VCRi: Pushing back the fuel consumption reduction limits Key results The results were measured on the different VCRi prototypes: single-cylinder engines, multi-cylinder engines and a demo car DOWNSIZING - DOWNSPEEDING: One of the automobile industry s main priorities is to reduce engine cubic capacity (downsizing) and mean operating speed (downspeeding) in order to reduce vehicle fuel consumption levels. This is also the primary objective of VCRi technology. To do this, it is necessary to reach the highest possible specific torque and power with the shortest possible turbo-lag, and the lowest possible specific consumption at high loads. planned for the next decade (4 bar of BMEP vs. 25). The 12 kw/l of specific power delivered by the twin turbo VCRi GDI is 2% higher than that of the best existing turbo GDI engines. With exceptional specific torque and power of 32 Nm/L and 12 kw/l, VCRi surpasses all the existing fixed compression ratio engines, and with 6 to 7% more torque than will have future fixed compression ratio turbo GDI engines These performances reflect the exceptional ability of VCRi to downsize and downspeed car engines, resulting in a significant decrease in fuel consumption and associated CO2 emissions. These excellent specific performances are reached thanks to VCRi s wide range, reduced friction and high load capacity transmission mechanism. VCRi GDI 1,484 cc - 2-stage turbocharger 6 16 5 4 12 1 3 8 2 6 Power (kw) Torque (Nm) 14 4 1 2 1 2 3 4 5 6 Speed (rpm) The 1.5L VCRi prototypes deliver the torque of a naturally-aspirated 4.8L engine and the power of a 3.2L V6 engine www.vcr-i.com 1
VCRi: Pushing back the fuel consumption reduction limits HIGH EFFICIENCY SUPERCHARGING: There is no hard downsizing without high supercharging. VCRi s supercharging with two turbocompressors contributes to its efficiency, with both excellent isentropic efficiency and excellent responsiveness to reach 8% of torque in under 2 seconds at 15 rpm. Supercharging efficiency is one of the keys to the success of this type of engine, with good exhaust temperature control, high efficiency at high loads and supercharging pressures in the order of 4 bar of absolute pressure. Particular attention was paid to the development of the two-stage supercharging of the VCRi. It comprises a low-pressure stage, a high-pressure stage and two air-water coolers positioned after each compressor (intercooler, aftercooler) www.vcr-i.com 2
VCRi: Pushing back the fuel consumption reduction limits COMPRESSION RATIO OPTIMIZATION: VCRi makes it possible to optimize the compression ratio according to speed and load, resulting in increased thermodynamic efficiency and significantly improved combustion stability. On the compression ratio map, we can distinguish high-load points for which the main objective is maximum torque and the most used, low-load points, for which the aim is to maximize efficiency. The compression ratio always serves the best compromise between efficiency, performance, pollutant emissions, stability and safety www.vcr-i.com 3
27 VCRi: Pushing back the fuel consumption reduction limits FUEL CONSUMPTION REDUCTION IN THE DRIVING CYCLE: In the driving cycle (example: NEDC), VCRi reduces vehicle fuel consumption by combining the gains provided by downsizingdownspeeding with those provided by compression ratio optimization. VCRi s limited friction losses also contribute to the results obtained. Note that the fuel consumption reduction is higher for powerful cars than for small ones. speed (kph) 14 12 1 8 6 4 2 New European Driving Cycle (NEDC) Part One - Urban Time (secs) Part Two - Extra Urban 1 2 3 4 5 6 7 8 9 1 11 12 1 % 9 % 8 % 7 % 6 % 5 % 4 % 3 % 2 % 1 % % Ref NA engine Torque Pumping losses Friction losses +32% efficiency +5% efficiency VCR NA engine Downsized VCR engine (turbo) Heat losses Combustion losses Otto losses The forecasted fuel consumption reductions refer to the NEDC VCR redefines the energy balance of engines 4 Specific fuel consumption map of the VCRi 1.5L GDI and corresponding operating point of the demo car on the New European Driving Cycle (NEDC) 35 32 3 BMEP (bar) 25 2 15 27 25 27 25 27 32 Max BMEP Steady state operating point Transient operating point 1 25 25 5 27 27 32 32 35 32 35 35 4 4 1 15 2 25 3 35 4 45 5 55 4 Engine speed (rpm) The gains made by VCRi are more due to the repositioning of the engine s operating points than to the improvement of the BSFC map www.vcr-i.com 4
VCRi: Pushing back the fuel consumption reduction limits Power Torque Fuel consumption NEDC 24 7 22 6 Power (kw) - emissions (g CO2/km) 2 16 14 5 4 3 2 Torque (Nm) 12 1 1 Original V6 Diesel DW12B MPFI (21) GDI (21) (211) VVA VVA S&S CAI S&S Power (kw) 155 125 16 16 Torque (Nm) 37 42 47 47 47 47 47 CO2/km - NEDC (g) 233 159 16 158 155 145 138 128 On a Peugeot 47 type vehicle, the most basic VCRi MPFI reduces fuel consumption by 31%. The most sophisticated version of the VCRi planned for the near future could bring this reduction down to 45% while providing 16% more power and 62% more torque NVH & AFTER-TREATMENT: VCRi also procures many other advantages that result in even greater fuel efficiency, more comfort and driving pleasure and reduced vehicle costs: Remarkable combustion stability: VCRi combustion stability is exceptionally high. Its coefficient of variation always remains under 3% (combustion speed dispersion), which makes it possible to reduce its idle speed to 55 rpm. With a high compression ratio and a limited FMEP (Friction Mean Effective Pressure) of roughly.55 bar, the hourly fuel consumption of an idling VCRi is lower than 3g of fuel. This opens up many possibilities and, in particular, that of not having to use Stop & Start, which avoids stopping the heating or air conditioning in the passenger compartment and also avoids cooling the catalyst. At high torque, VCRi s combustion stability leads to improved vehicle NVH behavior, with increased driving pleasure. During the catalyst light-off phases (strategies to rapidly increase catalyst temperature), it s possible to obtain more exhaust enthalpy from the VCRi at the same level of stability. It is therefore possible to either reduce the quantity of pollutants emitted in the certification driving cycle or to reduce the cost of the catalyst. www.vcr-i.com 5
VCRi: Pushing back the fuel consumption reduction limits More effective after-treatment strategies: During the catalyst s temperature increase phase (light-off), it s possible to obtain more exhaust enthalpy with the same level of combustion stability. This higher exhaust gas temperature can be obtained while producing less HC and CO. It is thereby possible to reduce the quantity of pollutants emitted in the certification driving cycle, and possibly to reduce the cost of the catalyst. With regard to pollutant emissions during the engine s most highly loaded phases (full torque), it s possible to benefit from better-positioned ignition advance by setting the compression ratio at the correct value. This leads to improved thermodynamic efficiency and cooler exhaust gases. It s then possible to limit or even eliminate the enrichment of the air-fuel mixture and to avoid high pollutant emissions and high fuel consumption at full power. VCR is also an interesting strategy to increase the external cooled EGR rate, since combustion stability is the main factor that limits the use of external EGR. By increasing the accessible level of EGR, it s possible to substantially decrease fuel consumption at high powers (2% and more for loaded cycle). VCR + GDI + two-stage turbocharging with air-water cooling + cooled EGR should lead to always lambda 1 engines throughout the whole range of use. For Gasoline Direct Injection, VCR adjusts the distance between the injector and the piston. At high loads, it s therefore possible to avoid wetting the piston, while at low loads, the piston bowl near the injector better confines the fuel spray and avoids wetting the cylinder walls. Particulate and soot emissions are thereby reduced by a factor of 4 to 5. The main charcteristics of the VCRi engine prototypes Architecture L4 Bore (mm) 75 Stroke (mm) 84 Capacity per cylinder (cc) 371 Total capacity (cc) 1484 Rod/crank ratio 4.2 Piston motion Conventional Variation in piston motion No variation Variation in CA for TDC No variation VCR control stroke [possible] (mm) 1.58 [13] CR min 6:1 CR max 15:1 CR control Continuous CR control flexibility Cylinder selective CR precision (piston altitude in mm) +/-.2 Max responsiveness CR max to CR min (ms) 5 Min responsiveness CR min to CR max (ms) 3 Max in-cylinder pressure (bar) 12 Speed limit at normal security factor (rpm) 65 Equipment of current VCRi prototypes (2 versions) Injection (version 1) Injection (version 2) Supercharging Intake cooling Base EMS CR specific ECU and amplifier Dual jet MPFI (Marelli on the shelf) GDI (Bosch - specific) 2 stage turbo Inter and after cooler Continental Mototron Clesse Electronique Performance of current VCRi prototypes (2 versions) 1.5 L Power (kw) Torque@15rpm (Nm) MPFI 16 42 (35 bar BMEP) GDI 2 48 (4 bar BMEP) www.vcr-i.com 6