US2800119A - Arrangement for cooling the piston of internal combustion engines - Google Patents

Description

y 1957 SCHMIDL 2,800,119

ARRANGEMENT coouue THE PISTON OF INTERNAL COMBUSTION mamas Filed May 5, 1955 INVENTOR United States Pate ARRANGEMENT :FoR cooLlNG THE PISTON- or INTERNAL COMBUSTION ENGINES I Rudolfl-SchmidL Numberg, Germany, assignonto Maschinenfabrik Augsburg-Numberg. A; G., Numberg, Germany:

Application-May 5, 1955, Serial No. 506,329

z-Claims.v (Cl. 12341.35)

Thisinventionrelatee-to anarrangement for-cooling thepisto'n of internal. combustion engines; andmore parpiston head, by means of a throwing device, preferablyar nozzle, under action of the full pressure of the oil in the lubricating system.

In high-duty diesel engines tor trucksa jet of oil is continuously sprayed against the piston .headin order to .con-

trol the temperature of the piston, and 'especia'lly'of the piston head. Normallythe oililis:sprayed into each of the cylinders through a nozzle whichds supplied .with oil from the main oiling circuit. The nozzle tends-to become obstructed by impurities of the oil. In order to avoid this, the diameter of the nozzle had to be made larger than re quired for the proper purpose of the nozzle. Thus, for instance, it has been found by practical experiences that the diameter of the nozzle should not be less than 1.5 mms. With such a nozzle diameter, however, the amount of fuel flowing oil through all of the nozzles of a multicylinder engine is very considerable. For instance, with an 8-cylinder engine in case of the above mentioned nozzle diameter of 1.5 mms., the total nozzle cross section for all cylinders would be about 14 mm. Referring this to a single symbolic substitute nozzle this would correspond to a nozzle diameter of about 3.5 mms. However, it has been found by practical measurements that the entire lubricating oil throughput of the engine is adapted only to the cross section of a symbolic substitute nozzle of about 4.5 mms. diameter, which shows that the share of lubricating oil flowing out through the spray nozzle is a very considerable one. Hence a sufiicien-tly large lubricating oil pressure must be accumulated in order that all oil consuming points of the engine are supplied with a sufficient amount of oil. This again requires a sufficiently high delivery of the oil circulation pump. Such large oil circulation pumps, however, are disadvantageous with a view to the efiiciency of the engine, since they absorb a considerable amount of energy which must be supplied by the engine. On the other hand, if the oil circulation pump is too small in relation to the oil spraying nozzles for cooling the piston, the lubricating oil pressure with slow or idle run of the engine will break down nearly to zero because the amount of oil which is supplied is decreasing proportional to the speed of the engine while the cross section of the nozzles remains unchanged.

Hereat the drawback exists that during slow or idle run of the engine the lubricating oil, following the path of lowest resistance, is discharged mainly from the nozzles having a relatively large bore while for instance the bearings will be supplied with a very small portion of the lubricating oil only, and that at a point of time where there is no actual necessity for cooling the piston or the piston head, respectively.

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Itwill he -understood that similar conditions may occur where inplaceof nozzles any other device is used for sprayingthemil against: the pistonhead and where for constructional reasons the throughput of oil for cooling the piston must be made larger than normally required.

It is an object of the presentinvention to provide means for 'avoidingthese drawbacks.-

More particularly, it is anobject of theinvention to control the share of lubricating oil branched 01$ for. cooling-thepistonor.thehead of. the piston, in dependence upon the'speed of the engine.

With these and further objects in view, accordingto the. presentinventiomthedevice-for branching off cooling oil from the-main oiling circuit and-casting it against the pistonihead .is provided with acheck valve which iscontrolledoby the oil pressure of the main oiling circuit, independently of the relief pressure valve normally arranged in the. oilingcircuit, in such. away that in case of a decrease of..this pressure to .aspredetermined lower limit, e. .g.-,.the idle run pressure of the oil pump, the discharge of-oilfrom the spraying device is. automatically prevented. Where" a'nozzleis used as .an injecting device, in per se knownmanner, a non-return valve is arranged inthe duct ,to=,the nozzle, said non-return valve responding to the pressure prevailing in themai-noiling circuit at slow or idle run .ofthe engine, in such away that the oil in this conditiomofipperation is prevented from issuing from the In-this manneritis: possible totdesign-the oil pump for a much smaller output without in any way reducing the elfective cooling capacity at the piston.

Other and further objects, features and advantages of the invention will be pointed out hereinafter and appear in the appended claims forming part of the application.

In the accompanying drawings a now preferred embodiment of the invention is shown by way of illustration and not by way of limitation.

Fig. l is an axial section through an injection type internal combustion engine with a nozzle for the piston cooling jet connected to the main oiling circuit, the nozzle with nozzle holder being partly shown in a perspective view;

'Fig. 2 is a side view, partly in section, showing the nozzle and the nozzle holder on a larger scale.

Similar reference numerals denote similar parts in the two figures.

Referring now to the drawing, and first to Fig. 1, it will be seen that the engine is a conventional injection-type internal combustion engine in which the combustion chamber 11 is provided in the head of the piston 1 jointed to a piston rod 15 and reciprocating in a cylinder 12 having a cover 13 in which the fuel nozzle system 14 is accommodated. Provided in the crank case is a nozzle holder 6 supporting a nozzle 3 through which lubricating oil is sprayed against the inner wall of the piston head 2.

The oil is delivered from a sump 16 through oil pump 17 into a main oiling circuit 19 from which parallelly connected lines 4 and 20 lead, respectively, to a cooling oil branch circuit and lubricating oil branch branch circuit for the lubrication points of the engine. The oil is returned to sump 16 either by drainage from the crankcase and/or through return 21. In case of an excess of pressure at the relief-pressure valve 18, the same will permit a portion of the oil to return directly to the sump 16, through a pipe 22, for keeping the pressure in the main oiling circuit within the normal limits.

As shown in Fig. 2 in greater detail, branch cooling oil circuit 4 contains the nozzle holder 6 accommodating a non-return valve 7 which is acted upon by a compression spring 8. The lubricating oil is fed from the branch cooling oil duct 4 connected to main oiling circuit pipe 19,

through a non-return valve 7 and the channelS in the nozzle holder 6, as indicated by the arrows 9. A cleaning opening 10 at the left hand end of the nozzle holder is normally closed by a plug 23. The tension of the spring 8 is adapted insuch a way that the same normally is overcome by the pressure prevailing in 'the oil duct 4, so that the valve 7 in normal operation of the engine remains always open, for spraying oil through the nozzle 3 against the piston head 2. Only when the oil pressure falls below a predetermined value which has been adjusted by the tension of the spring 8, the Valve 7 will be closed by the spring pressure which now preponderates, whereby the supply of oil to the nozzle 3 is checked and lubricating oil can flow only tothe remaining-lubricating points, and more particularly to the bearingsof' the engine. 7

The valve 7 before the spray nozzle 3 has nothing' to do With the'relief pressure valve 18 arranged in the lubricating oil circuit and serving to return a surplus of lubrieating oil to the sump 16, and it is quite independent of said relief pressure valve as to its function.

It will be appreciated that the oil pressure will fall below the above mentioned critical value for instance during slow or idle run of the engine. In this case, however, the amount of heat transmitted to the piston is relatively small, so that it is not necessary for the piston head to be sprayed with cooling oil in this Working condition.

While the invention has been described in detail with respect to a now preferred example and embodiment'of the invention it will be understood by those skilled in the art after understanding the invention that various changes and modifications may be made without departing from the spirit and scope of the invention and it is intended,

therefore, to cover all such changes and modifications in the appended claims.

I claim:

1. In an internal combustion engine such as a high output Diesel engine having a main oiling circuit, an oil circulating pump in said main circuit, at least one lubrication branch circuit leading from said main circuit to the engine lubrication points, and at least one piston cooling branch circuit leading from the main circuit to a spray nozzle for spraying cooling oil into the hollow interior of a piston, both branch circuits being connected in parallel to said main oiling circuit, respectively, the improvement comprising a spray nozzle in said piston cooling branch circuit having an opening of a size to provide a flow resistance to the passage of oil less than the flow resistance in the lubricating branch circuit at engine idling speeds, a check valve connected to said nozzle, and means for opening said valve under the pressure of the main oiling circuit during normal engine running speeds, but for closing said valve during low running or engine idling speeds. V

2. In an internal combustion engine as in claim 1, said opening and closing means comprising a spring automatically responsive to the oil pressure in said main oiling circuit.

References Cited in the file of this patent UNITED STATES PATENTS 1,992,339 Winslow Feb. 26, 1935 FOREIGN PATENTS 833,880 Germany Mar. 13, 1952 1037,0224 France Apr. 29, 1953

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