelenhancer", issued 25, Feb. 2008 and revised 1, Feb.
2012 concerns an additive for regular 4-stroke fuels. According to
the Safety Data Sheet, the additive contained ethanol, butanone,
isobutyl methyl ketone and ethyl acetate in addition to boric
acid.
SUMMARY
[0014] The present inventors have surprisingly found that
two-stroke engines can be operated with a significantly reduced
amount of oil, and in a preferred embodiment, in the total absence
of oil.
[0015] A first aspect of the invention is an oil-replacement
additive for two-stroke engine fuel, said additive comprising boron
and a carrier, wherein the boron concentration in said additive is
in the interval of 1 to 600 ppm, the carrier comprises an alcohol,
the amount of oil in the additive is less than 10% per weight, and
the balance is a fuel.
[0016] According to a preferred embodiment of said first aspect,
the amount of oil in the additive is less than 8%, preferably less
than 6%, more preferably less than 4%, and most preferably less
than 2% per weight.
[0017] More preferably said additive the amount of oil in the
additive is less than 1% per weight, and most preferably the
additive is substantially oil-free.
[0018] According to another embodiment, freely combinable with the
above aspects, said alcohol is chosen from methanol, ethanol,
propanol, and butanol, and said balance of fuel is a fuel having a
flash point similar to that of the two-stroke fuel to which the
additive is intended to be added.
[0019] According to a preferred embodiment, again freely combinable
with the above aspects, the concentration of boron is in the
interval of about 10 to about 600 ppm, preferably about 100 to
about 600 ppm. More preferably, the concentration of boron is in
the interval of about 100 to about 300 ppm.
[0020] According to another embodiment, freely combinable with the
above aspects, the boron is added in the form of a stable boron
solution prepared by dissolving a boron compound in an alcohol,
followed by vigorous mixing and exclusion of particles larger than
100 nm.
[0021] A second aspect is a novel two-stroke engine fuel comprising
an additive according to the above aspect and embodiments thereof,
wherein the boron concentration in the fuel is in the interval of 1
to 12 ppm. Preferably the boron concentration is in the interval of
1 to 6 ppm., most preferably about 2-3 ppm.
[0022] According to an embodiment of the second aspect, the fuel
contains less than 1% oil (w/w).
[0023] A third aspect relates to a method for reducing the
emissions from a two-stroke engine, wherein an additive comprising
boron dissolved in an alcohol, less than 10% oil (w/w), the balance
being a fuel and the concentration of boron in said additive is the
interval of 1 to 600 ppm, preferably in the interval of 10 to 600
ppm, most preferably about 100 to 300 ppm is added to the fuel.
[0024] According to an embodiment of said third aspect, said
additive is mixed into the fuel at a proportion of about 1 part
additive to 100 parts fuel.
[0025] According to another embodiment, said additive is injected
into the cylinder together with fuel at a proportion or about 1
part additive to 50 parts fuel.
[0026] Importantly, the invention allows the enhancement of
combustion in two-stroke engines, a significant reduction of the
emissions of total hydrocarbons (THC), CO and CO.sub.2 with
maintained or even improved lubrication of the two-stroke
engine.
DESCRIPTION OF EMBODIMENTS
[0027] Before the present invention is described, it is to be
understood that the terminology employed herein is used for the
purpose of describing particular embodiments only and is not
intended to be limiting, since the scope of the present invention
will be limited only by the appended claims and equivalents
thereof.
[0028] It must be noted that, as used in this specification and the
appended claims, the singular forms "a," "an," and "the" include
plural referents unless the context clearly dictates otherwise.
[0029] Where the concentration of boron is indicated in ppm, this
refers to the concentration of elemental boron in mg/kg
corresponding to ppm.
[0030] The term "oil" is used to indicate any oil, natural or
synthetic, currently used in two-stroke engines. Two-stroke oils
are sometimes referred to as two-cycle oils, 2-cycle oils, 2T oil
or "petroil". A characteristic requirement is that two-stroke oils
must have a lower ash content compared to regular lubricating oils,
as the two-stroke oil is burned along with the fuel. The base oil
is either petroleum, castor oil, semi-synthetic or synthetic oil or
various mixtures thereof. Currently, synthetic oils are more
frequently used, and different types of two-stroke oils have been
developed for specialized uses and engine types. The fuel to oil
mixing ratio ranges from 16:1 to as low as 100:1. The emission
problems are of course most accentuated at high mixing ratios, but
they remain also at lower ratios. In modern two-stroke engines, the
mixing ratio is generally low, 1-2%.
[0031] Lubricating oils are traditionally added to two-stroke fuel
either by mixing in the fuel when filling up the tank, by using
pre-mixed fuel, or by direct injection from a separate oil tank.
For many hand-held two-stroke engine powered tools, and in
particular for older or simpler engines, mixing the lubricating
additive into the fuel when refueling appears to be the most usual
method. In more advanced two-stroke engines, a separate oil tank is
provided, and the lubricating additive is automatically injected
when the engine is in operation. The additive disclosed herein is
applicable to all of these methods. It is conceived that the
oil-replacing additive is mixed into the bulk of fuel at a ratio of
approximately 1 part additive to 100 parts fuel (approximately 1 or
continuously added or injected, at a ratio of approximately 1 part
additive to 50 parts fuel (approximately 2%).
[0032] The general understanding until now has been that an
addition of a low concentration of boron is effective to reduce
friction and wear in four-stroke engines. This has been
successfully tested in field tests using passenger cars, i.e.
advanced four-stroke engines. A significant, or complete
elimination of oil in two-stroke engine fuel has however--to the
best knowledge of the present inventors--not been disclosed.
[0033] The present inventors have investigated how the
concentration of boron influences the emissions, the rate of
combustion, and fuel consumption in two-stroke engines.
[0034] In their experimental work using different two-stroke
engines, the inventors surprisingly found that the amount of oil
could be significantly reduced, and even substantially eliminated,
with maintained lubrication and with improved combustion, reduced
fuel consumption and reduced emissions. More surprisingly still,
this effect was achieved at significantly lower boron
concentrations than previously believed to be possible.
[0035] A first aspect of the invention is an oil-replacement
additive for two-stroke engine fuel, said additive comprising boron
and a carrier, wherein the boron concentration in said additive is
in the interval of 1 to 600 ppm, the carrier comprises an alcohol,
the amount of oil in the additive is less than 10% (w/w), and the
balance is a fuel.
[0036] Different sources of boron can be used. It is for example
possible to use a boron compound such as a crystalline boric acid,
boron oxide, boron trioxide etc. It is however preferable to use an
oxygen-bearing boron compound such as boric acid (H.sub.3BO.sub.3)
of pharmaceutical quality, i.e. with a purity of preferably at
least 99% and a molecular weight of 61.8 g/mol. An alternative is
to use boron oxide (B.sub.2O.sub.3), with a molecular weight of
69.6 g/mol, also known as anhydrous boric acid, also of
pharmaceutical quality. A stable boric solution where no particles
are larger than 100 nm is then prepared for example according to
the methods set out in WO2010134872, incorporated herein by
reference.
[0037] According to a preferred embodiment of said first aspect,
the amount of oil in the additive is less than 8%, preferably less
than 6%, more preferably less than 4%, and most preferably less
than 2% per weight.
[0038] More preferably said additive the amount of oil in the
additive is less than 1% per weight, and most preferably the
additive is substantially oil-free.
[0039] According to another embodiment, freely combinable with the
above aspects, said alcohol is chosen from methanol, ethanol,
propanol and butanol, and said balance of fuel is a fuel having a
flash point similar to that of the two-stroke fuel to which the
additive is intended to be added. Preferably said fuel is the same
as the fuel to which the additive is intended to be added. In
standard two-stroke applications, this is frequently standard 95
octane unleaded gasoline.
[0040] The flash point of a fuel is the lowest temperature where
enough fuel can evaporate to form a combustible concentration of
gas. In spark-ignition engines, fuel is mixed with air and ignited
by the spark plug. There are standardized test methods for the
measurement of flash points, well known to persons skilled in the
art.
[0041] The above embodiment where the fuel or carrier in the
additive has a flash point similar to that of the fuel to which it
is intended to be added, has a particular advantage. When the
oil-replacement additive comprises a fuel with the same flash point
as the bulk of fuel to which it is added, both fuels will combust
simultaneously, and the additive will increase the effect of the
engine. In contrast, when traditional two-stroke oils and oil
containing additives are used, the oil obviously has a higher flash
point, and will not contribute to the combustion, or does so only
to a limited degree. As a matter of fact, using traditional
two-stroke fuels and oils, a large portion of the oil is not at
all, or only partially combusted, which adds to the exhaust fumes
and increases pollution.
[0042] According to a preferred embodiment, again freely combinable
with the above aspects, the concentration of boron is in the
interval of 10 to 600 ppm, preferably about 100 to 600 ppm. More
preferably, the concentration of boron is in the interval of 100 to
300 ppm.
[0043] According to another embodiment, freely combinable with the
above aspects, the boron is added in the form of a stable boron
solution prepared by dissolving a boron compound in an alcohol,
followed by vigorous mixing and exclusion of particles larger than
100 nm.
[0044] Methods for the production of a stable boron solution are
disclosed in WO 2010/134872, incorporated by reference in its
entirety. This method involves vigorous mixing and a settling step.
The boron is incorporated in an organic solvent or a fuel,
preferably first incorporated in an alcohol and then diluted to the
desired concentration using a hydrocarbon carrier and/or a fuel.
Preferably said fuel is the same fuel as the fuel to which the
additive is intended to be added, or a fuel compatible with this
fuel. In two-stroke applications, the fuel is preferably unleaded
95 octane gasoline. Kerosene and naphtha can also be used as
carriers and/or diluents in the additive.
[0045] Without wishing to be bound by any theory, the inventors
contemplate that the stable boron solution produced according to
the methods disclosed in WO 2010/134872 is one key factor behind
the surprising results. It is contemplated that the controlled
particle size <100 nm and/or the electrostatic charge of the
particles contribute to the superior lubricating properties, making
it possible to eliminate the use of oil already using a very low
concentration of boron.
[0046] Consequently, a second aspect is a novel two-stroke engine
fuel comprising an additive according to the above aspect and
embodiments thereof, wherein the boron concentration in the fuel is
in the interval of 1 to 12 ppm. Preferably the boron concentration
is in the interval of 1 to 6 ppm, most preferably 2-3 ppm.
[0047] According to an embodiment of the second aspect, the fuel
contains less than 1% oil (w/w). The bulk of said fuel is
preferably standard two-stroke fuel, such as but not limited to
unleaded 95 octane gasoline.
[0048] A third aspect relates to a method for reducing the
emissions from a two-stroke engine, wherein an additive comprising
boron dissolved in an alcohol, less than 10% oil (w/w), the balance
being a fuel and the concentration of boron in said additive is the
interval of 1 to 600 ppm, preferably in the interval of 100 to 600
ppm, is added to the fuel.
[0049] According to an embodiment of said third aspect, said
additive is mixed into the fuel at a proportion of about 1 part
additive to 100 parts fuel. This is usually called a "premix" but
has so far only referred to oil-containing mixtures. Premix ratios
vary with the requirements of different engines, and a skilled
person can figure out a suitable ratio starting from the above
guidance, e.g. about 1 part additive to 100 parts fuel.
[0050] According to another embodiment, said additive is injected
into the cylinder together with fuel at a proportion or about 1
part additive to 50 parts fuel. Many two-stroke engines are
equipped with separate oil tanks and an oil injection system, and
the presently claimed additive can advantageously be applied also
to such systems, e.g. prefilled in the oil tank and then injected
into the cylinder during operation of the engine. Again, a skilled
person can adjust the settings of the injection system starting
from the above guidance, e.g. about 1 part additive to 50 parts
fuel.
[0051] One advantage with the inventive additives, fuels and
methods is that the emissions are significantly reduced, in
particular the emission of total hydrocarbons and carbon monoxide.
At the same time, the combustion efficiency is increased, and the
fuel consumption was reduced. It is clear that a combination of
reduced emissions and reduced fuel consumption is a significant
advantage. The examples show that the invention allows the
reduction of the emissions of total hydrocarbons, CO and CO.sub.2
with maintained lubrication of the two-stroke engine.
[0052] The combined effects are also very surprising. Additionally,
the first experiments were performed without intermediate cleaning
of the engine, and it appears that the effects of the boric acid
additive remains for a while. This lingering effect is likely
attributable to the controlled particle size and/or the
electrostatic charge of the particles.
[0053] An additional advantage is that boron, unlike many other
compounds that have been used or are suggested for use in
lubricating additives, is non-toxic and has no known impact on the
environment. As a matter of fact, boron is generally considered to
be non-toxic at levels normally encountered, and boron is widely
used cosmetics, products for oral hygiene, bath products and
products for waving hair. In these applications, the allowed
concentration (expressed as boric acid) ranges from 0.1 to 18%,
which is significantly higher than the ppm concentrations disclosed
herein.
[0054] According to the "Opinion on Boron Compounds issued in 2010
by the Scientific Committee on Consumer Safety (SCCS/1249/09),
boric acid is considered non-mutagenic based on the available in
vitro data. No data regarding a possible association between cancer
and boron exposure in humans has been found. In fact, different
boron compounds and in particular boric acid is already widely used
in cosmetics and healthcare products. Boron compounds are also
widely used in agriculture, as a component of fertilizers.
EXAMPLES
Example 1
A Comparative Example
[0055] The present inventors commissioned a study to be performed
at an accredited research institute (SMP, Svensk Maskinprovning AB,
part of RISE). The performance of a modern, commercially available
chain saw was studied in a test bench, investigating the
possibility to reduce or eliminate the addition of oil to the
two-stroke fuel.
Materials
[0056] Engine oil: Commercial engine oil for two-stroke engines was
used (Stihl standard oil "Low smoke 2 Stroke oil").
[0057] Oil replacement additive: An oil replacement additive was
prepared by mixing a stable ethanol solution of boric acid,
prepared according to the methods of WO 2010/134872 with an amount
of the above engine oil. In the final additive, the amount of oil
was 30% and the balance a mixture of kerosene and ethanol.
[0058] Fuel: Standard, commercial two-stroke fuel (unleaded 95
octane gasoline) was used. Standard oil was added to the fuel
according to the engine manufacturer's instructions, i.e. 2 parts
oil to 98 parts fuel (volume). In this test, the oil replacement
additive was however added in a smaller amount, 1 part additive to
99 parts fuel (volume).
[0059] Two-stroke engine: A modern, commercially available chain
saw (Stihl, Model MS181) was used. This chain saw has a 31.8 cc
engine with a nominal effect of 1.5 kW.
Methods
[0060] The method used for differentiate the two-stroke mixtures, a
standard oil and an additive according to embodiments of the
present disclosure, was the G3 Standard Cycle (according to ISO
standard 8178-4:2007), performed using a chain saw as defined
above. The ISO 8178 is an international standard for exhaust
emission measurement from a number of non-road engine applications.
It is used for emission certification and/or type approval testing
in many countries, including the United States, European Union and
Japan. Depending on the legislation, the cycle can be defined by
reference to the ISO 8178 standard, or else by specifying a test
cycle equivalent to ISO 8178 in the national legislation (as it is
the case with the US EPA regulations).
[0061] The ISO 8178 includes a collection of steady-state engine
dynamometer test cycles (designated as type C1, C2, D1, etc.)
designed for different classes of engines and equipment. Each of
these cycles represents a sequence of several steady-state modes
with different weighting factors.
[0062] The emissions, i.e. selected pollutants in the exhaust, were
measured according to the methods disclosed in ISO 8178 and EC
Directive 97/68.
[0063] Tests using the standard oil were designated A and A2, and
tests using a boric acid containing additive according to the
invention were designated B and B4. The test procedure was as
follows: [0064] 1. A shorter warm-up run (15 min) using (A) with 2%
injection, followed by [0065] 2. The actual test run with a load of
100% and 0% respectively, and simultaneous collection of data (fuel
consumption, temperature, emission). [0066] 3. A shorter warm-up
run (15 min) using (B) with 1% injection, followed by [0067] 4. The
actual test run with a load of 100% and 0% respectively, and
simultaneous collection of data (fuel consumption, temperature,
emission). [0068] 5. A shorter warm-up run (15 min) using (A2) with
2% injection, followed by [0069] 6. The actual test run with a load
of 100% and 0% respectively, and simultaneous collection of data
(fuel consumption, temperature, emission). [0070] 7. A shorter
warm-up run (15 min) using (B4) with 1% injection, followed by
[0071] 8. The actual test run with a load of 100% and 0%
respectively, and simultaneous collection of data (fuel
consumption, temperature, emission).
[0072] It should be noted that this chain saw (Stihl MS181) has an
automatic carburetor (IntelliCarb.TM. Compensating Carburetor)
designed to automatically adjust the air/fuel ratio when the air
filter becomes restricted or partially clogged and it thus
maintains the engine's correct RPM. Therefore there was no tuning
of the carburetor between test runs. It is contemplated that by
tuning the carburetor, the reduction in fuel consumption and
emissions would have become even more pronounced.
[0073] The fuel consumption and the specific fuel consumption are
shown in Table 1 below. It is evident that replacing the standard
two-stroke oil with a boric acid containing additive according to
an embodiment significantly reduces fuel consumption and enhances
combustion. Enhanced combustion is here evidenced as increased
cylinder head temperatures.
TABLE-US-00001 TABLE 1 Fuel consumption and combustion efficiency
A. HP Super A2. Syntetic B. Standard B4. C. Standard Additive oil
Additive Additive oil 2% 1%. 2% 1% No oil Engine 1.2 1.3 1.4 1.2
1.3 performance [kW] [.+-.2%] RPM 10000 9981 10018 9981 10004
Specific fuel 536 480 444 501 452 consumption [g/kWh] [.+-.3%]
Change: -10% -17% -7% -16% Fuel 625 613 594 584 577 consumption at
rated speed [g/h] [.+-.2%] Change: -2% -5% -7% -8% Cylinder 260 265
270 268 283 head temperature [.degree. C.] [.+-.2%]
[0074] In tests A and A2, a high performance super synthetic
standard oil was added to the fuel to a concentration of 2%. In B
and B4, the inventive additive was used together with 1% oil in the
fuel, and in C, the additive was used without any addition of
oil.
[0075] As there was no cleaning of the engine between the test runs
B and A2, a remaining effect of the boric acid can be seen. Further
tests investigating this phenomenon will be performed.
[0076] Without wishing to be bound by any theory, the inventors
contemplate that there is a lasting effect of the boric acid, due
to interactions between the boric acid and inner surfaces of the
engine. Earlier research shows the existence of a thin film,
confirmed by scanning electron microscope (SEM) investigations.
[0077] The results show that the boron containing additive
significantly reduced both the specific fuel consumption and the
fuel consumption at rated speed. The increase in cylinder head
temperature indicates a more effective combustion. The reduction in
fuel consumption and the increased temperature was most significant
in test C, where the inventive additive was used alone, without any
addition of oil.
[0078] In five test runs, the exhaust gases were collected and
analyzed. The average values are presented in Table 2.
TABLE-US-00002 TABLE 2 Specific emissions (g/kWh) Specific emission
(g/kWh) A2. A. B. Standard B4. C. Standard oil Additive oil
Additive Additive 2% 1% 2% 1% No oil THC + Nox 47.9 41.63 42.11
44.43 39.83 -13% -12% -7% -17% THC [.+-.8%] 45.4 38.56 37.46 40.44
36.96 -15.07% -17.49% -10.93% -18.59% CO [.+-.8%] 264.32 203.66
152.41 194.36 212.37 -23% -42% -26% -20% CO2 [.+-.8%] 1156 1095
1060 1170 996 -5% -8% 1% -14% NOx [.+-.8%] 2.5 3.07 4.65 3.99 2.87
23% 86% 60% 15%
[0079] Tests A and A2, B and B4, and C represent the same
conditions as above. The results show a significant reduction in
exhaust emissions, seen for total hydrocarbons (THC), CO and
CO.sub.2 as evident from Table 2. The increase in NOx is however an
expected result from the enhanced combustion and increased
temperature. This can possibly be addressed by fine-tuning the
carburetor.
[0080] Further tests are necessary to obtain repeatable results,
but the results so far already show that an unexpected and highly
desirable reduction of the amount of oil that is added to
two-stroke engine fuel can be achieved through the use of a boric
acid containing additive.
Example 2
Boron Additive Reduces Wear Scar Formation
[0081] Friction reduction and wear scar formation was investigated
for different two-stroke fuel mixtures, using a high-frequency
reciprocating rig according to ISO standard 12156. The boron
concentration was determined for each sample, Finally, a
coefficient of friction (CoF) was determined for each sample. See
Table 3.
TABLE-US-00003 TABLE 3 Wear scar and CoF Test 1 Elemental analysis
(oil) Test 2 Boron conc. HFRR Wear Information mg/kg Scar Sample
(FF5.5 w %, red ASTM EN ISO Sample ID Naphta 50%) D51185 mod 12156
CoF 1 003-39 2T Inj (B mg/kg 210 225 0.100 212) 2 003-40 2T Inj (B
mg/kg 390 182 0.104 415) 3 003-41 2T Inj (B mg/kg 130 201 0.104
128)
[0082] As can be seen in Table 3, the calculated boron
concentration was confirmed by the elemental analysis. All
concentrations were in the interval of 100 to 600 ppm (128 (130)
ppm; 212 (210) ppm; and 415 (390) ppm). Further, the determination
of wear scar and coefficient of friction confirmed the usefulness
of the additive.
Example 3
On-Going Multi-Variable Studies
[0083] The present inventors have commissioned a further study,
based on the ISO-standard, but with the following modifications:
[0084] the test engine will be operated for a longer duration when
changing from an additive according to embodiments of the invention
to a standard oil, in order to see how long the effect of the boric
acid can be seen, or [0085] the test engine will be cleaned between
test runs, in order to avoid "carry over" of previous test
conditions [0086] different concentrations of boric acid will be
tested, for example 200 mg/kg boron resulting in 2 and 4 mg/kg
boron in the fuel depending on whether the boron containing
oil-replacement additive is injected into the engine, or pre-mixed
into the fuel [0087] different concentrations of oil in the
additive will be tested, ranging from 0% to 30% per weight.
[0088] In another set-up, also commissioned by the present
inventors, different compositions will be tested. The boron
concentration in the additive will be in the interval of 1 to 100
ppm, resulting in a concentration of 0.01 to 1 in the fuel.
[0089] Similarly, the amount of oil will be in the interval of 0 to
30% of the additive, resulting in a concentration of 0 to 0.3 or
0.6% oil in the fuel after final mixing or injection. Compared to
standard two-stroke oils and two-stroke fuels, this represents a
significant reduction all the way to a total removal of the oil
component.
[0090] Preliminary results indicate that already a very low boron
concentration makes it possible to reduce the amount of oil. A
boron concentration in the interval of 0.01 to 1 ppm in combination
with a minimal addition of oil significantly reduces the emissions
and improves fuel combustion and as a consequence, reduces fuel
consumption.
[0091] Using a higher concentration of boric acid, but one which
still is very low compared to previously disclosed concentrations,
for example a concentration in the interval of 0.1 to 1 ppm, no oil
needs to be added to the two-stroke fuel.
[0092] Without further elaboration, it is believed that a person
skilled in the art can, using the present description, including
the examples, utilize the present invention to its fullest extent.
Also, although the invention has been described herein with regard
to its preferred embodiments, which constitute the best mode
presently known to the inventors, it should be understood that
various changes and modifications as would be obvious to one having
the ordinary skill in this art may be made without departing from
the scope of the invention which is set forth in the claims
appended hereto.
[0093] Thus, while various aspects and embodiments have been
disclosed herein, other aspects and embodiments will be apparent to
those skilled in the art. The various aspects and embodiments
disclosed herein are for purposes of illustration and are not
intended to be limiting, with the true scope and spirit being
indicated by the following claims.
* * * * *