This is an illustration of how the conventional motors (not just vacuum, but motors in general) work. Since they relay on Carbon brushes (see the number 3 in the pic) to deliver electricity to the motor, these brushes wear down as time goes on which "helps" to reduce the lifetime of the motor + emits harmful dust (carbon in this case) particles which are then caught by the filters.
So the more faster the motor spins, the faster the carbon brushes wear out, this has forced the engineers to build motors that are revolving around 35,000 RPM or below. Although they could be more faster, but as can be seen, then they'll dramatically reduce their lifetime. So when they had to choose between shorter-lifetime/cost for the users vs speed/meaning better suctions, well they went with their intuvision, "low cost" :).
A conventional vacuum motor has an average lifespan of 600 hours. And because of the materials that are being used, the conventional method do add some weight and size to the motor itself thus making the vacuum cleaner itself more heavier.
How Dyson overcame this issue?
Although it may sound easy, all you had to do was replace the problematic carbons with something else, yet engineers at Dyson took about a decade to come up with an answer!. The Dyson digital motor in simple terms, replaced the carbon brushes with an electronic circuit thus eliminating wearings which was one of the main drawback of the conventional design.
Faster and lighter!
It uses a magnet (which is one of the most heaviest parts of a motor) which is built using a material called called neodymium, which is ten times stronger and in digital motor it spins ten times faster too (104,000 per minute!).
There is an aluminum fan/s which is located at the bottom of the motor (under the low speed bearing, number 4 in the picture). In the Dyson digital motor, this is also replaced by lighter + stronger, reinforced-carbon fiber. In general with DDM, there are less wearing parts, less pollution, more powerful, durabel... yet light in weight when compared with a traditional motor!.
So, the Dyson digital motor is more efficient, third of a size of conventional motors + weights just about impressively lower 139 grams at the end, it is worth it?, well in my opinion it certainly is!.
