The good news is that heavy-duty diesel engine providers like Perkins have met the challenge of meeting Tier 4 Final and Stage IV regulations. But there was a price in engine complexity.
“For example the level of maps and control systems have increased by a factor of 10 since EPA Tier 3 [and the introduction of Tier 4 Final],” said Mike Cullen, Product Marketing Manager, Perkins. To meet the emissions, engine makers chose differing combinations of DOC, DPF, and SCR for engines at different rated powers, along with more complex turbocharging and EGR.
One way of dealing with added complexity in one part of the system is to reduce complexity in another—in particular the operator interactions.
“To effectively deal with complexity [of the engine] while improving ease of use for the customer/operator, we have worked to minimize the users’ engine interaction, such as switches and dials, and servicing intervals. We also introduced hydraulic tappets, multi-vee belts, and single side access, which reduce workshop time and service costs,” explained Cullen. To further simplify the package, they combined a DOC/DPF canister and SCR system into one integrated module. This can be positioned remotely in a machine chassis or directly on top of the engine, according to the company.
While engine systems have more components and elements, there is an upside. “We also now have more information about how the engine is performing and what its capability is at any given moment, which has enabled the powertrain to be more highly optimized,” said Cullen. This means better machine fuel consumption, he said, along with cleaner tail-pipe emissions.
As engines have evolved, so has calibration. “These new emissions standards have increased the challenge, but as calibration and control are interlinked, the more advanced the control system it generates, the more opportunity to minimize the calibration effort,” he said.
Cullen also noted that to support engine development, Perkins developed "significant" simulation capability to support engine development and reduce development effort. “Much of our calibration is developed virtually and then validated on the engine,” he said. Gone are the days of brute-force engine dyno work.
One of the results of this work is an engine in the Perkins 1200 series. “In the off-highway machinery world, the 1206F-E70TTA delivers an estimated 5% better cycle fluid consumption over previous models—that incorporates the diesel and the DEF necessary for the SCR technology,” said Cullen.