Schenk v. United Aircraft Corporation

Citation43 F. Supp. 679,51 USPQ 519
Decision Date07 August 1941
Docket NumberNo. 150.,150.
CourtU.S. District Court — District of Connecticut
PartiesSCHENK et al. v. UNITED AIRCRAFT CORPORATION.

Cromwell, Greist & Warden, and Raymond L. Greist, all of Chicago, Ill., and Lindsey & Robillard, and T. Clay Lindsey, all of Hartford, Conn., for plaintiffs.

Cooper, Kerr & Dunham, Drury W. Cooper, and C. Blake Townsend, all of New York City, for defendant.

HINCKS, District Judge.

This is an action by the administratrix and assignee of the patentee for infringement of Schenk Reissue Patent No. 21,031, which issued March 14, 1939, on an application filed December 27, 1938. The patent in suit is a reissue of Schenk Patent No. 1,815,868, which issued July 21, 1931, on an application filed October 17, 1929. The defenses are invalidity (on a number of grounds) and noninfringement.

The patent in suit discloses a completely automatic lubricating system for air-cooled, radial engines such as are generally used in airplanes. The complete disclosure, to be sure, contains a multitude of elements and sub-combinations which were old in the art. Thus it was nothing new in the lubrication of an internal combustion engine to conduct oil, as Schenk discloses, from the main reservoir by pressure through tappet (cam follower) guides and thence through hollow push rods to a joint with the rocker arm and thence through a hollow rocker arm to a joint with a valve stem, lubricating the rocker arm bearing en route. Nor was it new to provide for the accumulation of oil in an enclosed rocker arm box containing the valve gear where it was effective to lubricate joints in the valve gear by splash.

Nor was it new in internal combustion engines,—at least in the field of automobiles in which the cylinders were arranged in banks, whether or not the banks were arranged in a V,—to drain the oil by gravity out of the rocker arm boxes through conduits in the push rod casings or shrouds to a receptacle therefor in the crank case, and thence by suction pump to the main oil reservoir for the engine. Woolson, U. S., No. 1,836,637, 1927. But such a drainage means was operable only in engines in which the cylinders projected upwardly from the crank shaft,—so that oil accumulating in the rocker arm boxes on the cylinder heads could drain by gravity back to the crank case. Such was the usual arrangement in automobile engines.

But the solution of drainage by gravity for automobile engines did not meet the problem involved in the radial engine of the airplane. For obviously in the radial engine the boxes on cylinders below the horizontal plane of the crank shaft could not drain upward by gravity. For such engines, it was not a practical solution to locate the main oil supply below the lowermost rocker arm boxes as was common practice in automobile engines. For an oil reservoir large enough to serve an airplane engine would be altogether too bulky and heavy to have such a location. And so the problem was to find a means for returning the oil from each rocker arm box to the main supply which should be sufficiently compact and reliable to be practicable in the radial airplane engine without destroying its proper balance.

The solution of the problem was a long time in coming, due apparently, to the fact that there were numerous other problems in the development of aviation even more important, which were absorbing the attention of research engineers. And after all, even under the more primitive method of hand lubrication with a grease gun an engine could run for ten hours without undue wear on its valve gear and an airplane could go a long way in ten hours,— about as far I suspect as its fuel-carrying capacity would permit. This running period could be even further extended without jeopardy to safety requirements at the risk of some wear on valve gear, and even further extended by manually-operated devices whereby the pilot could periodically inject oil to the valve gear as in the so-called "one-shot" method of lubrication. Even without automatic lubrication, Lindbergh made his historic flight to France and Wiley Post flew around the world.

Nevertheless, that automatic lubrication was an important development in the art is fully demonstrated by the extent to which since its development it has superseded more primitive methods. The waste resulting from old methods which allowed surplus oil to escape into the atmosphere is apparent when one considers that in the modern devices for automatic lubrication something like an eighth of a pint of oil per minute is delivered at each rocker arm box. And lubrication by grease by hand was exceedingly laborious and subject to all the hazards of human fallibility. Thus the substantial utility of automatic lubrication in airplanes cannot be gainsaid.

On the record before me it appears that in radial air-cooled engines such as are commonly used for airplanes, no solution of this problem had been devised until Heron's design which was embodied in the so-called Curtiss R-1454 engine, three of which were ordered by the Government and of which at least one was delivered and tested in 1925. Although the test disclosed defects elsewhere in the engine, its system for automatic lubrication was found to be operable.

The lubrication system of the Curtiss R-1454 provided L-shaped scavenge pipes leading from each rocker arm box through an orifice in the middle of the wall of the rocker box into a circular manifold having a radius substantially less than the distance from the crank case to the top of the cylinder head. At the bottom of this circular manifold was a pipe connecting with a special suction pump which was adapted to suck oil from all the boxes and pass it on to the central reservoir in the fuselage of the plane. Thus Heron for the first time, so far as this record shows, in a radial engine achieved a closing of the circuit for oil lubricating valve gear making the system wholly automatic. It will be observed that to accomplish this, Heron relied entirely upon suction. This was especially so in respect of the cylinders whose attitude was such as to locate them below the horizontal plane passing through the crank shaft, for as to these gravity was obviously ineffective to drain the boxes on such cylinders. But even in respect of the cylinders located above that horizontal line, gravity, unaided by suction, was not wholly adequate under Heron's method. For on some of these cylinders the scavenge pipes for individual rocker boxes had an upward course at least for a part of the distance to their connection with the manifold, which only a considerable suction force could overcome.

The patentee, whose original application was filed October 17, 1929, also provided a drainage means to complete the circuit of the lubricating system; in that he followed rather than led the way. But unlike Heron, instead of providing for the evacuation of the rocker arm boxes by direct suction on each box in a single step, as it were, the patentee took two bites to the cherry; first, by providing scavenging pipes from an outlet in the lower part of each rocker box and thence extending continuously downwardly to a connection with his outer manifold through which the oil was conducted, still continuously downwardly, to a sump located between and slightly below the two lowermost rocker arm boxes, and second, by a scavenge pump only to return the oil from his sump to the central oil reservoir.

That Schenk's elaboration of Heron's means of drainage was indeed an improvement is, I think, fully demonstrated by the record. To be sure, I think the record requires a finding that Heron's apparatus was operable at least in the sense of the patent law; the 50 hour test proves that. But the 50 hour test shed little light on the efficiency of Heron's construction; it demonstrated merely operability. And Heron's own testimony shows quite clearly that in his apparatus there was one inherent defect which was eliminated by Schenk. For Heron testified that the Curtiss engine was originally equipped with scavenge pipes from each pair of boxes which formed a T with one stem only (for the pair) leading into the manifold. For this later was substituted a construction whereby each scavenge pipe led directly from its rocker box to the manifold. Heron explained this change by saying that the original construction failed to drain the boxes equally because one had more aid from gravity than the other, as was apparent from the blueprint which is Exhibit 119. But it is apparent even to a layman from the blueprint, Exhibit 120 which showed Heron's improved construction, that here too the arrangement of the scavenge pipes was such that many of them had more aid from gravity than others. And so it is scarcely surprising that Heron himself, answering a question addressed by defendant's counsel, said: "I regard the use of a sump as an improvement." One, at least, of the advantages of a dry sump is that it serves as a means to drain by gravity each rocker arm box. And a sump properly located, like that shown by Schenk and that used by the defendant, will so drain the boxes on cylinders below as well as above the horizontal of the crank shaft.

Moreover, the defendant itself before incorporating Schenk's disclosure into its infringing engines, tried even on a commercial scale a sumpless drainage system which, like the Curtiss R-1454, depended upon direct suction on each rocker arm box. This sumpless construction was abandoned because, in the words of the defendant's own expert, Willgoos,

"We found that when we shut the engine down the oil which drained out of the rocker boxes to the bottom of the engine would build up a level sufficient to overflow the valve stems so that some of the oil would find its way down the valve guides, and if the valve on that particular cylinder happened to be open it was free to flow into the combustion chamber. And if a sufficient amount of oil collected in the combustion chamber in that manner there was danger of...

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