GM Study Shows 10% Improvement in Fuel Economy Along With Reduction in Criteria Emissions from Mild Hybridization of 4-Cylinder Diesel
29 September 2010
Applying a production-intent second-generation GM Hybrid System (High Voltage Belt Alternator Starter—BAS) to a 4-cylinder common rail diesel can yield fuel economy improvements of up to 10%, as well as reductions in the emission of criteria pollutants, according to Maurizio Cisternino, GM Powertrain Europe Advanced Engineering Hybrid Innovation Manager.
In a presentation at the US Department of Energy’s 2010 Direction in Engine-Efficiency and Emissions Research Conference in Detroit (DEER), Cisternino described the results of an internal study that used both testbed experimental engine work as well as vehicle tests using an Opel Corsa equipped with a BAS-enhanced 1.3-liter diesel 95 hp Euro 5 engine with manual transmission.
| GM 2nd Gen BAS | |
|---|---|
| Operating voltage | ~115 |
| Power | ~15 kW peak |
| Torque | ~65N·m |
| Engine-motor coupling ratio | 2.4:1 |
| Battery capacity | 5.5 Ah |
Engine operation at the dynamic test bed was performed on a 1.3-liter diesel as well as a 1.9 liter Euro 4 diesel.
The activities were designed to investigate the optimization of hybrid control and calibration strategies targeting:
- Start/stop functionality (electric motor control for engine spin up and spin down ramp profile, fuel injection schedule calibration, throttle calibration for next NVH and cranking time consistency);
- Start/stop activation strategy with optimized clutch-based control;
- Enhancement of vehicle transient performance (launch/elasticity) through BAS torque/power assist; and
- Drivability subjective assessment in coast and brake regeneration modes, electric boost, clutch/gear shift at full e-boost, and transition from start mode to idle.
Bench testing showed a general improvement of CO and HC emissions due to the decrease of engine idling time (pre-Cat CO and THC reduction of 16% and 9% respectively) and to accelerated DOC light-off leading to substantial downstream CO and THC reduction (78% and 18%, respectively). The reduction of both engine out and tailpipe emissions was due to lower generation and quicker DOC light off (caused by higher gas temperatures by suppressing idling), Cisternino said.
NOx emissions also improved 13% if EGR functionality is well mated to the hybrid functionality. Electric assist during transients contributed to the moderate NOx decrease. PM engine-out emissions are unaffected by mild hybridization.
Vehicle tests showed a cranking time of 435ms (from 0 rpm to idle) with a spread of 55ms depending upon the engine stop position; very low NVH, 13% elasticity improvement; and an overall positive rating in drivability.
Future testing will evaluate the synergies of mild hybrid technology with a turbocharger for optimal turbomatching; a valve deactivation mechanism for energy recovery enhancement; lower temperature EGR and Euro 6 aftertreatment strategies (SCR, LNT) to improve conversion efficiency and to support efficient DPF regeneration).
Resources
Maurizio Cisternino (2010) Influence of Mild Hybridization on Performance and Emission in a 4-Cylinder In-Line Common Rail Diesel Engine (DEER 2010)
Something like a Honda Civic hybrid, with 1L engine, electric turbo/generator, more batteries and more aggressive use of the motor get you where you want to go.
Posted by: SJC | 29 September 2010 at 12:24 PM
I'm going to start chanting until I see someone shoot down this disruptive technology - Zinc-Air, Zinc-Air, etc. Leo Motors of Korea demonstrated their Zinc-Air fuel cell technology yesterday. Zinc is added to the cell as pellets. After use,the resultant Zinc-Oxide gets reprocessed and turned back into pellets outside the cell. Fresh pellets are added when the spent fuel is removed. This beats everything else in weight, range and cost. There are only 3 companies working on it as far as I can tell, Zinc-Air in Kalispel, Montana, Power-Air in Vancouver, and Leo Motors in Korea. Leo Motors seems to have the most mature technology
Posted by: joewilder | 29 September 2010 at 02:53 PM
It's rather funny that GM calls 115 "high voltage".
Posted by: dursun | 29 September 2010 at 06:27 PM
For a car it is.
Posted by: wintermane2000 | 29 September 2010 at 07:36 PM
I think the original BAS was 36 volts, so 115 would be high. GM was suppose to have a BAS+ coming, but I guess all that bankruptcy stuff got in the way.
Posted by: SJC | 29 September 2010 at 08:30 PM
Zn-air fuel cell is not a practical solution for cars, the need to recycle the Zn oxyde waste makes it very inconvenient to manage in my view, not mentioning that you have to build a whole infrastructure of recycling refilling stations.
Posted by: Treehugger | 29 September 2010 at 08:31 PM
The "revolution" was supposed to be 42-volt systems (which had large impacts on dash and entertainment electronics), but they got cancelled some years ago. Now the trend is to much higher voltages; quelle surprise.
joewilder: zinc-air fuel cell is a fuel cell. It has to be replenished, not recharged. It cannot fit the same niche.
Posted by: Engineer-Poet | 30 September 2010 at 12:44 AM
I've thought it would be fairly simple to use a heat pump to preheat the engine and precool the intercooler from grid power as a simple 'preflight' for a plug in diesel vehicle
Posted by: 3PeaceSweet | 30 September 2010 at 10:16 AM
"Electrical energy for the current generation of the system is stored in a 36V nickel metal hydride battery. The 5kW capacity of the motor/generator and 36V output of the battery limits the application capability of the system"
http://green.autoblog.com/2008/03/04/geneva-08-gm-announces-new-second-generation-mild-hybrid-syste/
That is the original BAS, the BAS+ was suppose to be 15kW and suppose to be available on Malibu for 2011, but that is not a sure thing.
Posted by: SJC | 30 September 2010 at 12:37 PM
Geez this would have been great news 10 or 15 years ago. Now its......maybe we do need more scientists and engineers, that know the METRIC system.
Posted by: fred | 30 September 2010 at 05:29 PM