Stewart-Warner Corp. v. A C Spark Plug Co.

5 F. Supp. 371, 1933 U.S. Dist. LEXIS 1211
CourtDistrict Court, E.D. Michigan
DecidedDecember 11, 1933
DocketNo. 445
StatusPublished
Cited by2 cases

This text of 5 F. Supp. 371 (Stewart-Warner Corp. v. A C Spark Plug Co.) is published on Counsel Stack Legal Research, covering District Court, E.D. Michigan primary law. Counsel Stack provides free access to over 12 million legal documents including statutes, case law, regulations, and constitutions.

Bluebook
Stewart-Warner Corp. v. A C Spark Plug Co., 5 F. Supp. 371, 1933 U.S. Dist. LEXIS 1211 (E.D. Mich. 1933).

Opinion

TUTTLE, District Judge.

This suit involves reissue patent No. 18,-112 to Moulet, a resident of France. On June 4, 1917, Moulet applied- for, and later secured, a substantially equivalent patent in France, No. 494,871. Then on July 9,1918, he filed a United States application, which was pending in the Patent Office until August 31, 1926, when it issued in its original form as patent number 1,597,689. This original patent was later assigned on October 11,1927, to the plaintiff in this case, and on April 10, 1930, the application for reissue was filed, and on June 23,1931, the reissue patent number 18,112 was issued.

The patent relates to the pumping of gasoline from the supply tank at the rear of an automobile to the engine carburetor which is under the hood at the front. This work of getting the gasoline, or gas as it is commonly referred to, from the large supply tank to the carburetor that uses it in mixing the gas with the air for the use of the engine has passed through four well-known stages:

The first stage used a gravity supply tank near the engine, either under the front seat or the cowl of the automobile and the gas flowed by gravity to the carburetor as needed. Mechanically that was a simple method, because gravity did the work and fed the gas to the carburetor. So long as the tank was kept above the carburetor, it did the work that was desired; but that was not a nice place to have ten or twenty gallons of gasoline. It was right near the occupants of the ear and it was doubly objectionable because the gasoline was near the engine, the sparks, and the heat that might start a fire.

The second stage was to mount an airtight supply tank at the back of the ear and use an engine driven pump to maintain a pressure of air in the tank to force the gas up to the carburetor. This, again, was not entirely satisfactory and an auxiliary hand pump was necessary to pump up pressure initially for starting. There was also a great danger of leaks and fire due to the pressure.

The third stage was, in a way, going back to the first stage: It consisted in placing a small two-chambered vacuum tank in the engine compartment under the hood and using the engine intake manifold vacuum to periodically suck air out of one chamber of the vacuum tank, so that the atmospheric air pressure on the vented rear supply tank [372]*372pushed the gas up into that first chamber of the small vacuum tank above the carburetor, and then by gravity the gas was periodically dumped into the second chamber and fed to the carburetor for its use.

While this third stage was a big improvement over what had gone before, and although it went into general use, it was far short of the fourth stage which we now have.

The fourth stage is so satisfactory in comparison with what has gone before (and the steps that may come hereafter are so hidden in the haze of the future) that every car now sold in the United States, as far as the record shows, is equipped with this fourth thing which, to us who live in this age, is very wonderful. It consists simply of a little pulsating pump which delivers the desired amount of gas from the supply tank to the carburetor just as it is needed — almost like the human heart in the circulatory system.

This fourth stage not only required a pump but it required a pump possessing special characteristics. I go now directly to what is being done by both the plaintiff and the defendant, who supply, either directly or indirectly, the demands of the whole United States. The thing that does the trick and distinguishes this fourth stage from what had previously been in use possesses these characteristics: A pump with a casing wall that is rigid and unyielding, with a circular opening in it and fastened across that circular opening several layers of airplane cloth or fabric that have been treated in a particular way so that gas or air cannot leak through; Metal discs or washers are attached to both the inside and the outside faces of this fabric at its center,-leaving a-flexible annular zone or ring that yields as'the center discs are moved in and out in piston fashion. An actuating mechanism is attached to the discs. There is a valve controlled intake and .a valve controlled outlet to this chamber casing. As the discs attached to the fabric are pulled outwardly, the chamber increases in size and sucks in gas, and as the discs and fabric are pushed in the valve that lets in the gas is closed, the size of the chamber inside is decreased, and the fluid in the chamber is forced out past the valve in the outlet opening, and so this little pulsating heart goes on being actuated by the engine, at direct camshaft speed.

It is so arranged, however, that this pushing in and pulling out is done in this way: The pull-out stroke, which means the suction stroke, the one that increases the size of the chamber, is made positively by a cam of the engine camshaft, and has a fixed outward limit. It always fills the chamber to its full capacity, because in that direction the stroke is fixed, but on the stroke in the opposite direction, which means the discharge stroke, there is lost motion with respect to the cam, and that discharge stroke that I refer to is caused by a spring.

I do not need to describe the spring, because it does not matter what kind of spring it is, but it is a resilient action, while the cam action is positive; that is to say, when the cam releases the actuating member, the spring takes it up and forces it back resiliently, and inasmuch as the discharge stroke is a resilient spring action stroke, it is not a certain stroke but a stroke depending on how much fluid flows from the pump to the carburetor, the carburetor being of the usual type arranged with a float valve.

The carburetor, I find, determines for itself how much gas is needed and used by the engine; and the amount of gas discharged by the pump, by this resilient spring pressing in the discs and fabric, is determined by how much is needed by the carburetor; therefore, we have the carburetor taking only the gas it wants for the engine, whether it be idling or coasting down hill and using little gas, or fighting through mud or sand or climbing a steep hill and using its maximum requirements. The carburetor always feeds the amount of gas the engine needs as the driver of the car steps on the accelerator or releases it, and the flow of gas is regulated by the float valve of the carburetor in so far as the •amount of gas that is taken from the pump is concerned, and the pump always keeps an excess supply of gas for the carburetor. If little gas is fed by the carburetor to the engine, then, of course, the resilient spring on the inward stroke of the plunger does not drive much gas out of the pump to the carburetor, and therefore the positive intake or pull-out stroke is not long and does not suck much gas into the pump. I find always the same amount of gas in the pump chamber at the end of each suction or cam stroke, which means, of course, taken with what I have said, that this intake suction stroke always brings in the same amount as has been forced out by the preceding resilient stroke for the use of the carburetor.

This is the thing that is working today in millions of cars now in use and now being made. This thing I have described is very wonderful. If a man could have gone completely from stage 3 to stage 4, he would, of course, have made a very meritorious invention, but no one person did it. . .

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5 F. Supp. 371, 1933 U.S. Dist. LEXIS 1211, Counsel Stack Legal Research, https://law.counselstack.com/opinion/stewart-warner-corp-v-a-c-spark-plug-co-mied-1933.