How Does a Scroll Compressor Work?

Once upon a time, I thought there was really just one kind of compressor. How many ways can their possibly be to make something smaller? Turns out, quite a few. Each type of compressor has its own quirks. Some designs are more efficient. Some require less maintenance. There’s just this endless list of trade offs in designs to get a solution. The Scroll Compressor however, sticks out as a more unique solution.


What’s The Scroll?

Competing compressor designs generally use interlocking screws, pistons, complex rotary vane systems, and a whole plethora of other designs. For the most part, these systems all require a ton of moving parts. There’s opportunities for wear, friction losses, and so on at every turn.

Scroll Compressors however, have only a handful of major moving parts. It all starts with two interlocked spirals, the Scrolls. One of the scrolls will move in a circular motion inside of the other, and that’s the genius of it. Gasses in the outtermost parts will have greater volumes, but as the scrolls moves, they’re forced deeper inside. The rings inside the spiral are smaller and smaller, there’s less and less space as the gasses are forced inside. The material must compress. The size of the spiral prevents any significant escape, so the need for a gasket is less on the interior.


Interlocked Spirals in a Scroll Compressor

The only other major moving component is the motor and in some configurations, a valve on the output side of the compressor. This ultimately means fewer moving parts and more efficiency from less friction. There are fewer parts to fail as well, which simplifies manufacturing and maintenance.

There is however, one major trade off: Manufacturing. The first scroll compressor was patented in 1905, but it was impossible to actually build it. Although the scrolls only need gaskets on the top and bottom, the actual shape of the scrolls must be precise. Any defect in manufacturing would cause the scrolls to fail. There needed to be absolute contact between them at all points. This couldn’t be achieved without advanced machining equipment to come in the following decades.


Is It That Big of a Deal?

Yes. This is one of those things that allows us to squeeze more performance and better lifetimes out of the equipment we use every day. It even applies across industries. Scroll Compressors are most common in HVAC equipment, but they’re also used in automotive in some super chargers and in manufacturing and research fields as vacuum pumps.

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