DE1099259B - Knock-proof fuel for gasoline engines - Google Patents

Description

The invention relates to fuels for gasoline engines with improved knock resistance.

It is known that internal combustion engines knock under many engine operating conditions, e.g. B. with yourself changing speeds, depending on the degree of pre-ignition, the compression ratio, the ratio the fuel-air mixture, the temperatures and the pressure on the inlet side. Because of these different Operating conditions of the engine can knock it under low or heavy load. the Industry understands "low" stress as a rule, when the engine is at relatively low Speed, delayed ignition or low operating temperatures, as is normally the case with the known passenger cars is observed. On the other hand, "heavy" stress occurs at high engine speeds, Preignition, high operating temperatures or high pressures in the feed line and is z. B. the case with high-speed motor vehicle engines or normal operation of aircraft engines.

The development of internal combustion engines with high compression ratios created a need high quality fuels with increased knock resistance over the whole of the above-mentioned range of Operating conditions of engines with them. Careful refining and blending of fuel components can give a fuel whose knock resistance is satisfactory under the above-mentioned conditions is. As a rule, however, tetraethyl lead is nowadays used as an anti-knock fuel for gasoline engines

Applicant:

E. I. du Pont de Nemours and Company, Wilmington, Del. (V. St. A.)

Representative: Dipl.-Ing. E. Prince

and Dr. rer. nat. G. Hauser, patent attorneys,

Munich-Pasing, Bodenseestr. 3 a

Claimed priority:
V. St. v. America February 18, 1957

Charles Anthony Sandy and James Herbert Werntz,

Wilmington, Del. (V. St. A.),
have been named as inventors

by a content of a lithium salt of an organic secondary carboxylic acid corresponding to an amount of at least 1.3-10 ~ ² g of lithium per liter. The carbon on the one adjacent to the carboxyl group

Ali-knock resistance can be used in these fuel mixtures to improve the organic groups in the atomic atom, which cannot be easily and economically, cycloaliphatic or aromatic, and economically be obtained by refining. Tetraethyl lead is widely used because it imparts improved anti-knock properties to the engine over the wide range of engine operating conditions noted above. However, the use of tetraethyl lead has its disadvantages. With each additional addition of tetraethyl lead, only a fraction of the improvement in anti-knock properties achieved with each previous addition is achieved. Certain fuels 40 for Otto engines, especially those containing large amounts of aromatic and / or olefinic constituents, react rather poorly to tetraethyl lead, especially at the normal upper limit of 0.8 ecm tetraethyl lead per liter in motor vehicle engines 45 dust or powder or with solvents introduced or 1.2 ecm per liter in aircraft engines. be in which they either alone or together

The invention now creates over the entire operating with the additional anti-knock solutions, z. B. the in area of the engine knock-resistant fuels. The aircraft engines according to the invention used water-alcohol mixtures new fuels are much more knock-resistant than all genes or the lead-lead tetraethyl used in motor vehicle engines containing alone. In particular, they can contain 5 ° tetraethyl alcohol mixtures.

this carbon atom can form a member of a ring system. The acids to be used according to the invention suitably contain 4 to 18 carbon atoms.

The fuels according to the invention are particularly suitable for engines with a fuel injection system, since at Ordinary gasification, many fuel additives are not drawn in strongly enough to cause precipitation to prevent in the intake system over a sufficiently long operating time. The additives according to the invention however, are independent of the method by which they are inserted into the engine cylinder, effective. Although they usually enter with the fuel, they can also be used separately

which are used in aircraft engines or in the more recently built automobile engines with high compression.
The fuels according to the invention are characterized by a number of examples in which the effect of the compounds according to the invention in unleaded and leaded fuels is shown by way of comparison.

109 509 / 30P

In Examples 1 to 7, fuel samples were taken from both simple and difficult Conditions in a single cylinder engine conforming to the Waukesha ASTM D 909-49 T-Knock Test Method to determine the knock area tested, the latter with a cylinder head with four openings and is equipped with a head-controlled valve with which different compression ratios can be achieved can. The engine is mounted on a test bench with a suitable generator, which the power of the Machine absorbs. A spark plug mounted in the position usual for this type of engine, a device for Measuring the rate of pressure change and a steel plug take three of the four openings in the Cylinder head. A fuel injector made according to the Waukesha-ASTM-D 909-49 T-Knock Test Method is used inserted into the fourth opening of the head by means of an adapter and with fuel from the fuel injection pump fed. In this way, the fuel is injected directly into the combustion chamber. at If the engine is running, knocking will occur as soon as there is a hint of knocking determined by means of the device arranged in the cylinder head for measuring the pressure change. That from The signal sent out by this device leads to a cathode ray oscillograph, and the occurrence of knocking phenomena turns out to be a tearing of the pressure change curve on the screen of the oscilloscope noticeable. The engine is operated under the following conditions.

Test conditions simple. more difficult 600 1200 13th 30th 50 50 0.0800 ± 0.0005 0.0700 ± 0.0005 750 750 100 100 93 93 71 71

Speed, revolutions per minute

Pre-ignition (degrees before top dead center)

Time of fuel injection (degrees after

top dead center on intake stroke)

Air-fuel ratio

Air pressure in the suction line (mm Hg absolute) ....

Coolant temperature, ⁰ C

Intake air temperature ^{, 0 C}

Oil temperature, ⁰ C

Compression ratio

Under these operating conditions, the knock resistance of all the fuels tested here is determined by comparison the highest knock free compression ratio of these fuels to that of high quality fuels determined the mixture of isooctane and n-heptane with a rating of less than 100 and isooctane plus Tetraethyl lead with a rating of over 100 pass. The knock resistance of all fuels tested is expressed in Army-Navy rating numbers, such as they are defined in Tables VII and VIII in the ASTM Aviation Method (D 614-49 T). This method is in the ASTM Manual of Engine Test Methods for Rating Fuels published by the American Society for Testing Materials, October 1952.

These tests and the test conditions were used to evaluate anti-knock agents under the same conditions, as they occur in the operation of motor vehicles.

The gasoline used in Examples 1 to 6 is a typical commercial gasoline having an octane number of 87 as the F-I test result.

example 1

To a 0.8 ecm tetraethyl lead and 50 ecm methanol per liter of gasoline sample containing a solvent aid with a rating number of 100 among the simple test conditions and 85 under the more severe test conditions become 1.2 g of lithium 2-ethylbutyrate added per liter. The evaluation numbers then increase under the simple test conditions to 107 and under the more stringent test conditions to 96.

Example 2

A gasoline sample containing 0.8 ecm of tetraethyl lead and 50 ecm of methanol per liter as a dissolving aid with a rating of 103 under the simple test conditions and 78 under the more stringent test conditions is varied with 1.2 g of lithium 2-ethyl caproate per so that starting
Knocking phenomena are noticeable

Liter offset. The rating numbers then increase to 115 and below under the simple test conditions the stricter test conditions to 87.

Example 3

A 0.8 ecm of lead tetraethyl and 50 ecm of methanol per Liters of gasoline sample containing a solvent aid with a rating of 102 among the simple ones Test conditions and 81 under the more stringent test conditions is made with 2.3 g of LitHum-2,3-dicyclohexylpropionate offset per liter. The rating number then increases under the simple test conditions to 108 and under the more stringent test conditions to 89.

Example 4

A 0.8 ecm of lead tetraethyl and 50 ecm of methanol per Liters of gasoline sample containing a solvent aid with a rating of 103 among the simple ones Test conditions and of 78 under the more stringent test conditions is made with 2.3 g of the lithium salt of cyclocaproic acid offset per liter. The rating number then increases under the simple test conditions to 108 and under the more stringent test conditions to 83.

Example 5

A 0.8 ecm of lead tetraethyl and 50 ecm of methanol per Liters of gasoline sample containing a solvent aid with a rating of 108 among the simple ones Test conditions and from 80 under the more stringent test conditions is with 2.1 g lithium diphenyl acetate per Liter offset. The rating number then rises to 113 and below under the simple test conditions the stricter test conditions to 84.

Example 6

A 0.8 ecm tetraethyl lead and 40 ecm glycated monoethyl ether per liter as a solvent containing

5 6

Gasoline sample with a rating of 98 among the lithium compounds in aqueous systems the simple test conditions and from 81 below, where you can then drum the water through more rigorous Test conditions are with 1.8 g of the lithium-drying, spray drying or other Salt of 2-methyl-2-neopentylcyclopropanecarboxylic acid removed in the usual manner.

offset per liter. This increases the rating number 5. The invention is based on hydrocarbon fuels under the simple test conditions on 107 and under for internal combustion engines and in particular on

the more stringent test conditions to 91. Fuels can be used that contain a mixture of gasoline

". · _{17 range} boiling hydrocarbons or from a

.Example / Refined Gasoline, as stated in the ASTM

A 50 ecm of methanol per liter as a dissolving aid io designation D288-53 (recognized 1939, revised 1953) containing gasoline sample is defined with a rating number of. The invention is particularly suitable for 80 under the simple test conditions and 69 fuels with a rating of 40 or higher, under the more stringent test conditions it is 1.4 g as with spark ignition engines for both Lithium-2-ethyl caproate added per liter. Thereupon motor vehicles as well as for airplanes are used, the rating figure rises under the simple test 15 and that they are over the entire operating range of the conditions usable on 87 and under the more stringent test engines. The connection conditions according to the invention on 74. However, fertilizers also serve as an anti-knock agent to a lesser extent Examples 8 to 10 are the tests in a valuable fuel of the kerosene or JP-4 type fuel injection engine according to (jet turbine fuels) when in high power dem specified ASTM procedure carried out to 20 capable machines with spark ignition, z. B. tractors the knock resistance of fuels after the grain etc., can be used. The use pressor method according to the invention to show. Deten lithium salts are suitable both in pure and

_,. -ίο also in leaded fuels that are up to 1.6 ecm

.Example 8 contain tetraethyl lead per liter. These fuels

Two samples of a commercially available aircraft can contain different amounts of conventional additives. keep the 1.1 ecm tetraethyl lead and 50 ecm ethanol, z. B. detergents, dyes, antioxidants Contains liters as dissolving aid, and one medium, antifreeze; Rust inhibitors, rating number of 130 according to ASTM-D 909-49T- 'corrosion, rubber formation, haze formation; Early Knock Test Method possessed, is with so much lithium fertilizing preventing agents, etc.

2-äthylkaproate added that the mixed gasoline 30 The fuels originating from the petroleum distillates, Contains 0.36 or 0.7 g / l. As a result, the ratings increase when the additives according to the invention are added Numbers according to the ASTM-D 909-49 T-Knock-Test can contain agents that increase the solubility Method to 150 or 161. promote the lithium compounds in the fuel.

. -in Such typical solubilizers are those in the

ice pie _3; . examples mentioned above, although others

An isooctane sample containing 0.4 ecm of tetraethyl lead per z. B. gasoline-miscible alcohols, glycols, esters, Liter, is with an ethanol solution of lithium ketones, amides and other polar organic liquid-2-ethylbutyrate offset so that the finished mixture can be used. The lithium salts 20 ecm of ethanol and 0.3 g of the lithium compound per can be dissolved directly in the gasoline mixture or as Liter contains. As a result, the rating number of 40 is lead to a concentrated solution in a dissolving aid Isooctane can be given from 133 to over 161 according to the.

ASTM-D 909-49 T-Knock Test Method increased. The amount of lithium commonly used changes

_. . of course depending on the quality and the intended

Examples of the end use of the fuel. Usually

In each case two isooctane samples are taken with an ethanol - 45 is the amount of lithium compound used Solution of lithium 2-ethylbutyrate added, so that between 0.01 and 13 g per liter of fuel, the finished mixture 20 ecm ethanol and 0.12 or 0.3 g range between 0.13 and 5.3 g / l regardless of the the lithium compound contains per liter. As a result, the tetraethyl lead content of the fuel is preferable. the rating of isooctane increases, determined by In contrast to the behavior of tetraethyl lead the ASTM-D 909-49 T-knock test method from 100 to 50 results in additional proportions of these lithium compounds 138 and 158 respectively. Even at concentrations of only usually an improvement in the knock resistance that 0.01 g of the lithium compound per liter is still roughly the same as that achieved with the previous portion Increase in rating achieved. speaks. That is, a graphical representation of the

The examples above to promote the response of fuels to these additives is im of the solution of the lithium compounds, Lö- 55 used an essentially linear approach.

The amount of solvent affects the rating of the lithium salts of secondary carboxylic acids with 4 to

Fuel not noticeable. 18 carbon atoms increase the rating numbers

In general, the Li- of gasoline-like fuels according to the invention, if they are in the anthium compounds secondary carboxylic acids are used in given amounts. In addition to the reaction of corresponding acidic organic compounds όο mentioned in the above examples can also fertilize with lithium or lithium hydride or hydroxide, nor the lithium salts of other acids, alkoxide or carbonate are produced. One obtains these are z. B. lithium 2-methylpropionate, lithium die Carboxylic acid salts easily neutralize the 2-methylbutanoate, lithium-2-cyclopentylpropionate, life-free Acid with every basic lithium compound, thium - ^ - methyl-S-cyclohexylpropionate, lithium-2-ethylz. B. with hydroxide or carbonate, and then 65 3,4-dimethyl caproate, the lithium salt of 2-methylcyclo separation of the salt from the solution. (The solvent caproic acid and the lithium salt of the 3,4,8,9-tetra-agents can be water, alcohol or an inert organic methylundecane-5-carboxylic acid.

Solvents.) The salts according to the invention can except for the pronounced anti-knock effect of the lithium

it has also been found that by saponification of an ester with a basic salt of secondary carboxylic acids Lithium compound can be obtained. Appropriately, 70 represents the maximum anti-knock effect, determined according to the

ASTM-D ^^ T-Knock-Test-Method, with one significant leaner air-fuel ratio than with untreated fuels occurs when this occurs Lithium compounds to increase the rating number close to or above the rating limit of the Motors, d. H. 161, can be used.

Another advantage that results from the use of the lithium salts according to the invention, in particular for Aircraft engines is that they are not only pronounced at rich air-fuel ratios But also show anti-knock effects, determined according to the ASTM-D 909-49 T-knock test method at lean air-fuel ratios such as those at normal average aircraft speeds prevail, have a pronounced anti-knock effect.

Claims (2)

Claims. 5 1. knock Solid fuel for gasoline engines, characterized by a content of an LitMumsalz a secondary organic carboxylic acid corresponding to an amount of at least 1.3 x 10 ^-2 g / l. ίο 2. Method for knock-proof operation of a gasoline engine using the fuel according to claim 1, characterized in that the salt is added to the fuel in the combustion chamber.