Tech Briefs
Ford hydrogen engine
 Ford's aluminum-intensive P2000 is powered by a hydrogen-fueled internal-combustion engine.   |
A production-viable vehicle powered exclusively by a hydrogen-fueled internal-combustion engine (H2ICE) has been developed and tested. This low-cost, low-emissions vehicle is viewed as a short-term driver for the hydrogen-fueling infrastructure ultimately required for fuel-cell vehicles. The vehicle features a highly optimized hydrogen ICE, a triple redundant hydrogen safety system, and a dedicated gaseous hydrogen fuel system. Engineers from the Ford Scientific Research Laboratory presented a paper on the vehicle during the SI Combustion Technical Session at the SAE Congress.
The engineers used an engine dynamometer facility to map a Zetec-based 2.0-L H2ICE at both a constant fuel-air equivalence ratio of 0.55 when throttled and over a range from 0.12-0.70 when unthrottled to provide a starting point for vehicle-calibration development. The engine was tested with a 14.5:1 compression ratio and fixed cam timing, but without EGR or an aftertreatment system. Following completion of the engine dynamometer development, the hydrogen engine team developed a plan to build and test the engine in a vehicle. This port fuel-injected four-valve-per-cylinder engine was integrated, together with a five-speed manual transaxle, into a P2000, an aluminum-intensive five-passenger family sedan developed by Ford to support PNGV work.
The vehicle control system consisted of an electronic throttle operated in a pedal follower configuration, an air meter based open-loop fuel control, and an electronically controlled coil on plug ignition. In addition, a PCV coalescing oil separator was added to prevent recirculation of oil into the combustion chamber, thus reducing the potential for preignition or backflash.
The fuel system was designed for safety as well as functionality. All of the major components of the hydrogen fueling system were located in the vehicle trunk except for the fuel rail solenoid and the fuel injectors. The fuel line feeding hydrogen gas from the trunk to the engine was located under the floor pan.
Safety was a fundamental vehicle design consideration for this first prototype. The team built upon the experience of Ford's hydrogen fuel cell and compressed natural gas programs to produce a unique system. This triple-redundant system combines active and passive ventilation with hydrogen detectors to enhance safety through redundancy. The heart of this system, the combustible gas detectors, consists of four sensors located in the engine compartment, passenger compartment, and trunk. Alarm conditions are triggered at hydrogen concentrations of 0.6, 1.0, and 1.6% (15, 25, and 40% of lower flammability limit for hydrogen). In addition to the detector, the safety system relied on several ventilation fans to circulate air within the trunk and engine compartments to prevent the formation of high concentration pockets of hydrogen within these areas and create more uniform mixtures at the sensors. Should hydrogen of sufficient concentration be detected, several measures are taken to minimize ignition potential. These measures include disabling the fuel supply and engine starter, opening the moon roof, and activating all ventilation fans if not already on.
Since hydrogen is significantly less dense than air, it will rise and disperse if it is not trapped. The passive elements of the safety system were designed to take advantage of this behavior. Hood louvers and the trunk seal vents (depressions in the trunk seal) allow hydrogen to escape to the atmosphere from the engine compartment and trunk, respectively. Thus, these elements further improve the vehicle's safety, providing redundancy without intervention from the other system elements.
Results of vehicle testing indicate the following:
- Carbon-based engine-out emissions testing indicated that HC and CO are less than SULEV standards, and CO2 emissions are reduced to about 0.4% of the tailpipe levels produced by a gasoline-fueled engine of the same displacement.
- The engine-out NOx emissions ranged from 0.23 to 0.46 g/km (0.37 to 0.74 g/mi).
- A metro cycle fuel economy improvement of up to 17.9% relative to gasoline.
- Smooth, acceptable drive feel in a city setting.
- Acceleration performance would require improvement for full customer acceptability. At equal performance, the metro cycle fuel economy advantage, relative to gasoline, is expected to decrease to about 11%.
Future testing should investigate technologies such as boosting, EGR, and various configurations of exhaust aftertreatment. Combinations of these are expected to substantially improve NOx emissions, specific power, and fuel economy.
- Linda Trego
The future for hybrids
 SAE 2002 host company Ford exhibited a Focus-based TH!NK fuel-cell vehicle, a 2003 Ford Expedition, and this Ford Escape hybrid-electric vehicle (HEV). When the Escape HEV goes on sale in 2003, Ford says it will be the most fuel-efficient SUV. |
Niche or mass market, that is the question panelists focused on during a panel session on hybrid-electric vehicles (HEV) at the SAE Congress. "The answer is mass market," Masatami Takimoto, Member of the Board, Toyota Motor Corp., said bluntly. "Hybrids have enormous potential to become mass-market (vehicles)."
Other members of the Executive Panel concurred. Benjamin Knight, VP, Honda R&D Americas, presented the Civic Hybrid, which is scheduled for release this spring, as evidence that incorporating gasoline-electric technology into a high-volume, mainstream vehicle is viable. The five-passenger sedan incorporates Honda's Integrated Motor Assist (IMA) technology that was used in the Insight. Its new electric motor has 30% more output capacity than the Insight's, at nearly the same size.
Likewise, Ford Motor Co.'s Prabhakar Patil, Chief Engineer of the Ford Escape HEV program, said that hybrid technology is the first credible alternative to the IC engine and discussed the automaker's Escape HEV sport utility vehicle that will debut in 2003. Capable of being driven over 805 km (500 mi) before refueling, it will have a 50-55% fuel-economy improvement over the regular Escape equipped with a V6 gasoline engine. In response to a comment that better fuel economy may not be a strong selling feature to U.S. consumers, Patil said, "If fuel economy translates into dollars, then [U.S.] consumers will be interested.... There is a growing [environmental] consciousness...where as long as [consumers] don't have to give up performance and quality," they'll be willing to do a little more for the environment by purchasing a hybrid vehicle.
Patil also believes that in North America, HEVs will be more successful than diesels because getting diesels to SULEV levels will be too costly. Conversely, Takimoto said that Toyota is currently developing clean diesel technologies and believes there may be a case for clean diesels over hybrid-gasoline vehicles in the future. He also brought up the possibility of vehicles incorporating diesel-electric technology.
Hybrid-electric technologies are key building blocks applicable to hydrogen fuel-cell vehicles, said Robert Kirk, Director, Office of Advanced Automotive Technologies, U.S. Dept. of Energy. Ford's Patil agreed, saying, "Hybrids are not contrary to fuel-cell development...and are a necessary precondition for fuel-cell advancements. They (hybrids and fuel cells) are on converging paths." Jason Mark, Director of the Clean Vehicles Program, Union of Concerned Scientists, noted that HEVs are also enhancing conventional vehicles; hybrids are becoming technological leaders since some of their advanced technologies, including packaging and weight-savings advancements, are being applied to IC-engine vehicles.
As might be expected, the panelists mentioned cost reduction as the key issue to be solved to ensure mass-market penetration. Toyota's Takimoto, for one, believes time will allow cost to be driven down with an eventual increase in mass production and competition.
John Wallace, Executive Director of Ford's The Th!nk Group, organized and moderated the panel session.
- Ryan Gehm
