FUEL ECONOMY

ECONOMIE DE CARBURANT

English Abstract

ABSTRACT OF THE DISCLOSURE
The fuel economy of an internal combustion engine can be improved
by adding to the lubricating oil used to lubricate the crankcase of said en-
gine from 0.25 to 2 weight percent of a fatty acid ester of glycerol.

Claims

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A lubricating oil composition comprising an oil of
lubricating viscosity and from 0.25 to 2 weight percent of a
fatty acid ester of glycerol.
2. A lubricating oil of Claim 1 containing 0.40 to 1.25
weight percent of a C8-22 fatty acid ester of glycerol.
3. A lubricating oil of Claim 2 wherein said fatty acid
ester of glycerol is glycerol monooleate.
4. A lubricating oil of Claim 2 wherein said fatty acid
ester of glycerol is glycerol tallowate.
5. A method of improving the fuel economy of an internal
combustion engine comprising lubricating the crankcase of said
engine with an oil of Claim 1.
6. The method of Claim 5 wherein said engine is a
compression-ignition engine.
7. The method of Claim 5 wherein said engine is a
spark-ignition engine.

Description

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0~ LNVENT[ON
~his invention relatcs to a method ~or in~roving the fuel economy
of an internal combustion engine.
BACKGROUND OF ~IF, INV~NTION
With -the crisis associated with diminishing amounts of ossil fuel
and the rapidly increasing prices for this fuel, there has been a great deal
of interest in il~Toving fuel economy, that is, the number of miles obtained
in a given vehicle per liter of fuel.
Some fatty acid esters of glycerol are known in the industrial oil
area, for use at low concentrations. Some are known to be oiliness agents;
however, since piston and ring lubrication is predominantly hydrodynamic,
gains in fuel economy through the use of additives in the lubricating oil
which reduce the coefficient of friction in mixed lubrication will probably
be small and difficult to assess.
SUMMARY OP T~IE INVENTION
It has now been found that if 0.25 to 2 weight of a fatty acid
ester of glycerol is added to the lubricating oil used to lubricate the crank-
case of an internal combustion engine a measurable improvement in the fuel
economy, that is, the miles per liter of fuell of the engine is observed.
DETAILED DESCRIPTION OF THE INVENTION
Adding from 0.25 to 2 weight percent, and preferably from 0.40 to
1.25 weight percent of a fatty acid ester to a crankcase lubricating oil sig-
nificantly improves the fuel economy of the internal combustion engine. Spe-
clfically, lmprovements in fuel mileage of from 2 to 3% on the average or
more have been observed in engine tests. This fuel economy lmprovement can
be obtained in both compression-ignition engines, that is, diesel engines,
~ and spark-ignition engines, that is, gasoline engines.
: Fatty acid esters of glycerol can be prepared by a variety of meth-
ods well known in the art. Many of these esters, such as glycerol monooleate
and glycerol tallowate, are manufactured on a commercial scale. The esters
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useful for tllis invention are oil-soluble and are preerably prepared from
C8 to C22 fatty acicls or mixtures thereof such as are Eound in natural prod-
ucts. ~e atty acid may be saturated or unsaturated. Certain compounds
found in acids from natural sources may include licanic acid which contains
one keto group.
Preferred fatty acids are oleic, stearic, palmitic, myristic,
palmitoleic, linoleic, laur:ic, linolenic, and eleostearic, and the acids from
the natural products tallow, palm oil, olive oil, peanut oil, corn oil,
neat's foot oil and the like.
Particularly preferred acids are oleic acid and the acids rom tal-
low.
When glycerol is esterified with a fatty acid, mono-, di- and tri-
esters form. Commercial glycerol monooleate, for example, contains a large
amount of dioleate and a minor proportion of trioleate. Mono-, di- and tri-
esters and mixtures thereof are contemplated for use in this invention.
When, for the sake of convenience, the common term such as "glycerol mono-
oleate" is used, the di and trioleates are to be included within the meaning
of glycerol monooleate.
The lubricating oil to which the fatty acid ester of glycerol can
be added can be any hydrocarbon-based lubricating oil. The hydrocarbon lubri-
cating oils may be derived from synthetic or natural sources and may be par-
affinic, naphthenic or asphaltic base, or mixtures thereof. A variety of ad-
ditives are ordinarily present in lubricating oils used to lubricate modern
internal combustion engines. These additives include antioxidants, dispers-
ants, rust inhibitors, foam inhibitors, corrosion inhibitors, antiwear
agents, and a variety of other well-known additives.