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New technology could convert older taxis to Euro 6 standard without impacting original engine says t

Tech could extend the age limits of current taxis

Taxis not meeting Euro 6 standards could easily be upgraded without impact on the original engine according to technology emission experts. As local authorities across the UK look to improve air quality in their area older taxis have come under attack. In fact, in London, Euro 5 standard taxis registered as early as 2015 could see their vehicle licensing age limits cut from fifteen years to twelve if City Hall proposals are successful. Taxis are seen as a significant contributor to toxic air quality, and are said to be responsible for 16% of NOx and 26% of Particulate Matter (PM) emissions in central London. However, a company called HJS say that they can offer a cost effective solution to reach Euro 6 standards by retrofitting a highly efficient SCR system without impact on the engine control unit. If the retrofit were approved by local authorities the industry could see a swifter move to cleaner vehicles. In London alone there are roughly 4,300 taxis running at Euro 5 standard who could make the change to extend their taxi age limit by three years. Now for the technical bit! The vehicles will be approved according to the Energy Savings Trusts Clean Vehicle Retrofit Accreditation Scheme (CVRAS). The retrofit centres around the exhaust system of the taxi. Existing after-treatment components DOC and DPF remain and standard OE parts are used to create the dosing system, AdBlue tank and sensors. The system also includes the usage of serial OE SCR coatings and HJS ACU as a control unit, already used in several OE systems.

The AdBlue dosing strategy is based on sensor signals (temperature, NOx) directly measured in exhaust flow and additional data from engine CAN (exhaust mass).

Diagnosis concept

The retrofit would include the installation of two lamps in the taxi dashboard for MIL (yellow) and refilling AdBlue (blue) Other features include:

Electrical diagnosis of all actuators and sensors

Further diagnosis functions (depending on system scope)

plausibility check of sensor signals,

plausibility check of NOx conversion (NOx sensor ds SCR required)

AdBlue level request for refilling AdBlue when level below certain limit (lamp). MIL activation when level drops below minimum threshold, error message to ECU possible if requested

AdBlue quality. MIL activation if quality is out of range, error message to ECU possible if requested

No derating measures by ACU 

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