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| Environmental issues such as global warming have great significance for Honda, which conducts business on a global basis. We have been committed to environmental efforts, such as the reduction of CO2 emissions, in various areas including not only product development but also production, distribution, and sales. In the area of product development, we have made proactive efforts to improve combustion efficiency and develop advanced technologies such as fuel cells and hybrid systems. In 2003, Honda announced its first diesel engine for automobiles. Diesel-powered vehicles which are more fuel efficient, therefore emit less CO2, are one of the effective methods to address the issue of global warming. In 2006, Honda announced the next-generation diesel engine with even cleaner exhaust. This engine complies with the U.S. Tier II Bin5 * exhaust emissions standard (according to Honda in-house measurements) which means it reduces emissions of nitrogen oxides(NOx) to a level on par with gasoline engines. This engine creates possibilities for diesel-powered vehicles in the area of environmental performance as well as driving performance. This special feature introduces Honda's efforts to develop clean diesel engines. |
*Tier II Bin5:
This standard for exhaust emissions was established in the United States by the Environmental Protection Agency based on the U.S. Clean Air Act and went into effect in 2004. The regulation value of NOx for emission category Bin5: 0.07g/mile. Meeting the Tier II Bin5 classification requires NOx exhaust volumes to be reduced by 75% or more from the previous emission standard. |
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| One of Every Two Cars in Europe Powered by Diesel |
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Diesel-powered vehicles are very popular in Europe. For many years, diesel-powered passenger cars have been more prevalent in Europe than any other part of the world, and this trend has grown stronger each year, to the point that in 2006, diesel-powered vehicles accounted for more than 50% of new car sales in Europe. In some European countries, such as France and Belgium, this ratio is as high as 60% to 70%.
One reason for the popularity of diesel-powered vehicles in Europe is the issue of global warming. European consumers are aware that diesel-powered vehicles offer good fuel economy, emit less CO2 and in general are more environmentally-responsible. Frequent long-distance trips enhance the importance of fuel economy, and many European countries offer tax credits that encourage diesel-powered vehicles.
Another major factor for the popularity of diesel-powered vehicles is the advancement of diesel engines. In the early 1990s, efforts to improve diesel engine emissions accelerated rapidly, against a backdrop of increasingly stringent emission regulations throughout the world. Ever since the Euro 1 automobile emission standards went into effect in 1992, emission regulations in Europe have gradually become more stringent. The current Euro 4 standards which were enacted in 2005 require a 97% reduction in NOx and hydrocarbon (HC) emissions and a 91% reduction in particulate matter (PM) compared with 1990 levels. In regions other than Europe as well, pollution is attributed to NOx and PM emissions. Particularly in Europe, automakers have improved electronic combustion-control and exhaust gas post-processing technologies to overcome this issue and meet regulatory standards. One such improvement emerged in the late 1990s. The common rail system, which used high-pressure fuel injection, offered substantially cleaner exhaust while at the same time boosting diesel engine performance. This system played a major role in accelerating the popularity of diesel-powered vehicles in Europe. |
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Although the overall size of the European auto market has not changed markedly, the percentage of diesel-powered vehicles has continued to increase.
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Figures for this graph are totals for the 15 EU countries (Ireland, United Kingdom, Italy, Austria, the Netherlands, Greece, Sweden, Spain, Denmark, Germany, Finland, France, Belgium, Poland and Luxembourg)and the 3 European Free Trade Association countries (Iceland, Switzerland and Norway). |
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AAA (Association Auxiliaire de l'Automobile) |
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| Common Rail System Transformed the Diesel Engine |
The advent of the common rail system was a major factor in the ensuing popularity of diesel-powered passenger cars in Europe. The common rail system electronically controls fuel-injection timing and volume with high-pressure fuel injection, ensuring that combustion is appropriate for current vehicle conditions.
Diesel engines employ spontaneous combustion. As piston pressure compresses air to a high temperature, fuel is injected directly, resulting in combustion. Injecting this fuel at high pressure causes fuel and air to mix, creating the right conditions for combustion. In the past, fuel-injection mechanisms were linked to the motive force of the engine, so reduced engine speed caused injection pressure to fall. As a result, air and fuel mixed incompletely, resulting in incomplete combustion and PM tended to form. PM tended to be more prevalent at lower travel speeds.
Diesel engines using the common rail system, on the other hand, employ an accumulator for high fuel pressurization. As a result, high-pressure fuel injection is sustained without relying on engine speed. Ultrahigh fuel-injection pressures have enabled finer fuel atomization, and therefore higher injection speeds. This situation makes it easier to mix air and fuel and allows fuel to be injected several times during each combustion cycle. Electronic control ensures consistently optimal combustion conditions so that NOx and PM production is kept to a minimum, even during low-speed travel.
Achieving smooth patterns of combustion also addressed such issues as noise and vibration that are normally associated with diesel engines. The common rail system delivered significant technological improvements and effectively overcame several of the downsides associated with diesel-powered vehicles—filthy exhaust, noise and vibration. Generally, diesel engines are more fuel-efficient than their gasoline-powered counterparts, and CO2 exhaust volumes are lower. In addition, the historic problems of NOx and PM emissions have been overcome, and diesel-powered vehicles now offer a more comfortable ride. Such changes have improved the reputation of diesel-powered vehicles significantly. |
Common Rail System |
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| Developing Honda's First Diesel Engine for Automobiles |
Principal members of the diesel engine development project, standing around the Accord , equipped with Honda's independently developed diesel engine. The third person from the right is Kenichi Nagahiro, the large project leader for the development. |
Honda launched a diesel engine development project in fall 1997, when diesel-powered vehicles were gradually becoming popular in Europe. Keenly aware of the issue of global warming, Honda was looking into CO2 reduction from the perspectives of improving gasoline engine fuel economy and developing new technologies involving hybrids and fuel cell vehicles. We recognized, however, that our CO2 reduction efforts needed to include development of the diesel engine's potential.
Recalling his assignment as the person responsible for achieving this task, Kenichi Nagahiro—Executive Chief Engineer at Honda R&D Co., Ltd.—now comments, "At first, I thought it was a joke. " Honda researchers and particularly the people who were involved in engine development had a strong preference for gasoline engines. Mr. Nagahiro himself had spent nearly 20 years working on the development of gasoline engines such as VTEC * that served as the foundation of Honda's gasoline engine technology. By comparison, diesel engines produced dirty exhaust, were noisy and offered poor drivability compared with gasoline-powered vehicles. For Honda's engineers, even though diesel engines were also internal combustion engines they were on an entirely different track. Therefore, hardly anyone had any experience with developing diesel engines. However, precisely because they had no experience in developing diesel engines and they were so strongly oriented toward gasoline engines, these engineers took it as a personal challenge to develop a diesel engine that seemed nothing like a diesel engine—which ultimately culminated in a successful venture.
When the project started, the common rail system had just been introduced, and the trend in fuel-injection systems was starting to shift from mechanical to electronic controls. Honda had already accumulated a wealth of experience in electronically controlled combustion gasoline engines and was approaching leadership status in this area. Still, Honda knew little about developing diesel engines. Many technical issues had to be overcome, and a steady parade of problems emerged that never would have occurred while developing gasoline engines. Even so, the project team applied the technical expertise and experience it had cultivated in developing gasoline engines to resolve these issues.
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Variable Valve Timing & Lift Electronic Control(VTEC)system
This system changes the timing and degree of lift of an engine's intake and exhaust valves, depending on whether the engine speed is high or low. By reacting instantaneously to change intake and exhaust valve openings from lower to higher, the system delivers excellent low-and medium-range torque, while also providing exhilarating power at high speeds. |
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| Achieving Clean, Smooth and Efficient Combustion |
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"Catching up with the leading automakers and developing a cutting-edge diesel engine meant that we had to be faster than the competitors and had to introduce new technologies that had not been used in the past, " explains Mr. Nagahiro.
During this period, the project team had almost completely tossed out their initial drawings, as they were making improvement after improvement.
First of all, it was essential for the project to fully utilize the common rail system. Overcoming conventional diesel engine weaknesses such as reducing NOx and PM and cutting down on noise and vibration depended on how to control combustion. The project objective was to achieve clean, smooth and efficient combustion. The team adjusted the timing and amount of fuel-injection as they pursued ideal combustion. As they approached ideal combustion volumes, the team was able to apply new technologies that derived from their gasoline engine experience, such as to vary the circulatory speed of intake air in the cylinders in line with engine speed. The team also made efforts to reduce engine weight by using an aluminum cylinder block.
Recognizing that reduced engine weight contributes to fuel economy and improves drivability, Honda now applies aluminum to all of its engines. Diesel engines, however, have higher combustion pressures than gasoline engines, which requires more rigid engine blocks. Suitable casting technology was required, therefore, to meet diesel engineering requirements. Utilizing its cumulative casting expertise, Honda succeeded in mass-producing the first such engine in the 2-liter class.
Honda announced its new i-CTDi, 2.2-liter diesel engine at a motor show in Geneva, Switzerland, in March 2003. In January 2004, we began equipping Accord models sold in Europe with this engine.
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A diesel engine production line at Honda's U.K. automobile plant
Advanced casting technology is required for this aluminum cylinder block to ensure sufficient space for the coolant to circulate around the cylinders in the area known as the water jacket.
Honda's first independently developed diesel engine, the 2.2-liter i-CTDi
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| Astonishing Europe with an Unconventional Diesel |
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The Accord models equipped with our diesel engines first went on sale in January 2004. They invigorated Honda's dealers throughout Europe that have long looked forward to highly competitive diesel-powered vehicles that embodied the Honda spirit. Our diesel-powered lineup eventually expanded to four models, as we added the CR-V in January 2005, the FR-V in August 2005 and the Civic in January 2006. Building on their popularity in Europe, cumulative sales of diesel-powered vehicles reached 100,000 units in only three years.
The i-CTDi diesel engine consolidated its popularity in Europe, the birthplace and heart of the diesel-powered vehicle market, and in 2005 this engine was named International Engine of the Year in the 2-liter to 2.5-liter category. Bestowed by the U.K. publication Engine Technology International, the award was deemed appropriate for the i-CTDi diesel engine by 56 journalists from 26 countries. Among the reasons cited for the selection were its exceptional comfort while driving, its low levels of noise and vibration, and its many differences from other diesel engines. Environmental performance naturally being important, these comments were high praise for Honda—which had concentrated on the development of diesel-powered vehicles equal to gasoline-powered cars in the area of driving comfort.
In our pursuit of both environmental performance and the joy of driving, the i-CTDi diesel engine has opened our eyes to the possibilities of diesel-powered vehicles. |
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| Meeting the U.S. Tier II Bin5 Exhaust Standard |
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One expectation of diesel-powered vehicles is that they deliver the same level of emission cleanliness as their gasoline-powered counterparts. U.S. Tier II Bin5 emission requirements provide some of the world's most stringent standards in this category. Rather than resting on the laurels of its success in Europe, Honda decided to pursue technical developments to take on the challenge of clearing this hurdle. In September 2006, Honda announced its own developed next generation super-clean diesel engine that exceeds the Tier II Bin5 standard (according to our in-house measurement).
Based on the i-CTDi diesel engine, this next generation super-clean diesel engine involves an optimally shaped combustion chamber, a shortened fuel injection interval through a common rail system with injection pressure of 2,000 atmospheres and highly efficient exhaust gas recirculation*. This system controls combustion with even better precision, reducing NOx and PM generation. The new NOx catalyst we have developed for the next-generation diesel engine also makes exhaust emissions cleaner.
The catalysts that have been used in the past for gasoline engines are insufficient for diesel engines, which consume large amounts of oxygen during combustion. Large diesel engines, such as those used in trucks, employ urea as a catalyst, inconveniently requiring periodic refilling of large tanks of urea that resulted in the increased size of the system.
By contrast, our own developed NOx catalyst for next-generation diesel engines converts NOx to N2 by using ammonia, which is generally regarded as an excellent cleaner. We use a two-layer structure, generating the ammonia inside that catalyst. The first layer absorbs the NOx in exhaust gases and converts it to ammonia, while the second absorbs the converted ammonia and uses it to clean the NOx in the exhaust gas to N2. This method avoids the hassle of supplying urea periodically, results in a compact and lightweight catalyst and improves NOx cleaning performance in the range in which diesel engines mainly operate—between 200°C and 300°C. The end result is cleaner exhaust gases.
In addition to commercializing this exhaust gas cleaning technology, Honda is developing a diesel fuel that has a different cetane number, and is therefore more easily combustible. Based on this research, we expect to begin sales in the United States by 2009.
*Exhaust gas recirculation: A system whereby some exhaust gases are returned to the intake to reduce combustion temperatures and decrease NOx production. |
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| Strive to Reduce CO2 While Maintaining a Global Viewpoint |
At a press conference in mid-2006, Honda announced its 2010 global CO2 reduction targets for products and production operations, which the Company is currently striving to achieve. In accordance with these targets, we aim to reduce automobile emissions by 10% from our 2000 figures, and diesel-powered vehicle emissions are also in line with these targets. In 2009, we plan to offer a vehicle with a clean diesel engine in the U.S., and we are developing a V-6 diesel engine to power larger cars.
Masaaki Kato, President of Honda R&D Co., Ltd., elaborated on the role of R&D in the future as follows.
"We are pursuing initiatives to raise the fuel economy of our gasoline engines, strengthen hybrids in the compact car market and expand diesel offerings into the mid-size and larger vehicle markets. As we move in these directions, we will optimize environmental technologies and work to reduce CO2 emissions. "
The performance of our diesel-powered vehicles has been greatly improved as demonstrated by the praise for our diesel-powered vehicle in Europe. By clearing the same Tier II Bin5 environmental performance standards that requires the emissions levels equivalent to their gasoline-powered counterparts, we have expanded the possibilities for diesel-powered vehicles. At the same time, diesel engine technologies have become an important part of Honda's CO2 reduction efforts.
In 1973, Honda became the first company to achieve the 1970 U.S. Clean Air Act (Muskie Law*1) regulations with its CVCC engine*2. An ongoing link exists between our interpretation of this success as the basic concept of developing environmental technologies, and our announcement of 2010 global CO2 reduction targets and the development of a superclean diesel engine. Automobiles remain essential to our lifestyles, and as long as this remains the case Honda will work to meet the expectations of its customers and society and strive to fulfill the environmental targets it has established for itself.
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Muskie Law
In 1970, the so-called "Muskie Law, " an amendment to the U.S. Clean Air Act, was passed. Under the new law, the carbon monoxide, hydrocarbon and nitrogen oxide levels in emissions of 1975- and 1976-model vehicles had to be at least 90% lower than for 1970 and 1971 models. At the time, these were the most stringent emission standards in the world. |
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CVCC engine
This engine employs a pre-combustion chamber alongside the main combustion chamber, enabling lean combustion and making possible substantial reductions in CO, HC and NOx. This engine was used on the Civic CVCC, which in 1973, became the first vehicle to pass the 1970 U.S. Clean Air Act requirements. CVCC is an acronym for Compound Vortex Controlled Combustion. |
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