How the CLOVER works

Most of you probably haven't seen the Clover in action, so the way it works is probably a mystery. It's sort of a combination of a french press and a vacuum brewer. After watching a bunch of extractions at Gimme, I was fortunate to be able to ask Clover engineer Zander Nosler some questions. He was very open and answered everything. When I suggested that I might do an online writeup, he liked the idea. So here we go....

Zander, please look this over and correct the mistakes in my drawings and/or explanation! Also, this is the first time I've used Adobe Illustrator, so please take pity on my graphics.

The working parts that you see from the top are a stainless steel cylinder (drawn in black), and a piston (red) that is moved up and down by the mechanical system down below. The piston has a porous stainless mesh on top and some one-way valves (green) called "umbrella valves" underneath. The umbrella valves allow liquid to flow down, but are automatically forced closed if liquid tries to move upwards. At the bottom of the cylinder there are two drain valves (my drawing shows just one in purple) that open and close upon electronic command:


When you push the start button, the piston moves all the down to the bottom and the drain valve closes:



Meanwhile, you manually add ground coffee and the Clover automatically sprays temperature-controlled water onto the grounds:



Next the coffee/water mixture sits and steeps. You get to adjust how long this is, per your taste. Typically it's 30-45 seconds:


Next the actuator mechanism forces the piston upwards with the drain valve closed. This creates a vacuum underneath the piston, drawing liquid coffee down through the perforated screen and umbrella valves:


Hopefully in all the excitement you've remembered to put a coffee cup below the drain spout. The drain valve opens and piston moves downwards, pushing your fresh-brewed coffee out the bottom of the cylinder and into your cup:


Lastly, the piston moves all the way up, pushing the spent grounds above the top surface of the machine. Here they can be easily squeegied off into the grounds receptacle. After a quick wipe with a towel, the Clover is ready for another cup. Cycle time for a fast-moving barista is 1:15-1:30 per brew cycle:


It all seems so simple; brilliant engineering always makes it look that way.