U.S. patent application number 17/511668 was filed with the patent office on 2022-04-28 for lubricating oil composition with renewable base oil.
The applicant listed for this patent is CHEVRON U.S.A. INC.. Invention is credited to Mihir K. PATEL, Willem VAN DAM.
Application Number | 20220127545 17/511668 |
Document ID | / |
Family ID | |
Filed Date | 2022-04-28 |
![](/patent/app/20220127545/US20220127545A1-20220428-M00001.png)
United States Patent
Application |
20220127545 |
Kind Code |
A1 |
VAN DAM; Willem ; et
al. |
April 28, 2022 |
LUBRICATING OIL COMPOSITION WITH RENEWABLE BASE OIL
Abstract
A lubricant composition and method for improving engine
performance using a renewable base oil composition comprising
hydrocarbon mixtures and a lubricant additive having a sulfur
content of up to about 0.4 wt. % and a sulphated ash content of up
to about 0.5 wt. % is described herein.
Inventors: |
VAN DAM; Willem; (Novato,
CA) ; PATEL; Mihir K.; (San Ramon, CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
CHEVRON U.S.A. INC. |
San Ramon |
CA |
US |
|
|
Appl. No.: |
17/511668 |
Filed: |
October 27, 2021 |
Related U.S. Patent Documents
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
|
|
63106538 |
Oct 28, 2020 |
|
|
|
International
Class: |
C10M 171/02 20060101
C10M171/02 |
Claims
1. A lubricating composition that comprises a. a mixture of base
oil having at least 25 wt. % renewable base oil comprising a
hydrocarbon mixture in which (a) the percentage of molecules with
even carbon number is .gtoreq.80% according to FIMS (b) the
BP/BI.gtoreq.-0.6037 (Internal alkyl branching per molecule)+2.0
(c) on average there are 0.3 to 1.5 5+ methyl per molecule; and b.
an additive composition having a sulfur content of up to about 0.4
wt. % and a sulfated ash content of up to about 0.5 wt. %, as
determined by ASTM D874 and comprising of (a,) at least one
oil-soluble of dispersed oil stable boron containing compound
having from 400 ppm to no more than 2000 ppm of boron, based upon
the total mass of composition (b) at least one oil-soluble or
dispersed oil stable molybdenum containing compound having from
about 700 ppm of molybdenum to no more than 1500 ppm of molybdenum,
based upon the total mass of composition; wherein the lubricating
oil composition has a ratio of sulfur to molybdenum of about 0.5:1
to less than or equal to about 4:1, and further wherein the
lubricating oil composition is substantially free of zinc dialkyl
dithiphosphate. wherein the total additive concentration ranges
from about 20% to 30% and base oils mixtures from about 70% to
80%.
2. The lubricating composition of claim 1, wherein lubricating
high-temperature high shear viscosity is less than or equal to 3.2
cP, based on ASTM D5481.
3. The lubricating composition of claim 1, wherein lubricating
kinematic viscosity at 100.degree. C. is less than or equal to 12.5
cSt, based on ASTM D445.
4. The lubricating composition of claim 1, wherein lubricating low
temperature cold cranking viscosity at -25.degree. C. is less than
or equal to 7000 mPas, based on ASTM D5293.
5. The lubricating composition of claim 1, wherein low temperature
pumping viscosity is less than or equal to 60,000 mPaS at
30.degree. C. without any yield stress, based on ASTM D4686.
6. A method of improving fuel economy retention, extending oil
drain interval and reducing oil consumption of an internal
combustion engine with lubricants that comprises a. a mixture of
base oil having at least 25 wt. % renewable base oil comprising a
hydrocarbon mixture in which (a) the percentage of molecules with
even carbon number is .gtoreq.80% according to FIMS (b) the
BP/BI.gtoreq.-0.6037 (Internal alkyl branching per molecule)+2.0
(c) on average there are 0.3 to 1.5 5+ methyl per molecule; and an
b. additive composition having a sulfur content of up to about 0.4
wt. % and sulfated ash content of up to about 0.5 wt. %, as
determined by ASTM D874 and comprising of (a,) at least one
oil-soluble of dispersed oil stable boron containing compound
having from 400 ppm to no more than 2000 ppm of boron, based upon
the total mass of composition (b) at least one oil-soluble or
dispersed oil stable molybdenum containing compound having from
about 700 ppm of molybdenum to no more than 1500 ppm of molybdenum,
based upon the total mass of composition; wherein the lubricating
oil composition has a ratio of sulfur to molybdenum of about 0.5:1
to less than or equal to about 4:1, and further wherein the
lubricating oil composition is substantially free of zinc dialkyl
dithiphosphate.
7. The method of claim 6, wherein fuel economy retention is
improved by more than 0.2%.
8. The method of claim 7, wherein the internal combustion engine is
a heavy duty diesel engine.
9. The method of claim 6, wherein the oil drain interval is
extended by more than 30%.
10. The method of claim 9, wherein the internal combustion engine
is a heavy-duty diesel engine.
11. The method of claim 6, wherein the oil usage is reduced by more
than 50%.
12. The method of claim 11, wherein the internal combustion engine
is a heavy duty diesel engine.
13. A method for reducing the loss of fuel economy in internal
combustion engines to no more than 6% by supplying the composition
of claim 1.
14. The method of claim 13, wherein the internal combustion engine
is a medium duty diesel engine.
15. The method for reducing loss of peak torque in internal
combustion engines to no more than 70 Nm by supplying the
composition of claim 1.
16. The method of claim 15, wherein the internal combustion engine
is a medium duty diesel engine.
17. A method for reducing loss of peak power in internal combustion
engines to no more than 20 KW by supplying the composition of claim
1.
18. The method of claim 17, wherein the internal combustion engine
is a medium duty diesel engine.
19. A method for reducing rise in the exhaust manifold temperature
in internal combustion engines to no more than 50.degree. C. by
supplying the composition of claim 1.
20. The method of claim 19, wherein the internal combustion engine
is a medium duty diesel engine.
21. A method for reducing oil usage in internal combustion engines
to no more than 7500 grams by supplying the composition of claim
1.
22. The method of claim 21, wherein the internal combustion engine
is a medium duty diesel engine.
Description
FIELD OF THE INVENTION
[0001] A lubricating oil composition containing a renewable base
oil comprising hydrocarbon mixtures and a lubricant additive having
a sulfur content of up to about 0.4 wt. % and a sulphated ash
content of up to about 0.5 wt. %. Method of improving engine
performance with lubricant oil composition containing renewable
base oil comprising hydrocarbon mixtures and a lubricant additive
having a sulfur content of up to about 0.4 wt. % and a sulphated
ash content of up to about 0.5 wt. %, have been developed which
possess unique compositional characteristics and which demonstrates
improvement of fuel economy retention, turbocharger efficiency
retention, peak torque retention, peak power retention, reduction
in the exhaust manifold temperature, and reducing oil usage over
the life of the lubricant when used to lubricate various types of
internal combustion engines.
BACKGROUND OF THE INVENTION
[0002] In efforts to reduce global warming, emission regulations of
the automobile industries are becoming tighter year after year.
Because of these regulations, the automobile industry is looking
for options to improve fuel economy (FE).
[0003] Because fuel economy derived from the advanced lubricants
comes at a smaller cost than redesigning hardware, it is
increasingly seen as an attractive route to efficiency improvement.
OEMs are looking for higher vehicle efficiency and have also
started looking for methods to retain vehicle efficiency. Hence,
retention of fuel economy throughout the useful life of a lubricant
is becoming an important criterion. During automotive engine
operation, lubricant deteriorates due to its oxidative and thermal
degradation. Oxidative and thermal degradation can deteriorate
lubricating properties such as viscosity, oxidative resistance,
wear resistance, etc. This degradation can result in premature
failure of critical engine components and loss of fuel economy.
[0004] Base stocks are commonly used to produce various lubricants,
including lubricating oils for internal combustion engines,
turbines, compressors, hydraulic systems, etc. They are also used
as process oils, white oils, and heat transfer fluids. Finished
lubricants generally consist of two components, base oils, and
additives.
[0005] Base oil, which could be one or a mixture of base stocks, is
the principal constituent in these finished lubricants and
contributes significantly to their characteristics, such as
viscosity and viscosity index, volatility, stability, and
low-temperature performance. In general, a few base stocks are used
to manufacture a wide variety of finished lubricants by varying the
mixtures of individual base stocks and individual additives.
[0006] A method of improving engine fuel efficiency with a
lubricant composition containing fatty acid esters is outlined in
U.S. Pat. No. 9,885,004.
[0007] The American Petroleum Institute (API) categorizes base
stocks in five groups based on their saturated hydrocarbon content,
sulfur level, and viscosity index (Table 1 below). Group I, II, and
III base stocks are mostly derived from crude oil via extensive
processing, such as solvent refining for Group I, and
hydroprocessing for Group II and Group III. Certain Group III base
stocks can also be produced from synthetic hydrocarbon liquids via
a Gas-to-Liquids (GTL) process, and are obtained from natural gas,
coal, or other fossil resources. Group IV base stocks, the
polyalphaolefins (PAO), are produced by oligomerization of alpha
olefins, such as 1-decene. Group V base stocks include everything
that does not belong to Groups I-IV, such as naphthenic base
stocks, polyalkylene glycols (PAG), and esters. Most of the
feedstocks for large-scale base stock manufacturing are
non-renewable.
TABLE-US-00001 TABLE 1 API Base Oil Classification (API 1509
Appendix E) Viscosity Saturates API Index by ASTM Sulphur, Group
(ASTM D2270) D2007 % Description I 80-120 <90% >.03%
Conventional (solvent refining) II 80-120 .gtoreq.90% .ltoreq..03%
Hydroprocessing III .gtoreq.120 .gtoreq.90% .ltoreq..03% Severe
Hydroprocessing IV PolyAlphaOlefins (PAO) V All other base stocks
not included above e.g. esters
Automotive engine oils are by far the largest market for base
stocks. The automotive industry has been placing more stringent
performance specifications on engine oils due to requirements for
lower emissions, long drain intervals, and better fuel economy.
Specifically, automotive OEMs (original equipment manufacturers)
have been pushing for the adoption of lower viscosity engine oils
such as OW-20 to OW-8, to lower friction losses and achieve fuel
economy improvement. Base Oils with a lower Noack Volatility in an
engine oil allows the formulation to retain the designed viscosity
for longer operation time allowing for increased fuel economy
retention and longer drain intervals is discussed in U.S. Pat. No.
6,300,291. Group I and Group II's usage in OW-xx engine oils are
highly limited because formulations blended with them cannot meet
the performance specifications for OW-xx engine oils, leading to
increased demands for Group III and Group IV base stocks.
[0008] Group III base stocks are mostly manufactured from vacuum
gas oils (VGOs) through hydrocracking and catalytic dewaxing (e.g.
hydroisomerization). Group III base stocks can also be manufactured
by catalytic dewaxing of slack waxes originating from solvent
refining, or by catalytic dewaxing of waxes originating from
Fischer-Tropsch synthesis from natural gas or coal-based raw
materials also known as Gas to Liquids base oils (GTL).
[0009] Manufacturing processes of Group III base stocks from VGOs
is discussed in U.S. Pat. Nos. 5,993,644 and 6,974,535. Their
boiling point distributions are typically broader when compared to
PAOs of the same viscosity, causing them to have higher volatility
than PAOs. Additionally, Group III base stocks typically have
higher cold crank viscosity (i.e., dynamic viscosity according to
ASTM D5293, CCS) than Group IV base stocks at equivalent
temperatures and viscosities.
[0010] GTL base stock processing is described in U.S. Pat. Nos.
6,420,618 and 7,282,134, as well as U.S. Patent Application
Publication 2008/0156697. For example, the latter publication
describes a process for preparing base stocks from a
Fischer-Tropsch synthesis product, the fractions of which with
proper boiling ranges are subjected to hydroisomerization to
produce GTL base stocks.
[0011] Such structures and properties of GTL base stocks are
described, for example, in U.S. Pat. Nos. 6,090,989 and 7,083,713,
as well as U.S. Patent Application Publication 2005/0077208. In
U.S. Patent Application Publication 2005/0077208, lubricant base
stocks with optimized branching are described, which have alkyl
branches concentrated toward the center of the molecules to improve
the base stocks' cold flow properties. Nevertheless, pour points
for GTL base stocks are typically higher than PAO or other
synthetic hydrocarbon base stocks.
[0012] A further concern with GTL base stocks is the severely
limited commercial supply, a result of the prohibitively large
capital requirements for a new GTL manufacturing facility. Access
to low-cost natural gas is also required to profitably produce GTL
base stocks. Furthermore, as GTL base stocks are typically
distilled from an isomerized oil with a wide boiling point
distribution, the process results in a relatively low yield to the
base stock with a desired viscosity when compared to that of a
typical PAO process. Due to these economic and yield constraints,
there is currently only a single manufacturing plant of group III+
GTL base stocks, exposing formulations that use GTL to supply chain
and price fluctuation risks.
[0013] Polyalphaolefins (PAOs), or Group IV base oils, are produced
by the polymerization of alpha-olefins in the presence of a Friedel
Crafts catalyst such as AlCl3, BF3, or BF3 complexes. For example,
1-octene, 1-decene, and 1-dodecene have been used to manufacture
PAOs that have a wide range of viscosities, varying from low
molecular weight and low viscosity of about 2 cSt at 100.degree.
C., to high molecular weight, viscous materials with viscosities
exceeding 100 cSt at 100.degree. C. The polymerization reaction is
typically conducted in the absence of hydrogen; the lubricant range
products are thereafter polished or hydrogenated to reduce the
residual unsaturation. Processes to produce PAO based lubricants
are disclosed, for example, in U.S. Pat. Nos. 3,382,291; 4,172,855;
3,742,082; 3,780,128; 3,149,178; 4,956,122; 5,082,986; 7,456,329;
7,544,850; and U.S. Patent Application Publication
2014/0323665.
[0014] Prior efforts to prepare various PAOs that can meet the
increasingly stringent performance requirements of modern
lubricants and automotive engine oil particularly have favored low
viscosity polyalphaolefin base stocks derived from 1-decene, alone,
or in some blend with other mineral oils. However, the
polyalphaolefins derived from 1-decene can be prohibitively
expensive due to its limited supply. Attempts to overcome the
availability constraint of 1-decene have led to the production of
PAOs from C8 through C12 mixed alpha-olefin feeds, lowering the
amount of 1-decene that is needed to impart the properties.
However, they still do not completely remove the requirement for
providing 1-decene as the predominate olefin feedstock due to
performance concerns.
[0015] Similarly, previous efforts to use linear alpha-olefins in
the C14-C20 range made polyalphaolefins with unacceptably high pour
points, which are unsuitable for use in a variety of lubricants,
including OW engine oils.
[0016] Therefore, there remains a need for a lubricant composition
having properties within commercially acceptable ranges, for
example, for use in automotive and other applications, with such
properties including one or more of viscosity, Noack volatility,
and low-temperature cold-cranking viscosity. Furthermore, there
remains a need for lubricant compositions having improved
properties and methods of manufacture thereof, where the base stock
compositions have reduced amounts of 1-decene incorporated therein,
and may even preferably eliminate the use of 1-decene in the
manufacture thereof.
[0017] In addition to the technical demands for the automotive
industry, environmental awareness and regulations are driving
manufacturers to use renewable feedstocks and raw materials in the
production of base stocks and lubricants. It is known that esters
and some Group III hydrocarbon base stocks (U.S. Pat. No.
9,862,906B2) of renewable and biological origin have been used in
applications such as refrigeration compressor lubricants, hydraulic
oils, and metalworking fluids, and more recently in automotive and
industrial lubricants (US20170240832A1). Common biological sources
for hydrocarbons are natural oils, which can be derived from plant
sources such as canola oil, castor oil, sunflower seed oil,
rapeseed oil, peanut oil, soybean oil, and tall oil, or palm oil.
Other commercial sources of hydrocarbons include engineered
microorganisms such as algae or yeast.
[0018] Due to the increasing demand for high performing lubricant
base stocks, there is a continuing need for improved hydrocarbon
mixtures. The industry requires these hydrocarbon mixtures to have
superior Noack Volatility and low-temperature viscometric
properties that can meet stricter engine oil requirements,
preferably from renewable sources.
[0019] Exhaust after-treatment devices are installed on the
internal combustion engines to enable them to comply with emission
regulations. Combustion byproducts of fuels and lubricants can
reduce the useful life of exhaust after-treatment devices. In
particular, sulfur coming from fuel and lubricant, phosphorus
coming from a lubricant, and sulphated ash coming from lubricants
are known to reduce the durability of exhaust after-treatment
devices. Hence to prolong the life of exhaust after-treatment
devices certain types of lubricants are being developed with
reducing amount of sulphated ash, phosphorus, and sulfur, commonly
known as low SAPS formulations.
[0020] U.S. Pat. No. 9,523,061 B2 discloses a lubricating oil
composition having a sulfur content of up to about 0.4 wt. % and
sulphated ash of up to about 0.5 wt. %.
SUMMARY OF THE INVENTION
[0021] An embodiment of the invention is a lubricating oil
composition containing a renewable base oil comprising hydrocarbon
mixtures and a lubricant additive package having a sulfur content
of up to about 0.4 wt. % and a sulphated ash content of up to about
0.5 wt. %.
[0022] Another embodiment is a method of improving engine
performance with lubricant oil composition containing renewable
base oil comprising hydrocarbon mixtures and a lubricant additive
package having a sulfur content of up to about 0.4 wt. % and a
sulphated ash content of up to about 0.5 wt. %, have been developed
which possess characteristics demonstrating improvement of fuel
economy retention, turbocharger efficiency retention, peak torque
retention, peak power retention, reduction in the exhaust manifold
temperature, and reducing oil usage over the life of the lubricant
when used to lubricate various types of internal combustion
engines.
DESCRIPTION OF THE INVENTION
[0023] In accordance with one embodiment of the invention, a
lubricant composition possessing a "renewable base oil", as defined
herein as a base oil with a saturated hydrocarbon mixture having
greater than 80% of the molecules with an even carbon number
according to FIMS, with the mixture exhibiting a branching
characteristic of BP/BI.gtoreq.-0.6037 (Internal alkyl branching
per molecule)+2.0, and when the hydrocarbon mixture is analyzed by
carbon NMR as a whole, has on average at least 0.3 to 1.5 5+ methyl
branches per molecule. One way to synthesize the hydrocarbon
mixture disclosed herein is through the oligomerization of C14-C20
alpha or internal-olefins, followed by hydroisomerization of the
oligomers.
[0024] Using C14-C20 olefins would ease the demand for high-price
1-decene and other crude oil or synthetic gas-based olefins as
feedstocks and making available alternate sources of olefin
feedstocks such as those derived from C14-C20 alcohols. The
hydrocarbon compositions are derived from one or more olefin
co-monomers, where said olefin comonomers are oligomerized to
dimers, trimers, and higher oligomers. The oligomers are then
subjected to hydroisomerization. The resulting hydrocarbon mixtures
have excellent pour point, volatility and viscosity
characteristics, and additive solubility properties.
[0025] An embodiment of the invention is a lubricating oil
composition having a renewable base oil described above blended
with an additive package wherein sulfur content of up to about 0.4
wt. % and a sulphated ash content up to about 0.5 wt. % as
determined by the ASTM D874 is provided which comprises (1)
oil-soluble boron containing compound which contributes from about
400 ppm and no more than 2000 ppm of boron based upon the total
mass of the composition and preferably from about 600 ppm and no
more than 1000 ppm of Boron based upon the total mass of the
composition; (2) oil-soluble molybdenum containing compound which
contributes from about 700 ppm of molybdenum and no more than 1500
ppm of molybdenum based upon the total mass of the composition
wherein lubricating oil composition has ratio of sulfur to
molybdenum of about 0.5:1 to less than and equal to 4:1; further
wherein the lubricating oil composition is substantially free of
zinc dialkyl dihiophosphate compounds. Representative additive
packages are described in U.S. Pat. No. 9,523,061 B2, herein
incorporated by reference.
[0026] In accordance with another embodiment of the invention, a
lubricant oil composition having renewable base oil with low
sulphated ash additive package where kinematic viscosity at
100.degree. C. is less than or equal to 12.5 cSt, based on ASTM
D445; high-temperature high shear viscosity is less than or equal
to 3.2 cP, based on ASTM D5481; low-temperature cold cranking
viscosity at -30.degree. C. is less than or equal to 6600 mPas,
based on ASTM D5293; SAE viscosity grade less than or equal to
5W-30, based on SAE J300, for example, 5W-20, OW-30, OW-20, OW-16,
OW-12 and OW-8.
[0027] "Conventional lubricant" is herein defined as lubricant
compositions not employing the "renewable base oil" described
herein.
[0028] "Internal combustion engine" as defined herein comprises
diesel engines, including heavy and medium duty diesel engines.
[0029] A further embodiment of the invention is a method where
supplying the lubricant composition to a heavy-duty diesel engine
results in an improvement in fuel efficiency retention, wherein the
internal combustion engine includes a diesel engine. Particularly,
resulting in improving fuel economy retention by at least 0.2% and
a method for improving fuel efficiency retention in internal
combustion engines preferably by more than 0.4% better than a
conventional lubricant of equal viscosity.
[0030] An additional embodiment is a method of reducing oil usage
by supplying the lubricant composition to a heavy-duty diesel
engine. Total oil usage has described the lubricant consumed during
the engine operation and lubricant drained due to loss in its
effectiveness to lubricate internal combustion engines. The
reduction in oil usage is at least 30% and preferably by more than
50% as measured against a conventional lubricant of equal
viscosity.
[0031] The method of supplying the lubricating composition as
described herein to a heavy-duty diesel engine results in extending
oil drain interval that is at least 50% preferably by more than 60%
as compared to a conventional lubricant of equal viscosity.
[0032] The method of supplying the lubricant composition to a
medium-duty diesel engine as described herein, provides additional
improvements comprising: [0033] (a) loss of fuel economy relative
to the start of the test that is less than 5% and preferably no
more than 3% compared to a conventional lubricant of equal
viscosity; [0034] (b) total oil consumption that is below 7500
grams preferably below 6500 grams than a conventional lubricant of
equal viscosity; [0035] (c) loss of peak torque relative to the
start of the test that is no more than 50 Nm and preferably no more
than 30 Nm compared to a conventional lubricant of equal viscosity;
[0036] (d) loss of peak power relative to the start of the test
that is no more than 20 KW and preferably no more than 10 KW
compared to conventional lubricant of equal viscosity; [0037] (e)
loss of turbocharger efficiency by less than 10% and preferably no
more than 5%. [0038] (f) an increase in exhaust manifold
temperature relative to the start of the test is below 50.degree.
C. and preferably no more than 20.degree. C. compared to a
conventional lubricant of equal viscosity.
Example
[0039] A comparative lubricating oil composition 1 was prepared by
blending mineral base oil group II with an additive package with a
conventional level of sulphated ash. A comparative lubricating oil
composition 2 was prepared by blending mineral base oil group II
with an additive package with a low level of sulphated ash. A
comparative lubricating oil composition 3 was prepared by blending
renewable base oil with an additive package with a conventional
level of sulphated ash. A lubricant of the invention was prepared
by blending renewable base oil with an additive package with a low
level of sulphated ash. Viscosity modifier and trimming fluid were
added to obtain kinematic viscosity at 100.degree. C. between
7.25-8.25 cSt and high-temperature high shear viscosity at
150.degree. C. between 2.5 to 2.6 cP. Table 1 shows the detailed
composition of lubricating oils and the respective additive
concentrations.
TABLE-US-00002 TABLE 1 Lubricating oils composition Com- Com- Com-
Lubricant parative parative parative of Examples lubricant 1
lubricant 2 lubricant 3 Invention 1 Mineral Base Oil 75.13 69.38 --
-- (group II) (%) 2 Renewable base oil -- -- 80.80 77.10 (%) 3
Conventional 19.00 -- 19.00 -- sulphated ash Additive Package (%) 4
Low sulphated ash -- 22.7 -- 22.7 Additive Package (%) 5 Pour Pt.
0.2 0.2 0.2 0.2 Depressant (%) 6 Trim Fluid (%) 5.67 7.72 -- -- 7
Total (%) 100 100 100 100 Additives 8 Phosphorus, ppm 750 0 750 0 9
Zinc, ppm 850 0 850 0 10 Boron, ppm, 400 800 400 800 11 Molybdenum,
ppm 120 1100 120 1100 12 Sulfur, wt % 0.2 0.16 0.2 0.16 13
Sulphated Ash, % 0.9 0.4 0.9 0.4
Testing in a Heavy Duty Diesel Engine
[0040] It is well known that during automotive engine operation,
lubricant deteriorates due to its oxidative and thermal
degradation. Oxidative and thermal degradation can deteriorate
lubricating properties such as viscosity, oxidative resistance,
wear resistance, etc. This can result in premature failure of
critical engine components and an increase in fuel consumption or
loss of fuel economy. To measure fuel economy loss and oil usage a
Volvo D-13/MP8 13L, in-line six-cylinder, four-cycle diesel engine
equipped with a turbocharger and exhaust gas recirculation, running
on ultra-low sulfur diesel fuel was used.
Determination of Fuel Economy Retention (%)
[0041] To measure the fuel economy retention due to the degradation
of lubricating properties during engine operation, a test was
designed that sequentially measures Fuel efficiency-Oil degradation
(aging)-Fuel efficiency. This cycle was repeated until engine
operation exhibited a significant loss of fuel economy.
[0042] The fuel efficiency cycle was run as a discrete mode cycle
utilizing EPA Supplemental Emission Testing (SET) procedure. The
SET cycle consists of a 13-mode steady-state engine dynamometer
test. In each mode, the engine runs at a specific speed and load
combination for the prescribed time and move to the next mode. A
13-mode cycle was repeated seven times and the average fuel
consumption of seven cycles was measured in grams/minutes. The oil
degradation (aging) cycle was operated at engine speed 1500 rpm,
fuel flow 68 kg/h, oil gallery temperature 130.degree. C. Detailed
description of degradation (aging) test condition is described in
ASTM D8048.
[0043] The fuel economy retention test was started by measuring the
fuel consumption of engine oil filled with undegraded lubricant
using the 13-mode SET cycle as mentioned above. This is followed by
the oil degradation (aging) cycle as per the engine test conditions
mentioned above. The oil degradation cycle was operated for 90
hours. This is followed by the fuel efficiency cycle to measure a
change in fuel consumption due to oil degraded for 90 hours. Fuel
Efficiency-Oil degradation-Fuel Efficiency cycle was repeated for
360 hours with equal 90 hours segments.
[0044] Furthermore, fuel consumption values for undegraded
lubricant and aged lubricant (at each 90 hours segment) were used
to compute the change in the fuel economy (%). Furthermore, average
fuel economy change after 360 hours of engine operation was
calculated by averaging the average values of fuel economy change
calculated at 90, 180, 270, and 360 hours. A summary of the average
fuel economy change of comparative examples and lubricant of the
invention is provided in table 2.
Determination of Oil Drain Interval Capability
[0045] A lubricating oil that operates under the test conditions
described in the ASTM D8048 for 360 hours is likely to worsen its
lubricating properties and may no longer be usable for normal
engine operation. Once lubricating oil degrades to such condition
then it should be drained out of the engine and replaced with fresh
lubricating oil. The rejection limit of a lubricant varies
depending on the applications and severity of applications. One
skilled in the art knows that determining a unified rejection point
or condemning limit for all lubricating oils is difficult. Hence,
for the given experiment, a loss of 0.5% fuel efficiency was used
as a point of lubricating oil replacement. Hence oil drain interval
(ODI) is defined as a period of engine operation in hours from the
start of the test to the replacement of a new lubricating oil. If
any lubricating oil did not show a loss of 0.5% fuel economy by 360
hours of engine operation, then the test cycle was extended until
it showed deterioration in fuel economy of 0.5%. A summary of the
oil drain interval after a loss of 0.5% fuel economy by comparative
examples and lubricant of the invention is provided in the table
2.
Determination of Oil Usage
[0046] The total lubricant used during the engine operation was
calculated by adding the initial charge of fresh lubricant and
lubricant consumed during the engine operation. The initial charge
of the lubricant was 21.5 kg. Lubricant consumed during the engine
operation was calculated by monitoring the lubricant level in the
engine over the duration of the test by periodically checking an
oil level indicator, and by translating that observed lubricant
level into an amount of oil present in the engine. This amount was
then corrected for the lubricant sample that was removed from the
engine and by the amount of fresh lubricant that was added to
maintain the lubricant level every 30 hours. The total lubricant
consumed after 360 hours was calculated by adding oil consumed in
grams at every 30 hours interval. A summary of the total oil
consumed after 360 hours of engine operation by comparative
examples and lubricant of the invention is provided in Table 2.
TABLE-US-00003 TABLE 2 Composition of lubricants and respective
change in fuel economy (%) and oil drain interval Com- Com- Com-
Lubricant parative parative parative of the Examples Example 1
Example 2 Example 3 Invention 1 Avg. FE Change after -0.493 -0.389
-0.591 -0.012 360 hrs (%) 2 ODI after 0.5% FE 230 280 200 450 Loss
(Hours) 3 Oil consumed after 16.031 8.889 10.686 5.790 360 hrs (kg)
4 Improvement in fuel -- 0.104 -0.098 0.481 economy retention
relative to example 1 (%) 5 Improvement in the ODI -- 21.73 -13.05
95.65 relative to example 1 (%) 6 Reduction in the oil usage --
44.55 33.34 63.88 relative to example 1 (%)
[0047] Table 2 summarized the average fuel economy change (%) after
lubricants aged for 360 hours, oil drain intervals when engine lost
0.5% fuel economy and total oil consumed after 360 hours. As shown
in Table 2, the lubricant of the invention shows the lowest change
in the fuel economy loss after it degraded for 360 hours compared
to comparative examples. Also, the lubricant of the invention shows
the longest oil drain interval compared to comparative examples.
Furthermore, the lubricant of the invention shows the lowest amount
of oil consumed after 360 hours of engine operation compared to
comparative examples.
[0048] Comparative example 1 was formulated with conventional base
oil and conventional lubricant additive package. Comparative
example 2 was formulated by replacing conventional lubricant
additive package with low sulphated ash additive package and kept
conventional base oil as it is. Comparative examples 3 was
formulated by replacing conventional base oil with renewable base
oil and kept conventional lubricant additive package as it is.
Lubricant of the invention was formulated with low sulphated ash
additive package and renewable base oil. In order to determine
their relative performance, comparative example 2, 3, and lubricant
of the invention were compared to the example 1. For example,
example 2 and 3 show improvement in the fuel economy retention
relative to example 1 by 0.104% and -0.098%. While lubricant of the
invention shows improvement in the fuel economy retention relative
to example 1 by 0.481%. These results demonstrated that combining
renewable base oil and low sulphated ash additive package would
improve fuel economy retention by more than the sum of the
individual contributions of low sulphated ash additive package
(example 2) and renewable base oil (example 3). This indicates the
synergy between renewable base oil and low sulphated ash additive
technology. Similarly, improvement in the ODI after engine lost
0.5% fuel economy also indicates synergy between renewable base oil
and low sulphated ash additive technology.
Testing in Medium-Duty Diesel Engine:
[0049] The crankcase of an internal combustion engine accumulates
gases and oil mist, known as blow-by. Crankcase blow-by gases can
be a source of particulate emissions, and also contribute to
increased oil consumption, deposit build-up on pistons and liners,
and reduce engine cleanliness. Some IC engines use closed crankcase
ventilation (CCV) systems to reduce the harmful impact of blow-by
gases on the environment. US EPA has listed CCV as a retrofit
system to reduce PM by about 10%. In the CCV system, blow-by gases
are recirculated via an oil-mist separator (OMS) to the engine air
intake system to return to the combustion process. The OMS works on
the principle of coalescence to separate the oil from the gases. As
blow-by gases pass through the medium (filters or baffles), small
oil droplets collect on the medium's surface. These oil droplets
coalesce and collect at the bottom of the OMS and return to the oil
sump. The clean blow-by gases get mixed with the engine intake air
and enter the combustion chamber via the turbocharger. Although the
modern CCV system is highly efficient, the CCV system's filtration
efficiency is limited to keep crankcase pressure under limits.
Hence some of the oil particles (mist) escape from the CCV system
and accumulate on the turbocharger compressor and form a
soot-containing deposit in the compressor. This phenomenon causes
significant deterioration of turbocharger efficiency and,
consequently, higher fuel consumption and reduction in the engine
specific power. To measure the reduction in the turbocharger
efficiency and consequent reduction in the peak torque and fuel
economy and increase in the exhaust temperature, a Ford 6.7 liter
V8 engine was used. The Ford 6.7 liter V8 engine is equipped with
direct injection common rail, exhaust gas recirculation, and
variable geometry turbocharger and is rated at 1050 lb-ft peak
torque at 1800 rpm.
[0050] In order to determine change in the turbocharger efficiency
and subsequent change in the fuel consumption, peak power, peak
torque, exhaust gas temperatures, and oil consumption, the test was
conducted in three steps.
Step 1: Fuel Consumption and Power Sweep at the Start of the
Test
[0051] At the start of the test, the engine was operated to run
power sweep and fuel efficiency tests. The fuel efficiency cycle
ran as a discrete mode cycle utilizing EPA Supplemental Emission
Testing (SET) procedure. The SET cycle consists of a 13-mode
steady-state engine dynamometer test. In each mode, the engine ran
at a specific speed and load combination for the prescribed time
and moved to the next mode. The engine repeated the 13-mode cycle
four times and measured the average fuel consumption of four cycles
in grams/minute.
[0052] A power sweep measures the diesel engine's torque (Nm) and
power (KW) produced at different engine speeds (rpm). Engine torque
and power values were generated by connecting a dynamometer to the
diesel engine and measuring the torque and power the engine can
produce at different speeds. For the given experiment, the engine
is run at 1000 rpm and the maximum torque value is recorded. This
is followed by measuring a maximum torque at next higher speed. In
the given experiment, torque and power values were recorded for
engine speeds between 1000 and 3000 rpm in 100 RPM increments.
Ford. 6.7 L engine is rated to produce peak torque at 1800 rpm and
peak power at 2800 rpm. Peak torque and peak power values were used
to compare comparative example 1 and lubricant of the
invention.
Step 2: Turbocharger Efficiency
[0053] The engine is operated at nearly full load conditions to
target 3% soot generation at the end of 100 hours. During this
stage, temperature (T.sub.in) and pressure (P.sub.in) going into
the inlet of the turbocharger compressor and temperature
(T.sub.out) and pressure (P.sub.out) coming out of the compressor
going to the charge air cooler were also measured. These
temperatures and pressures were used to calculate turbocharger
efficiency using the following equation.
.eta. C = T in .function. [ ( P out P in ) ( K - 1 ) K - 1 ] ( T
out - T in ) ##EQU00001##
[0054] Cylinder outlet (exhaust) temperature was also measured.
This stage was considered complete once the cylinder outlet
temperature exceeded 800.degree. C. (rated temperature of
turbocharger). The loss of turbocharger efficiency was noted at
this point. The point where this rise in exhaust temperature
occurred for the Comparative Example 1 lubricant, defined the test
duration for the test on the Lubricant of the Invention.
Step 3: Fuel Consumption and Power Sweep Step at the End of the
Test
[0055] Power sweep and fuel efficiency tests were conducted for
Comparative Example 1 lubricant, as mentioned in step 1. A
subsequent test on the Lubricant of the Invention was conducted as
per the procedure mentioned in steps 1-3.
[0056] Change in the turbocharger efficiency was measured
throughout the test. To calculate the loss in the turbocharger
efficiency, the measured turbocharger efficiency was compared to
the turbocharger efficiency at the start of the test, when all
engine components were clean. Table 3 summarizes the loss of
turbocharger efficiency relative to the start of test for
Comparative Example 1 and Lubricant of the Invention.
[0057] Similarly, fuel efficiency change (%), loss of peak power,
loss of peak torque, increase in the exhaust gas temperatures were
calculated by subtracting values of each parameter at the end of
the test and at the start of the test. Table 3 summarizes these
parameters for Comparative Example 1 and Lubricant of the
Invention.
TABLE-US-00004 Comparative Lubricant of Examples Example 1 the
Invention 1 Loss in the turbocharger efficiency 13.5 0.6 relative
to SOT (%) 2 Loss in fuel economy relative to 7.33 1.12 SOT (%) 3
Loss in the peak torque relative to 78.7 9.4 SOT (N m) 4 Loss in
the peak power relative to 25.3 5.1 SOT (KW) 5 Increase in exhaust
manifold temp. 55.4 4.3 relative to SOT (.degree. C.) 6 Total oil
consumption at EOT (grams) 7757.62 6335
[0058] As shown in Table 3, the Lubricant of the Invention shows a
smaller turbocharger efficiency loss, smaller fuel economy loss,
smaller peak power loss, smaller peak torque loss, smaller increase
in the exhaust gas temperature and less total oil consumption than
Comparative Example 1.
* * * * *