Title of Programme

SIXTH FRAMEWORK PROGRAMME

PRIORITY 6

SUSTAINABLE DEVELOPMENT, GLOBAL CHANGE & ECOSYSTEMS

Financing Code for Project

EUROPEAN COMMISSION

RESEARCH DIRECTORATE-GENERAL

Specific Targeted research Project

Commissariat a l Energie Atomique et aux Energies Alternatives (CEA)

Microcomponents, Swatch Group (MCO)

Centre Suisse d'Electronique et de Microtechnique SA (CSEM)

Aerosol and Particle Technology Laboratory (APTL)

Uncooled Infrared Silicon (ULIS)

Electronic Marin, Swatch Gtroup (EM) 

 

The IMPECC2 project aimed to develop an optical on board sensor system to measure two specific exhaust gas components like NO, NO₂, CH₄, CO or CO₂ with fast response times in the range of 10 ms. 

In order to address the future near zero emissions vehicles, a fast response, on board measurement system for exhaust gas components is an excellent tool for the control of internal combustion engines, advanced exhaust after-treatment systems as well as the specific vehicle emission performances (on board diagnostics, DBD for example). To be able to fulfil those stringent requirements an onboard gas sensor based on the infrared optical spectroscopy technology is being developed. 

The sensor system specifications had been defined for hydrocarbons and carbon monoxide to comply with those various fields of applications. Fast sensor response times were targeted on one side to transfer the advantage of fast optical measurements into in-situ internal combustion (IC) engine control strategies. On the other side, accurate and absolute low level exhaust gas concentration values were targeted for exhaust after-treatment control and diagnostics. The reference transparency measurements, necessary to correct for any opacity changes in the optical path was also be used to extract the information on the exhaust gas particle content. The sensor should comply with the typical automotive reliability requirements. 

Understanding the physics of gas absorption is essential to comprehend the measuring principle of the future sensor and to qualify the signal delivered from the device. Considering the calculated and simulated interactions of the IR gas measurement technology with ambient variables, such as pressure and temperature for example, a concept selection study was conducted to address the exhaust gas sampling and gas conditioning strategies. 

Narrow band emitters, based on a micro-cavity design, were realised for the respective absorption bands of the various gas constituents to be measured. A low cost detector, based on the bolometer technology, suitable to work with this sensor system, was defined, designed and realised in the frame of this project. 

The sensor system integration into the engine exhaust system together with the adequate electronics, consisting of the emitter laser diode drivers, the detector amplifiers and the signal processing had been developed. 

The re-adjustments which had been agreed upon at the beginning of the project, in respect to the sensor demonstrator application, with the resulting changes of the requirements and specifications did at the end somewhat perturb the overall project timing and deliverables. However, the consortium was able to handle these adaptations and closely respect the initially planned project targets and financial boundary conditions. 

Understanding the physics of gas absorption spectroscopy and the measuring principle specific to the IMPECC sensor, a qualification of the signal delivered from the device was performed. Considering these boundary conditions the best sensor system concept had been selected to address the exhaust gas sampling and gas conditioning strategies as well as the exhaust gas species detection. 

Narrow band emitters, tuned to the detection of hydrocarbons and carbon monoxide together with a reference', i.e. no absorption, wavelength, based on the micro-cavity design, had been realised for the respective absorption bands of the various gas constituents to be measured. A low cost detector, based on the bolometer technology, suitable to work with this sensor system, had been defined, designed and realised within the frame of this project, in accordance to the emitter wavelengths. For timing constraints, state of the art photo voltaic detectors were used with the demonstrator. The performance of the bolometer detectors had been validated and quantified on a laboratory level. 

The selected sensor system concept requested a decoupling from the engine tailpipe including a maintenance free exhaust gas preconditioning system. The required electronics, consisting of the emitter laser diode drivers, the detector amplifiers and the signal processing had been designed and built. Together with the specifically developed optical layout, all of those components / sub-systems had been integrated into a demonstrator. This demonstrator was than validated for its performances.