The drafting of claims is crucial. Which is the target audience I want to address with a patent application? First reaction of many people is: "the inventor". Then after some reflection they may say: "The Patent Office"! Yes, this is closer. A clearly structured claim, setting out how the invention distinguishes itself from the closest prior art  helps to convince the Examiner to grant a patent. But, is this the end? What is the ultimate goal of a patent proprietor who spend a lot of money for getting a patent granted. Apart from the patent being in most cases a deterrent that prevents third parties to copy his invention the ultimate goal is to convince an infringement court to stop an infringing party. Patent claims therefore ideally enable an infringement court to come to a quick and favorable decision for the patent proprietor.

In the following case study I analyse a famous historical case. Nicolaus August Otto had experimented with an internal gas combustion engine. After hitting some difficulties he abandoned this project temporarily and perfected an atmospheric gas engine with a flying piston. A combustible gas / air mixture is ignited in a cylinder and "shoots" the flying piston upwards. The piston then engages in its top position with its toothed racket to a main shaft and a flywheel. After this explosion the cylinder is cooled by the surrounding air and a partial vacuum is established in the cylinder. Under the effect of the atmospheric pressure and its own weight the piston falls back to the bottom of the cylinder, thereby turning the shaft as it falls and performing work.

This machine was a commercial success as its efficiency was much higher than the original machines from Lenoir.

However, Nicolaus Otto was driven back to his previous idea and tried to perfect it. Watching the smoke of a chimney starting dark and getting more and more faint as it mounts in the air, as it gets diluted, he has the idea that in order to avoid the explosions in his engine, the gas-mixture should equally by layered so as to start with a powerful combustion that fades as the combustion is progressing in the combustion chamber. A great idea, but today we know this idea was completely wrong as the four stroke engine once the "layered" gas-air mixture has been expanded and then compressed again has been sufficiently mixed. Despite the wrong idea Nicolaus Otto perfected his four stroke engine and was even more successful with this machine and which is today known as the gasoline engine, although in German speaking countries we call it the "Otto engine".

We will see who this genius, tried to block all competitors, even those with a two-stroke engine with his patent and the revocation actions of his competitors to to unblock this situation.

Prior art

The layered mixture claim of patent DE 532

The four-stroke-claim of patent DE 532

Improvement by an ignition channel Patent DE 2735

Patent DE 14254