High in the mountains near Colorado Springs, the dynamometers at Sturman Industries have to be adjusted to sea level conditions rather than altitude. Always different.
|Sturman’s HVA-4A is a two-stage actuator with variable lift and is most suited to use on camless gasoline engines. The first stage uses low pressure to move the spool in the 3-way proportional valve. The 3-way proportional valve controls the high pressure to the actuator. The actuator opens the engine valve. |
Sturman’s early innovations included digital latching valves which were applied to the Apollo Space program in the 1960s. These digital valves use the principle of residual magnetism to open and close working at blinding speeds and consuming minimum energy. And today he continues to innovate new efficient designs.Always saving energy.
Co-founder Carol Sturman and Eddie have put together the most breathtaking combination R&D and production facility I have ever seen. Housed in a 60,000 sq.ft. structure featuring vaulted wooden ceilings, Herman Miller furniture and situated across the valley from the magnificent Pike’s Peak, it is an atmosphere that attracts the best and brightest and a creates a culture that thrives on freethinking and innovation.
Just last month Rick Dunagan, executive director for General Motors Powertrain for the past six years, signed on at Sturman as CEO. His mission is to continue the commercialization of Sturman’s digital systems (DHOS) by seeking strategic manufacturing alliances globally. A 22 year veteran with GM, Dunagan has broad experience with fuel injection systems including several year stints in both Brazil and China.
AI visited the rustic development/production center very recently, meeting there with Dunagan, the Sturmans, engineering manager David Burt, and a host of other development and production specialists. It’s our third visit in six years and the pace and scope of the activity never ceases to amaze. This time was no different. Sturman produced its first Hydraulic Valve Actuation (HVA) System in 1996. This is what provides for the camless actuation of an engine’s intake and exhaust valves. The system can and has been applied to both diesel and gasoline engines.
No question, Eddie Sturman is a diesel enthusiast because the cycle is inherently more efficient. He firmly believes that the improvements he sees coming in diesel fuel near and medium term will greatly enhance its advantages, an important subject for another time. Work on the HVA (camless) system has been ongoing for eight years. The first vehicle in operation with HVA was fielded in 1999, a medium duty truck. Another truck was fitted with a more advanced system in 2000. A VW Jetta passenger car was equipped with camless technology last year.
Sturman is now working with 10 customers worldwide, a handful of them are automakers, “Interest is growing here,” says Dunagan, “and we’ve got plenty on our plate as it is. What we’re trying to do, what I’ve come here to do, is to bring the focus that achieves application of the DHOStm technology on a production platform and that will happen in this decade.
“Here in the U.S. we are kind of stumbling around with hybrids and the hydrogen economy and long-term hydrogen may or may not be an answer. But so much right now is political posturing and grandstanding and diminishes efforts on the near and medium term. That’s where we will fit in.”
Since the advent of common rail fuel injection, the mechanical camshaft no longer plays a role in fuel management. It only manages the air side of the combustion equation and occupies a lot of real estate to accomplish that. In Sturman’s view, the mechanical camshaft, even with cam phasers and variable valve timing, doesn’t permit the same control flexibility and latitude with air management as has been achieved in fuel management.
“It is really a question of achieving a balanced approach to combustion,” says Sturman. “Not that we can’t go farther in refining our management of fuel. We are still working on many advances there. But we haven’t made the same progress in managing the air. It has not received nearly as much attention and yet it is obvious that it is just as important.
“To make further significant gains in fuel economy, performance, reduce emissions while reducing after treatment requirements, and further reduce noise, we need to control both fuel and air together with the same flexibility and precision. It can’t be done with a camshaft.” Since 1999, the HVA family has evolved from a single-stage open loop actuator with fixed lift, the HVA-2, to a single-stage closed loop actuator with variable lift, the HVA-3, in 2000. In 2001 came the HVA-4A, this actuator being a two-stage actuator with variable lift. This is the valve actuator most suited to use on camless gasoline engines.
The latest, coming last year, is the HVA-4D and this is a family of two-stage open loop actuators including one with 2-lift positions, another with 3-lift positions, and a third featuring variable lift.
This family is intended for camless engine applications. The design objectives for the HVA-4D were achieve a more robust design, eliminate an engine valve sensor, reduce controls complexity and lower production costs. The valve is controlled completely with respect to the precise lift timing, the amount of lift itself, the duration of the lift and even the seating of the lift to control noise.
Each valve of every cylinder is independently controlled and so a cylinder deactivation or partial deactivation strategy can also be applied to every combustion event. Imagine that, partial cylinder deactivation. The engine is effectively tuned instantaneously to produce only the performance and power required. As to packaging, the profile of an HVA head would fall in between the height of push rod engine and an overhead cam. But since it’s claimed to augment power per unit of displacement, a somewhat smaller engine would be envisioned on an application by application basis.
On the fuel management side, Sturman has just introduced its new S1 diesel injector which combines the advantages of mechanical unit injectors, high pressure common rail injectors, and intensifier style injectors in a single package complete with active rate shaping.
“The real benefits will occur as we balance our air and fuel control technology and bring it together with the third leg of our triangle, closed-loop combustion control,” says Sturman. “We are doing this now on our test benches and the cylinder-to-cylinder balancing capability is just outstanding.”
Sturman sees HVA as having equal weight with other development areas, but it is certainly the one that makes the camless engine possible. As Dunagan sees it, “If what’s needed is something you can just plug in near term, with no implications to infrastructure, then HVA will surely find its place probably in Europe first, but with Japan not far behind. Eventually, it will migrate here.”