The changes in thermal state, emissions and fuel economy of a 1.0-L, three-cylinder direct injection spark ignition engine when a cylinder is deactivated have been explored experimentally. Cylinder deactivation improved engine fuel economy by up to 15% at light engine loads by reducing pumping work, raising indicated thermal efficiency and raising combustion efficiency. Penalties included an increase in NOx emissions and small increases in rubbing friction and gas work losses of the deactivated cylinder. The cyclic pressure variation in the deactivated cylinder falls rapidly after deactivation through blow-by and heat transfer losses. After around seven cycles, the motoring loss is ~2 J/cycle. Engine structural temperatures settle within an 8- to 13-s interval after a switch between two- and three-cylinder operation. Engine heat rejection to coolant is reduced by ~13% by deactivating a cylinder, extending coolant warm-up time to thermostat-opening by 102 s.

Michael (2016) The effects of cylinder deactivation on the thermal behaviour and performance of a three cylinder spark ignition engine. SAE International Journal of Engines, 9 (4). ISSN 1946-3944 Access from the University of Nottingham repository: http://eprints.nottingham.ac.uk/40940/1/2016-01-2160.pdf Copyright and reuse:The Nottingham ePrints service makes this work by researchers of the University of Nottingham available open access under the following conditions. This article is made available under the University of Nottingham End User licence and may be reused according to the conditions of the licence. For more details see: http://eprints.nottingham.ac.uk/end_user_agreement.pdf A note on versions:The version presented here may differ from the published version or from the version of record. If you wish to cite this item you are advised to consult the publisher's version. Please see the repository url above for details on accessing the published version and note that access may require a subscription.For more information, please contact eprints@nottingham.ac.uk INTRODUCTIONIn recent years, the downsizing of direct injection spark ignition engines for light duty automotive applications has made a major contribution to improving the fuel economy of private passenger vehicles. Turbocharging and direct injection fuelling have been key technologies which allow smaller capacity engines to be used to meet required power and torque output requirements. These smaller engines operate at higher cylinder mean effective pressures across the load range than the engines they supersede. At part-load, throttling losses are reduced, gross indicated thermal efficiency is improved and reductions in engine capacity reduce friction power losses. The improvements under part-load conditions make a strong contribution to improving vehicle fuel consumption over drive cycles such as the New European Drive Cycle (NEDC).Downsized engines with a swept capacity of around 1.0litre are most commonly three-cylinder designs. Further downsizing by reducing cylinder capacity or the number of cylinders is possible, but other directions of technical innovation may be preferred for the next generation of small engines. One area of technology receiving attention is cylinder deactivation as a means of reducing the effective cylinder displacement for light load operation. Past applications in the automotive area have commonly been to relatively large displacement engines with six or more cylinders [1,2,3,4,5,6,7,8]. Since 2012, however, VW have produced a 1.4l, 4 cylinder TSI engine with Active Cylinder Technology [2]. This enables the deactivation of two of the four cylinders within an envelope of light load operating conditions. Ford have also reported exploring the application of cylinder deactivation to the three cylinder 1.0l Ford EcoBoost engine [3], [9].Various systems for deactivating cylinders have been described in the literature, including systems which eliminate piston reciprocation to reduce friction [10] or deactivate all cylin...