U.S. patent application number 15/873075 was filed with the patent office on 2018-07-26 for lubricating oil compositions and method for preventing or reducing low speed pre-ignition in direct injected spark-ignited engines.
The applicant listed for this patent is Chevron Oronite Company LLC. Invention is credited to Ian G. Elliott, Willem Van Dam.
Application Number | 20180208872 15/873075 |
Document ID | / |
Family ID | 61569386 |
Filed Date | 2018-07-26 |
United States Patent
Application |
20180208872 |
Kind Code |
A1 |
Elliott; Ian G. ; et
al. |
July 26, 2018 |
LUBRICATING OIL COMPOSITIONS AND METHOD FOR PREVENTING OR REDUCING
LOW SPEED PRE-IGNITION IN DIRECT INJECTED SPARK-IGNITED ENGINES
Abstract
A lubricant composition for a direct injected, boosted, spark
ignited internal combustion engine that contains at least one
potassium and/or lithium-containing compound is disclosed. This
disclosure also relates to a method for preventing or reducing low
speed pre-ignition in an engine lubricated with a formulated oil.
The formulated oil has a composition comprising at least one oil
soluble or oil dispersible potassium and/or lithium compound.
Inventors: |
Elliott; Ian G.; (Vacaville,
CA) ; Van Dam; Willem; (Novato, CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Chevron Oronite Company LLC |
San Ramon |
CA |
US |
|
|
Family ID: |
61569386 |
Appl. No.: |
15/873075 |
Filed: |
January 17, 2018 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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62448621 |
Jan 20, 2017 |
|
|
|
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
C10M 2207/028 20130101;
C10M 2215/064 20130101; C10N 2040/255 20200501; C10M 169/04
20130101; C10M 2205/02 20130101; C10N 2030/52 20200501; C10N
2060/14 20130101; C10M 2207/262 20130101; C10M 2215/28 20130101;
C10M 2227/066 20130101; C10N 2040/25 20130101; C10M 2203/1025
20130101; C10N 2010/02 20130101; C10M 141/12 20130101; C10M
2223/045 20130101; C10M 2219/046 20130101 |
International
Class: |
C10M 169/04 20060101
C10M169/04 |
Claims
1. A method for preventing or reducing low speed pre-ignition in a
direct injected, boosted, spark ignited internal combustion engine,
said method comprising the step of lubricating the crankcase of the
engine with a lubricating oil composition comprising from about 300
to about 3500 ppm of metal from at least one potassium-containing
compound, based on the total weight of the lubricating oil.
2. The method of claim 1, wherein the engine is operated under a
load with a break mean effective pressure (BMEP) of from about 12
to about 30 bars.
3. The method of claim 1, wherein the engine is operated at speeds
between 500 and 3,000 rpm.
4. The method of claim 1, wherein the potassium-containing compound
is a potassium-containing detergent.
5. The method of claim 4, wherein the detergent comprises one or
more of a sulfonate detergent, a phenate detergent, a carboxylate
detergent, a salicylate detergent, or combinations thereof
6. The method of claim 1, wherein the lubricant composition further
comprises at least one other additive selected from an ashless
dispersant, an ashless antioxidant, a phosphorus- containing
anti-wear additive, a friction modifier, and a polymeric viscosity
modifier.
7. The method of any one of claims 1 to 6, wherein there is a
reduction in the number of LSPI events of at least 50 percent, at
least 60 percent, at least 70 percent, at least 80 percent, at
least 90 percent, at least 95 percent.
8. The method of any one of claims 1 to 7, wherein the low speed
pre-ignition events are reduced to less than 10 LSPI events per
100,000 combustion events.
9. The method of any one of claims 1 to 8, wherein the low speed
pre-ignition events are reduced to less than 5 LSPI events per
100,000 combustion events.
10. A lubricating engine oil composition for a direct injected,
boosted, spark ignited internal combustion engine comprising from
about 300 to about 3500 ppm of metal from at least one
potassium-containing compound, based on the total weight of the
lubricating oil.
11. A lubricating engine oil composition comprising a lubricating
oil base stock as a major component; and at least one
potassium-containing compound, as a minor component; and wherein
the engine exhibits greater than 50% reduced low speed
pre-ignition, based on normalized low speed pre-ignition (LSPI)
counts per 100,000 engine cycles, engine operation at between 500
and 3,000 revolutions per minute and brake mean effective pressure
(BMEP) between 10 and 30 bar, as compared to low speed pre-ignition
performance achieved in an engine using a lubricating oil that does
not comprise the at least one potassium-containing compound.
12. The lubricating engine oil composition according to claim 11,
wherein the amount of metal from the potassium-containing compound
is from about 300 to about 3500 ppm, based on the total weight of
the lubricating oil.
13. Use of a at least one potassium-containing compound for
preventing or reducing low speed pre-ignition in a direct injected,
boosted, spark ignited internal combustion engine.
14. Use of claim 13, wherein the at least one potassium-containing
compound is present in from about 300 to about 3500 ppm of metal
from the at least one potassium-containing compound, based on the
total weight of the lubricating oil.
15. A method for preventing or reducing low speed pre-ignition in a
direct injected, boosted, spark ignited internal combustion engine,
said method comprising the step of lubricating the crankcase of the
engine with a lubricating oil composition comprising from about 100
to about 900 ppm of metal from at least one lithium-containing
compound, based on the total weight of the lubricating oil.
16. The method of claim 15, wherein the engine is operated under a
load with a break mean effective pressure (BMEP) of from about 12
to about 30 bars.
17. The method of claim 15, wherein the engine is operated at
speeds between 500 and 3,000 rpm.
18. The method of claim 15, wherein the lithium-containing compound
is a lithium- containing detergent.
19. The method of claim 18, wherein the detergent comprises one or
more of a sulfonate detergent, a phenate detergent, a carboxylate
detergent, a salicylate detergent, or combinations thereof
20. The method of claim 15, wherein the lubricant composition
further comprises at least one other additive selected from an
ashless dispersant, an ashless antioxidant, a phosphorus-
containing anti-wear additive, a friction modifier, and a polymeric
viscosity modifier.
21. The method of any one of claims 15 to 20, wherein there is a
reduction in the number of LSPI events of at least 50 percent, at
least 60 percent, at least 70 percent, at least 80 percent, at
least 90 percent, at least 95 percent.
22. The method of any one of claims 15 to 21, wherein the low speed
pre-ignition events are reduced to less than 10 LSPI events per
100,000 combustion events.
23. The method of any one of claims 15 to 22, wherein the low speed
pre-ignition events are reduced to less than 5 LSPI events per
100,000 combustion events.
24. A lubricating engine oil composition for a direct injected,
boosted, spark ignited internal combustion engine comprising from
about 100 to about 900 ppm of metal from at least one
lithium-containing compound, based on the total weight of the
lubricating oil.
25. A lubricating engine oil composition comprising a lubricating
oil base stock as a major component; and at least one
lithium-containing compound, as a minor component; and wherein the
engine exhibits greater than 50% reduced low speed pre-ignition,
based on normalized low speed pre-ignition (LSPI) counts per
100,000 engine cycles, engine operation at between 500 and 3,000
revolutions per minute and brake mean effective pressure (BMEP)
between 10 and 30 bar, as compared to low speed pre-ignition
performance achieved in an engine using a lubricating oil that does
not comprise the at least one lithium-containing compound.
26. The lubricating engine oil composition according to claim 25,
wherein the amount of metal from the lithium-containing compound is
from about 300 to 3500 ppm, based on the total weight of the
lubricating oil.
27. Use of a at least one lithium-containing compound for
preventing or reducing low speed pre-ignition in a direct injected,
boosted, spark ignited internal combustion engine.
28. Use of claim 27, wherein the at least one lithium-containing
compound is present in from about 100 to about 900 ppm of metal
from the at least one lithium-containing compound, based on the
total weight of the lubricating oil.
Description
[0001] This application claims priority to U.S. Provisional Patent
Application No. 62/448,621 which was filed on Jan. 20, 2017.
FIELD OF THE INVENTION
[0002] This disclosure relates to a lubricant composition for a
direct injected, boosted, spark ignited internal combustion engine
that contains at least one potassium and/or lithium-containing
compound. This disclosure also relates to a method for preventing
or reducing low speed pre-ignition in an engine lubricated with a
formulated oil. The formulated oil has a composition comprising at
least one oil soluble or oil dispersible potassium and/or lithium
compound.
BACKGROUND OF THE INVENTION
[0003] One of the leading theories surrounding the cause of low
speed pre-ignition (LSPI) is at least in part, due to auto-ignition
of engine oil droplets that enter the engine combustion chamber
from the piston crevice under high pressure, during periods in
which the engine is operating at low speeds, and compression stroke
time is longest (Amann et al. SAE 2012-01-1140).
[0004] Although engine knocking and pre-ignition problems can be
and are being resolved by optimization of internal engine
components and by the use of new component technology such as
electronic controls and knock sensors, modification of the
lubricating oil compositions used to lubricate such engines would
be desirable.
DESCRIPTION OF RELATED ART
[0005] U.S. Patent Application Nos. US20140165942, US20150322367,
US20150322368, US20150322369, US20150322372, US20150307802,
20160348028, foreign application JP2014152301, and international
applications WO2015042337, WO2015042340, WO2015042341,
WO2015023559, WO2015114920 disclose methods and/or formulations to
address low speed pre-ignition as it relates to the lubricant.
Non-patent publications that discuss the problem of LSPI and
potential lubricant solutions include; Dahnz et al. SAE
2010-01-0355, Zadeh et al. SAE 2011-01-0340, Takeuchi et al. SAE
2012-01-1615, Amann et al. SAE 2012-01-1140, Hirano et al. SAE
2013-01-2569, Okada et al. SAE 2014-01-1218, Miyasaka et al. SAE
2014-32-0092, Miura et al. SAE 2015-32-0771, Moriyoshi et al. SAE
2015-01-0755 and SAE 2015-01-0756, Morikawa et al. SAE
2015-01-1870, Moriyoshi et al. SAE 2015-01-1865, Onodera et al. SAE
2015-01-2027, Welling et al. SAE 2014-01-1213, Amann et al. SAE
2011-01-0342, and Zaccadi et al. SAE 2014-01-2688.
[0006] The present inventors have discovered a solution for
addressing the problem of LSPI through the use of potassium and/or
lithium containing additives.
SUMMARY OF THE INVENTION
[0007] Provided herein is a method for preventing or reducing low
speed pre-ignition in a direct injected, boosted, spark ignited
internal combustion engine, said method comprising the step of
lubricating the crankcase of the engine with a lubricating oil
composition comprising from about 300 to about 3500 ppm of metal
from at least one potassium-containing compound, based on the total
weight of the lubricating oil.
[0008] Also provided is a method for preventing or reducing low
speed pre-ignition in a direct injected, boosted, spark ignited
internal combustion engine, said method comprising the step of
lubricating the crankcase of the engine with a lubricating oil
composition comprising from about 100 to about 900 ppm of metal
from at least one lithium-containing compound, based on the total
weight of the lubricating oil.
DETAILED DESCRIPTION OF THE INVENTION
Definitions
[0009] The term "boosting" is used throughout the specification.
Boosting refers to running an engine at higher intake pressures
than in naturally aspirated engines. A boosted condition can be
reached by use of a turbocharger (driven by exhaust) or a
supercharger (driven by the engine). Using smaller engines that
provide higher power densities has allowed engine manufacturers to
provide excellent performance while reducing frictional and pumping
losses. This is accomplished by increasing boost pressures with the
use of turbochargers or mechanical superchargers, and by
down-speeding the engine by using higher transmission gear ratios
allowed by higher torque generation at lower engine speeds.
However, higher torque at lower engine speeds has been found to
cause random pre-ignition in engines at low speeds, a phenomenon
known as Low Speed Pre-Ignition, or LSPI, resulting in extremely
high cylinder peak pressures, which can lead to catastrophic engine
failure. The possibility of LSPI prevents engine manufacturers from
fully optimizing engine torque at lower engine speed in such
smaller, high-output engines.
[0010] As used herein, the following terms have the following
meanings unless expressly stated to the contrary: The term "alkali
or alkaline metal" refers to lithium or potassium. The term
"oil-soluble" refers to a material that is soluble in mineral oil
to the extent of at least about one gram per liter at 25.degree.
C.
[0011] The term "sulfated ash" as used herein refers to the
non-combustible residue resulting from detergents and metallic
additives in lubricating oil. Sulfated ash may be determined
using
[0012] The term "Total Base Number" or "TBN" as used herein refers
to the amount of base equivalent to milligrams of KOH in one gram
of sample. Thus, higher TBN numbers reflect more alkaline products,
and therefore a greater alkalinity. TBN was determined using ASTM D
2896 test. Unless otherwise specified, all percentages are in
weight percent.
[0013] In general, the level of sulfur in the lubricating oil
compositions of the present invention is less than or equal to
about 0.7 wt. %, based on the total weight of the lubricating oil
composition, e.g., a level of sulfur of about 0.01 wt. % to about
0.70 wt. %, 0.01 to 0.6 wt.%, 0.01 to 0.5 wt.%, 0.01 to 0.4 wt.%,
0.01 to 0.3 wt.%, 0.01 to 0.2 wt.%, 0.01 wt. % to 0.10 wt. %. In
one embodiment, the level of sulfur in the lubricating oil
compositions of the present invention is less than or equal to
about 0.60 wt. %, less than or equal to about 0.50 wt. %, less than
or equal to about 0.40 wt. %, less than or equal to about 0.30 wt.
%, less than or equal to about 0.20 wt. %, less than or equal to
about 0.10 wt. % based on the total weight of the lubricating oil
composition.
[0014] In one embodiment, the levels of phosphorus in the
lubricating oil compositions of the present invention is less than
or equal to about 0.09 wt. %, based on the total weight of the
lubricating oil composition, e.g., a level of phosphorus of about
0.01 wt. % to about 0.09 wt. %. In one embodiment, the levels of
phosphorus in the lubricating oil compositions of the present
invention is less than or equal to about 0.08 wt. %, based on the
total weight of the lubricating oil composition, e.g., a level of
phosphorus of about 0.01 wt. % to about 0.08 wt. %. In one
embodiment, the levels of phosphorus in the lubricating oil
compositions of the present invention is less than or equal to
about 0.07 wt. %, based on the total weight of the lubricating oil
composition, e.g., a level of phosphorus of about 0.01 wt. % to
about 0.07 wt. %. In one embodiment, the levels of phosphorus in
the lubricating oil compositions of the present invention is less
than or equal to about 0.05 wt. %, based on the total weight of the
lubricating oil composition, e.g., a level of phosphorus of about
0.01 wt. % to about 0.05 wt. %.
[0015] In one embodiment, the level of sulfated ash produced by the
lubricating oil compositions of the present invention is less than
or equal to about 1.60 wt. % as determined by ASTM D 874, e.g., a
level of sulfated ash of from about 0.10 to about 1.60 wt. % as
determined by ASTM D 874. In one embodiment, the level of sulfated
ash produced by the lubricating oil compositions of the present
invention is less than or equal to about 1.00 wt. % as determined
by ASTM D 874, e.g., a level of sulfated ash of from about 0.10 to
about 1.00 wt. % as determined by ASTM
[0016] D 874. In one embodiment, the level of sulfated ash produced
by the lubricating oil compositions of the present invention is
less than or equal to about 0.80 wt. % as determined by ASTM D 874,
e.g., a level of sulfated ash of from about 0.10 to about 0.80 wt.
% as determined by ASTM D 874. In one embodiment, the level of
sulfated ash produced by the lubricating oil compositions of the
present invention is less than or equal to about 0.60 wt. % as
determined by ASTM D 874, e.g., a level of sulfated ash of from
about 0.10 to about 0.60 wt. % as determined by ASTM D 874.
[0017] Low Speed Pre-Ignition is most likely to occur in
direct-injected, boosted (turbocharged or supercharged),
spark-ignited (gasoline) internal combustion engines that, in
operation, generate a break mean effective pressure level of
greater than about 15 bar (peak torque), such as at least about 18
bar, particularly at least about 20 bar at engine speeds of from
about 1500 to about 2500 rotations per minute (rpm), such as at
engine speeds of from about 1500 to about 2000 rpm. As used herein,
break mean effective pressure (BMEP) is defined as the work
accomplished during one engine cycle, divided by the engine swept
volume; the engine torque normalized by engine displacement. The
word "brake" denotes the actual torque/power available at the
engine flywheel, as measured on a dynamometer. Thus, BMEP is a
measure of the useful power output of the engine.
[0018] In one embodiment of the invention, the engine is operated
at speeds between 500 rpm and 3000 rpm, or 800 rpm to 2800 rpm, or
even 1000 rpm to 2600 rpm. Additionally, the engine may be operated
with a break mean effective pressure of 10 bars to 30 bars, or 12
bars to 24 bars.
[0019] LSPI events, while comparatively uncommon, may be
catastrophic in nature. Hence drastic reduction or even elimination
of LSPI events during normal or sustained operation of a direct
fuel injection engine is desirable. In one embodiment, the method
of the invention is such that there are less than 15 LSPI events
per 100,000 combustion events or less than 10 LSPI events per
100,000 combustion events. In one embodiment, there may be less
than 5 LSPI events per 100,000 combustion events, less than 4 LSPI
events per 100,000 combustion events, less than 3 LSPI events per
100,000 combustion events, less than 2 LSPI events per 100,000
combustion events, less than 1 LSPI event per 100,000 combustion
events, or there may be 0 LSPI events per 100,000 combustion
events.
[0020] Therefore, in an aspect the present disclosure provides a
method for preventing or reducing low speed pre-ignition in a
direct injected, boosted, spark ignited internal combustion engine,
said method comprising the step of lubricating the crankcase of the
engine with a lubricating oil composition comprising at least one
potassium and/or lithium-containing compound. In one embodiment,
the amount of metal from the at least one potassium compound is
from about 400 to about 3000 ppm, or from about 500 to about 2500
ppm, from about 600 to about 2500 ppm, or from about 700 to about
2500 ppm, or from about 800 ppm to about 2500 ppm, or from about
900 to about 2500 ppm, or from about 1000 to about 2500 ppm. In one
embodiment, the amount of metal from the at least one
lithium-containing compound is from about 100 to about 1000 ppm, or
from about 100 to about 900 ppm, from about 100 to about 800 ppm,
or from about 100 to about 700 ppm, or from about 100 ppm to about
600 ppm, or from about 100 to about 500 ppm, or from about 100 to
about 400 ppm. In one embodiment, all of the metal in the
lubricating oil composition is derived from the potassium compound.
In one embodiment, all of the metal in the lubricating oil
composition is derived from the lithium compound.
[0021] In one embodiment, the method of the invention provides a
reduction in the number of LSPI events of at least 10 percent, or
at least 20 percent, or at least 30 percent, or at least 50
percent, or at least 60 percent, or at least 70 percent, or at
least 80 percent, or at least 90 percent, or at least 95
percent.
[0022] It has now been found that the occurrence of LSPI in engines
susceptible to the occurrence of LSPI can be reduced by lubricating
such engines with lubricating oil compositions containing a
potassium and/or lithium compound.
[0023] In another aspect, the present disclosure provides a method
for reducing the severity of low speed pre-ignition events in a
direct injected, boosted, spark ignited internal combustion engine,
said method comprising the step of lubricating the crankcase of the
engine with a lubricating oil composition comprising at least one
potassium and/or lithium-containing compound. LSPI events are
determined by monitoring peak cylinder pressure (PP) and mass
fraction burn (MFB) of the fuel charge in the cylinder. When either
or both criteria are met, it can be said that an LSPI event has
occurred. The threshold for peak cylinder pressure varies by test,
but is typically 4-5 standard deviations above the average cylinder
pressure. Likewise, the MFB threshold is typically 4-5 standard
deviations earlier than the average MFB (represented in crank angle
degrees). LSPI events can be reported as average events per test,
events per 100,000 combustion cycles, events per cycle, and/or
combustion cycles per event. In one embodiment, the number of LSPI
events, where both MFB02 and Peak Pressure (PP) Requirements that
were greater than 90 bar of pressure, is less than 5 events, less
than 4 events, less than 3 events, less than 2 events, or less than
1 event. In one embodiment, the number of LSPI events that were
greater than 90 bar was zero events, or in other words completely
suppressed LSPI events greater than 90 bar. In one embodiment, the
number of LSPI events where both MFB02 and Peak Pressure (PP)
Requirements that were greater than 100 bar of pressure is less
than 5 events, less than 4 events, less than 3 events, less than 2
events, or less than 1 event. In one embodiment, the number of LSPI
events that were greater than 100 bar was zero events, or in other
words completely suppressed LSPI events greater than 100 bar. In
one embodiment, the number of LSPI events where both MFB02 and Peak
Pressure (PP) Requirements that were greater than 110 bar of
pressure is less than 5 events, less than 4 events, less than 3
events, less than 2 events, or less than 1 event. In one
embodiment, the number of LSPI events that were greater than 110
bar was zero events, or in other words completely suppressed LSPI
events greater than 110 bar. For example, the number of LSPI events
where both MFB02 and Peak Pressure (PP) Requirements that were
greater than 120 bar of pressure is less than 5 events, less than 4
events, less than 3 events, less than 2 events, or less than 1
event. In one embodiment, the number of LSPI events that were
greater than 120 bar was zero events, or in other words completely
suppressed very severe LSPI events (i.e., events greater than 120
bar).
[0024] It has now been found that the occurrence of LSPI in engines
susceptible to the occurrence of LSPI can be reduced by lubricating
such engines with lubricating oil compositions containing a
potassium and/or lithium-containing compound.
[0025] The disclosure further provides the method described herein
in which the engine is fueled with a liquid hydrocarbon fuel, a
liquid nonhydrocarbon fuel, or mixtures thereof.
[0026] The disclosure further provides the method described herein
in which the engine is fueled by natural gas, liquefied petroleum
gas (LPG), compressed natural gas (CNG), or mixtures thereof.
[0027] Lubricating oil compositions suitable for use as passenger
car motor oils conventionally comprise a major amount of oil of
lubricating viscosity and minor amounts of performance enhancing
additives, including ash-containing compounds. Conveniently,
potassium and/or lithium is introduced into the lubricating oil
compositions used in the practice of the present disclosure by one
or more potassium and/or lithium containing compounds. One class of
compounds capable of this are detergents. Suitable detergent
architectures are described herein.
Oil of Lubricating viscosity/Base Oil Component
[0028] The oil of lubricating viscosity for use in the lubricating
oil compositions of this disclosure, also referred to as a base
oil, is typically present in a major amount, e.g., an amount of
greater than 50 wt. %, preferably greater than about 70 wt. %, more
preferably from about 80 to about 99.5 wt. % and most preferably
from about 85 to about 98 wt. %, based on the total weight of the
composition. The expression "base oil" as used herein shall be
understood to mean a base stock or blend of base stocks which is a
lubricant component that is produced by a single manufacturer to
the same specifications (independent of feed source or
manufacturer's location); that meets the same manufacturer's
specification; and that is identified by a unique formula, product
identification number, or both. The base oil for use herein can be
any presently known or later-discovered oil of lubricating
viscosity used in formulating lubricating oil compositions for any
and all such applications, e.g., engine oils, marine cylinder oils,
functional fluids such as hydraulic oils, gear oils, transmission
fluids, etc. Additionally, the base oils for use herein can
optionally contain viscosity index improvers, e.g., polymeric
alkylmethacrylates; olefinic copolymers, e.g., an
ethylene-propylene copolymer or a styrene-butadiene copolymer; and
the like and mixtures thereof.
[0029] As one skilled in the art would readily appreciate, the
viscosity of the base oil is dependent upon the application.
Accordingly, the viscosity of a base oil for use herein will
ordinarily range from about 2 to about 2000 centistokes (cSt) at
100.degree. Centigrade (C.). Generally, individually the base oils
used as engine oils will have a kinematic viscosity range at
100.degree. C. of about 2 cSt to about 30 cSt, preferably about 3
cSt to about 16 cSt, and most preferably about 4 cSt to about 12
cSt and will be selected or blended depending on the desired end
use and the additives in the finished oil to give the desired grade
of engine oil, e.g., a lubricating oil composition having an SAE
Viscosity Grade of OW, OW-8, OW-12, OW-16, OW-20, OW-26, OW-30,
OW-40, OW-50, OW-60, 5W, 5W-20, 5W-30, 5W-40, 5W-50, 5W-60, 10W,
10W-20, 10W-30, 10W-40, 10W-50, 15W, 15W-20, 15W-30, 15W-40, 30, 40
and the like. Group I base oils generally refer to a petroleum
derived lubricating base oil having a saturates content of less
than 90 wt. % (as determined by ASTM D 2007) and/or a total sulfur
content of greater than 300 ppm (as determined by ASTM D 2622, ASTM
D 4294, ASTM D 4297 or ASTM D 3120) and has a viscosity index (VI)
of greater than or equal to 80 and less than 120 (as determined by
ASTM D 2270).
[0030] Group II base oils generally refer to a petroleum derived
lubricating base oil having a total sulfur content equal to or less
than 300 parts per million (ppm) (as determined by ASTM D 2622,
ASTM D 4294, ASTM D 4927 or ASTM D 3120), a saturates content equal
to or greater than 90 weight percent (as determined by ASTM D
2007), and a viscosity index (VI) of between 80 and 120 (as
determined by ASTM D 2270).
[0031] Group III base oils generally refer to a petroleum derived
lubricating base oil having less than 300 ppm sulfur, a saturates
content greater than 90 weight percent, and a VI of 120 or
greater.
[0032] Group IV base oils are polyalphaolefins (PAOs).
[0033] Group V base oils include all other base oils not included
in Group I, II, III, or IV. The lubricating oil composition can
contain minor amounts of other base oil components. For example,
the lubricating oil composition can contain a minor amount of a
base oil derived from natural lubricating oils, synthetic
lubricating oils or mixtures thereof. Suitable base oil includes
base stocks obtained by isomerization of synthetic wax and slack
wax, as well as hydrocracked base stocks produced by hydrocracking
(rather than solvent extracting) the aromatic and polar components
of the crude.
[0034] Suitable natural oils include mineral lubricating oils such
as, for example, liquid petroleum oils, solvent-treated or
acid-treated mineral lubricating oils of the paraffinic, naphthenic
or mixed paraffinic-naphthenic types, oils derived from coal or
shale, animal oils, vegetable oils (e.g., rapeseed oils, castor
oils and lard oil), and the like.
[0035] Suitable synthetic lubricating oils include, but are not
limited to, hydrocarbon oils and halo-substituted hydrocarbon oils
such as polymerized and interpolymerized olefins, e.g.,
polybutylenes, polypropylenes, propylene-isobutylene copolymers,
chlorinated polybutylenes, poly(1-hexenes), poly(1-octenes),
poly(1-decenes), and the like and mixtures thereof; alkylbenzenes
such as dodecylbenzenes, tetradecylbenzenes, dinonylbenzenes,
di(2-ethylhexyl)-benzenes, and the like; polyphenyls such as
biphenyls, terphenyls, alkylated polyphenyls, and the like;
alkylated diphenyl ethers and alkylated diphenyl sulfides and the
derivative, analogs and homologs thereof and the like.
[0036] Other synthetic lubricating oils include, but are not
limited to, oils made by polymerizing olefins of less than 5 carbon
atoms such as ethylene, propylene, butylenes, isobutene, pentene,
and mixtures thereof. Methods of preparing such polymer oils are
well known to those skilled in the art.
[0037] Additional synthetic hydrocarbon oils include liquid
polymers of alpha olefins having the proper viscosity. Especially
useful synthetic hydrocarbon oils are the hydrogenated liquid
oligomers of C.sub.6 to C.sub.12 alpha olefins such as, for
example, 1-decene trimer.
[0038] Another class of synthetic lubricating oils include, but are
not limited to, alkylene oxide polymers, i.e., homopolymers,
interpolymers, and derivatives thereof where the terminal hydroxyl
groups have been modified by, for example, esterification or
etherification. These oils are exemplified by the oils prepared
through polymerization of ethylene oxide or propylene oxide, the
alkyl and phenyl ethers of these polyoxyalkylene polymers (e.g.,
methyl poly propylene glycol ether having an average molecular
weight of 1,000, diphenyl ether of polyethylene glycol having a
molecular weight of 500-1000, diethyl ether of polypropylene glycol
having a molecular weight of 1,000-1,500, etc.) or mono- and
polycarboxylic esters thereof such as, for example, the acetic
esters, mixed C.sub.3-Cs fatty acid esters, or the C.sub.13 oxo
acid diester of tetraethylene glycol.
[0039] Yet another class of synthetic lubricating oils include, but
are not limited to, the esters of dicarboxylic acids e.g., phthalic
acid, succinic acid, alkyl succinic acids, alkenyl succinic acids,
maleic acid, azelaic acid, suberic acid, sebacic acid, fumaric
acid, adipic acid, linoleic acid dimer, malonic acids, alkyl
malonic acids, alkenyl malonic acids, etc., with a variety of
alcohols, e.g., butyl alcohol, hexyl alcohol, dodecyl alcohol,
2-ethylhexyl alcohol, ethylene glycol, diethylene glycol monoether,
propylene glycol, etc. Specific examples of these esters include
dibutyl adipate, di(2-ethylhexyl)sebacate, di-n-hexyl fumarate,
dioctyl sebacate, diisooctyl azelate, diisodecyl azelate, dioctyl
phthalate, didecyl phthalate, dieicosyl sebacate, the 2-ethylhexyl
diester of linoleic acid dimer, the complex ester formed by
reacting one mole of sebacic acid with two moles of tetraethylene
glycol and two moles of 2-ethylhexanoic acid and the like.
[0040] Esters useful as synthetic oils also include, but are not
limited to, those made from carboxylic acids having from about 5 to
about 12 carbon atoms with alcohols, e.g., methanol, ethanol, etc.,
polyols and polyol ethers such as neopentyl glycol, trimethylol
propane, pentaerythritol, dipentaerythritol, tripentaerythritol,
and the like.
[0041] Silicon-based oils such as, for example, polyalkyl-,
polyaryl-, polyalkoxy- or polyaryloxy-siloxane oils and silicate
oils, comprise another useful class of synthetic lubricating oils.
Specific examples of these include, but are not limited to,
tetraethyl silicate, tetra-isopropyl silicate, tetra-(2-ethylhexyl)
silicate, tetra-(4-methyl-hexyl)silicate,
tetra-(p-tert-butylphenyl) silicate,
hexyl-(4-methyl-2-pentoxy)disiloxane, poly(methyl)siloxanes,
poly(methylphenyl)siloxanes, and the like. Still yet other useful
synthetic lubricating oils include, but are not limited to, liquid
esters of phosphorous containing acids, e.g., tricresyl phosphate,
trioctyl phosphate, diethyl ester of decane phosphionic acid, etc.,
polymeric tetrahydrofurans and the like.
[0042] The lubricating oil may be derived from unrefined, refined
and rerefined oils, either natural, synthetic or mixtures of two or
more of any of these of the type disclosed hereinabove. Unrefined
oils are those obtained directly from a natural or synthetic source
(e.g., coal, shale, or tar sands bitumen) without further
purification or treatment. Examples of unrefined oils include, but
are not limited to, a shale oil obtained directly from retorting
operations, a petroleum oil obtained directly from distillation or
an ester oil obtained directly from an esterification process, each
of which is then used without further treatment. Refined oils are
similar to the unrefined oils except they have been further treated
in one or more purification steps to improve one or more
properties. These purification techniques are known to those of
skill in the art and include, for example, solvent extractions,
secondary distillation, acid or base extraction, filtration,
percolation, hydrotreating, dewaxing, etc. Rerefined oils are
obtained by treating used oils in processes similar to those used
to obtain refined oils. Such rerefined oils are also known as
reclaimed or reprocessed oils and often are additionally processed
by techniques directed to removal of spent additives and oil
breakdown products.
[0043] Lubricating oil base stocks derived from the
hydroisomerization of wax may also be used, either alone or in
combination with the aforesaid natural and/or synthetic base
stocks. Such wax isomerate oil is produced by the
hydroisomerization of natural or synthetic waxes or mixtures
thereof over a hydroisomerization catalyst.
[0044] Natural waxes are typically the slack waxes recovered by the
solvent dewaxing of mineral oils; synthetic waxes are typically the
wax produced by the Fischer-Tropsch process.
[0045] Other useful fluids of lubricating viscosity include
non-conventional or unconventional base stocks that have been
processed, preferably catalytically, or synthesized to provide high
performance lubrication characteristics.
Potassium and/or Lithium Compound
[0046] The lubricating oil composition of the present invention can
contain a detergent. Metal-containing or ash-forming detergents
function as both detergents to reduce or remove deposits and as
acid neutralizers or rust inhibitors, thereby reducing wear and
corrosion and extending engine life. Detergents generally comprise
a polar head with a long hydrophobic tail. The polar head comprises
a metal salt of an acidic organic compound. The salts may contain a
substantially stoichiometric amount of the metal in which case they
are usually described as normal or neutral salts. A large amount of
a metal base may be incorporated by reacting excess metal compound
(e.g., an oxide or hydroxide) with an acidic gas (e.g., carbon
dioxide).
[0047] Detergents that may be used include oil-soluble neutral and
overbased sulfonates, phenates, sulfurized phenates,
thiophosphonates, salicylates, and naphthenates and other
oil-soluble carboxylates of potassium, lithium, or a combination
thereof.
[0048] Commercial products are generally referred to as neutral or
overbased. Overbased metal detergents are generally produced by
carbonating a mixture of hydrocarbons, detergent acid, for example:
sulfonic acid, carboxylate etc., metal oxide or hydroxides (for
example potassium/lithium oxide or potassium/lithium hydroxide) and
promoters such as xylene, methanol and water.
[0049] In one embodiment, the potassium and/or lithium detergent is
a low overbased detergent, e.g., an overbased salt having a BN
below 100. In one embodiment, the BN of a low overbased salt may be
from about 5 to about 50. In another embodiment, the BN of a low
overbased salt may be from about 10 to about 30. In yet another
embodiment, the BN of a low overbased salt may be from about 15 to
about 20.
[0050] In one embodiment, the potassium and/or lithium detergent is
a medium overbased detergent, e.g., an overbased salt having a BN
from about 100 to about 250. In one embodiment, the BN of a medium
overbased salt may be from about 100 to about 200. In another
embodiment, the BN of a medium overbased salt may be from about 125
to about 175.
[0051] In one embodiment, the potassium and/or lithium detergent is
a high overbased detergent, e.g., an overbased salt having a BN
above 250. In one embodiment, the BN of a high overbased salt may
be from about 250 to about 550.
[0052] In one embodiment, the potassium and/or lithium detergent is
a neutral detergent in that is does not include an overbasing step
in its manufacture. In one embodiment, the potassium and/or lithium
detergent is an overbased salt having a BN above 550.
[0053] In one embodiment, the detergent can be one or more
potassium and/or lithium metal salts of an alkyl-substituted
hydroxyaromatic carboxylic acid. Suitable hydroxyaromatic compounds
include mononuclear monohydroxy and polyhydroxy aromatic
hydrocarbons having 1 to 4, and preferably 1 to 3, hydroxyl groups.
Suitable hydroxyaromatic compounds include phenol, catechol,
resorcinol, hydroquinone, pyrogallol, cresol, and the like. The
preferred hydroxyaromatic compound is phenol.
[0054] The alkyl substituted moiety of the potassium and/or lithium
metal salts of an alkyl-substituted hydroxyaromatic carboxylic acid
is derived from an alpha olefin having from about 10 to about 80
carbon atoms. The olefins employed may be linear, isomerized
linear, branched or partially branched linear. The olefin may be a
mixture of linear olefins, a mixture of isomerized linear olefins,
a mixture of branched olefins, a mixture of partially branched
linear or a mixture of any of the foregoing.
[0055] In one embodiment, the mixture of linear olefins that may be
used is a mixture of normal alpha olefins selected from olefins
having from about 12 to about 30 carbon atoms per molecule. In one
embodiment, the normal alpha olefins are isomerized using at least
one of a solid or liquid catalyst.
[0056] In another embodiment, the olefins are a branched olefinic
propylene oligomer or mixture thereof having from about 20 to about
80 carbon atoms, i.e., branched chain olefins derived from the
polymerization of propylene. The olefins may also be substituted
with other functional groups, such as hydroxy groups, carboxylic
acid groups, heteroatoms, and the like.
[0057] In one embodiment, the branched olefinic propylene oligomer
or mixtures thereof have from about 20 to about 60 carbon atoms. In
one embodiment, the branched olefinic propylene oligomer or
mixtures thereof have from about 20 to about 40 carbon atoms.
[0058] In one embodiment, at least about 75 mole % (e.g., at least
about 80 mole %, at least about 85 mole %, at least about 90 mole
%, at least about 95 mole %, or at least about 99 mole %) of the
alkyl groups contained within the potassium and/or lithium metal
salt of an alkyl-substituted hydroxyaromatic carboxylic acid such
as the alkyl groups of a potassium and/or lithium metal salt of an
alkyl-substituted hydroxybenzoic acid detergent are a C.sub.20 or
higher. In another embodiment, the potassium and/or lithium metal
salt of an alkyl-substituted hydroxyaromatic carboxylic acid is a
potassium and/or lithium metal salt of an alkyl-substituted
hydroxybenzoic acid that is derived from an alkyl-substituted
hydroxybenzoic acid in which the alkyl groups are the residue of
normal alpha-olefins containing at least 75 mole % C.sub.20 or
higher normal alpha-olefins.
[0059] In another embodiment, at least about 50 mole % (e.g., at
least about 60 mole %, at least about 70 mole %, at least about 80
mole %, at least about 85 mole %, at least about 90 mole %, at
least about 95 mole %, or at least about 99 mole %) of the alkyl
groups contained within the potassium and/or lithium metal salt of
an alkyl-substituted hydroxyaromatic carboxylic acid such as the
alkyl groups of a potassium and/or lithium metal salt of an
alkyl-substituted hydroxybenzoic acid are about C.sub.14 to about
C.sub.18.
[0060] The resulting potassium and/or lithium metal salt of an
alkyl-substituted hydroxyaromatic carboxylic acid will be a mixture
of ortho and para isomers. In one embodiment, the product will
contain about 1 to 99% ortho isomer and 99 to 1% para isomer. In
another embodiment, the product will contain about 5 to 70% ortho
and 95 to 30% para isomer.
[0061] The potassium and/or lithium metal salt of an
alkyl-substituted hydroxyaromatic carboxylic acid can be neutral or
overbased. Generally, an overbased potassium and/or lithium metal
salt of an alkyl-substituted hydroxyaromatic carboxylic acid is one
in which the BN of the potassium and/or lithium metal salt of an
alkyl-substituted hydroxyaromatic carboxylic acid has been
increased by a process such as the addition of a base source and an
acidic overbasing compound (e.g., carbon dioxide).
[0062] Sulfonates may be prepared from sulfonic acids which are
typically obtained by the sulfonation of alkyl substituted aromatic
hydrocarbons such as those obtained from the fractionation of
petroleum or by the alkylation of aromatic hydrocarbons. Examples
included those obtained by alkylating benzene, toluene, xylene,
naphthalene, diphenyl or their halogen derivatives. The alkylation
may be carried out in the presence of a catalyst with alkylating
agents having from about 3 to more than 70 carbon atoms. The
alkaryl sulfonates usually contain from about 9 to about 80 or more
carbon atoms, preferably from about 16 to about 60 carbon atoms per
alkyl substituted aromatic moiety.
[0063] The oil soluble sulfonates or alkaryl sulfonic acids may be
neutralized with oxides, hydroxides, alkoxides, carbonates,
carboxylate, sulfides, hydrosulfides, nitrates, borates and ethers
of the metal. The amount of metal compound is chosen having regard
to the desired TBN of the final product but typically ranges from
about 100 to about 220 wt. % (preferably at least about 125 wt. %)
of that stoichiometrically required.
[0064] Potassium and/or lithium metal salt of phenols and
sulfurized phenols are prepared by reaction with an appropriate
metal compound such as an oxide or hydroxide and neutral or
overbased products may be obtained by methods well known in the
art. Sulfurized phenols may be prepared by reacting a phenol with
sulfur or a sulfur containing compound such as hydrogen sulfide,
sulfur monohalide or sulfur dihalide, to form products which are
generally mixtures of compounds in which 2 or more phenols are
bridged by sulfur containing bridges.
[0065] A further potassium and/or lithium containing compound can
be one derived from a Mannich condensation product. In general,
conventional oil-soluble Mannich condensation products are formed
from the reaction of substituted phenols (i.e.,
polyisobutyl-substituted phenols) with formaldehyde and an amine or
a polyamine. For example, U.S. Pat. Nos. 7,964,543; 8,394,747;
8,455,681; 8,722,927 and 8,729,297, the disclosures of which are
incorporated in their entireties herein by reference, disclose a
Mannich condensation product of a polyisobutyl-substituted
hydroxyaromatic compound wherein the polyisobutyl group is derived
from polyisobutene containing at least 50 weight percent
methylvinylidene isomer and having a number average molecular
weight in the range of about 400 to about 5000, an aldehyde, an
amino acid or ester thereof, and an alkali metal base.
[0066] Generally, the amount of the potassium and/or lithium
containing detergent can be from about 0.001 wt. % to about 25 wt.
%, from about 0.05 wt. % to about 20 wt. %, or from about 0.1 wt. %
to about 15 wt. %, or from about 0.5 wt. % to about 5 wt. %, from
about, 1.0 wt. % to about 4.0 wt. %, based on the total weight of
the lubricating oil composition.
[0067] A large number of these detergents are well known in the art
and are commercially available. The potassium and/or lithium
containing detergents may be prepared using the procedures
described in for example, U.S. Pat. Nos. 6,235,688, 8,030,258,
8,188,020, 8,969,273, which is incorporated herein by reference in
its entirety, or by any procedure known to a person skilled in the
art.
[0068] In an aspect, the present disclosure provides a lubricating
engine oil composition for a direct injected, boosted, spark
ignited internal combustion engine comprising at least one
potassium and/or lithium-containing compound. In one embodiment,
the amount of metal from the at least one potassium compound is
from about 400 to about 3000 ppm, or from about 500 to about 2500
ppm, from about 600 to about 2500 ppm, or from about 700 to about
2500 ppm, or from about 800 ppm to about 2500 ppm, or from about
900 to about 2500 ppm, or from about 1000 to about 2500 ppm. In one
embodiment, the amount of metal from the at least one
lithium-containing compound is from about 100 to about 1000 ppm, or
from about 100 to about 900 ppm, from about 100 to about 800 ppm,
or from about 100 to about 700 ppm, or from about 100 ppm to about
600 ppm, or from about 100 to about 500 ppm, or from about 100 to
about 400 ppm. In one embodiment, all of the metal in the
lubricating oil composition is derived from the potassium compound.
In one embodiment, all of the metal in the lubricating oil
composition is derived from the lithium compound.
[0069] In one embodiment, the potassium and/or lithium-containing
compound can be combined with other conventional lubricating oil
detergent additives such as magnesium and calcium salts of those
detergent additives described herein. In one embodiment the calcium
detergent(s) can be added in an amount sufficient to provide the
lubricating oil composition from 0 to about 2400 ppm of calcium
metal, from 0 to about 2200 ppm of calcium metal, from 100 to about
2000 ppm of calcium metal, from 200 to about 1800 ppm of calcium
metal, or from about 100 to about 1800 ppm, or from about 200 to
about 1500 ppm, or from about 300 to about 1400 ppm, or from about
400 to about 1400 ppm, of calcium metal in the lubricating oil
composition. In one embodiment, the magnesium detergent(s) can be
added in an amount sufficient to provide the lubricating oil
composition from about 100 to about 1000 ppm of magnesium metal, or
from about 100 to about 600 ppm, or from about 100 to about 500
ppm, or from about 200 to about 500 ppm of magnesium metal in the
lubricating oil composition.
[0070] In one embodiment, the disclosure provides a lubricating
engine oil composition comprising a lubricating oil base stock as a
major component; and at least one potassium and/or
lithium-containing compound, as a minor component; and wherein the
engine exhibits greater than 50% reduced low speed pre-ignition,
based on normalized low speed pre-ignition (LSPI) counts per
100,000 engine cycles, engine operation at between 500 and 3,000
revolutions per minute and brake mean effective pressure (BMEP)
between 10 and 30 bar, as compared to low speed pre-ignition
performance achieved in an engine using a lubricating oil that does
not comprise the at least one potassium and/or lithium-containing
compound.
[0071] In one aspect, the disclosure provides a lubricating engine
oil composition for use in a down-sized boosted engine comprising a
lubricating oil base stock as a major component; and at least one
potassium and/or lithium-containing compound, as a minor component;
where the downsized engine ranges from about 0.5 to about 3.6
liters, from about 0.5 to about 3.0 liters, from about 0.8 to about
3.0 liters, from about 0.5 to about 2.0 liters, or from about 1.0
to about 2.0 liters. The engine can have two, three, four, five or
six cylinders.
[0072] In an aspect, the present disclosure provides the, use of a
at least one potassium and/or lithium-containing compound for
preventing or reducing low speed pre-ignition in a direct injected,
boosted, spark ignited internal combustion engine. In one
embodiment, the amount of metal from the at least one potassium
compound is from about 300 to about 3500 ppm, from about 400 to
about 3000 ppm, or from about 500 to about 2500 ppm, from about 600
to about 2500 ppm, or from about 700 to about 2500 ppm, or from
about 800 ppm to about 2500 ppm, or from about 900 to about 2500
ppm, or from about 1000 to about 2500 ppm. In one embodiment, the
amount of metal from the at least one lithium-containing compound
is from about 100 to about 1000 ppm, or from about 100 to about 900
ppm, from about 100 to about 800 ppm, or from about 100 to about
700 ppm, or from about 100 ppm to about 600 ppm, or from about 100
to about 500 ppm, or from about 100 to about 400 ppm. In one
embodiment, all of the metal in the lubricating oil composition
derives from the potassium compound. In one embodiment, all of the
metal in the lubricating oil composition is derived from the
lithium compound. In yet another embodiment, all of the metal in
the lubricating oil composition is derived from only the potassium
and lithium compound.
[0073] In an aspect, the present disclosure provides the use of a
at least one potassium and/or lithium-containing compound for
preventing or reducing low speed pre-ignition in a direct injected,
boosted, spark ignited internal combustion engine.
Lubricating Oil Additives
[0074] In addition to the dispersant described herein, the
lubricating oil composition can comprise additional lubricating oil
additives.
[0075] The lubricating oil compositions of the present disclosure
may also contain other conventional additives that can impart or
improve any desirable property of the lubricating oil composition
in which these additives are dispersed or dissolved. Any additive
known to a person of ordinary skill in the art may be used in the
lubricating oil compositions disclosed herein. Some suitable
additives have been described in Mortier et al., "Chemistry and
Technology of Lubricants", 2nd Edition, London, Springer, (1996);
and Leslie R. Rudnick, "Lubricant Additives: Chemistry and
Applications", New York, Marcel Dekker (2003), both of which are
incorporated herein by reference. For example, the lubricating oil
compositions can be blended with antioxidants, anti-wear agents,
additional detergents such as metal detergents, rust inhibitors,
dehazing agents, demulsifying agents, metal deactivating agents,
friction modifiers, pour point depressants, antifoaming agents,
co-solvents, corrosion-inhibitors, ashless dispersants,
multifunctional agents, dyes, extreme pressure agents and the like
and mixtures thereof. A variety of the additives are known and
commercially available. These additives, or their analogous
compounds, can be employed for the preparation of the lubricating
oil compositions of the disclosure by the usual blending
procedures.
[0076] For example, the lubricating oil composition of the present
invention can contain one or more friction modifiers that can lower
the friction between moving parts. Any friction modifier known by a
person of ordinary skill in the art may be used in the lubricating
oil composition. Non-limiting examples of suitable friction
modifiers include fatty carboxylic acids; derivatives (e.g.,
alcohol, esters, borated esters, amides, metal salts and the like)
of fatty carboxylic acid; mono-, di- or tri-alkyl substituted
phosphoric acids or phosphonic acids; derivatives (e.g., esters,
amides, metal salts and the like) of mono-, di- or tri-alkyl
substituted phosphoric acids or phosphonic acids; mono-, di- or
tri-alkyl substituted amines; mono- or di-alkyl substituted amides
and combinations thereof. In some embodiments examples of friction
modifiers include, but are not limited to, alkoxylated fatty
amines; borated fatty epoxides; fatty phosphites, fatty epoxides,
fatty amines, borated alkoxylated fatty amines, metal salts of
fatty acids, fatty acid amides, glycerol esters, borated glycerol
esters; and fatty imidazolines as disclosed in U.S. Pat. No.
6,372,696, the contents of which are incorporated by reference
herein; friction modifiers obtained from a reaction product of a
C.sub.4 to C.sub.75, or a C.sub.6 to C.sub.24, or a C.sub.6 to
C.sub.20, fatty acid ester and a nitrogen-containing compound
selected from the group consisting of ammonia, and an alkanolamine
and the like and mixtures thereof. The amount of the friction
modifier may vary from about 0.01 wt. % to about 10 wt. %, from
about 0.05 wt. % to about 5 wt. %, or from about 0.1 wt. % to about
3 wt. %, based on the total weight of the lubricating oil
composition.
[0077] The lubricating oil composition of the present invention can
contain one or more anti-wear agents that can reduce friction and
excessive wear. Any anti-wear agent known by a person of ordinary
skill in the art may be used in the lubricating oil composition.
Non-limiting examples of suitable anti-wear agents include zinc
dithiophosphate, metal (e.g., Pb, Sb, Mo and the like) salts of
dithiophosphates, metal (e.g., Zn, Pb, Sb, Mo and the like) salts
of dithiocarbamates, metal (e.g., Zn, Pb, Sb and the like) salts of
fatty acids, boron compounds, phosphate esters, phosphite esters,
amine salts of phosphoric acid esters or thiophosphoric acid
esters, reaction products of dicyclopentadiene and thiophosphoric
acids and combinations thereof The amount of the anti-wear agent
may vary from about 0.01 wt. % to about 5 wt. %, from about 0.05
wt. % to about 3 wt. %, or from about 0.1 wt. % to about 1 wt. %,
based on the total weight of the lubricating oil composition.
[0078] In certain embodiments, the anti-wear agent is or comprises
a dihydrocarbyl dithiophosphate metal salt, such as zinc dialkyl
dithiophosphate compounds. The metal of the dihydrocarbyl
dithiophosphate metal salt may be an alkali or alkaline earth
metal, or aluminum, lead, tin, molybdenum, manganese, nickel or
copper. In some embodiments, the metal is zinc. In other
embodiments, the alkyl group of the dihydrocarbyl dithiophosphate
metal salt has from about 3 to about 22 carbon atoms, from about 3
to about 18 carbon atoms, from about 3 to about 12 carbon atoms, or
from about 3 to about 8 carbon atoms. In further embodiments, the
alkyl group is linear or branched.
[0079] The amount of the dihydrocarbyl dithiophosphate metal salt
including the zinc dialkyl dithiophosphate salts in the lubricating
oil composition disclosed herein is measured by its phosphorus
content. In some embodiments, the phosphorus content of the
lubricating oil composition disclosed herein is from about 0.01 wt.
% to about 0.14 wt., based on the total weight of the lubricating
oil composition.
[0080] The lubricating oil composition of the invention contains a
molybdenum-containing friction modifier. The molybdenum-containing
friction modifier can be any one of the known molybdenum-containing
friction modifiers or the known molybdenum-containing friction
modifier compositions.
[0081] Preferred molybdenum-containing friction modifier is, for
example, sulfurized oxymolybdenum dithiocarbamate, sulfurized
oxymolybdenum dithiophosphate, amine-molybdenum complex compound,
oxymolybdenum diethylate amide, and oxymolybdenum monoglyceride.
Most preferred is a molybdenum dithiocarbamate friction
modifier.
[0082] The lubricating oil composition of the invention generally
contains the molybdenum-containing friction modifier in an amount
of 0.01 to 0.15 wt. % in terms of the molybdenum content.
[0083] The lubricating oil composition of the invention preferably
contains an organic oxidation inhibitor in an amount of 0.01-5 wt.
%, preferably 0.1-3 wt. %. The oxidation inhibitor can be a
hindered phenol oxidation inhibitor or a diarylamine oxidation
inhibitor. The diarylamine oxidation inhibitor is advantageous in
giving a base number originating from the nitrogen atoms. The
hindered phenol oxidation inhibitor is advantageous in producing no
NOx gas.
[0084] Examples of the hindered phenol oxidation inhibitors include
2,6-di-t-butyl-p-cresol, 4,4'-methylenebis (2,6-di-t-butylphenol),
4,4'-methylenebis(6-t-butyl-o-cresol), 4,4'-isopropylidenebis
(2,6-di-t-butylphenol), 4,4'-bis(2,6-di-t-butylphenol),
2,2'-methylenebis(4-methyl-6-t-butylphenol),
4,4'-thiobis(2-methyl-6-t-butylphenol),
2,2-thio-diethylenebis-[3-(3,5-di-t-butyl-4-hydroxyphenyl)
propionate], octyl 3-(3,5-di-t-butyl-4-hydroxyphenyl) propionate,
octadecyl 3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate, and octyl
3-(3,54-butyl-4-hydroxy-3-methylphenyl)propionate.
[0085] Examples of the diarylamine oxidation inhibitors include
alkyldiphenylamine having a mixture of alkyl groups of 4 to 9
carbon atoms, p,p'-dioctyldiphenylamine, phenyl-naphthylamine,
phenyl-naphthylamine, alkylated-naphthylamine, and alkylated
phenyl-naphthylamine.
[0086] Each of the hindered phenol oxidation inhibitor and
diarylamine oxidation inhibitor can be employed alone or in
combination. If desired, other oil soluble oxidation inhibitors can
be employed in combination with the above-mentioned oxidation
inhibitor(s).
[0087] The lubricating oil composition of the invention may further
contain an oxymolybdenum complex of succinimide, particularly a
sulfur-containing oxymolybdenum complex of succinimide. The
sulfur-containing oxymolybdenum complex of succinimide can provide
increased oxidation inhibition when it is employed in combination
with the above-mentioned phenolic or amine oxidation
inhibitors.
[0088] Lubricating oil compositions useful in the practice of the
method of the present invention preferably contain from about 10 to
about 1000 ppm, such as 30 to about 750 ppm, or 40 to about 500 ppm
of molybdenum, or about 50 to about 400 ppm (measured as atoms of
molybdenum). The inventors have shown that higher levels of calcium
detergents (i.e., calcium sulfonates, salicylates, carboxylates, or
phenates), that typically would cause multiple LSPI events, can be
used by including from as little as about 200 ppm of potassium
metal from a potassium containing compound to bring the number of
LSPI events down to acceptable levels.
[0089] This synergism coupled with the use of higher levels of
molybdenum in the formulation can further reduce the number of LSPI
events. This allows the inventors to enjoy higher levels of calcium
in the lubricating composition and the acid neutralization benefits
that come with calcium detergents. Therefore, in an embodiment, the
present disclosure provides a synergistic combination of a
potassium detergent, calcium detergent (i.e., at higher levels of
Ca, e.g., 1400-2800), and a molybdenum containing additive.
[0090] In the preparation of lubricating oil formulations it is
common practice to introduce the additives in the form of 10 to 80
wt. % active ingredient concentrates in hydrocarbon oil, e.g.
mineral lubricating oil, or other suitable solvent.
[0091] Usually these concentrates may be diluted with 3 to 100,
e.g., 5 to 40, parts by weight of lubricating oil per part by
weight of the additive package in forming finished lubricants, e.g.
crankcase motor oils. The purpose of concentrates, of course, is to
make the handling of the various materials less difficult and
awkward as well as to facilitate solution or dispersion in the
final blend.
Processes of Preparing Lubricating Oil Compositions
[0092] The lubricating oil compositions disclosed herein can be
prepared by any method known to a person of ordinary skill in the
art for making lubricating oils. In some embodiments, the base oil
can be blended or mixed with the potassium and/or lithium compounds
described herein. Optionally, one or more other additives in
additional to the potassium and/or lithium compounds can be added.
The potassium and/or lithium compounds and the optional additives
may be added to the base oil individually or simultaneously. In
some embodiments, the potassium and/or lithium compounds and the
optional additives are added to the base oil individually in one or
more additions and the additions may be in any order. In other
embodiments, the potassium and/or lithium compounds and the
additives are added to the base oil simultaneously, optionally in
the form of an additive concentrate. In some embodiments, the
solubilizing of the potassium and/or lithium compounds or any solid
additives in the base oil may be assisted by heating the mixture to
a temperature from about 25.degree. C. to about 200.degree. C.,
from about 50.degree. C. to about 150.degree. C. or from about
75.degree. C. to about 125.degree. C.
[0093] Any mixing or dispersing equipment known to a person of
ordinary skill in the art may be used for blending, mixing or
solubilizing the ingredients. The blending, mixing or solubilizing
may be carried out with a blender, an agitator, a disperser, a
mixer (e.g., planetary mixers and double planetary mixers), a
homogenizer (e.g., Gaulin homogenizers and Rannie homogenizers), a
mill (e.g., colloid mill, ball mill and sand mill) or any other
mixing or dispersing equipment known in the art.
Application of the Lubricating Oil Compositions
[0094] The lubricating oil composition disclosed herein may be
suitable for use as motor oils (that is, engine oils or crankcase
oils), in a spark-ignited internal combustion engine, particularly
a direct injected, boosted, engine that is susceptible to low speed
pre-ignition.
[0095] The following examples are presented to exemplify
embodiments of the invention but are not intended to limit the
invention to the specific embodiments set forth. Unless indicated
to the contrary, all parts and percentages are by weight. All
numerical values are approximate. When numerical ranges are given,
it should be understood that embodiments outside the stated ranges
may still fall within the scope of the invention. Specific details
described in each example should not be construed as necessary
features of the invention.
Examples
[0096] The following examples are intended for illustrative
purposes only and do not limit in any way the scope of the present
invention.
Baseline Formulation
[0097] The base line formulation contained a Group 2 base oil,
mixture of primary and secondary dialkyl zinc dithiophosphates in
an amount to provide 770 ppm phosphorus to the lubricating oil
composition, mixture of polyisobutenyl succinimide dispersants
(borated and ethylene carbonate post-treated), a molybdenum
succinimide complex in an amount to provide 180 ppm molybdenum to
the lubricating oil composition, alkylated diphenylamine
antioxidant, a borated friction modifier, foam inhibitor, a pour
point depressant, and an olefin copolymer viscosity index improver.
The lubricating oil compositions were blended into a 5W-30 or
10W-30 viscosity grade.
Example 1
[0098] A lubricating oil composition was prepared by adding 2280
ppm of potassium in the form of a potassium carboxylate (additive
concentrate: TBN 84 mg KOH/g, C.sub.20-C.sub.28 hydrocarbyl group K
content: 5.25 wt %) detergent to the formulation baseline.
Example 2
[0099] A lubricating oil composition was prepared by adding 1221
ppm of potassium in the form of a potassium carboxylate (additive
concentrate: TBN 84 mg KOH/g, C.sub.20-C.sub.28 hydrocarbyl group K
content: 5.25 wt %) detergent, and 1218 ppm of calcium in the form
of a mixture of overbased calcium sulfonate (additive concentrate:
TBN 425 mg KOH/g, C.sub.20-C.sub.24 hydrocarbyl group Ca content:
16.0 wt %) and overbased sulfurized calcium phenate (additive
concentrate: TBN 250 mg KOH/g, Ca content: 9.6 wt %) detergents to
the formulation baseline.
Example 3
[0100] A lubricating oil composition was prepared by adding 2184
ppm of potassium in the form of a potassium carboxylate (additive
concentrate: TBN 84 mg KOH/g, C.sub.20-C.sub.28 hydrocarbyl group K
content: 5.25 wt %) detergent to the formulation baseline.
Example 4
[0101] A lubricating oil composition was prepared by adding 1075
ppm of potassium in the form of a potassium carboxylate (additive
concentrate: TBN 84 mg KOH/g, C.sub.20-C.sub.28 hydrocarbyl group K
content: 5.25 wt %) detergent, and 1127 ppm of calcium in the form
of an of overbased calcium sulfonate (additive concentrate: TBN 425
mg KOH/g, C.sub.20-C.sub.24 hydrocarbyl group Ca content: 16.0 wt
%) detergent to the formulation baseline.
Example 5
[0102] A lubricating oil composition was prepared by adding 532 ppm
of potassium in the form of a potassium carboxylate (additive
concentrate: TBN 84 mg KOH/g, C.sub.20-C.sub.28 hydrocarbyl group K
content: 5.25 wt %) detergent, and 1785 ppm of calcium in the form
of a mixture of overbased calcium sulfonate (additive concentrate:
TBN 425 mg KOH/g, C.sub.20-C.sub.24 hydrocarbyl group Ca content:
16.0 wt %) and overbased sulfurized calcium phenate (additive
concentrate: TBN 250 mg KOH/g, Ca content: 9.6 wt %) detergents to
the formulation baseline..
Example 6
[0103] A lubricating oil composition was prepared by adding 404 ppm
of lithium in the form of a lithium sulfonate (additive
concentrate: TBN 500 mg KOH/g, C.sub.20-C.sub.28 hydrocarbyl group
Li content: 6.5 wt %) detergent, and 6 ppm of calcium, likely as an
impurity.
Example 7
[0104] A lubricating oil composition was prepared by adding 216 ppm
of lithium in the form of a lithium sulfonate (additive
concentrate: TBN 500 mg KOH/g, C.sub.20-C.sub.28 hydrocarbyl group
Li content: 6.5 wt %) detergent, and 1174 ppm of calcium in the
form of a mixture of overbased calcium sulfonate (additive
concentrate: TBN 425 mg KOH/g, C.sub.20-C.sub.24 hydrocarbyl group
Ca content: 16.0 wt %) and overbased sulfurized calcium phenate
(additive concentrate: TBN 250 mg KOH/g, Ca content: 9.6 wt %)
detergents to the formulation baseline.
Comparative Example 1
[0105] A lubricating oil composition was prepared by adding 2255
ppm of calcium in the form of a mixture of overbased calcium
sulfonate (additive concentrate: TBN 425 mg KOH/g,
C.sub.20-C.sub.24 hydrocarbyl group Ca content: 16.0 wt %) and
overbased sulfurized calcium phenate (additive concentrate: TBN 250
mg KOH/g, Ca content: 9.6 wt %) detergents to the formulation
baseline.
Comparative Example 2
[0106] A lubricating oil composition was prepared by adding 2359
ppm of calcium in the form of an overbased calcium sulfonate
(additive concentrate: TBN 425 mg KOH/g, C.sub.20-C.sub.24
hydrocarbyl group Ca content: 16.0 wt %).
Comparative Example 3
[0107] A lubricating oil composition was prepared by adding 2342
ppm of calcium in the form of an overbased sulfurized calcium
phenate (additive concentrate: TBN 250 mg KOH/g, Ca content: 9.6 wt
%).
Comparative Example 4
[0108] A lubricating oil composition was prepared by adding 2432
ppm of calcium in the form of an overbased calcium salicylate
(additive concentrate: TBN 175 mg KOH/g, C.sub.14-C.sub.18
hydrocarbyl group, Ca content: 6.25 wt %).
LSPI Testing
[0109] Low Speed Pre-ignition events were measured in two engines,
a Ford 2.0L Ecoboost engine and a GM 2.0L Ecotec engine. Both of
these engines are turbocharged gasoline direct injection (GDI)
engines.
[0110] The Ford Ecoboost engine is operated in four-4 hour
iterations. The engine is operated at 1750 rpm and 1.7 MPa break
mean effective pressure (BMEP) with an oil sump temperature of
95.degree. C. The engine is run for 175,000 combustion cycles in
each stage (first 170,000 valid engine cycles), and LSPI events are
counted.
[0111] Additionally, LSPI testing was conducted on a 2.0 L,
4-cylinder TGDI GM Ecotec engine. A six segment test procedure was
used to determine the number of LSPI events that occurred at two
different specified engine load and speed conditions. Each segment
of the test procedure comprised 25,000 engine cycles, where one
cycle corresponds to 720 degrees of crank shaft rotation. The first
set of conditions was 2000 RPM and 18 bar BMEP, hereafter referred
to as "High Load". The second set of conditions was 1500 RPM and
16.5 bar BMEP, hereafter referred to as "Low Load". The test
procedure comprised two segments of High Load, followed by two
segments of Low Load, followed by two segments of High Load. A 20
minute warm up at 2000 RPM and 4 bar BMEP was also conducted prior
to commencing the test procedure.
[0112] This test procedure was repeated four times for each of the
lubricants tested. LSPI events were counted during the High Load
segments only, using pressure transducers placed in each of the 4
cylinders to monitor the peak cylinder pressure.
[0113] LSPI events are determined by monitoring peak cylinder
pressure (PP) and mass fraction burn (MFB) of the fuel charge in
the cylinder. When either or both criteria are met, it can be said
that an LSPI event has occurred. The threshold for peak cylinder
pressure varies by test, but is typically 4-5 standard deviations
above the average cylinder pressure. Likewise, the MFB threshold is
typically 4-5 standard deviations earlier than the average MFB
(represented in crank angle degrees). LSPI events can be reported
as average events per test, events per 100,000 combustion cycles,
events per cycle, and/or combustion cycles per event. The results
for each of these tests are shown in Tables 1 and 2 below.
TABLE-US-00001 TABLE 1 Ford LSPI Test Results Ex. 1 Ex. 2 Ex. 5
Comp. Ex. 1 K (ppm) 2280 1221 532 0 Ca (ppm) 6 1218 1785 2255
Average Cycles "Both"* 1.25 0.5 4.5 19.25 *Counts all cycles of
LSPI where both MFB02 and Peak Pressure Requirements are met
TABLE-US-00002 TABLE 2 GM LSPI Test Results Comp. Comp. Comp. Ex. 3
Ex. 4 Ex. 2 Ex. 3 Ex. 4 K (ppm) 2184 1075 0 0 0 Ca (ppm) 7 1127
2359 2342 2432 Average 2.56 2.56 16.75 18.13 24.00 Cycles "Both"*
*Counts all cycles where both MFB02 and Peak Pressure requirements
are met
TABLE-US-00003 TABLE 3 Ford LSPI Test Results Comp. Ex. 6 Ex. 7 Ex.
1 Li (ppm) 404 216 0 Ca (ppm) 6 1174 2255 Average Cycles "Both"*
17.5 7.25 19.25 Average Cycles "Both" 5.25 1.5 13.25 with peak
pressure >90 bar Average Cycles "Both" 2 0.25 8.25 with peak
pressure >120 bar *Counts all cycles of LSPI where both MFB02
and Peak Pressure Requirements are met
[0114] The data shows that Applicant's inventive examples
comprising potassium provided significantly better LSPI performance
than the comparative examples which did not contain potassium in
both the Ford and GM engines. Furthermore, the use of potassium
containing detergents allows for the use of higher levels of
calcium containing detergents without drastically increasing LSPI
events which implies there is a synergistic effect.
[0115] Further, the data in Table 3 show the inventive examples
comprising lithium provided significantly better LSPI performance
than the comparative example which did not contain lithium in the
Ford engine. Specifically, the data show a reduction in LSPI events
of about 60 to 88% at peak pressures>90 bar, and a reduction in
LSPI events of about 73 to 96% at peak pressures>120 bar.
* * * * *