Waukesha Motor Co. v. Willys-Overland
| Decision Date | 05 June 1935 |
| Docket Number | No. 6647.,6647. |
| Citation | 77 F.2d 906 |
| Parties | WAUKESHA MOTOR CO. v. WILLYS-OVERLAND, Inc. |
| Court | U.S. Court of Appeals — Sixth Circuit |
Arthur H. Boettcher, of Chicago, Ill. (and Brown, Jackson, Boettcher & Dienner, of Chicago, Ill., and Marshall, Melhorn, Marlar & Martin, of Toledo, Ohio, on the brief), for appellant.
Charles Neave, of New York City (J. L. Stackpole and H. L. Kirkpatrick, both of Boston, Mass., and Braselton, Whitcomb & Davies, of Toledo, Ohio, on the brief), for appellee.
Before HICKS, SIMONS, and ALLEN, Circuit Judges.
In a suit brought by the appellant as plaintiff below for infringement of Ricardo patent No. 1,474,003, for an internal combustion engine, the District Court found no infringement in the defendant's accused engine, made no decision as to patent validity, and dismissed the bill. The plaintiff appeals.
The patent relates to internal combustion engines of the four-cycle constant volume type, operating on the so-called Otto principle, which have the valves placed in side pockets adjacent the cylinder. It relates also to a type known as L-head engines, because in their earliest form the cylinder and combustion chamber represented an inverted L. Understanding of the nature of the invention necessitates a brief exposition of principles of operation and description of construction detail.
In an engine operating on the Otto principle, the combustion mixture is formed outside the engine's cylinder, is then drawn into it by suction, and, while under compression, is ignited by an electric spark. It is the expansion of the gases upon combustion which drives the mechanism. The four-cycle type is one in which the piston makes four strokes, or two complete reciprocations, in each cycle of operation. Of the four strokes, the first is downward, a suction or intake stroke, which draws the fuel into the cylinder through the open intake valve; the second is an upward compression stroke, which, made with the valves closed, compresses the combustible mixture in the cylinder head. The downward power stroke follows, and the upward exhaust or scavenging stroke, which expels the burned gases through the open exhaust valve, completes the cycle. The top or cover of the cylinder is called the head, and here is located the combustion chamber. In the L-head type of engine the inlet and exhaust valves are disposed side by side in the same pocket, and open upwardly into the combustion chamber. Heads are sometimes made integral with the cylinder, and sometimes separable. Viewed from above in horizontal cross-section, the cylinder and the two valves for each combustion chamber are disposed in triangular relation. Of prime importance in designing engines of this type is the compression ratio, which is the ratio of the volume of the space over the piston with the valve closed and the piston at bottom dead center, to its volume with the valves closed and the piston at top dead center. Important also in the combustion chamber is the ratio of surface area to the volume of gas, a low surface ratio permitting the most desirable compression ratio, and reducing the tendency to detonation or "knocking"; a spherical combustion chamber being in consequence the ideal aimed at, though never for practical reasons achieved.
The faults which Ricardo claims to have noted in prior art engines resulted from the utilization therein of shallow combustion chambers. The ratio of surface to volume in such chambers was unduly large. The turbulence created therein by the entry of gas at high velocity so essential in producing a rapid spread of flame upon combustion, and at the same time preventing isolation and subsequent detonation of a portion of the charge, was too speedily damped out by skin friction, with the result that a layer of gas remained in contact with the walls of the combustion chamber too stagnant and chilled to burn completely upon ignition. To overcome these difficulties and achieve a more violent turbulence, Ricardo disposed the major portion of his combustion space over the inlet and outlet valves, with a port or passage having substantially the same area as the inlet valve port serving as a communication between this combustion space and the end or bore of the cylinder. "By employing this construction," he asserts, "not only is the area of the combustion chamber greatly reduced for a given volume, but at the same time violent turbulence is set up in the combustion chamber throughout the compression stroke and immediately before ignition occurs as the result of the passage of the gases from the cylinder through the somewhat restricted port communicating with the combustion chamber." The latter is formed by a recess in the flat head of the cylinder, the greater part of the recess lying over the valves, but a portion of the recess extending into and overlapping part of the cylinder. The remaining portion of the cylinder bore is substantially closed. Mechanical reasons prevent complete closure, but the inventor states that, while clearance is imperative, he makes such clearance the minimum which must be provided on purely mechanical grounds. This clearance, however, involves the formation of a thin layer of more or less stagnant gas entrapped between the cylinder head and the piston, but so chilled that it does not burn completely, and, while it is therefore partially lost from a thermodynamic standpoint, for the same reason it cannot detonate. He claims for his cylinder, having a combustion chamber thus formed, greater power and economy, with the advantage of a much higher compression ratio without a tendency to detonation.
Of the five claims allowed to Ricardo, claim 4 alone is in issue. This claim is for a combination, and for the sake of clearness we number and paragraph its elements:
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