The Future Of Steering
When you've been designing, engineering and producing steering systems for more than 100 years, and anticipate doing so for the next century, you get a sense of the future of the technology.
There are a couple ways to look at the "future" of the title. For one thing, there is the issue of the source of this information, Delphi Steering, an organization with sales on the order of $2.5-billion (2007) and a global footprint that includes 18 manufacturing plants and six regional engineering centers. It is a company with a rich heritage in steering, having invented hydraulic power steering more than 50 years ago, and having been in steering for another 50 years before that.
But here's where the "future" comes in for Delphi Steering: On February 21, 2008, the the U.S. Bankruptcy Court for the Southern District of New York approved Delphi Corporation's request to sell its global steering and halfshaft business (i.e., Delphi Steering) to Platinum Equity. When I spoke with Bob Remenar, he was president of Delphi Steering and Ron Voigt was the director of its Steering Business Unit, and Ted Seeger the chief engineer of Electronic Steering Systems. At some point in the near-future-perhaps before you have read these words-the deal with Platinum Equity will have been consummated and the "Delphi Steering" name will have been replaced by something else. But Remenar will be president, and Voigt will be . . .
Remenar described what was to be as "a stand-alone organization completely dedicated to the steering space." And he stated, "We're in this for the long haul-for the next 100 years."
Future, Part 2
But what of the technology of steering? So far as they're concerned, the going tech is electric power steering (EPS), which they've been producing for more than 15 years. Unlike 15 years ago, some of the advantages of EPS are even more compelling. Seeger enumerated:
- "The first one is fuel economy. Depending on what you're comparing and how good the previous hydraulic system was, there is a 4% to 5% improvement in fuel economy." Much of this gain is a result of the fact that there's no pump working all the time as is the case with hydraulic systems.
- "It reduces proliferation for the OEMs." He explained that most vehicle platforms have multiple engine combinations. For a hydraulic-based steering setup, "Each of those ends up with its own set of accessory brackets, hoses, and belts, and each goes on separately." EPS is simpler: "Typically, the hardware is 100% the same." To accommodate the platform variations, the changes are made in the EPS controller.
- Related to the previous point, there is a savings in the OEM assembly plant, which Seeger said is on the order of 4 to 7 minutes. This is because the EPS unit goes in as a single mechanism and because there are no issues like hydraulic reservoir evac and fill.
- Faster development time. "With a hydraulic system, tuning is based on the shape of the hydraulic valve," Seeger said. What this means is that you grind a valve, assess what the vehicle is doing and what is desirable, then grind another valve profile, try it again, and repeat until the objectives are met. With an EPS system, it is more a case of a laptop in a car and calibrations are made as needed.
Given that, hydraulic systems are doomed, right? Wrong. Voigt said, "We see the hydraulic market at over 50% of the total global market through 2012." Note well the global aspect. He explained that the market driven by fuel economy concerns or CO2 emissions regulations are going to EPS. Places like Western Europe, Japan, Korea, and North America. But elsewhere, there are a number of reasons for staying hydraulic, such as existing tooling, lower-cost vehicles, or higher-load or larger vehicles.
Waiting for Power
The last point brings us forward to the future. Or back to the future. Remember a few years back when everyone was talking about "42-volt architectures"? We're, for the most part, still waiting. And this is one of the reasons why there is the limitation of the use of EPS in vehicles. Seeger explained that there is "a practical limit of how many amps you can handle." You can have big motors to handle low-speed parking torque or evasive maneuvers, but unless there is that someday move to 42-volt architectures, EPS won't go much beyond a light-duty pickup truck. "We can steer up to 15 kN, the load for a pickup truck or a Cadillac Escalade or Chevy Suburban," Seeger said.
Beyond that? Well, that goes to the point of the electrical architecture of the vehicle. Seeger has some confidence that this may actually occur at some not-too-distant time because:
- Vehicle manufacturers are working on hybrid powertrains, which involve higher power.
- Vehicle manufacturers are looking at all manner of motor driven items, from water-pumps to air conditioning compressors, as well as valve timing control, all of which mean there is a need for higher voltage.
But what about way ahead in the future, all the way to steer-by-wire. Seeger suggested that it is "a natural outgrowth of electric power steering; it uses many of the same building blocks." He reckons that the architecture that Delphi has developed is scalable from A-segment cars to full-size trucks-the same motor architecture and electronics can be sized as needed and deployed, and about 80% of the software modules they have can be used. Said Remenar: "We will have more than 10 million electric power steering systems in the field by the end of 2008. It is important for OEMs to know that we're not reinventing the systems every time."
One of the big challenges in moving to steer-by-wire is, Seeger said, communications. That's right: The internal network. Because a steer-by-wire system has no mechanical connection between the steering wheel and the front wheels, instead of creating a system that is fail-safe, one that is fault-tolerant is needed: If something goes wrong, the system still operates. This means data redundancy is the system. "Rather than the CAN communications that we used today, we need something like FlexRay to allow high-speed communications between the components." So there is a bandwidth issue. And, of course, higher power requirements. "Today with electric power steering, the driver inputs some torque and we multiply it. With steer-by-wire, 100% of the effort to steer the vehicle has to come from the electric motor."
Interestingly, Delphi actually had a steer-by-wire system in the market. The model year 2002 GMC Sierra Denali and the 2003 Chevy Silverado and GMC Sierra were offered with Quadrasteer four-wheel steering. The rear wheels were essentially a steer-by-wire system.
Looking ahead, Seeger suggested that the first car to use a full steer-by-wire system will be a luxury model-quite possibly a large sedan, with plenty of electric amenities, which would need, yes, higher power. Which will come...no one wants to venture a guess. Call it "the future."