Camless Control
Sturman's technology kicks out the camshaft
Steve Sturgess
Senior Editor
High on a mountain in Woodland Park, Colo., sits an office building where people gaze out of three-story windows at the breathtaking views. They are being creative. They are the engineers at Sturman Industries.
And the creations of the 90 or so managers, engineers and technicians all lead in one direction: to advance the management of fuel and air in an internal combustion engine and control emissions, performance and economy independently of a conventional camshaft.
Sturman Industries is a research and development hothouse. Its designs are licensed. And most are based on the digital valve technology originally developed by Eddie Sturman for the Apollo space program of the mid-60s. Sturman Industries was created by Eddie and Carol Sturman to develop and commercialize applications for his innovative latching digital valve.
A good example is the International hydraulically actuated unit fuel injector: Sturman was a technology partner and enabler for the injector, which is now in large-scale production. A fundamental differentiator and enhancement of the hydraulic unit injector - like the common rail injector - is that it is removed from the constraints of camshaft actuation. That's where the unit injector, unit pump and even PLN injectors have to rely on the profile and timing of a camshaft for their operation. Thus the modern electronically controlled injectors like the HEUI are now completely independent of crankshaft position and can feature not only widely variable timing, but multiple injection events within the same injection stroke.
For Eddie Sturman, though, that is only half the solution - and maybe even the lesser half. What he sees is similar control of the air handling in the engine. Sturman's hydraulic valve activation completely decouples valve position and movement from the crankshaft by eliminating the camshaft altogether.
As Sturman's business development manager, Eric Cefus, points out, if you can inject fuel into an engine at 30,000 psi using the engine's own hydraulics, cracking open a few valves is a simpler task.
And once the valves are freed from camshaft control, engine designers can set about optimizing valve timing, lift and other valve events with complete freedom, controlling combustion in the cylinders with a whole new set of tools unavailable within the constraints even of a variable timing arrangement on a conventional camshaft.
Sturman has already demonstrated the technology in International trucks, one of which has driven up Pikes Peak, which you can see from Sturman Industries' windows. In a second demonstration - a much more extensive coast-to-coast run - the engine ran quietly and efficiently for more than 16,000 kilometers.
That truck, incidentally, sits in a barn on the Sturman property in Woodland Park.
It is exciting stuff, but because it is revolutionary, it is still some way in the future. Sturman is working with a number of automotive interests and has recently brought on board Rick Dunagan, a 22-year veteran with General Motors Powertrain and components groups, to develop and commercialize the technologies with suppliers in the East as well as in Europe and North America. According to Dunagan, who is CEO of Sturman Industries, the camless technology may well make its commercial debut first in other markets than ours, despite the early lead shown by International.
The technology to open and close valves hydraulically is not as challenging, as Eric Cefus points out. It's deciding what and how much the industry needs of the available technology that has already been designed and developed in a workable engine.
For an engine designer, the camshaft-less valve actuation is an incredibly powerful tool. In the design stages, the hydraulically actuated valve timing with variable lift allows an engine designer in real time, on a dynamometer, to adjust "cam" profiles, lift and overlap, timing and valve ramp speed without having to go back and grind another camshaft every time a change is desired.
Those same capabilities in a closed-loop control situation could mean the valve timing and lift can be varied throughout the operating range of a production engine, allowing for control that can vary each cylinder's performance to supply only the horsepower required from the foot pedal's position.
And, of course, features like individual cylinder deactivation and engine retarder functions come along with the package absolutely free of charge.
While Sturman's ability to control the fuel and the air in an engine is remarkable, it is only the introduction to what those engineers looking out over the Colorado mountains see in the future. Commercialization of these technologies may be 10 years away - or may be hastened by the 2007/2010 emissions requirements - but ultimately, Sturman engineers see the development of an environmental engine. It is a diesel, but it incorporates hydraulically actuated valves that enable pumping cylinders to provide a supercharger capability when it is desired. It has the completely decoupled fuel control, with a number of Sturman advantages - not the least of which is safety through a completely contained high pressure system within the injector (unlike a common rail) and exceptional combustion control that minimizes exhaust aftertreatment.
And here's the kicker: Eliminate all that complicated mechanical drive and linkage that is part of the camshaft and valvetrain and you're saving cost and weight as well.
It's in the future, but if the future is anywhere close to what is being envisaged on that Colorado mountainside, we'll all get a cleaner, brighter view of the mountains.
