Urban Larsson, Head of Product Development at Volvo Penta, has been at the company for 30 years and worked with its complete product range, including the journey along all the global emissions Tier platforms as regulations steadily increased. His experience includes the renewal of the Volvo Penta engine range from the “pre-emissions technology” engine products up to today’s range with state-of-the-art technology in the base engine, combustion system, and aftertreatment. SAE Off-Highway Engineering Managing Editor Jean Broge recently spoke with Larsson about current trends in off-highway engines. Following is an excerpt of their conversation.
What are some of the more important things you learned from past programs that provided the most help, or insight, in meeting Tier 4 challenges?
The Volvo Penta Tier 4 Final engines are based on the Volvo truck engines and previous Volvo Penta off-highway engines. Because of this, we had a very good understanding and knowledge of how the engines would perform when it came to features and emissions. Because the Tier 4 Interim products are equipped with an SCR solution, we gained a lot of knowledge and experience of that particular technology in advance of Tier 4 Final.
How are Volvo Penta’s Tier 4F technologies different from Tier 4I, and how may they be the same?
The heavy-duty T4F engines (D11, D13, and D16) are an evolution of the T4I solutions, and the overall system is based on an inline six-cylinder fixed geometry turbo engine. The exhaust aftertreatment is a vanadium SCR catalyst. What differs from the T4I system is that the vanadium is extruded instead of coated and a light EGR circuit has been added as a heat management device. The medium-duty T4F engines (D5, D8) are equipped with a variable geometry turbo and cooled EGR, which is the same technology as for the T4I. These engines also have the same exhaust aftertreatment as the heavy-duty range.
Can you talk to engine technologies that may have critical to use in the past, but had become obsolete in engines designed to meet Tier 4 regulations?
Diesel particulate filters are a technology that is being used by several competitors both for T4I and T4F, but not us. However, while this technology was not at all of interest to the Volvo Penta for the T4F product line, it is likely to be used for products to meet future regulations.
Are Volvo Penta engineers leaning toward (or away from) any particular technology that will be used through the company’s future engine platforms?
Keeping it simple is a good way of thinking to design robust, cost-efficient products. Our philosophy is that, in general, it is better to have as few systems on the engine as possible. For instance, the combustion system in the heavy-duty T4F engines is designed to meet the particulate limit, while the aftertreatment system is designed to reduce the NOx and meet that limit. By securing technological advances in those systems, we were able to eliminate others, including a cooled EGR system and a DPF.
How will the potential increased use of advanced alternative and/or renewable fuels have an impact on current combustion systems, and affect the design of future combustion systems?
The alternative fuels issue is an important one. On the engine itself, it is necessary to secure that both the fuel injection system and a cooled EGR system are specifically designed for alternative fuels. Also, the aftertreatment system will have to be designed to cope with different fuels. Another thing that needs to be taken care of is the emissions. Different types of fuels will affect the emissions and systems that compensate for this may be needed.
What are some technology breakthroughs (i.e., materials advances, testing & simulation techniques, manufacturing breakthroughs, etc.) that you believe will be necessary for future advances in engine performance and efficiencies, both in terms of combustion and various other engine components/technologies?
Aftertreatment is at the moment the system with the most rapid development. Year by year they are getting more efficient, durable and less sensitive to heat, chemicals etc. In the future, within reach, I think, it is time for the combustion engine to become camless, with other solutions such as actuators for the inlet and outlet valves being game changers. It will improve the engine in so many aspects. Emissions, power density, weight, engine brake, load response, etc., are other areas for future improvements. The development of the new off-highway engine range from Volvo Penta has indeed been an interesting and challenging journey where we really had to stretch our skills and capabilities. The simple target for us was to put products into the market with the best competitive solution. The concept for the T4F products with a highly optimized combustion system and a high efficient SCR, excluding DPF, has given us, we believe, the best solution on the market.