Glossary: Key technical terms

Oct 10, 2018

48-volt electrical system: Offers four times the power of its 12-volt predecessor system at identical currents and makes fuel savings possible. Ancillaries such as the refrigerant compressor of the climate control system can be operated on electric power. The low-voltage system does not require the additional safety architecture of a high-voltage network.

9G-TRONIC plug-in hybrid transmission: The third-generation hybrid transmission evolved on the basis of the 9G-TRONIC PLUS automatic transmission. The torque converter, clutch and electric motor are housed in the innovative hybrid drive unit. The remarkably compact design was achieved by integrating and connecting the separating clutch, torsional vibration damper and torque converter lock-up clutch within the rotor of the electric motor.

Boost function: Temporary assistance for a combustion engine from an electric motor during acceleration. The system output of both engines together can be higher than the performance potential of the combustion engine alone, or it is apportioned in a way that prevents running the combustion engine at an operating point that is unfavourable for fuel consumption or emissions.

Fuel cell: Special galvanic cell that generates electricity from the chemical reaction between hydrogen and oxygen. A fuel cell consists of electrodes separated by a membrane or electrolyte (ion conductor). The fuel cell generates electric power and heat. By virtue of its high performance and efficiency, the PEM fuel cell is particularly suitable for automotive use. It has a plastic membrane as an electrolyte (PEM = Polymer Electrolyte Membrane) capable of conducting protons. Its operating temperature is around 80 degrees Celsius.

CO2: Carbon dioxide is a chemical compound of carbon and oxygen with the molecular formula CO2. Given a sufficient supply of oxygen, CO2 is produced, for example, when carbon-containing substances are burned. The CO2 emissions of combustion engines are proportional to their fuel consumption.

EQ Boost: The electrification of conventional combustion engines to increase their efficiency by àintegrated starter generators (ISG) and àbelt-driven starter generators (BSG) in a 48 volt electrical system in addition to the stop/start function also supply a temporary torque boost to the combustion engine and recover energy during deceleration.

EQ-optimised navigation: Route guidance system that accounts for the electric range of the battery depending on its state of charge and the availability of public charging stations along and near the route, and selects the most economical routing based on these parameters.

EQ Power: Mercedes-Benz is advancing its plug-in hybrids under this label. Plug-in hybrids enable locally emission-free driving on all-electric power over short distances, particularly in the city. On long distances, they benefit from the range and the existing infrastructure of the combustion engine. Further advantages are the recovery of the vehicle's kinetic energy during deceleration by charging the battery, and the assistance for the combustion engine from the electric motor to save fuel.

Euro 6d-TEMP: The European Union sets the emissions limits for motor vehicles in regulations. In the Euro 6d-TEMP emissions phase, an RDE test must confirm both the Euro 6 nitrogen oxide limits and the Euro 6 limits for the particulate number after legally defined conformity factors have been taken into consideration. In addition, as in the Euro 6c emissions phase, the Euro 6 limits, also measured in the lab, must be confirmed according to WLTP. Euro 6d-TEMP applies to new emission types from 1.9.2017 and to all newly registered vehicles from 1.9.2019. From 2020, emissions must be determined according to the Euro 6d follow-up standard.

Since September 2017, Mercedes-Benz has been testing all new emission types according to Euro 6d-TEMP. àWLTP and àRDE are part of the new standard. At the same time, àNEDC consumption and CO2 value will continue to be determined and disclosed in press and advertising material. The àWLTP test results are converted into an NEDC value using the CO2MPAS tool required and provided by the authorities. With certain restrictions, NEDC tests are conducted alternatively or in addition in accordance with the EU regulation.

DC charging: Batteries can only be charged on direct current. Power grids only work with alternating current. Chargers such as the àon-board charger or the Wallbox charger transform the voltage and the alternating current. The transformation of voltages and from alternating current into direct current involves losses, which manifest themselves as waste heat. These losses are avoided when connecting directly to direct current and the battery can be charged with a higher capacity. Quick-charge stations provide this direct current.

Haptic accelerator pedal: provides the driver feedback on the combustion engine's switch-on point or signals via double impulse when the driver should lift his foot off the accelerator pedal to àsail and àrecover energy.

Integrated Starter Generator (ISG): The functions of starter and alternator are combined in one electric machine. Unlike a àBSG, these starter generators are not driven by a belt

Intelligent powertrain management: The intelligent operating strategy for hybrid and electric vehicles anticipates the course of the road and the traffic situation for maximum efficiency. This includes radar-based àenergy recovery, an anticipatory shifting and operating strategy, a route-based operating strategy and ECO Assist.

IONITY: operating company for the establishment of a pan-European quick-charging network for electric cars, founded in November 2017 as a joint venture of BMW Group, Daimler AG, Ford Motor Company and Volkswagen Group with Audi and Porsche. IONITY will erect and operate some 400 quick-charging stations along the main traffic arteries in Europe by 2020, which will allow EQ vehicles to be charged on àdirect current with 110 kW and consequently will make comfortable long-distance journeys with battery-electric vehicles possible.

Lithium-ion battery: Electrochemical, rechargeable voltage supply based on lithium. The advantages of lithium-ion batteries are their high energy density at a relatively low weight, their immunity to the so-called memory effect, and the low self-discharge.

NEDC: So far, emission and consumption values in Europe have been determined according to the NEDC (New European Driving Cycle). The first European driving cycle was introduced in 1970 with the aim of providing customers with comparable and reproducible values across all manufacturers. In 1992, it was extended beyond urban driving. Since the inclusion of cold starting in 2000, the NEDC has not undergone any further fundamental change. Up until the end of 2020, NEDC values will continue to be determined in addition to the WLTP values to allow verification of compliance with fleet targets.

New emission type: If, for example, a new engine is installed in a vehicle or an engine is so modified that its emissions behaviour changes or a new or modified transmission is installed or another part of the powertrain is modified or changes are made to the exhaust system, this results in a new emission type according to WLTP.

NOx: Nitrogen oxides and nitrous gases are collective terms for the gaseous oxides of nitrogen. They are abbreviated to NOx, as there are several nitrogen/oxygen compounds on account of the many oxidation states of nitrogen. Sometimes, the abbreviation NOx (NOX) is used synonymously with the nitrous gases produced during the combustion of fossil fuels.

On-board charger: an installed device that transforms the alternating current voltage of a household socket or the output voltage of a Wallbox charger into the correct direct current to charge the traction battery of the vehicle. The waste heat produced by this process is dissipated by a water cooling circuit to increase operational safety.

RDE: RDE stands for Real Driving Emissions and is a road test for pollutant emissions. In connection with compliance with emissions limits with the application of conformity factors, it must be verified – for particulates from emissions phase Euro 6c according to WLTP or additionally for NOx from emissions phase Euro 6d-TEMP – that the Euro 6 limits are not exceeded in road tests within the legally valid parameters. In the past, emissions measurements for type approval were carried out exclusively on a dynamometer. With effect from March 2016, emissions must increasingly also be certified under real driving conditions within defined parameters. From September 2017, for new emission types the Euro 6 limits for both nitrogen oxides NOx and particulate count PN must be met in RDE road tests subject to the application of conformity factors. From 1 September 2019, this will apply to all newly registered vehicles.

Energy recovery: The recovery of the vehicle's kinetic energy. The electric motor works as a generator in this process. The electric power it produces is controllable and brakes the vehicle with greater or lesser effect. Energy for charging the battery can be produced in this way, when the vehicle descents a hill at a constant speed or when it is decelerated because the traffic situation or the course of the road require.

Belt-driven starter-alternator (BSA): A combination of starter and alternator, which, like a conventional alternator, is connected to the crankshaft by a belt drive.

Sailing: The rolling of the vehicle with smallest possible resistance. The engine does not supply energy and no energy is recovered. Rolling resistance and aerodynamic drag brake the vehicle very slowly.

Stepped-bowl combustion process: A characteristic feature of the pistons of a direct-injection diesel engine is a recess (bowl) in the piston crown in which the injected fuel is swirled and mixed with air. If the bowl is stepped (instead of having the conventional omega shape), this has a number of advantages, such as excellent air utilisation with low particulate emissions and higher efficiency thanks to a higher burning rate. The changed flow conditions in the combustion chamber result in reduced heat loss across the cylinder wall as well as in a more uniform temperature distribution at the cylinder head and reduced loading on the highly stressed valve lands. The overall result is reduced wall heat loss, which likewise contributes to increased efficiency.

Pre-entry climate control: Temperature control of the vehicle interior prior to departure by electrically powered refrigerant compressor and high-temperature auxiliary heater, while the plug-in hybrid or the battery-electric \vehicle is hooked up to the power grid. This function can be set either in the vehicle or by smartphone app and protects the electrical range in cold or especially hot weather.

Well-to-wheel: Consideration of the life-cycle assessment and especially the carbon CO2 footprint of the energy consumption of a vehicle while driving, taking into account the primary energy required to provide the energy all the way to fuelling the vehicle (for combustion engines from the oil well, for power plants from the production of the primary energy – wind, water, gas, coal, etc.)

WLTC: The driving cycle of the àWLTP is called WLTC – Worldwide Harmonized Light Vehicles Test Cycle. For different vehicle models, the WLTP has three different driving cycles, which take account of the respective power-to-weight ratio. Most cars registered in the EU, which have a power-to-weight ratio of more than 34 kW/t (46 hp/t), are assigned to WLTC Class 3. The test cycle for Class 3 vehicles is made up of four parts – low, medium, high, extra-high. These simulate urban, extra-urban and motorway driving.

WLTP: The abbreviation stands for Worldwide Harmonized Light Vehicle Test Procedure, which is a test procedure for measuring the consumption and emissions values of a vehicle on a chassis dynamometer. Starting on 1 September 2017, the WLTP is being rolled out gradually to replace the previous NEDC test procedure. Thanks to its dynamic focus, the WLTP is significantly more realistic than the previous procedure. At the same time, many requirements, e.g. in relation to the determination of road loads or the conduct of dynamometer tests, have been made significantly tighter compared with the NEDC. Especially these modified parameters lead to a numerical increase of the CO2 values, although the efficiency of the vehicles is not changed by the new measurement procedure.

Hydrogen generation: Hydrogen can be generated e.g. by fermenting biomass or the electrolysis of water. At present this energy source is mainly generated from fossil fuels, above all natural gas (by steam reformation under high pressure).