Honda Fuel Cell Clarity-Engineering a Fuel Cell Car that Rivals Gasoline Cars
Honda Fuel Cell Clarity-Engineering a Fuel Cell Car that Rivals Gasoline Cars
author Added by FuelCellsWorks, January 10, 2017
  • Realized the world's first five-seat sedan package for an FCV
  • Achieved a cruising range of 750 Kilometers, on par with gasoline vehicles
  • Placed occupant comfort at the forefron of design
  • Set a benchmark for future FCV's

Pointed criticism shapes development of the all-new Clarity Fuel Cell

Kiyoshi Shimizu,  Chief Engineer and large project leader (LPL) of the Clarity Fuel CellLead developer confident that new FCV is ‘second to none’

The Clarity Fuel Cell made its debut appearance last October at the 2015 Tokyo Motor Show. The unveiling of the all-new fuel cell vehicle (FCV), its styling a more realistic version of the previous year's concept model, the Honda FCV Concept, signaled Honda's readiness to deploy fuel cell technology on a production scale and create a market for FCVs.
Honda sprang into action in March 2016, when it delivered its first lease model of the Clarity Fuel Cell to Japan's Ministry of Economy, Trade and Industry, and began leasing to other government agencies and municipalities across the country thereafter.

The Clarity Fuel Cell is the fourth generation in Honda's line of FCVs. Kiyoshi Shimizu, Chief Engineer at Honda R&D’s Automobile R&D Center, offers a self-evaluation of the vehicle whose development he led.

"We succeeded in engineering a distinctive vehicle that holds its own against gasoline vehicles in every category of performance, from comfort and trunk space to cruising distance and design. And it has plenty to offer in the area of fun driving as well. When test-driving our competitor's vehicles, there was no category where I felt we had fallen behind."
The father's love for his child is only natural, of course. And while Shimizu is hardly an unbiased source, he has a reason to be so confident. "I put special emphasis on not settling for second best. I encouraged the development team to set aside all notions that because this is a clean, eco-friendly FCV, we can ignore or disregard certain standards of customer satisfaction. We put a lot of work into expanding the convenience and value-added features normally expected from a vehicle. Without that approach, FCVs would never be able to compete on equal footing with gasoline engine vehicles. Thanks to the persistence and hard work of my development team, we came up with something infinitely close to the car we had envisioned."

The Honda developers faced the task of not simply developing a functional FCV, but engineering a great car that inspires passion and pride in every owner and driver. The Clarity Fuel Cell stands as evidence of their high standards.

Getting at the feelings behind user's honest feedback

Shimizu's insistence on creating an FCV with features that "compete on equal footing with gasoline engine vehicles" was motivated by an experience he had in the US eight years previously.

n November 2007, around the time the FCX Clarity had its sensational debut at the Los Angeles Auto Show, Shimizu was transferred to the US for a new job position. His assignment there was not FCV development, but rather to help with attracting new customers to the already developed FCX Clarity. As Shimizu travelled the country meeting with users and hearing their thoughts, one comment took him by surprise.

"Honda is calling this a sedan, but I don't think you understand what a sedan really is."

Those words—which essentially called into question Honda’s understanding of the most basic form of automobile, the sedan—were painful for Shimizu to hear.
Bear in mind that the FCX Clarity was the most cutting-edge FCV at the time. It featured elegant styling made possible by a layout that positioned the fuel cell stack, which was dramatically smaller than the previous model, down the center of the vehicle between the seats. This did not allow for five seats, but such were the technical limits in those days.

Feeling somewhat defensive, Shimizu continued to listen. The user followed up with a number of examples of the FCX Clarity's “flaws”: It had less cargo space, a shorter cruising range, and fewer features than gasoline engine models of the same class, for instance. Taking it all in, Shimizu realized something:
"He was giving me his heartfelt, honest opinion. It was his way of caring."

FCX Clarity users were the early adopters and innovators, people who were sensitive to emerging trends and new sources of value and who took joy in being the first to incorporate them into their lives. This user recognized great value in the FCX Clarity and drove it every day so people could see it. And yet at the same time, he seriously regretted having to use another car simply because it couldn’t fit five people, or more luggage, or drive farther distances.

"This car is still lacking as a sedan."

Such pointed words were not motivated merely by the desire for five seats. What the man was really trying to say, Shimizu realized, was: "This car does not provide the level of convenience and value that typically comes with sedans. Do you understand how disappointing that is?"

"To Americans, the automobile is a symbol of freedom and a means of living out that freedom," explains Shimizu. "Excuses that call attention to the vehicle's fuel cells or environmental performance simply don’t fly here. Without the type of value universally expected from an automobile, customers will never be satisfied with an FCV. I felt on a visceral level that we really need to take users' honest opinions—and the care they express toward our products—seriously."

Fitting the entire powertrain under the front hood—a seemingly impossible goal

From ‘sedan-type’ to full-fledged ‘sedan’

After his sojourn in the US, Shimizu was appointed to LPL (large project leader) of the next Honda FCV. After hearing raw feedback from American users, Shimizu was now being tasked with leading development of the next-generation model.
That model, the fourth generation in Honda's line of FCVs, would no longer be for testing or test marketing, but rather for bringing FCVs to the masses. The goal would be impossible without a level of convenience and value comparable to gasoline engine vehicles. With American users’ comments still echoing in his mind, Shimizu drew up a new set of development goals:

"To engineer an FCV that rivals gasoline engine vehicles in every category: driving performance, cruising range, riding comfort, trunk space, convenience, and design."

Like the FCX Clarity, the next-generation model would be a midsize sedan, a popular segment in the US, the world's largest FCV market. To achieve these goals, the new FCV would have to be equipped with the same level of convenience and added value as a sedan of the same class—in other words, a five-seat package with ample cargo space would be absolute requirements of the next model. To do that, the project team "decided on development goals that would achieve the same packaging as a gasoline-engine sedan. We would further downsize the fuel cell stack that was placed in the central tunnel of the FCX Clarity so the entire powertrain could fit under the front hood, like an engine, securing maximum space for the cabin and trunk."
 The time had come for the Honda FCV to leave behind its "sedan-type" name and proudly proclaim itself as a genuine sedan.

‘If someone’s going to do it, let it be us.’

Current technology, however, made fitting the entire powertrain under the front hood seem like nothing but a dream. Chief Engineer Kenichiro Kimura, who was appointed to powertrain assistant large project leader (A-LPL), looks back.
"There's no way it’ll fit. That’s honestly what I thought. After all, when we tried, it got so high it blocked half the windshield and you couldn't see out," he says, laughing.

Though skeptical at first, Kimura felt increasingly ambitious as he listened to Shimizu's dreams of creating an FCV that rivals gasoline vehicles.

 As long as FCVs continue to evolve, Kimura reasoned, making fuel cell stacks smaller will always be an objective. That means someone will eventually succeed in installing the powertrain in the front end. In that case it might as well be Honda. If we could bring it down to the size of a V6 engine, he concluded, the fuel cell powertrain could fit inside under the front hood of a midsize sedan. Kimura thus began the work of downsizing all of the powertrain components.

The biggest hurdle was the fuel cell stack. A single stack consisted of 500 layers of cells “stacked” on top of one another. This number had to be reduced by about 30 percent for the stack to fit under the hood. And for that, the electric potential of each cell would have to be increased by 50 percent.
There was no magical, one-time solution to this problem. Kimura instructed his team to carry out a comprehensive redesign of the cell structure to make efficiency improvements in all areas, including water removal, gas diffusion, and uniform quantity of electricity. Very slowly but steadily, generation capacity improved.

"We just kept searching for areas to improve," says Kimura. After continuing this process for two years, they became confident they could reach their goal. And a year after that, they had a fuel cell powertrain about the size of a V6 engine.

Tackling the noise paradox: greater quietness increases sensitivity to noise

A perplexing requirement for near-silent performance

While Kimura was grappling with the powertrain's excessive size, Chief Engineer Kenji Uchibori was focused on improving the powertrain's noise performance.
Uchibori, who joined Kimura in powertrain development, decided to change the design of the air compressor, the part that delivers air to the fuel cell stack, from the conventional rotary-screw type to a new electric turbo type.
"The air compressor is an important component that can influence the fuel cell stack's generation capacity," says Uchibori. "We weren’t sure if we could reach the performance required from the new FCV simply by improving the existing compressor’s design. So we tested different types of compressors from various angles and determined that an electric turbocharger type would do well at satisfying all of the requirements."

Uchibori got to work on developing a compressor for the new FCV. But he soon ran into an unexpected problem.

"They said it was too noisy."

That can't be, Uchibori thought, questioning his own hearing ability. Structurally speaking, the electric turbocharger type is quieter than the conventional rotary-screw type. Skeptical, Uchibori dug a little further and discovered an important phenomenon.
"FCVs are quiet to begin with, but the Honda team had taken that quietness to the next level with the new FCV. That made even the smallest sounds coming from electric turbo air compressor stand out," he explains.
Any quieter and the compressor would practically be silent. Is such a thing possible? Feeling unsure of himself, Uchibori consulted the manufacturing partners with whom Honda was working on development.
"We had trouble seeing eye to eye at first. Turbochargers are typically used when the engine is running, so noise when idling is rarely a problem. The level of quietness we were hoping to achieve, therefore, was an order of magnitude beyond what common knowledge of turbochargers could provide. From their perspective, they didn’t have a clue about what could be done."

Uchibori relentlessly continued to explore and test out various solutions. He also sought input from turbocharger experts in the company. The manufacturing partners eventually came around to Uchibori's persistent enthusiasm, lending some momentum to the development effort. The end result, an innovative coaxial two-stage compressor, is not only quieter but also led to a smaller fuel cell stack, smaller body apertures and, by extension, improved aerodynamic performance.

Designing for design’s sake—with aerodynamics built in

Creating that European luxury sedan feeling

Exterior design was critical to achieving a value and appeal exceeding that of gasoline engine vehicles. Ken Sahara, Seniour Designer at the Automobile R&D Center who oversaw the Clarity Fuel Cell's exterior design, describes aspects of his design approach that were a priority:

"Given the model's large price tag, the goal was to create distinctiveness and feel that measured up to European luxury sedans in the same price range. A low profile, small tires, and cramped look would not be commensurate with its price. It needed a dignified frame with balanced proportions, with wheels and tires of matching size, all working together to convey a sense of stability. In a sense, we aimed for proportions that set it apart from other Japan-made cars."

Aerodynamics was another crucial element of the new FCV's design. That's because extending its cruising range to the level of gasoline engine vehicles meant minimizing all forms of driving resistance, including air drag. Shugo Kamemoto, Assistant Chief Engineer at the Automobile R&D Center in charge of aerodynamic properties of the Clarity Fuel Cell, explains the importance of aerodynamics for the Clarity Fuel Cell.

"Gasoline engine vehicles see their fuel economy improve when cruising at faster speeds. But for FCVs it's the exact opposite; whether cruising or not, motor efficiency declines when speed increases. For that reason, improving aerodynamic performance and reducing driving resistance has a greater impact for FCVs than it does for gasoline vehicles. That's why I felt that, to achieve the cruising range target set for the new FCV, we also needed to push the boundaries of aerodynamics."

But aerodynamics is heavily dependent on exterior design. In many cases, unique, free-spirited design and high aerodynamic performance are mutually exclusive, as cars with a low air resistance tend to look the same.

With Sahara's design priorities on the one hand, and Kamemoto's airflow requirements on the other, the two would need to compromise somewhere—if, that is, they were following a conventional approach. This time, however, they decided to try out of a new development approach to achieve the impossible.

Showing by example the synergies of design and aerodynamics

"Before getting into the design process, we started by having the designers meet with the aerodynamics engineers to talk and develop a shared vision for what kind of car we wanted," says Kamemoto.
 In the conventional approach, the two teams start work separately, converging at a later time. But for this project, the two groups met face-to-face on day one, deciding design and airflow characteristics as a team.

"Designers generally know what kind of designs or forms are more aerodynamically efficient. But in this project the topic never came up. Instead, the two groups talked repeatedly about what kind of design would be suitable for a flagship FCV sedan, what aspects of the design created drag, and how to fix it. That way the designers never added an element they didn't want simply because it improved aerodynamics," says Sahara.

Instead of aerodynamics, the designers prioritized creating an attractive, distinctive, one-of-a-kind exterior. This resulted in overall proportions for the Clarity Fuel Cell that achieve advanced aerodynamic performance as an inherent function. They also actively incorporated airflow features that were in the spirit of the design concept. Symbolizing this process are the air curtains incorporated into the front and rear wheel wells.

Although the Clarity Fuel Cell is the first sedan in the world to include rear air curtains, Kamemoto prefers to downplay their significance as an innovation.
"The impact of the air curtains themselves is not particularly large. But they are part of a whole series of improvements that add up to a significant impact on overall driving resistance. The result is an impressive sedan that sets an example for the kind of synthesis that can be achieved between design and aerodynamics."

With a solid understanding of packaging, A young engineer makes a confident decision for the team

An FCV that looks like an engine vehicle—but built like an FCV

Another Honda associate who deserves mentioning when talking about the Clarity Fuel Cell's design is packaging designer Kei Kobayashi.
As a packaging designer, Kobayashi’s job was to coordinate the work of the designers and engineers and bring their conceptual aspirations to a practical resolution. Though younger and less experienced than his colleagues, Kobayashi feels satisfied with the Clarity Fuel Cell despite the various challenges he faced when designing its packaging.

"People have said the Clarity Fuel Cell has a very natural, car-like design," he says. "We fit the entire powertrain into the front end, so they assume we benefited from our knowledge of engines, but that's far from the truth. FCVs have a load of functional parts—hydrogen tanks, for example—that aren’t used in engine vehicles. The number of parts we had to fit between the four wheels doesn't even compare to an engine vehicle. If we designed the FCV like an engine vehicle, it would look nothing like it."
At motor shows and other events, Kobayashi has taken a secret pleasure in surprising journalists who examine the Clarity Fuel Cell and find parts in unexpected places. It's part of the joy of being a packaging designer, he says.

The packaging designer also plays an organizational role among the development staff, gathering requests and suggestions from designers and engineers and coordinating them from a bird’s eye view of the project. The hydrogen tanks are an illustrative example.

 One unique feature of the Clarity Fuel Cell is that it has two hydrogen storage tanks: one behind the rear seats and the other below the floor. There was a time in development when the engineers sought to combine the tanks to reduce weight, but this required sacrificing hydrogen capacity, riding comfort, or cargo space—a decision that could negatively impact the product's value.

"Kobayashi gave a definitive answer: 'One hydrogen tank will be disastrous for the vehicle,'" laughs Shimizu. "So we gave up on the single tank idea and everyone went back to the drawing board to think of how we could add storage somewhere else."
Despite his age, Kobayashi told Shimizu his opinion directly and without hesitation, and Shimizu accepted without objection. Such a relationship was possible because Kobayashi had a solid understanding of what packaging design was most appropriate for passengers, and because it aligned with Shimizu's vision for the FCV.

The Ultimate Eco-Car Requires the Ultimate Expression of a Time-honored Philosophy

Healthy for the planet—but healthy for people?

Two philosophies that underlie the design and engineering of all Honda automobiles are "respect for the individual" and “man maximum, machine minimum,” or MM. The latter is a design approach that prioritizes comfort and utility for occupants, while making the mechanical components as small and high performing as possible.
Minoru Ueda, Chief Engineer at the Automobile R&D Center and Body Design Large Project Leader (LPL), took this MM philosophy to its logical end: For the Clarity Fuel Cell, he devised a concept called Total Air Quality Management.

Prior to the Clarity Fuel Cell, Ueda had built a career in developing car air conditioners and interiors. This experience led him to a certain suspicion about the quality of the interior space in the development of FCVs, commonly recognized as the ultimate eco-cars.
"FCVs are considered the ultimate eco-friendly vehicles because they emit only water, and in that sense they are the cleanest for the planet. And that's when I thought, well how clean are they for the people riding them?" 
Then Ueda recalled Honda's core philosophies for making great cars. Thinking through them once again, Ueda came to the conclusion that, as long as Honda expressed a commitment to "respect for the individual," MM could not simply refer to spaciousness and convenience, but rather the best environment for humans in all ways. In other words, a cabin space that is easy on the body and supports health is the ultimate expression of Man Maximum.
"When I reread the Honda Environment Statement, I noticed the part, 'make efforts to contribute to human health and the preservation of the global environment,'" recalls Ueda. "I knew then that my thinking was correct and that we should incorporate an approach in the FCV's interior development that would contribute to human health."

Ueda decided to introduce an air quality-enhancing technology that turns a ride in the FCV into a comfortable and healthy way to spend time on the move. To eradicate harmful airborne particles and bacteria, remove unpleasant odors, and create a cleaner cabin space than the outside air, Ueda equipped the Clarity Fuel Cell with a sensor that discerns the quality of incoming air, a purifying filter, plasma cluster ionizer technology that releases disinfecting ions, and floor mats made from a material that absorbs and breaks down harmful substances and odors.
"I wanted our customers to see the Clarity Fuel Cell as a vehicle they feel most comfortable about taking their loved ones in. I want to make cars that are beneficial for occupants' health," says Ueda with a smile.


The developers buckle down in a moment of truth

Putting the customer at the center of design

Dignified proportions, large wheels, wide tires, two hydrogen tanks, genuine leather trim, power seats... With each feature added to the new FCV that was not in the FCX Clarity—all in the name of creating the "value and appeal that rivals gasoline engine vehicles”—came more weight.
Extra weight is a literal drag on fuel efficiency, cruising range, and driving performance. At a certain point in the project, lightweight became the development team’s primary mission.

Despite employing various solutions to cut weight in increments as small as a few grams, however, the team faced the real possibility of not meeting their weight target. They found themselves in an increasingly tough position.

"Eventually we came to an impasse, so we project leaders went straight to the Large Project Leader," recalls Ueda. "Late in the night we all went to Shimizu's desk and told it to him straight: We need you to make a decision. Either get rid of the cruising range target or some of the features."

But Shimizu's answer was this: "Keep both. Don't get rid of either."

"The decision wasn't about which target to drop,” he explains. “The real question was: are the targets necessary for the people riding the vehicle? If both are necessary, what approach is available that would allow us to keep both? And what is needed for that? Money? Time? A new technology? That's where my role as a decision maker came in.”

But the team had clearly already thought of everything and come up empty. One would think they would feel disheartened with Shimizu's response, but that was not the case.
"In fact, everyone buckled down. We figured there's only one way out, and that's through," says Kamemoto. "Actually, we all had a vague suspicion Shimizu would say that. We were stuck and at a loss. We needed the push that would bring us all together and help us decide which direction to go."

From that point on it was a renewed fight to cut down on weight. Lightweighting on any fundamental level requires trimming mass from the car's body and frame. So the team decided to use aluminum for nearly all exterior parts, including the doors, hood, and trunk, as well as an extensive amount of lightweight high-tensile steel for the frame. They employed a particularly innovative type of steel, a high λ (hole expansion ratio)-type 980 MPa high-tensile steel—the first time in the world for a car part. They also used lightweight materials for a number of parts where lightweighting was conventionally difficult, bringing them ever closer to the target weight.

"The car could easily have exceeded two metric tons using conventional methods," says Shimizu. "But two tons is inconceivable for a sedan of this size. We used a lot of lightweight steel for the body frame, but we also worked as an entire team to redesign components to be lighter. As a result, we were able to cut almost 200 kilograms of weight."
The result, the finished Clarity Fuel Cell, weighs in at 1,890 kilograms. This is not exactly light compared to gasoline engine models in the same class, but the fact that the Honda engineers could cut that much weight is truly remarkable given the prodigious number of parts required in an FCV and all the comfort and convenience-enhancing features they decided to keep.
"You would never guess the Clarity Fuel Cell’s weight going on things like acceleration power, driving, and braking performance alone. The team did a fantastic job, not only in reducing weight but in bringing close attention to all areas of the vehicle. The result is a fun, smooth driving car."

Despite the seemingly insurmountable challenges the Honda developers faced, what carried them through was their unshakable resolve in creating an FCV that inspires passion and pride in every driver and owner. By adopting the needs of customers and passengers as the sole standard for making their design and engineering decisions, they succeeded in setting a benchmark for new FCVs that possesses the convenience and value everyone has come to expect from an automobile.

Associates who contributed to this article

Final thoughts on development of the Clarity Fuel Cell

(From left)

Kenji Uchibori, Chief Engineer

Fuel cell design project leader (PL) of the Clarity Fuel Cell
Automobile R&D Center, Honda R&D Co., Ltd.
"I'm especially proud of our young engineers. With an FCV, there are no other models that serve as a reference, so they had to start from scratch. Despite having nowhere to run, they never lost heart, helping us to achieve the kind of car we did."

Shugo Kamemoto, Assistant Chief Engineer
Finished vehicle performance project leader (PL) of the Clarity Fuel Cell
Automobile R&D Center, Honda R&D Co., Ltd.
"Everyone in charge of the final car's performance was highly motivated by the awareness that we were setting an example for the popularization of FCVs. We've received high reviews in all basic categories, including driving, braking, handling, and quietness. I think the Clarity Fuel Cell will end up being an important milestone in the history of FCVs."

Minoru Ueda, Chief Engineer
Body design assistant large project leader (A-LPL) of the Clarity Fuel Cell
Automobile R&D Center, Honda R&D Co., Ltd.
"There are few people working in FCV development, even when you factor in other companies. In that sense, the knowledge we've gained is a valuable asset. To keep that knowledge alive, we need to use it in the next project. That's one reason why I think it's extremely important that we keep going."

Kiyoshi Shimizu, Chief Engineer
Large project leader (LPL) of the Clarity Fuel Cell
Automobile R&D Center, Honda R&D Co., Ltd.
"FCVs and other hydrogen energy technologies will become increasingly important as a cornerstone of environmental technology. To deploy them on a broader level, we need to diversify these technologies, and offer them at more affordable prices. I'll keep doing my best for future generations."

Kenichiro Kimura, Chief Engineer
Powertrain assistant large project leader (A-LPL) of the Clarity Fuel Cell
Automobile R&D Center, Honda R&D Co., Ltd.
"I think we came significantly closer to our goal of making FCVs as common as other types of automobiles. The Clarity Fuel Cell is the ultimate clean car, with zero emissions, and yet people have nothing to sacrifice in the way of comfort and convenience. I want everyone to experience what this car is like."

Ken Sahara, Seniour Designer
Exterior design project leader (PL) of the Clarity Fuel Cell
Automobile R&D Center, Honda R&D Co., Ltd.
"In '60s and '70s there were lots of cars with imaginative designs. Where's the imagination in a car that is environmentally friendly but doesn't look cool? We aspired to create a car that people will buy for its design, not necessarily its clean performance. The result is the Clarity Fuel Cell."

Kei Kobayashi, Designer
Packaging designer of the Clarity Fuel Cell
Automobile R&D Center, Honda R&D Co., Ltd.
"The FCV is still a special kind of car. There are no theories or rules about how to make them. For that reason, the Clarity Fuel Cell allowed us to offer our customers just one of the various possible packaging designs FCVs can take that are easy to use."