Physical combinability is not required for a finding of obviousness. It is true that the combination of teachings must be operable, but not that the physical combination of the particular devices in the references themselves must be operable. Typically, the better argument is that one skilled in the art would be able to make some combination, but that combination would turn out to be something other than the claimed invention.
Background / Facts: The application here is drawn to a device that stirs a liquid while injecting a gas into the liquid in order to form a gas-liquid dispersion. The claimed apparatus comprises a drive shaft fitted with one or more axial rotors and a “deflector” at its lower end that converts the axial flow into a radial flow. The primary reference (“Kwak”) teaches each limitation of claim 1, except that Kwak’s deflector is not attached to the drive shaft but is attached to the floor of the basin container. A secondary reference (“Howk”), however, utilizes a deflector that is secured to the drive shaft below the rotor in the manner claimed.
Issue(s): Whether it would have been obvious to combine the teachings of the two prior art references when a physical combination of their respective devices would be inoperable in that the radial liquid flow would be directed into the wall of a tube wall found in the Kwak device (evidently because of mismatching drive shaft lengths), thus preventing the gas-liquid mixture from achieving suitable aeration.
Holding(s): Yes. “Chevalier’s arguments demonstrate that he misapprehends the nature of the obviousness inquiry.” The obviousness inquiry does not ask “whether the references could be physically combined but whether the claimed inventions are rendered obvious by the teachings of the prior art as a whole.” Here, Chevalier does not dispute that the combination, if successfully implemented, “would facilitate a more rapid and more complete conversion from axial flow to radial flow of the liquid exiting from the bottom of the device” (probably because this is exactly what his invention does), and Chevalier has (for some reason) admitted that the deflectors of Kwak and Howk are “recognized equivalents performing the same function of converting axial flow to radial flow.” Thus, the different deflectors are mere substitutes, regardless of whether additional routine skill would have been required to combine them.