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Reported in the current paper is a study into the cycle efficiency effects of utilising a complex valvetrain mechanism in order to generate variable in-cylinder charge motion and therefore alter the dilution tolerance of a Direct Injection Spark Ignition (DISI) engine. A Jaguar Land Rover Single Cylinder Research Engine (SCRE) was operated at a number of engine speeds and loads with the dilution fraction varied accordingly (excess air (lean), external Exhaust Gas Residuals (EGR) or some combination of both). For each engine speed, load and dilution fraction, the engine was operated with either both intake valves fully open - Dual Valve Actuation (DVA) - or one valve completely closed - Single Valve Actuation (SVA) mode. The engine was operated in DVA and SVA modes with EGR fractions up to 20% with the excess air dilution (Lambda) increased (to approximately 1.8) until combustion stability was duly compromised.

The context for real-world emissions compliance has widened with the anticipated implementation of EU7 emissions regulations. The more stringent emissions limits and deeper real-world driving test fields of EU7 make compliance more challenging. While EU6 emissions legislation provided clear boundaries by which vehicle and powertrain Original Equipment Manufacturers (OEMs) could develop and calibrate against, EU7 creates additional challenges. To ensure that emissions produced during any real-world driving comply with legal limits, physical testing conducted in-house and in-field to evaluate emissions compliance of a vehicle and powertrain will not be sufficient. Given this, OEMs will likely need to incorporate some type of virtual engineering to supplement physical testing.

The effects of driving style, traffic density and altitude on engine performance and emissions across multiple Real Driving Emissions (RDE) cycles were investigated using an Engine-in-the-Loop (EiL) strategy combined with a virtual toolset comprised of a virtual route, vehicle and driver. This is part of HORIBA’s Road to Rig (R2R) RDE Plus (RDE+) programme for whole vehicle RDE compliance. An offline Design of Experiments (DoE) methodology was used to first parameterise a driver model to achieve a defined definition of driving style across the virtualised RDE route (itself created from an equivalent real RDE route) incorporating fixed traffic then for a fixed driving style with varying traffic density. By performing these scenario-based simulations in an offline format initially, complete compliance with RDE regulations for each of the scenarios being investigated could be achieved without the need for intensive testbed testing.

To aid Original Equipment Manufacturers (OEM) in meeting real-world driving regulation criteria across challenging boundary conditions of temperature, altitude and driving style throughout different territories, an integrated Road to Rig (R2R) whole vehicle development, calibration and verification programme known as RDE Plus (RDE+) has been developed by HORIBA. Connecting road, chassis dynamometer, Engine-in-the-Loop (EiL) and virtual testing methodologies, OEMs can frontload real-world driving scenarios further upstream during vehicle and engine development programmes to ensure compliance with localised regulations. Reported in this paper are the results from the replication of several road tests covering a multitude of altitudes and temperatures adopting an EiL methodology.

Vehicle manufacturers will need to overhaul current development methods used to guarantee emissions compliance with the introduction of more stringent emissions legislation. Climatic boundaries of temperature and altitude and in-service conformity mileage compliance will likely be extended alongside alterations to trip dynamics; this will require robust calibrations for emissions compliance. Consequently, assessing this vast array of scenarios will be impossible with physical testing of prototype vehicles and overseas climatic testing alone. To reduce reliance on physical testing for compliance, a frontloading vehicle and powertrain development programme has been established where road, chassis dynamometer, Engine-in-the-Loop (EiL) and digital twin virtual toolset methodologies are used.

Reported in the current paper is a study of the effects of Nitric Oxide (NO) within a simulated Exhaust Gas Residual (sEGR) on Spark Ignition (SI) engine end gas autoignition. A modified version of the single cylinder Leeds University Ported Optical Engine Version 2 (LUPOE-2) engine was designed to completely eliminate retained residual gas and so allow unambiguous definition of the composition of the in-cylinder charge. The engine was alternately operated on stoichiometric mixtures of iso-octane, two Primary Reference Fuels (PRF), a Toluene Reference Fuel (TRF), and a commercially available Unleaded Gasoline (ULG) and air. These mixtures were diluted with sEGR (products of the complete stoichiometric combustion of the given fuel/air mixture) in mass fractions ranging from 0-15%; with and without 5000ppm NO (0.52% by mass) within that sEGR.