Off-the-Shelf Hydraulics & The X Prize: Lightning Hybrids
X Prize competitor Lightning Hybrids is using off-the-shelf hydraulics to bust loose at 0-60 mph in six seconds and still get 150 mpg.
The most shocking thing about the LH4—a silky hybrid concept from startup Lighting Hybrids (www.lightninghybrids.com
; Loveland, CO)—isn’t its clamshell/flip cell phone design nor its projected (but as yet unproven) 150 mpg top speed. The car being developed is vying to win the Progressive Automotive X Prize (www.progressiveautoxprize.org
), the $10-million contest to develop a 100-mpg or equivalent vehicle ready for mass production.
No, what’s most surprising about the Lightning LH4 (and the LH3, a three-wheeled variant) is that it’s powered by an off-the-shelf hydraulics system and a small diesel engine, a combination that places them closer to the next-generation of garbage trucks than the alluring Tesla Roadster.
“We’ve seen hydraulics work well for robots and in hybrids for delivery trucks, so we said ‘Why can’t we apply this to a car?’” says Lightning Hybrids co-founder Tim Reeser, who oversees marketing, sales, fund raising, and startup operations. “We’re trying to be a little more pragmatic in looking at what’s available today and what we could do with a little innovation.”
The pragmatic innovation is led by CEO Dan Johnson, who founded, and for 16 years ran, S.A. Robotics (www.sarobotics.com
; Loveland, CO), which makes hydraulically powered robots with 60-ft. long carbon fiber arms used to haul around highly radioactive spent fuel rods at nuclear power plants. He sold the company to focus on Lightning Hybrids, which is evaluating a powertrain with a small (<70 lb.) hydraulic motor/pump and accumulator, potentially from Bosch Rexroth. The system under evaluation kicks out 150 hp to launch the LH4 from 0-60 mph in less than six seconds—at least theoretically. In a typical setup on a large truck, the Bosch Rexroth hydraulic hybrid drivetrain links a gearbox with a variable axial piston unit to convert regenerative braking energy into hydraulic energy by filling a hydraulic accumulator with fluid. The process is reversed during acceleration, as pressurized fluid is discharged from the accumulator through the variable axial piston, which provides energy for the mechanical drivetrain.
LH would work in similar fashion and require a small engine—Lightning is using a Volkswagen 1.4-liter TDI diesel that’s used in the Euro Polo BlueMotion—which unleashes just 90 horses. But paired with the hydraulics, it would theoretically reach 240 hp and a top speed of 110 mph.
In the LH4 setup, the additional accumulator, which operates between 5000-7000 psi, helps capture 80% of total potential braking energy. If that holds true, the vehicle would be twice as efficient in snagging regenerative braking energy as the current-generation Prius, according to Reeser. (Toyota says it does not have a percentage range on how much energy is captured in its regenerative braking system).
“We think the Prius is great technology, but we think the car is ugly and we don’t want to buy one,” says Reeser, who is currently the COO of Cenergy, Colorado State University's clean technology commercialization program. “We want to make something people will want to buy.”
Which brings us to styling. The LH clearly borrows several cues, including the split window, from the Corvette, not surprising since CEO Johnson is an aficionado who restored a ’63 Vette. Instead of doors, LH4’s clamshell opens hydraulically with a mechanical backup built in. The four-bar linkage moves it both up and back, providing low-angle access. The LH4, at least in the CAD model, has a 0.20 co-efficient of drag.
The frame will be fabricated from chrome-molybdenum tubing, which they plan to replace in the 2012 models in favor of a carbon-fiber composite, the complete makeup of which is still to be determined but may involve an advanced fiberglass blend.
With powertrain dynamometer testing under way, the company plans to have a working prototype completed this spring and has every intention of passing National Highway Traffic Safety Board tests that will follow.
“This isn’t a joke for us, we’re in it to produce a real vehicle,” Reeser says, regardless of the X-Prize outcome.