HW2 (Fernando Rodriguez)
The purpose of this document is to dwell on weather or no patent US4529393 for a infinitely variable belt transmission, would satisfy the requirements for non obviousness outlined in two different Supreme Court rulings, those outlined in Hotchkiss as well as A&P and those in Lyon.
The patent references several different patents in its background section. Most important to the analysis of whether or not the previous patent was valid are patents US3969958 and US4433594. One of them for an output split type hydrostatic transmission and the other one a variable pulley transmission.
The output split type hydrostatic transmission functions by a system of gears (differential) and a set of positive displacement hydraulic motors that control the input speeds into the differential which allows a summation or subtraction of the speeds allow for forward an reverse speeds, this device also uses a hydraulic clutch for engaging the main shaft.
The variable pulley mechanism patent describes a mechanism that uses a typical set off pulleys that change their effective diameters of the pulleys and therefore its transmission ratio. The improvement of this mechanism over other pulley-belt CVTs, lies in a slippage clutch that prevents the over torquing of the motor.
Hotchkiss and A&P
In the first case in of Hotchkiss and to an extent A & P it was decided that a combination of elements is usually valid for obtaining a patent. The requirement for non obviousness being that a worker of average skill in the art would not be able to create the aforementioned product. Also it was decided that the action obtained from the combination of the parts should be greater in utility (as in exceed) those of the parts.
Observing the previous patents it would be decided that the proposed patent for a infinitely variable transmission would not be valid so much as it is only a combination of the previous patents. The proposed system has a different way to drive the pulleys by ways of a hydraulic system that drives the pulleys closer or farther apart. As it was established before both the belt pulleys and their changing diameters, as well as hydraulically actuating them. The main improvement then lies with using a different gear system than the previously suggested differential (planetary) system. In this case this would be deemed as a mere substitution to not as important part. Furthermore at this time it would be possible that this would be in violation of the previous patent. Furthermore all of the parts that compose the system where previously contained in other inventions. The main improvement on previous work not being better performance but a lower price (similar to replacing the metal doorknob for one made out of pottery. Furthermore the sum of the parts does not change what was previously developed in the cited references (a CVT capable of going forward and in reverse), and on top of that the patent seems to in a sense emulate A & P in being as confusing in its description as possible, in order to further increase the range of its claim.
However when this is evaluated under the decisions outlined in Lyons and the current requirement of non obviousness it seems that the patent would be valid. As the change in the synchronizer which substitutes the speed differential would in fact not be obvious to someone skilled in the art. However it is important to state that the mechanism proposed is clearly anticipated by the art and as a result it would still be a complicated question to whether or not enough of a benefit and skill was necessary to basically combine all the references cited onto one single mechanism. However if in fact this mechanism was no previously used and since has become a standard for IVt fabrication, and its usefulness in simplifying and lowering the price of IVTs then the patent would be deemed valid. However as it stands it seems to be that the main claim, and the one that should be granted should only relate to the synchronizer as hydraulically operating pulley system is not something that wasn't used before. This could be however a case where other individuals have tried a similar system and abandoned them due to its inefficiency and hence tha patent would be valid as it was the case in Lyons.