London’s local transport revolutionized
Exhaust gas after-treatment and cloud services – how do these fit together? Sensor-Technik Wiedemann (STW), together with their client HJS Emission Technology, has implemented a solution for the remote condition monitoring of exhaust gas after-treatment systems for London’s local transport – not just as an academic approach (theoretical discourse), but as a specific application.
For years now, the exhaust emissions of diesel vehicles have been an almost daily matter for public debate. In September 2012, the International Agency for Research of Cancer of the WHO classified such exhaust emissions as a Group 1 complex of pollutants. As a result, they placed them in the same category as asbestos, arsenic or mustard gas with regard to their carcinogenic properties. An increasing number of legislative specifications and limit values for air pollution control at a national and European level have to be implemented. There is an urgent need for action to fulfill these regulations, especially for in part highly polluted metropolitan regions. In particular, local public transport contributes greatly towards air pollution, because stop-and-go operation frequently discharges unnecessary emissions, and engines must execute their work in unfavorable operating conditions.
However, this fact provides an ideal point of approach for possible improvements. The so-called environmental zones introduced in parts of Germany permit the entry of only low-emission vehicles into conurbations and large cities as a regional traffic prohibition.
Outside Germany, Great Britain, and in particular London, is a significant pioneer in the implementation of measures for air pollution control. Shortly after taking office last year, London’s mayor Sadiq Khan brought into force his “Clean Air Action Plan” and set up so-called Low Emission Zones (LEZ). A further intensification is to follow as of September 2020 through the introduction of Ultra Low Emission Zones (ULEZ). This more than 1500 square-kilometer-zone extends across the entire Greater London area. Daily charges of between 100 and 200 pounds are due for the entry and operation of HGVs, buses, delivery vans and all heavy-duty traffic which cannot verify compliance with the required emissions quality. Those who are caught in this camera-monitored zone must reckon with a penalty of between 250 and 1,000 pounds. To fulfill the regulations and ensure further operation, many vehicles are therefore dependent on the retrofitting of exhaust gas treatment systems for diesel engines.
The SCRT® (Selective Catalytic Reduction Technology) retrofit systems provided by HJS Emission Technology reduce soot particles and nitrogen oxide (NOx) through the addition of urea (AdBlue®) and the use of particle filters and catalysts in several stages. The system comprises of temperature and differential pressure sensors, a NOx sensor and an injection system for urea. A control unit monitors the necessary operating parameters via the CAN bus of the vehicle and accurately calculates the necessary injection quantities for the control of the urea pump.
This method of after-treatment is so effective that a retrofitted Euro IV/V vehicle almost fulfills the emissions standard Euro VI. As a result, the emissions of the retrofitted vehicles are already better prepared than the vehicles currently delivered by manufacturers with Euro IV and V standards. By 2021, more than 5,000 busses from companies which operate for Transport for London will be equipped with retrofitting solutions.
Warnings and fault notifications will be signaled to the bus drivers in several stages via an information system. This includes a warning notification in case of a low fill level in the AdBlue® additional tank. If the tank is not re-filled, then a noticeable reduction of approximately 30-40% in power of the drive unit will occur via the vehicle control system. The same mechanism is activated in case of a malfunction or failure of the pollutant reduction system. In case a fault is not eliminated within a certain time, i.e. re-filling of the urea tank or troubleshooting and rectification by a workshop, then the power of the drive unit will reduce so that only emergency operation is possible. The intention is to prevent vehicles are operating with a non-functioning system.
Due to the fact that the cycles for exhaust gas tests are often not comparable with real conditions, great interest has been shown in the determination of the actual pollutant emissions in daily operation. This decisive data should be centrally recorded and initially stored for 60 days because of the existing verification obligations. Similarly, live access to current parameters with response times totaling only a few seconds must be provided if required. Transmitting the aggregated data once at the end of the day, for example, is no longer sufficient.
The implementation of real-time condition monitoring has effortlessly been achieved using the telematics platform ESX-TC1 and the device and application management portal “machines.cloud” by STW. Amongst other things, the TC1 with embedded Linux system, which has been especially optimized for mobile applications in adverse environments, features an integrated GPS module, a mobile telecommunications modem and two CAN interfaces for reading the required parameters from the existing vehicle bus. The parameters recorded in this way are reliably provided with a time stamp, and with the availability of an Internet connection, wirelessly transferred to the STW telematics/IoT portal “machines.cloud”. Here, current performance parameters, location and status messages can be visualized at any time. The data history is also available here for further analysis. A data channel is set up directly to the vehicle if required through the unique “Live Widget”, and values are transmitted and displayed in one second intervals. As a result, current values can be monitored, for example, the NOx reduction, particulate matter reduction, fill level of the urea tanks, current location and speed, and possible fault messages and alarms of individual vehicles or vehicle groups or the entire fleet. The data history can be exported using the reporting function on an hourly, daily, weekly or monthly basis according to the specification.
Interfaces to existing CRM or ERP third party systems can be easily realized thanks to the extendibility and open interfaces of the cloud solution. The same applies for the integration of customer-specific applications. A system expansion for supplemented driver information is also possible: An app on a tablet could allow drivers to request exact current and average parameters. Likewise, passengers in the vehicle or at bus stops can be effectively informed via a passenger information system. The data connection can either be established directly via the vehicle TC1 gateway or also be realized independently via the cloud. As a result, all requirements can be fulfilled through the interconnection of all components using the telematics platform ESX-TC1 up to integration in “machines.cloud”.