US2575543A - Diesel starting fluid - Google Patents

Description

Patented Nov. 20, 1951 DIESEL STARTING FLUID Hebert D. Young, Harvey, 11]., assignor to Sinclair Refining Company, New York, N. Y., a corporation oi Maine No Drawing. Application March 31, 1949, Serial No. 84,738

2 Claims. 1

This invention relates to the cold weather starting of compression-ignition engines, and provides improved. methods and new starting fluids for cold weather ignition. In one aspect the invention provides an improved diesel cold weather starting fluid comprising a predominately saturated, generally parailinic, low pour point, light petroleum fraction boiling in the approximate range of 100 to 350 F. in admixture with diethyl ether. In another aspect the invention provides a starting fluid as described above which has been contacted with oxygen prior to ignition for even greater effectiveness.

In the normal operation of compression-ignition engines, that is, diesel engines, the fuel is ignited by the temperature prevailing in the working cylinder as the fuel is injected. In starting a cold engine, however, temperatures suflicient to ignite the regular fuel are attained only after sufiicient work has been done in the compression of the charge admitted to the working cylinder so as to bring the parts of the engine in a direct heat exchanging relationship with the contents of the working cylinder, as well as elevating the charge undergoing compression to a relatively high temperature. It the atmospheric temperature is between about 60 and 80 F., this can be accomplished with a minimum of difliculty and without imposing too much of a load on the starting mechanism. However, if the atmospheric temperature falls, the difliculty of starting a compression-ignition engine increases at an accelerated rate and becomes almost impossible at temperatures much below F.

To overcome this diiliculty, special auxiliary starting fuels, capable of ignition at relatively low temperatures, are advantageously used. Conventionally, such special auxiliary starting fuels are injected into the working cylinder of the engine, usually at a point as close to the admission valve of the cylinder as is practicable in the particular engine. Diethyl ether is one of the best of these auxiliary starting fuels. However, diethyl ether suffers several disadvantages; it is expensive, volatile, highly inflammable, and frequently explosive.

I have now discovered, however, that readily available mixtures of light hydrocarbons, particularly those of a relatively narrow boiling range having an initial boiling point considerably above the boiling point of diethyl ether, a low pour point, derived from the fractionation of naphthas and light petroleum fractions, possess unusual capacity in combination with a relatively minor proportion of diethyl ether for promoting cold weather starting of c: myres qion-ignition engine's. Moreover, I have discovered that mixtures of such light hydrocarbons with'diethyl ether possess a surprising susceptibility to the action of oxygen which upon extended contact or pressurization, promotes or accentuates their valuable cold weather starting capacities.

The cold weather compression-ignition starting fluid of my invention is a predominately saturated, generally paraiilnic, low pour point, light petroleum fraction boiling in the approximate range of to 350 in admixture with diethyl ether. The startiig fluid mosadvantageously comprises mixtures by volume of about 85 to 50% of the light parailimc petroleum fraction and about 15 to 50% of diethyl ether.

My invention also inc'iudes the related discovery that when fluids as I have described are contacted with oxygen prior to ignition an even greater improvement in starting results. This contact may be advantageously accomplished by allowing the starting fluid to stand for an extended period of time in contact with air under normal atmospheric conditions, i. e., the liquid may be weathered" in an open container for a period exceeding, say, ten or twenty days and for as long as three or four months. More practically, however, the liquid is simply confined in a closed container and subjected to superatmospheric air pressure, for instance, 100 p. s. 1. Or the starting fluid may be injected into the working cylinder in a stream of an oxygen-containing gas. This is preferably accomplished by atomizing the liquid into a stream of air leading to the working cylinder where it is ignited.

As illustrative of the predominately paraffinic, low pour point, light petroleum fractions used in admixture with diethyl ether are those fractions comprising substantially normal nonane and the lighter normal paraflins. In particular, I recommend a fraction composed mainly of one or more of the normal paraflins, heptane, octane, and decane.

Although my invention is not predicated upon any particular hypothesis, it is my belief that the starting effectiveness of diethyl ether is due, not so much to its high volatility, but to its instability under the severe tempertaures and pressures encountered in a compression-ignition engine working cylinder. As a result, this may be why petroleum fractions containing thermally unstable, straight chain paraflins react somewhat similarly and therefore have value in starting diesel engines. In addition, I believe that the formation of peroxides may be an intermediate step in the conversion of such fluids into highly explosive compounds within the engine cylinder prior to ignition, which is apparently why the eifectiveness of a starting fluid composition, in accordance with the preceding definition, is increased upon contact with oxygen prior to ignition. Under these conditions relatively minute quantities of peroxides then may be formed, serving to accelerate the rate at which the starting fluid reaches the explosive stage inside the cylinder. And this even though the peroxides may be relatively stable under normal conditions of temperature and pressure.

The principles of my invention are well illustrated by the following examples of engine tests under controlled conditions. A four cylinder marine diesel engine was placed in a laboratory "cold room" and tested with different starting fluids and procedures. The engine was cranked by a battery-operated starting motor. In the examples the engine and fluids were chilled for about eight hours to a given temperature. At this temperature, the engine was cranked for a period not exceeding one minute, and if the particular fluid used failed to start it in that period after several attempts, the fluid was designated as unsatisfactory for the temperature. As a result, the cold-room temperature was then elevated until the engine started satisfactorily. A "start was defined as a firing followed by sustained running of the engine under its own power; spasmodic firing did not constitute a start.

Example I A commercial grade diesel fuel cut back with 20% kerosene was used for starting without a special starting fuel or procedure. The diesel fluid had the following characteristics:

Cetane number 52.0 Gravity, A. P. I 40.3 Pour point, F Initial boiling point, F 356 10% off at, F 409 50% of! at, F 471 90% ofi at, "F 575 End point, F 655 The diesel engine failed to start at temperatures below about plus 40 F.

Example 11 A relatively low boiling solvent naphtha was used as a starting fluid, having the following characteristics:

Cetane number 25.1 Gravity, A. P. I 57.3 Aniline point, F 130 Initial boiling point, F 188 10% off at, F 204 50% off at, F 218 90% ofi at, F 24'? End point, F 267 A mechanically-operated pump, or primer," was used to inject the fluid for starting. The mechanical primer was essentially a hand-operated piston located within a cylinder containing the starting fluid, to which was attached a nozzle so as to atomize the liquid into the air intake line leading to the working cylinder. The diesel engine failed to start at temperatures below about plus 40 F. using the solvent naphtha. A mixture by volume of 80% of the solvent naphtha and 20% of diethyl ether was then use as a starting fluid in the mechanical primer. The mixture had the following characteristics:

The diesel engine started at a minimum temperature of about minus 6 F., at a battery voltage of 12 and a cranking speed of 180 R. P. M., in fifty seconds, with 42 cc. of this mixture being injected. There was a medium detonation, while the combustion continuity was good.

Example III A predominantly C7 straight run naphtha cut was used as a starting fluid in the mechanical primer, of the following characteristics:

Cetane number 51.0 Gravity, A. P. I 74.2 Initial boiling point, F 207 10% off at, F 208 50% oif at, F 208 off at, F 208 End point, F 228 The diesel engine started at a minimum temperature of about plus 5 F. A mixture by volume of 80% of the C7 straight run naphtha cut and 20% of diethyl ether was then used as a starting fluid in the mechanical primer. The mixture had the following characteristics:

Cetane number 51.6 Gravity, A. P. I 72.4 Reid vapor pressure 5.4 Pour point, F below 80 Initial boiling point, F 10% oif at, F 154 50% on at, F 204 90% off at, F 208 End point, F 1- 232 The diesel engine started at a minimum temperature of about minus 11 F., at a battery voltage of 12 and a cranking speed of R. P. M., in twelve seconds, with 12 cc. of this mixture being injected. There was a medium detonation, while the combustion continuity was good.

This starting fluid compared very favorably with, for instance a commercial starting fuel which is basically an ethyl ether composition, containing over 85 per cent by volume of ethyl ether with a balance of lubricating oil. Used in the mechanical primer as described hereinbefore, the commercial starting fuel started with a more severe detonation, followed by a noticeably poorer combustion continuity after firing was initiated. Employing the commercial starting fuel, the diesel engine started at a minimum temperature of about minus 2 F., at a battery voltage of 12 and a cranking speed of 180 R. P. M., in four seconds, with 48 cc. of this fuel being injected.

At a starter battery voltage of 18 and a cranking speed of 180 R. P. M., this C7-rich mixture started the diesel engine at a minimum temperature of about minus 14 F., with 18 cc. of the fluid being injected.

At a starter battery voltage of 24 and a cranking speed of 200 R. P. M., this C1-rich mixture started the diesel engine at a minimum temperature 01' about minus 18 F., with 18 cc. of the fluid being injected.

Example IV A starting fluid comprising a mixture by volume of 80% of a (Iv-rich naphtha out similar to that of Example III and 20% of diethyl ether was contacted with oxygen at an elevated pressure, by containing the'liquid in a six-ounce "pressurized bomb" under 100 p. s. i. of air pressure. The bomb was equipped with a valve and air hose connection at the exit end and so located on the diesel engine as to deliver the oxygencontaining fluid into the intake line of the working cylinder.

At a starter battery voltage of 12 and a cranking speed o! 150 R. P. 11., use bomb-injected mixture started the engine at a minimum temperature of about minus 9 F. in two seconds. There was a medium detonation, while the combustion continuity was good.

At a starter battery voltage of 24 and a cranking speed of 140 R. P. M., this bomb-injected mixture started the engine at a minimum temperature 01 about minus 25 1''.

Example V A starting fluid comprising a mixture by volume of 80% 01 a Ca-rich naphtha out similar to that oi. Example 111 and 20% of diethyl ether was contacted with oxygen for a prolonged period of time prior to ignition. The mixture was allowed to stand in the air for ninety days in an open, clear glass container exposed to natural light. Over a forty-tour day period, the loss or liquid through evaporation amounted to about 20%. the loss including both the dietlnvi ether and 100 p. s. i. of air pressure as described in Example IV.

At a starter battery voltage of 12 and a cranking speed of 150 R. P. M., this bomb-injected mixture started the engine at a minimum temperature of about minus 8 F., in two seconds. There was a medium detonation, while the combustion continuity was good.

Example VII A mixture by volume of 80% of a predominately 010 straight run naphtha cut in admixture with 20% of diethyl ether was used as a starting fluid, having a cetane number over 70, an A. P. I. gravity of 613 and a pour point or minus 21.5 F. The mixture was contacted with oxygen at an elevated pressure by containing the fluid in a six-ounce pressurized bomb" under 100 p. s. i. 0! air pressure as described in Example IV.

At a starter battery voltage of 12 and a cranking speed of 150 R. P. M., this bomb-imected mixture started the engine at a minimum temperature of about minus 9 F., in two seconds. There was a medium detonation, while the combustion continuity wa good.

(Jr-rich naphtha cut. During a iorty-iour day period, the peroxide content increased from 0 to 2.1 mg.

Using this weathered" fluid in the mechanical primer, the diesel engine started at a minimum temperature of about minus 17 F., at a battery voltage of 12 and a cranking speed or 180 R. P. M. in two seconds, with 3 cc. of this mixture being inJected. There was a moderate detongotilon. while the combustion continuity was I ammle Vi A. P. I. gravity of 683 and a pourpoint 0! minus 702 F. The mixture was contacted with oxygen at an elevated pressure by containing the fluid in a six-ounce "pressurised bomb" under I claim: I

1. A starting fluid for compression-ignition engines containing about 15. to 50 per cent by volume of diethyl ether and to 50 per cent of a predominantly straight chain parafllnic, low

pour point, light close out petroleum traction boiling within the approximate range of to 350 F- selected from the group consisting of normal C1, Cs. Cs and Cm cuts.

2. A starting fluid for compression ignition engines containing about 15%-50% by volume diethyl ether and 85%-50% of normal heptane.

HOBERT D. YOUNG.

REFERENCES CITED The following references are of record in the flle of this patent:

Cloud et al., Sp cial Cold-Starting Fuels for Diesel Engines," 8. A. E. Journal, vol. 52, pp. 223-227, June 1944.

Claims (1)

1. A STARTING FLUID FOR COMPRESSION-IGNITION ENGINES CONTAINING ABOUT 15 TO 50 PER CENT BY VOLUME OF DIETHYL ETHER AND 85 TO 50 PER CENT OF A PREDOMINANTLY STRAIGHT CHAIN PARAFFINIC, LOW POUR POINT, LIGHT CLOSE CUT PETROLEUM FRACTION BOILING WITHIN THE APPROXIMATE RANGE OF 100* TO 350* F. SELECTED FROM THE GROUP CONSISTING OF NORMAL C7, C8, C9 AND C10 CUTS.