"Have to offer a counter view
"Have to offer a counter view on the link between a patent and part numbers. I’ve worked for a couple of OEM’s (original equipment manufacturer) and also file for patents.
There is no link between a patent and part number, patents are for inventions or “claims”. A patent is specific in describing the invention and how it works or how it is applied. A patent can never be tied to a specific part as you want the patent to be broad in scope but still enforceable in the eyes of the law, thus protecting your invention from copy cats.
The reason an OEM has a part number is simply control of the business, what gets built, sold and how it is maintained and guaranteed. A part number represents a something that is physically fabricated or assembled and it is defined by a set of engineering documents, i.e. paper drawings, electronic data, production specifications, inspection methods and maintenance procedures. All of this information must be maintained and controlled; NO matter if it is in production or not, the cost and maintenance of this business overhead is FOREVER! (Until it is no longer offered)
Take the cylinder head for example and not the item that has the valve train and other bits, just the head, a chunk of metal. It will have a unique part number and more specifically a unique dash number. i.e. xxxxxxx-xx, first part is the part number and second part is the dash number. Every company does it their way, it might be xxxxxxxAxx, doesn’t matter.
Just the head will have a part number and “dash”, thus the rough casting will be a (-4), then it gets forged (squeezed in a press for strength) or heat treated (same purpose) it can now be a (-3), now it is machined to a specific configuration to mount to engine “A” with a two barrel carb manifold with a unique hole pattern, now (-1). It may get machined to a different hole pattern for engine “B”, a 4 barrel carb manifold and a new number (-2). You may take an extra .020” off the deck for an different high performance gasket….new number.
Now when you put a valve guide into the head, another new number because now it is an assembly, add the valve train, new number. What drives change while a part is in active production, a million different things: new hole pattern but same casting, change in metal alloy, different hole for different valve guide, new finish, and on and on. Also if it is an assembly and a part of that assembly changes it can change the part numbers all the way up the chain to the final product.
Part numbers generally change as a rule of thumb if the change alters: fit, form, function, strength, performance, durability and/or maintenance procedure. And this is why serial numbers are important; that serial number of an engine has a specific BOM (bill of material) so you know what part is in that engine or boat.
And of course there is a whole string of tools both electronic and physical with each individual part number and assembly part number. And then there are assemblies but both are a whole new story."