SHANGHAI – Better driving habits could improve energy efficiency by 17 percent, but suppliers have little influence over drivers. They can propose devices to advise drivers to improve, but otherwise, they are challenged to make the tiny improvements possible by reducing internal friction and the mass of their components.
Where power is lost for 70hp diesel car
Road and tires 50% 40%
Aerodynamics 20% 46%
Bearings and seals 30% 14%
At the 2009 Presidents’ Forum and CBU/CAR‘s 14th Annual International Conference, suppliers described the kinds of products they are offering automakers. While the ideas are generally well known, brought together they indicate that the automobile industry can go a long way to saving fuel before they have to switch to fuel cells or hybrid drives.
U.S. President Barack Obama has noted that the Ford Model T of 90 years ago could drive 20 miles with a gallon of gasoline, and today’s average in the United States is the same. Modern cars are of course much larger, heavier, safer and more powerful, but the challenge in his remark to the industry is clear.
Moving a car uses 13 percent of the energy available in the fuel, said David Royce, vice president for strategic planning at TRW Automotive. Accessories like lights and radios use 2 percent, operating the engine uses 62 percent, mostly wasted as exhaust heat, friction in the driveline uses 6 percent, and driver behavior 17 percent.
Thus, said Royce, suppliers of parts outside the engine can attack a large percentage of fuel efficiency problems.
Electric assisted hydraulic power steering provides a 5 percent improvement over standard hydraulic systems, he said. Moving from a drum brake to an integrated parking brake saves 1.6 kg of weight. Redesigning the electronic architecture to combine functions in fewer ECUs saves weight too. A reduction from 20 ECUs to 5 would save 7 kg, a 0.4 percent fuel savings.
Fitting a 6-speed manual transmission with energy efficient taper bearings, said Alex Teng of SKF China, can save 0.5-1.2 g/km. SKF has a new wheel bearing unit that reduces rolling friction, said Teng, and a customer in China has chosen it.
When automakers move to hybrid drives or battery electric vehicles, suppliers can offer other unique energy saving components. TRW’s Royce said that BYD and Chang’an have hybrid models with regenerative braking that provide a 7 percent boost.
“We do’t supply regenerative braking or electric power steering system to BYD,” said Royce, “but it is clearly a customer that is on everybody’s radar, not only for their needs here, but for their export markets.”
Thanks to the many sensors now in cars, said Royce, “we have the ability to understand driving habits.”
Instruments in the Toyota Prius tell the driver how efficient he is driving every five minutes, Ford has an instrument panel that shows a driver when he is doing well, and some manual transmission cars have had indicators for years that suggest a gear change to driver.
Navigation systems can save energy, by informing drivers of the best route to follow and traffic jams or road works.
But saving the fuel wasted by customers is more difficult. Tires under inflated by 0.4 bar cause a 2 percent fuel penalty, and a tire monitoring system that tells the driver about under inflation could save that fuel, but only, said Royce, if the driver refills the tires.