Camless Engines

Camless Engines

What Does a Cam Do?

At the heart of every hard-working automotive engine, you find hard-working cylinder valves. They regulate the flow of gases to and from each cylinder. But did you know cams are responsible for opening these valves at just the right time?

Each eccentric cam is mounted on a rotating shaft, appropriately called a camshaft. As it revolves, the high spot on the egg-shaped cams presses on tappets or rocker arms, forcing open the cylinder valves to let gas in or out.

Camshaft Alternatives

Camshafts are the de-facto standard, but they do have limitations. For example, multiple cams are mounted on a single shaft and you cannot adjust valves independently. So, not surprisingly, there are alternatives.

While not currently in showrooms, Koenigsegg FreeValve has developed a camless engine. As the name implies, the cams are gone. Instead, individual electrically controlled actuators control the valves. Also, fuel is port injected and controlled via the intake cylinder valves.

How Camless Engines Work

When electronically triggered “on,” a valve actuator uses compressed air to open the valve. The actuator also employs hydraulics to set the valve lift, or the degree of “open.”

When “off,” the compressed air is released and a mechanical or air spring closes the valve. The hydraulics are again used as the valve closes to dampen the action, protecting the valve and port from damage.

Camless vs. Traditional Engines

The radical camless design has promise like it is:

• Smaller, 

• Lighter, 

• More fuel-efficient,

• More powerful with higher torque and horsepower, 

• Cleaner with reduced emissions.

There are many reasons for the camless engine’s fuel efficiency. One example, by using port injection of the fuel, this motor eliminates the throttle body. This removes the air resistance caused by a butterfly.

Camless operated valves also respond quicker compared to the slower, rotating cam. Additionally, it controls the timing and lift height for each valve, independently. This has long been a fantasy for engineers. It allows fine-tuning the engine’s performance depending on the driver’s needs.

With individual control, you can employ the Atkinson cycle for fuel-efficiency. Or, you even can turn pistons off if not needed. Want more power? Adjust the timing and lift to maximize the compression ratio and supply a leaner air/fuel mixture; instant increase in horsepower and torque.

During cold starts, a camless motor sends waste gas from all its exit valves into the exhaust system. This significantly reduces the preheat time needed for the catalytic converter. So, another advantage is pre-catalytic treatment of the exhaust is no longer needed.  

In short, engineers have more control to optimize and manage performance with a camless engine. At the same time, the engine is simplified. This is simply impossible with camshafts.

Summary

The camshaft currently remains the king. But the camless engine offers a new vision for the future. The costs may still be high and more testing is needed. But due to its many advantages, camless engines might be something under your hood soon.