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Risk Reducing Product and Process Design DuringNew Product Development

Peter Bovenzi, Don Bender, Ray Bloink and Michael Conklin

Delphi Corporation Advanced Powertrain - USA

2010-01-0391

Published04/12/2010

John Abrahamian

Shainin LLC

Copyright © 2010 SAE International

ABSTRACT

In today's dynamic automotive environment, reducing thelead-time to introduce new product technologies to themarket place can be a key competitive advantage. Employingproactive risk reduction techniques to define key product andprocess relationships is essential to enhance the productionworthiness of a design while it is still in the advanceddevelopment phase of the program.

This paper describes how Delphi Powertrain Systems appliedthe Shainin proactive risk reduction methodology inadvanced product development to focus resources onunderstanding and mitigating the risk associated with thedevelopment of a new Delphi ammonia sensor.Organizational and technical strategies to accelerate profoundknowledge capture, along with corresponding test results, arepresented and discussed.

Due to the proprietary nature of the Delphi ammonia sensor'sfunction and operation, this paper limits the disclosure ofdetailed product characteristics and specifications to genericnomenclature, while still maintaining the technical intent ofthe paper.

In a Diesel engine SCR system, the ammonia sensor istypically situated behind the SCR catalyst. The SCR systemhelps reduce NOx emissions in Diesel powertrain systemsthrough a chemical reaction in which ammonia reacts withNOx to produce nitrogen and water. Ammonia is typicallyintroduced into the exhaust flow upstream from the SCR inthe form of liquid urea. The ammonia sensor detects excessammonia in the exhaust gas allowing for more precise dosingof urea and onboard diagnostics (OBD) functionality. Thisadded precision allows for optimal SCR system efficiencyand prevents the release of excess ammonia into theatmosphere.

The Delphi ammonia sensor is typically used to detectammonia within a range of 0 to 200 ppm. It is based on aplanar alumina substrate with an integral temperature sensorand a thick-film heater for optimum performance. The sensoris equipped with two sensing electrodes. The first electrodeoutputs the concentration of ammonia as a voltage while thesecond electrode outputs the concentration of NO2 as avoltage. Because the ammonia electrode is cross-sensitive toNO2, the voltage from the NO2 electrode is used as acorrection factor to improve the accuracy of the ammoniaINTRODUCTION

The Delphi ammonia sensor uses a unique Delphi technologyto directly measure ammonia levels in the exhaust of Dieselvehicles equipped with a selective catalytic reduction (SCR)aftertreatment system. The sensor output can be used toprovide feedback to the SCR system helping provide optimalreduction of NOx emissions.

AMMONIA SENSOR

technology to directly measure ammonia levels in the exhaustof a Diesel vehicle equipped with an SCR aftertreatmentsystem. Electrical power is supplied by a sensor controllerthrough an electrical harness with additional connector pins

for data communication.