With Euro 5 now effective for light-duty engines in Europe, the focus for vehicle manufacturers and suppliers is shifting to the 2014 Euro 6 requirements and beyond. For light-duty diesel engines, the adoption of selective catalytic reduction (SCR) exhaust aftertreatment is a likely avenue to help meet the tighter limits for emissions of oxides of nitrogen (NOx).
The technology, already in widespread use for heavy-duty diesels, means light-duty engines will need to adopt similar aftertreatment equipment. To that end, Delphi is developing an SCR dosing system scheduled for production in 2014, and in 2012 it will introduce a sensor to detect and help control the level of ammonia produced in the exhaust when urea is introduced into an SCR system.
John Fuerst, Managing Director of Delphi Diesel Systems, explained the technology in these developments to AEI at the recent Frankfurt Auto Show.
“Our SCR dosing system is differentiated by higher pressure, which provides better distribution, better mixing, and more uniform distribution of urea across the face of the catalyst," said Fuerst. This results in better performance, which allows you to be closer-coupled where you’ve got geometry that may not be conducive to get mixing. If you have a lot of room to mix, you can use a lower-pressure injector and you’ve got all this mixing time and it’s fine. But once you’re out of packaging space, our high-pressure device is valuable in a hot close-coupled environment. We include a cooling water jacket to make sure it will survive in the heat.”
Delphi has integrated the controls for the SCR dosing system, which means that it does not require a separate feed pump in the urea tank. The flow of urea is produced by the pump in the dosing nozzle, which helps to reduce system cost.
“The urea flows into a pumping chamber, where the pressure is taken up to about 40 bar,” Fuerst said, “then across a poppet nozzle that breaks at 20 bar, so we’re injecting at 20 plus bar. Our injector costs more than some competitors', because it’s pumping and injecting and it’s got a water jacket.”
Used in conjunction with the ammonia sensor, it should mean that the size of the SCR and ammonia slip catalyst could be reduced, containing cost elsewhere in the system.
Among the developments in active safety at Delphi's Frankfurt booth was a project to combine a forward-looking radar and video camera in one package, with production scheduled for 2014/15. Current systems involve a radar sensor built into the front fender area and a camera housed in an assembly behind the windshield, near the rearview mirror. This means that the radar sensor is vulnerable in a frontal impact and also has to deal with engine bay temperatures combined with surrounding ambient air.
"We will combine our radar with a camera, and we package it between the windshield and the rearview mirror,” said Henrik Carlsen, Manager for Delphi Advanced Engineering, Active Safety in Europe.
The unit is packaged with a combined glare shield and radome. “We can hide the whole unit behind the rearview mirror,” he noted.
Delphi is developing low-emission radar technology for the project, emitting less radiation than a cell phone. This permits the positioning inside the vehicle, where it will not interfere with other on-board systems.
“So even though we have a smaller radar antenna than the one we have in production today, and we have the absorption of the glass in the windshield, we have longer range than with the system we have today,” Carlsen said. This is because the system pulses the radar waves and also changes the radar frequency. The antenna also uses an electronic scanning system, not a mechanical scanning system, eliminating moving parts.
“What we can do with this is full-speed range-adaptive cruise control, full collision warning, and autonomous braking for vehicles and pedestrians. We’re also exploring braking for animals,” he said. “The state of the art is adaptive cruise control with stop-and-go features. We will pass that, and the next-generation systems will detect stationary targets. If you are in a queue in city traffic, the car is stopping automatically behind the car in front and will automatically resume. If a pedestrian walks between your car and the car in front, you do not want the automatic resume. We will take care of those kinds of situations.”