Free Valve! It\u2019s the Only Way to Achieve a True Engine Democracy

Free Valve! It\u2019s the Only Way to Achieve a True Engine Democracy

03/26/2020

To achieve true independent control of combustion in each and every cylinder of a car’s engine, you need command over three things: air, fuel, and spark. For a little while now, most every engine controlled the latter two pretty well. The latest fuel-injectors squirt fuel at high pressure with immense speed and precision. And the latest computer-driven engine software gives similar control to spark.

But air? Air was the tough one. Throttles and valves controlled the air and we could only do so much to a camshaft to make adjustments. Hyundai recently came up with a novel solution to this problem, with a low cost, fully mechanical solution, which it called CVVD, or Continuously Variable Valve Duration. That solution offers both low additional cost and high durability. But what it does not offer is full independence. There is still a camshaft, valve lift is fixed, and the duration adjustability is finite.

Now Freevalve, a company that’s technically separate but closely tied to Koenigsegg, has taken the concept of independent valve control further with a complicated, high-tech, camshaft free solution — one that gives complete control over air in each and every cylinder and takes combustion engine efficiency and emissions output to the most advanced levels we’ve seen yet.

Instead of a camshaft, each valve is controlled by an independent actuator and spring system. Each spring system can open or close the valve when it wants (timing), as much as it wants (lift), and for as long as it wants (duration). That means that the computer controlling all this can decide to run the engine on whatever cycle (Otto, Atkinson, Miller) it wants, as well as deactivate any cylinder at any time. And that’s in addition to all the usual power and efficiency benefits mentioned.

Watch the video above and you’ll see that each spring system controls the valve by having springs on both sides of the action, meaning opening and closing. Closing is actually controlled by two springs, one steel and the other pneumatic, or air. The opening spring is also pneumatic. Air pressure overpowers the force of the steel closing spring and opens the valve until it hits a pin. The pin’s height is also adjustable and hydraulically controlled. The pin’s height determines valve lift. When it’s time to close the valve, the pneumatic pressure shifts and closes the valve quite quickly.

Another impressive feat of Freevalve technology is its compact size and weight. Compared to a typical overhead cam engine, Freevalve cylinder heads are shorter, narrower, and thinner. That’s in part because there’s no chain drive to run the camshafts, as well as no camshafts, or lifters, or anything other than the valve and the spring and actuator system.

There are a couple of drawbacks to this system, of course, and both are easy to spot: cost and complexity. We have no concrete figures, but intuitively, you are replacing pieces of metal with advanced electronics as well as high pressure seals for both air and oil controls. Seals can and do wear. And when they do, they leak. Long-term robustness for such a system is not yet known. And, when failure does occur, it’s likely very expensive to fix. There a few extra parts to consider as well. For example, while the engine benefits from not having to drive camshafts, it now does need to drive an auxiliary air pump.

The benefits of Freevalve are undeniable, however, granting an engine massive amounts of additional flexibility to operate at high levels under a wide variation of conditions. Things like fuel quality, fuel type, air temp, air quality, and so many other factors can be adjusted for. Koenigsegg claims between 15 and 20 percent improved fuel consumption when compared to a typical 2.0-liter engine as well as a 60 percent improvement in cold-start emissions. And, of course, power. Making 600 horsepower in the Tiny Friendly Giant is impressive on most every level.

The question is, how will engineers learn to drive the cost of a system like this down to more mainstream car levels? And can they do it in time to keep internal combustion engines running in our quickly transforming battery electric powertrain age?


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