US2262527A - Lubrication - Google Patents

Description

Nv.11,1941. M,FA.R, ,E`ETAL 2,262,527

LUBRICATION Filed July l5, 1958 7eazea7 //y Beoard E Bea/re gg uw ATTORNEYS Patented Nov. 11, 1941 LUBRICATION Matthew Fairlie and Leonard E. Beare, Hammond, Ind., assignors to Sinclair Refining Company, New York, N. Y., a corporation of Maine IApplication July 15, 1938, Serial No. 219,457

(ci. 12s-19s) 5 Claims.

This invention relates to lubrication and is concerned particularly with the lubrication of internal combustion engines with liquid lubricants of petroleum origin. The invention aims to prolong the useful life of petroleum lubricating oils and to inhibit deleterious action of the oils upon machine parts with which they come in contact.

Petroleum oils in service in a crank case of an internal combustion engine tend to deteriorate. In general, the higher the crank case temperature the greater and more rapid is the deterioration of the oil. Deposits of carbon and of insoluble sludge tend to form within the engine and the oil loses lubricating qualities coincident with increases in its viscosity, sludge content, and acidity. Moreover, as tars and asphaltenes form in the oil due to polymerization or other chemical action, it becomes difficult properly to supply the oil to the metal surfaces requiring lubrication and to maintain moving parts in a clean condition. The deposition of carbon in a form that is not friable and hence not removable from the engine as a normal incident to its operation and the formation of tars or asphaltenes may result in sticking of piston rings and other mechanical diiliculties. Moreover, and especially at elevated tact with a mass containing one or more of the aforementioned solids. Such treatment apparently exerts a benecial iniluence upon the character of the carbon formed during service and renders it more friable so that its tendency to deposit permanently upon the engine parts is diminished. The treatment also inhibits the formation of tars, asphaltenes, fgums, and sludge. In consequence, the engine surfaces are kept cleaner than would otherwise be the case; piston lacquering and ring sticking are substantially diminished; there is less difficulty in assuring an adequate supply of oil to the surfaces which must be lubricated; and service life of the oil is greatly increased.

' Conveniently, additional heat may be supplied to the oil by passing it in heat exchange relationship with exhaust gases from the'engine, which contains as heat from 25 to 33% of the total energy content of the fuel burned in the engine. In this Way, heat which would otherwise be wasted may be employed to lengthen the time intervals between engine overhauls and meanwhile insure better service by reducing sludging and temperatures of operation, many oils tend to corrode certain metal surfaces with which they come in contact.

As a result of our investigations, we have discovered that the corrosion of metal parts in an engine by a petroleum base lubricating oil may be inhibited if the oil is heated toa temperature approximating 2l0"300 F. and, while heated, circulated in contact vwith a solid selected from the group consisting of the alkaline earth metals (i. e., calcium, barium, and strontium) and inorganic compounds of these metals, the oils being subsequently returned to the metal surfaces. We have discovered that, in general, the temperature which oils assume in the crank case of an internal combustion engine through which they are circulated is not sullicient to permit the alkaline metals, either in elemental form or inorganic combination, to exert their maximum inuence from a standpoint of corrosion inhibition. We have discovered, moreover, that even in those instances when the oil exhibits little or no tendency to corrode the metal surfaces with which it service, and while the oil is heated, pass it in conring sticking. Thus, the oil may be Withdrawn from the crank case of the engine, passed through a heat exchanger in heat exchange relationship with the exhaust gases, and thence after contact with a solid selected from the aforementioned group, be returned to the engine.v Conveniently also, the additional heat necessary to bring about the favorable action of the alkaline earth metals and inorganic compounds thereof, may be supplied by maintaining the contact mass of alkaline earth metal or inorganic compound thereof at an elevated temperature. For example, the contact mass may itself be heated by passing exhaust gases from the internal combustion engine in heat exchange relationship therewith. The precise temperature to which the o should be heated in order to obtain optimum results through contact with the alkaline earth metal or inorganic compound thereof, will de# pend in some measure upon the nature of the oil. Generally speaking, and with reference to modern petroleum base lubricating 'cils and present day conditions of service, the temperature should be upwards of about 210 F. and, below a limit established by the thermal stability of the particular oil, the higher the oil is heated the better are the results obtained. Thus, in a` given case, corrosion will be less, piston lacquering will be diminished and ring sticking Will be less if the oil is treated at a temperature of 300 F., as contrasted with treatment at, say 225 F., but good results generally have been obtained in a range of 240 to 300 F.

Our invention, therefore, contemplates the improvement in treating a petroleum base lubricant which comprises heating the lubricant to a temperature approximating 210-300 F., preferably 240-300 F., and passing the lubricant thus heated in contact with a solid selected from. the group consisting of the alkaline earth metals (i. e., calcium, strontium, and barium) and inorganic compounds of these metals.

We have also discovered that in the case of petroleum base oils initially containing substantial proportions of soap of an alkaline earth metal, corrosion is reduced if the oil in the lubrieating system is circulated in contact with the aforementioned contact mass, even though the oil in contact with the mass is not heated substantially above normal operating temperature, butthis discovery is described and claimed in our copending application, Serial No. 219,456, filed July 15, 1938. The contact mass, with or without heating, likewise exerts a substantial corrosion inhibiting effect upon oils containing aluminum soaps, as described and claimed in our copending application Serial No.- 219,459, illed July 15, 1938. We have discovered, moreover (as described and claimed in our copending application Serial No. 219,458, filed July 15, 1938), that contact masses in the form of mixtures containing more than one alkaline earth metal in elemental or combined inorganic form are more eiiicacious from the standpoint of inhibiting corrosion, ring sticking, and the like than are contact masses containing only one of the alkaline earth metals. Thus a mixture of calcium and bariumV hydroxide is more efficacious than an equal amount of either hydroxide alone.

Our invention will be more clearly understood in the light of the following detailed description taken in conjunction with the accompanying single figure which shows a combined filter and heat exchange unit for treating oil in accordance with our invention and illustrates schematically a lubricant circulation system of an internal combustion engine in which the unit is connected, heat being supplied to the oil from the exhaust gases from the engine. The apparatus comprises a tank I with an upright cylindrical wall II provided with an annular upper flange I2 and an annular lower flange I3. A cover plate I4 is bolted tightly to the upper flange and a bottom plate I5 likewise is bolted to the lower ange. Gaskets, not shown, may be interposed between plates and flanges to insure a tight joint.

A heat exchange unit I6 projects upwardly and concentrically into the tank through the bottom, and comprises an outer shell I1, preferably cylindrical, and provided with a top I8 bolted tightly onto an inner flange I9 which is fastened to the upper edge of the shell. An inner cylindrical shell 20 projects through the bottom of the tank upwardly into the outer shell and concentric therewith. In the lower portion of the inner shell is a first tube sheet 2| from which project upwardly a number of oil tubes 22, 23, 24, 25, 26, 21. These tubes are sealed into the first tube sheet and also into a second tube sheet 28 which extends horizontally across the outer shell near the top thereof forming a manifold chamber 29. Anotherseries of oil tubes 30, 3l, 32, 33 are sealed into the second tube sheet and extend downwardly between the inner and outer sheet to a third and annular tube sheet 34 which is fastened horizontally in the annular space between the inner and outer sheets at the lower end of the latter.

The lower end of the inner shell is closed byl a flange 35 to which is attached an oil inlet pipe 36, so that a second header or manifold chamber 31 is formed between the rst tube sheet and the flange.

A hot fluid, for example, exhaust gas from the internal combustion engine, is caused to flow around the outside of the tubes from an inlet pipe 38 which projects through the bottom of the tank and is connected to an annular chamber 39 which surrounds a lower portion of the inner shell. The wall of the inner shell adjacent the chamber has perforations 40 through which the fluid enters and rises above the upper end of the inner shell in the space around the first set of tubes. Thence, the hot iluid ilows downwardly around the second set of tubes in the space between the inner and outer shells. A lower portion of the outer shell contains perforations 4I and is surrounded by a second annular chamber 42, to which is connected an outlet 43 that projects out of the bottom.

Disposed immediately above the outlet between the outer shell and the wall of the tank is a horizontally disposed annular perforated plate The space 45 directly above the plate is packed with cotton waste or the like and overlying the waste is packed an annular bag 46 lled with the contact mass 41. The mass is in the form of granules, preferably not larger than pea-size and not smaller than 8 to 14 mesh. The bag is packed securely into the annular space so that it fits tightly against the shell and the wall of the tank.

Overlying the bag is a cylindrical wastepacked zone 48 (in which additional quantities of the contact mass may be substituted if desired) and overlying this zone is another zone 49 adapted to be packed with cotton waste or the like. A distributor mechanism 50 consisting of a series of concentric perforated rings 5I, 52, 53, 54, 55, suspended from a perforated disk 56, is fastened near the top of the tank below an upwardly rising oil outlet pipe 51. If desired, the rings may be covered with fabric 58 as shown, to form a, series of concentric circular filter leaves 59, 60, 6I, 62, 63.

In the operation of the device of Fig. l, oil to be treated is passed into the apparatus at the oil inlet pipe at the bottom of the apparatus, rises through the rst series of tubes to the header or manifold chamber. Thence, the oil ows downward through the second series of tubes and enters the lower space between the shell and the -Wall of the tank. From this space the oil is forced upwardly through the bed of waste and the bagenclosed contact mass into the upper space, Thence it ows through the upper bed of waste into the distributor and out at the top of the apparatus.

At the same time, a fluid that is hotter than the entering oil, say exhaust gas from the internal combustion engine from which the oil is drawn, iiows into the first annular chamber and thence into the space around the tubes in the first shell where it rises upwardly and then down around the second series of tubes to the perforations in the lower portion of the wall of the outer shell. Flowing through these perforations the hot uid enters the second annular chamber from whence it is withdrawn from the apparatus through the outlet'. The hot fluid thus passes in heat exchange relationship with the oil, which in consequence becomes heated, and also in heat exchange relationship with theV contact mass which surrounds the space through which the hot gas passes. In the heated condition the oil ows through the contact mass to the oil outlet.

The attachment of the above-described apparatus in the lubricant circulation system of an internal combustion engine is illustrated schematically in the drawing. The oil to be treated is circulated from a crank case of an engine through the tubes of the heat exchanger and the contact mass and back into the, crank case by means of a pump disposed between the crank case and the heat exchanger. At the same time hot exhaust gas from the engine is introduced into the heat exchanger and forced through the spaces around the tubes to the outlet I3.

The eicacy of the contact mass diminishes in service, and eventually it becomes necessary to replace it. The enclosure of the mass within the bag makes replacement a quick and simple task. The cover plate on the tank is removed; the upper layer of waste is taken out; and then the bag and its contents are withdrawn and replaced with a new bag containing a fresh mass.

As indicated hereinbefore, the contact mass should be selected from the group consisting of calcium, barium, and strontium lin elemental form or as inorganic compounds, for example, the carbides, carbonat-es, oxides, or hydroxides. Carbides and oxides `are useful in that in addition to functioning as a contact mass they react with water entrained by the oil and aid in its removal from the system. However, of the inorganic compounds the hydroxides are perhaps to be preferred because they are both eiiicacious and relatively inexpensive. Oddly enough, magnesium and its inorganic compounds, although like calcium, barium, and strontium and their corresponding inorganic compounds in many respects, are not useful in the practice of our invention.

'I'he contact mass should be in such condition that .it presents a large surface to exposure Yto the oil. Generally speaking, the mass should be as finelyl porous or as nely divided as possible without offering too great a resistance to the pasy sage of the oil and without running the risk of carryingflne particles out of the contact mass into the lubricating system where they may cause damage by abrasion. -For most services, the con- Vtact mass particles should not be larger than pea size or smaller than about 14 mesh. The

particles may be consolidated into a coherent mass by means of a suitable binder, such as plaster of Paris, but it is preferable to employ them as loose particles retained within a pervious container, for example, a perforated canister of Monel metal or, better still, a fabric bag.

Because of the great difference in density of barium, strontium and calcium hydroxides it may be more convenient to refer to these relationships in terms of volume rather than weight. In general we have found that with a contact mass of about 1500 ccs., or 20% of the volume of oil tio ."ring sticking" and piston lacquering."

in circulation, the rate of circulation should be about 2500 ccs. per minute or of the volume of oil in the system, depending greatly upon thel pellet size and contact temperature.

The life of a contact mass depends upon its size, composition, surface area, service temperature and general severity of service, but in general we have found that a Contact mass weighing say 30% of the weight of the oil in circulation will last from to 200 hours.

Our invention is useful in improving the life and service characteristics of so-called uncompounded petroleum base lubricating oils to which substantially no amount of another class of lubricant has been added and also of the "compounded lubricants, such as those containing soaps. This is shown by the results of the following tests employing (l) a high grade uncompounded petroleum lubricating oil for aircraft engine lubrication and (2) a compounded lubricant made by including in a petroleum oil a small proportion ofa soap of an alkaline earth metal, in this instance, calcium phenyl stearate. Ring sticking, piston lacquering, sludging, etc. are-greatly reduced by the practice of our invention with both compounded and uncompounded oils, but in general our invention oiTers greater advantages with'respect to corrosion inhibltion when compounded oils are employed.

Tests were run with a high grade of uncompounded petroleum oil of Pennsylvania origin intended for aircraft service and designated hereinafter as G base" oil. This oil does not cause appreciable corrosion in aircraft service, Where the oil introduced into the crank case by the circulatory system normally does not have a temperature in excess of 185 F. However, the oil after considerable service does tend to cause As the tests show,vtreatment of the oil in accordance with our invention substantially prevents ring sticking and either inhibits deposition of solids upon the pistons or renders the solids so friable that they do not cause ring sticking. In case l1 the G base oil, vis. /210"` F. was subjected to test by circulating it through the crank case of an internal combustion engine for 50 hours. In the other case exactly similar oil was subjected to identical service, but was heated to a temperature of 300 F. and passed through a contact mass in the form of pea size pellets of lime (Ca(OH)z). In both instances the circulation rate overv the contact mass Was 3000 ccs. per minute, which represented circulation of approximately 45% `of the contents of the crank case per minute. Results obtained in both cases after 50 hours of service are given below:

Another series of tests was made with an uncompcunded petroleum oil intended for aircraft service and of Pennsylvania origin. This oil differed from that of the tests reported above in that it had a viscosity of Saybolt at 210 F.

This oil was subjected to service in a gasoline engine for 50 hours, in one case without benefit of contact mass, and in the other two cases with benefit of contact masses of barium hydroxide and strontium hydroxide, respectively. 'I'he oil pressure in the circulatory system was in all cases 15 pounds per sq. in., while the circulation rate was 3000 ccs. per minute or approximately 0.45 times the crank case contents per minute. Filters containing the contact masses in cases 4 and were maintained at a temperature of 290 F., and the jacket temperature of the engine in all cases was maintained at 250 F. 'Ihe results obtained after 50 hours of service are given below:

Case 3 Case 4 Case 5 No Contact Contact Conditions conmass mass tact Ba(OH)z Sr(OH)2 mass at 290 F. at 290 F Asphaltenes in used oil percent.. 148 048 080 P'Bton deposits:

Pistons l and 2 .grams.. .773 1. 413 1.825 Pistons 3 and 4 do.. 1. 501 1. 641 2.133 Total .do.. 2.274 3. 054 3. 958 Piston ring rating, percent free. 73. 3 87.0 i 100.0 Bearing corrosion loss, grams: g

Babbitt- A 0.014 0.054 B .l 0.017 0.031 C 0. 015 0. 028 D 0.013 0. 023

It will be' noted that the piston deposits in cases 4 and 5 are higher than in case 3, but that the piston ring ratings after service in both case 4 and case 5 are higher than in case 3. 'I'his is attributed to the fact that treatment of the oil with the contact masses rendered the carbon deposit friable and hence innocuous in so far as operation of the engine was concerned. Economic vconsiderations aside, barium hydroxide probably is to be preferred to calcium ori strontium hydroxide. It is slightly less active as an inhibitor of ring sticking than the hydroxides of the other two metals, but exerts a greater iniluence from the standpoint of corrosion inhibition.

It will also be noted that, although the corrosion of Babbitt bearings with G^base" oil is slight even when the oil is not subjected to treatment with a contact mass, it is even less when the contact masses are employed at high temperatures, so that our invention oiers a further, albeit not so important, advantage in this respect.

Tests madef'upon "compounded oils also show the advantages which accrue tothe treatment of such oils while heated with a contact mass selected from the group consisting of the alkaline earth metals and their inorganic compounds. The oil, in this case is compounded lubricant adapted for automobile use and the like and containing a small amount of calcium phenyl stearate, was subjected `to service for 50 hours in a gasoline engine. The conditions of operation in all cases were identical, except as follows: Case 6: No contact mass employed, oil in circulation heated to 210-225 F. Case '7: Contact mass of CaKOI-Dz employed, oil

in circulation heated to 21o-225 F.

Case 8: No contact mass employed, oil 'in circulation heated to 250 F.

Case 9: Contact mass of Ca(OH)z employed oil in circulation heated to 250 F.

Tests of the oil in each case after 50 hours of use are given below:

Case No.

Characteristics of used oil:

Grav` y 18. 7 19. 3 16. 7 1B. 9 Viscosity at 210 F 63. 9 59.0 86. 4 60. 6 Carbon percent l. 394 1. 3. 230 1.214 Tar do 1.428 .820 4.040 .504 Asphaltenes do 996 524 3. 252 236 Insolubles in chloroform 0.... 432 296 788 268 Bearing corrosion loss, grams:

Cadmium silver- 0.090 0.030 Cadmium silver- C 0. 718 0. 138 2. 108 0.089 D '0.594 0.096 1.844 0.054 "Satco" (lead with sodium or calclam)- These tests show the benefits which accrue to heating the oil to a relatively high temperature preparatory to treatment with the contact mass. At the higher temperature, treatment with the contact mass (case 9) results in a lower formation of carbon, of tar, of asphaltenes, and of insolubles than does treatment with a similar mass at a lower temperature (case 7). Moreover, treatment with the contact mass at the high temperature (case 9) is optimum with respect to bearing corrosion.

We claim:

1. In the operation of a system for lubricating surfaces with a petroleum base lubricating oil which involves repeated contacting of said oil from a 'body thereof with the surfaces to be lubricated and circulation thereof through a treating zone, the improvement which comprises bringing the oil in said treating zone into contact with a solid selected from the group consisting of the alkaline earth metals and inorganic compounds thereof at a rate suicient to bring into contact with said solid 'an amount of oil equivalent to a substantial part of said oil body per minute and controlling the temperature of the oil in said treating zone to maintain it at a value between about 240 F. and 300 F.

2. In the operation of a system for lubricating the bearing surfaces of an internal combustion engine with a petroleum base lubricating oil which involves repeated contacting of said oil from a body thereof normally at a temperature less than approximately 180 F. with the surfaces to be lubricated and circulation of said oil through a treating zone, the improvement which comprises bringing' the oil in said treating zone into contact yvith a solid selected from the group consisting of the alkaline earth metals and inorganic compounds thereof at a rate suicient to bring into contact with said solid an amount of oil equivalent to a substantial part of said oil body per minute and heating the oil entering said treating zone at a rate suicient to maintain` i'n said treating zone a temperature approximating 210-300 F.

i 3. In the operation of a system for lubricating an engine with a petroleum base lubricating oil which involves repeated contacting of said oil from a body thereof with the surfaces to be lubricated and circulation of said oil through a treating zone, the improvement which comprises heating the oil flowing through said treating zone to a temperature approximating 210-300 F. andl passing the oil in said treating zone through a porous mass consisting principally of a solid selected from the group consisting of elemental calcium, strontium, and barium, and inorganic compounds of these elements at a rate suliicient to bring into contact with said porous mass an amount of oil equivalent to a substantial part of said body of oil per minute.

4. In the operation of a system -for lubricating surfaces with a petroleum base lubricating oil which involves repeated contacting of said oil from a body thereof with surfaces to be lubricated and circulation of said oil through a treating zone, the improvement which comprises passing the oil in said treating zone through a mass of particles of a solid selected from the group consisting of elemental calcium, strontium, and barium, and inorganic compounds of these elements, the size of said'particles ranging from about pea size to about 14 mesh at a rate suflicient to bring into contact with said mass an amount of oil equivalent to a substantial part of said oil body per minute, and heating the oil circulating through said treating zone to maintain in said treating zone a temperature approximating 210-300 F.

5. In the operation of a system for lubricating surfaces with a petroleum base lubricating oil which involves repeated contacting of said oil from a body thereof with surfaces to be lubricated and circulation of said oil through a treating zone, the improvement which comprises passing the oil in said treating zone through a mass of particles of a solid selected from the group consisting of elemental calcium, strontium and barium, and inorganic compounds of these elements, the size of said particles ranging fromV about pea size to about 14 mesh at a rate sufficient to bring into contact with said mass an amount of oil equivalent to a substantial part of said oil body per minute, and controlling the temperature of the oil circulating through said treatingV zone to maintain in said treating zone a temperature ranging from about 240 F. to about 300 F.

MATTHEW FAIRLIE.

LEONARD E. BEARE.

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