At its most basic level, an engine is an air pump. Internal combustion engines breathe fresh air and expel wasted exhaust gases to make power. Something has to tell those intake and exhaust valves when to open, and how far, and that job falls to the brain of an engine: the camshaft.
A mechanical piece attached to the valves, the camshaft is turned by a crankshaft via a pulley, while the pulley itself is turned by a rubber timing belt or metal timing chain. The setup sounds mechanically complicated, and it is. In addition, every old-fashioned camshaft design makes compromises on how well the camshaft performs under certain conditions.
But what if it didn't? England's Camcon Auto created a new kind of digital valvetrain that replaces the traditional camshaft with a set of digitally controlled electric motors to open and close valves. Camcon partnered with Jaguar Land Rover on the project, which is called Intelligent Valve Technology.
A digital valvetrain is less complicated than an all-mechanical system as well, since severing the mechanical link means no timing belt or chain is needed. Instead, each valve has an electric actuator that works a mini-camshaft, opening and closing each valve independently from the others. Overall, it's a faster way of adjusting to an engine's power demands.
You won't see this technology in an average car next year. But IVT, like new breakthroughs in variable compression ratios and homogeneous charge compression ignition, breaks the old rules about the limits of a car engine.
What Took So Long?
Let's say you pick up a car from the dealership, and the new ride is fitted with a tame factory camshaft that tells the engine to remain calm while you're puttering around town at low rpm. Later, you decide to swap in a performance camshaft that trades city-street drivability for high-revving power on the track. Either direction you go, you end up optimizing the engine's timing for certain circumstances at the expense of others.
Automakers have long been trying to engineer their way around this great compromise. Their best attempt came with variable valve timing (VVT), which could change its timing on the fly, bringing car engines a little closer to having the best of all worlds. By the early 1990s, automakers were selling VVT tech under catchy trademarked names. Honda's VTEC appeared suddenly in huge numbers of Preludes, Civics, Integras, and Accords. BMW introduced its VANOS to the 3 Series and 5 Series, joining the N-VCT that Nissan had been sprinkling into its lineup since the late 1980s.
But the all-mechanical VVT was not a panacea. For example, a VVT engine changes its timing either through cam-changing, via an electronic control unit, or a "cam phaser" that adjusts the angular position of the lobes on the camshaft. Changing the lobes' positioning changes the engine's timing regarding when it releases spark to ignite the explosive reaction that turns the engine. By adjusting the ignition timing, VVT can tweak the engine to suit different driving demands, from full power under heavy acceleration to light and easy, full-efficient cruising. However, it takes time for a cam phaser to shift the lobes into new positions, especially at low speeds. The engine keeps firing while the lobes are repositioning, though, and during that time the camshaft is opening and closing in sub-optimal conditions.
Camcon's digital IVT involves no such compromises. This tech repositions the lobes as fast as an engine can change ignition timing, and so there's no gap of time where the camshaft is in a compromised position. It can adjust quicker than VVT and to a wider range of settings for timing, duration, and lift. It doesn't tie the engine into being better at a certain part of its powerband and worse at another the way conventional camshafts do.
“We can effectively change the camshaft every time the engine turns over," says Mark Gostick, Camcon's chief operating officer. "We can ensure that the engine has the 'right' cam profile for both high rpm and low rpm, and for both high-load and low-load.”
For example: When the engine needs more power, IVT configures to be stronger at the expense of burning more fuel. When the car is loping comfortably along, it reconfigures to run more economically and cleaner. Gostick says IVT improves an engine's fuel economy by up to 20 percent and lowers its carbon dioxide emissions by the same percentage.
IVT works on any kind of piston-driven internal combustion engine—naturally aspirated or forced induction, gasoline or diesel, large or small displacement, inline- or V-cylinder arrangement—and it can be retrofitted to an existing engine design that wasn't designed for it. You'd have to modify or delete the timing drive and redesign the cylinder head to remove the conventional valvetrain and insert the electrical actuators, but Gostick says it's not difficult to do, and the block, the bulk of what comprises an engine, could be left “more or less” unchanged.
New Tech, Old Tricks
There's an old engineering trick behind this modern innovation. IVT uses a desmodromic valve system—a layout featuring an array of cam-driven mechanical actuators to open and close valves (rather than doing what typical camshafts do, which is to rely on valve springs to close them). A century ago, desmodromic valves were a breakthrough, a precise way to enable the engine to run at high rpm in which springs often couldn't close valves fast enough and would often fail.
However, the setup required complicated maintenance at shorter intervals, and today's valve-spring systems have gotten so good that the old way is rarely used. (Ducati, whose motorcycles are still famous for their desmodromic-valve engines, retains it out of tradition.) Although improvements in motor oils, low-friction coatings, and lightweight parts have lessened the maintenance requirements, working on a desmo is still a specialized skill.
IVT uses its version of the desmodromic system so that each valve can be opened, closed, and adjusted independently of each other, which allows for a huge range of customization in how the engine runs. But in contrast to an all-mechanical desmodromic system, IVT doesn't require any periodic adjustments over the lifetime of the engine, Gostick says, and so it shouldn't need any more maintenance than a typical valve spring arrangement.
The digital valvetrain has been a long time coming, and not just because of the valve issue. “At the time when the idea was conceived, it would have been impossible to develop,” says Gostick. Improvements in rare-earth magnets have made it realistic to develop tiny electric motors powerful enough to open and close the valves as quickly as IVT demands, and on-board computers have advanced to the point where they can calculate these adjustments fast enough.
For now, Camcon, which has spent seven years on IVT, is focusing on putting the tech into forced-induction gasoline engines. Forced induction includes engine-belt-driven superchargers as well as exhaust-driven turbochargers, but turbos especially are popular now as they turn waste energy into power, and the industry is in a mad drive to drastically increase fuel efficiency, fast. It's a huge potential market. Everything from bottom-feeder, milk-fetching econo-boxes to snooty luxury coupes has a turbo these days.
How soon will you see IVT in a showroom? Camcon won't say which OEMs have expressed an interest in IVT, only that they're from China and Japan. Gostick sees IVT debuting on higher-end models because young technologies tend to be expensive when first adopted, and they typically appear first on pricey models for which customers are more willing to absorb the passed-along cost.
Electric powertrains may grab most of the headlines, but automakers aren't finished squeezing all the power and efficiency out of internal combustion that they can. IVT is one more trick up the industry's sleeve, and, in a weird way, a miniature-electrified solution to keep internal combustion relevant and competitive against electric cars.