Cooperative design and development programs help optimize engine applications

  • 19-Jul-2010 10:07 EDT

Jim Berry, Product Director, Perkins Engines Co.

Tier 4 Interim emissions regulation has been one of the biggest challenges to face the industry for many years.

Perkins’ engineers have responded to the highly technical challenge by focusing on engine solutions that meet the needs of our OEM customers. In addition to achieving Tier 4 Interim, we’ve taken this opportunity to deliver better performance, while providing flexible, highly integrated engine solutions that will provide the end user with a productive machine operating with low cost throughout its life.

As the regulations start to come into effect, most of the industries Perkins serves, particularly agriculture, construction, and general industrial applications, are aggressively downsizing the displacement of the engines in the vehicles and equipment they use. This places a very high premium on power density that is directly related to operating efficiency and lower CO2 output.

So, in addition to complying with the most stringent emissions regulations yet to take effect, Perkins and the rest of the industry also has to meet customer demands for engines that pack more power into a smaller package. Conventional wisdom says those requirements are mutually exclusive, but in this case conventional wisdom has proven to be wrong.

First, all of our new Tier 4-compliant engines will offer up to 8% better fuel efficiency than comparable Tier 3 engines, and they will deliver equivalent power from physically smaller packages. All of the lessons learned in meeting Tier 1 through 3 requirements have been integrated into these new designs, along with many new innovations developed in cooperation with our customers.

We believe the degree of customer involvement in the development of these engines is quite unprecedented. Perkins has always paid close attention to the “voice of the customer” in developing new products, but the Tier 4 development process has added a whole new dimension to this concept.

Uniquely, Perkins has developed and undertaken more than 200 technical integration workshops with OEMs, with application engineers working with customers from an early stage to optimize the entire application, not just the engine installation, saving the OEM both development time and money.

These technical integration workshops have been held at various Perkins locations and in the customers’ own design centers. Working together we help customers use advanced modeling technologies to optimize engine installations and aftertreatment component locations as well as the power of onboard electronics to integrate engine, transmission, and hydraulic systems to improve overall efficiency.

In case after case, this approach has proved its value in reducing development time by as much as six months, while producing a more fuel-efficient product with increased performance, resulting in a machine that is more productive. One important lesson learned from this process is that while downsizing is not automatically the best solution for every customer requirement, optimized application and deep integration are.

Of course, none of these efforts means much if the Tier 4-compliant engines supplied for an optimized application don’t deliver high levels of quality, reliability, and durability for the customer. Every engine OEM extensively tests prototype, preproduction, and production engines to make sure they meet design specifications, and Perkins is no different.

To support our optimized application approach, however, we have taken these test protocols a step further with our largest-ever formalized field test program using a new quality measurement technique called internal machine reliability growth.

Under this program a comprehensive range of applications are run in the field to prove the capability of the engines, with testing taking place in hot and cold climates and at high altitudes. Examples of the tests include cold start, breather systems, and DPF regeneration systems during conditions that range from -30 to -25°C (-22 to -13°F), where we proved the capability of the whole engine and aftertreatment solution.

These test results have also helped us to confirm our simulation techniques to better understand how an engine will run over time in a particular application. Simulation results are compared continuously to field test results, allowing engineers to correlate the simulation software to further improve the accuracy of the data produced and enable us to virtually integrate engines and machines in the future.

This extensive testing and customer collaboration have given us a real-world experience base to guide our Tier 4 engine design decisions. In several cases the lessons learned from this experience contradict widely accepted industry perceptions.

For example, some sectors of the industry perceive that the best fuel economy in engines of 300 hp or less is achieved with a “two-fluid” solution using a catalyst and urea fluid. Perkins’ testing, however, clearly shows that an aftertreatment methodology based on utilizing our NOx reduction system and a DPF delivers up to 4% better fuel economy than SCR-based systems in real-world applications and parity elsewhere.

Further we have a wide range of engines with a power range of 12-300 hp (9-224 kW) and have tailored solutions within the range for best performance and fuel consumption. Prime examples are our aftertreatment systems where we have test data to support differing design decisions on multiple engine platforms. Our conclusion is that one size definitely does not fit all in aftertreatment technologies, and this is verified by hundreds of thousands of hours of data logging under actual operating conditions.

As such, Perkins tailored aftertreatment to each engine model for best package performance, fuel economy, and lifetime cost. For instance, knowing how customers actually use our engines led us to design a service-free DPF for use on the 1206E-E66TA and 1204E engines. These engines use low-temperature regeneration technology that eliminates high engine bay heat while being completely transparent to the operator.

In these models the DPF requires no ash service over the projected life of the engine. That means, among other things, that customers can install it in less accessible areas of the machine and free up space for more frequently serviced components. Other benefits include hydraulic valve lash adjusters and durable poly-V belts to drive accessories, while Perkins continues with the 500-h oil change interval that has been standard for many years.

We have also customized the DPF used with the new 850E Series, in this case, to make it compatible with the very compact installations for which this engine is optimized. Actual customer installations were the guiding force behind the design with collaboration taking place before the design was finalized.

Simulation, testing, and real-world experience have also shown that much existing technology works well for Tier 4 engines. Our new engines use field-proven electronic sensors and controls as well as fixed geometry turbochargers.

The new Tier 4 engines have been designed for higher powers with the increased power density of the new engines requiring design modifications to blocks and heads to accommodate the increased operating forces. Bore spacing has been adjusted to optimize cooling efficiency, while heads have been strengthened to handle higher forces and heat loads. All of these factors, and our largest ever validation program, lead to an engine system that is dependable and proven for our customers.

While Tier 4 emissions regulations are a challenge, Perkins chose to address them as an opportunity to improve both our engines and, more importantly, our customer relationships, by working with our customers at an early stage. The result is a series of new or enhanced engines that uniquely meet both emerging customer requirements and mandated emissions levels while delivering improved fuel economy and lower overall operating costs.

Jim Berry, Product Director, Perkins Engines, wrote this article for SAE Off-Highway Engineering.

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