http://www.greencarcongress.com/2008...ws-n.html#more





Ford Previews Next-Generation Hybrids

14 February 2008

by Jack Rosebro
Speaking at the 2008 SAE Hybrid Vehicle Technology Symposium in San Diego yesterday, Sherif Markaby, Global Core Engineer for hybrids at Ford Motor Company, provided some technical details of the coming 2009 Ford Fusion and Mercury Milan hybrids, due at the end of the year, as well as of the 2009 Escape and Mariner hybrids, which are scheduled to be released in a few months.
All four hybrids will share a new powertrain that combines a 2.5L inline four-cylinder engine with a series-parallel transaxle. While the basic layout and packaging of the powertrain and related components remains for the most part unchanged from the 2005-2008 Escape component architecture, many of those components have been redesigned for improved efficiency.
Markaby also noted that Ford has sold 70,000 Escape hybrids to date, and that some units have reached 200,000 miles in service with no service problems.
The next-generation hybrid system applied in the Fusion, for example, will provide a more than 60% improvement in city cycle fuel economy over a non-hybrid I4 engine, Markaby said, and a more than 80% improvement over a V6 on the city cycle.
Variable-Voltage Converter (VVC). The new powertrain’s inverter assembly utilizes a DC-DC buck-boost converter, which Ford refers to as a Variable-Voltage Converter, to step up the voltage potential of current from the battery pack before it is synthesized into a three-phase AC waveform to power the transaxle’s two electric motor-generators.
Every model-year 2004 and up Toyota/Lexus hybrids utilizes a buck-boost converter; however, this is the first time that the architecture has been employed in a mass-produced passenger hybrid vehicle built by another manufacturer.
Stepping up voltage allows the powertrain to produce a given output using less current, which reduces resistance losses and increases efficiency. It also allows the manufacturer to use a smaller, lighter battery: the 275V, 5.5Ah, 27 kW peak power NiMH battery pack used in the new Fusion/Milan hybrids features improved cell chemistry, and is more compact, for example, than the 2005-2008 Escape hybrid’s 330V battery pack.
One of the most important attributes of VVC, according to Markaby, is “reducing the cost of the battery.” Previous Escape and Mariner hybrids used a stand-alone air conditioning loop to cool the battery pack during peak operating temperatures: the new powertrain uses only a forced-air ventilation system.
High-Efficiency Internal Combustion Engine (ICE). The 2.5L iVCT I-4 engine gets variable valve timing on the intake side (Intake Variable Cam Timing, iVCT), as well as a wide-band lambda sensor in place of a conventional oxygen sensor. The compression ratio in the engine is 12.3:1.
Idle-stop and start events are much quicker, and enable greater efficiency with as many as two times the starts and stops in a given driving cycle as the previous system. The quicker engine shut-downs and pre-positioning (for the next start) also reduces O2 build-up in the engine’s catalyst. Decel Fuel Shut-Off (DFSO) mode and electric-only mode have also been expanded.
High-Efficiency DC-DC Converter. The conventional DC-DC converter, which steps down system voltage to run the vehicle’s 12V accessory bus and charge the auxiliary 12V battery, has been redesigned to operate at higher temperatures. The unit remains liquid cooled, and can switch at higher frequencies.
The VVC variably boosts traction battery voltage to operate the motor and generator more efficiently. Click to enlarge.High-Efficiency Transaxle. The maximum RPM of the new transaxle’s permanent-magnet synchronous motor-generators has been increased, and a new low-drag transaxle fluid has been formulated. The higher available voltages from the variable-voltage converter allow greater torque at higher speeds. Typically, such voltages also enable a more efficient recuperation of kinetic energy via regenerative braking.
Update on the SCE PHEVs. Markaby also made mention of the plug-in hybrid Escapes that Ford is delivering to Southern California Edison (SCE) for V2G research. The PHEV Escapes use a 10kWh Li-ion battery pack, and are getting as much as 120 MPG in testing. The PHEV powertrain operates in three distinct modes: electric drive (ED) mode, blended mode (a combination of engine operation and charge-depleting electric drive), and conventional hybrid mode.

 

Stepping up voltage allows the powertrain to produce a given output using less current, which reduces resistance losses and increases efficiency. It also allows the manufacturer to use a smaller, lighter battery: the 275V, 5.5Ah, 27 kW peak power NiMH battery pack used in the new Fusion/Milan hybrids features improved cell chemistry, and is more compact, for example, than the 2005-2008 Escape hybrid’s 330V battery pack.
One of the most important attributes of VVC, according to Markaby, is “reducing the cost of the battery.” Previous Escape and Mariner hybrids used a stand-alone air conditioning loop to cool the battery pack during peak operating temperatures: the new powertrain uses only a forced-air ventilation system.

I'm assuming this means the size of the hybrid battery steel case is smaller than the current verison. Does this mean the hybrid vehicle will obtain a small cargo space below the floor level? A floor hook(s) above the small cargo space? IF the current hybrid battery steel case is maintained would this mean there is "space inside" to stuff a few more battery cells?

The forced-air ventilation system--is this similar to what the Prius uses?

 

Forced air means simply... a fan or blower. No freon chiller. The blower fans would take up roughly the same space as the current model. The freon chiller right now is in the side wall of the FEH, under the air vent on the rear window glass... so it's out of the cargo space now. The blower fans are in the cargo space now.

Look at watt-hours to get an idea of size.
Since we (they) are still talking about NiMH cells, they will be the same size per watt-hour.

They are lowering the voltage... keeping amp-hours the same as now, so that does mean a lower watt-hour battery, hence, you can assume a smaller battery... but I didn't see a watt-hour number.

With a smaller battery, you could keep the same watt-hours as now, with less voltage, by doing a 30-70% cycle, vs. 40-60%. Add better electronics mentioned, and a 275v battery going 35-65% may be able to porovide the same MPG boost as a 330v 40-60% battery.

Will the 275v battery add the same fuel economy keeping the 40-60% range... I don't see how... unless other areas are improved so much to over-compensate for the weaker battery.

The 275v battery is for sure a weaker battery. It just sounds like they are going to utilize it better than the 330v one we have now... perhaps not baby it as much as ours.
-John

 

Is the 2009 FEH/MMH getting the 275V battery pack too? Or is it staying with its current 330V battery pack?

As mentioned, what would decreasing the battery pack size give the FEH/MMH? Room for a tissue holder or store a pair of repair gloves?

Though, eliminating the freon lines might allow Ford to offer the towing package. Right now, the freon lines and the tow package's wiring make use of the same hole, and is why Ford doesn't support both.

 

The few FORD plug-in Escapes on the road now have this lower voltage battery. It would not surprise me if all 2009 Escapes did. Just the consumer ones will be NiMH and the PHEV uses Lithium based.

 

The other question is with the Fusion/Milan Hybrid. Did Ford need to make a smaller hybrid battery pack to better "fit" the space in the Fusion/Milan Hybrid? We will find out sometime later this year.

 

I'm trying to find out if the newer versions will have an A/C which runs off the electric motor during auto stop, like the Civic and Prius?

Thanks!

 

Do you think that Ford will use the exact same physical battery pack in the Escape/Mariner and the Fusion/Milan?? I don't know, but I would assume while the internals would be very similar, the outside case would be designed to "fit" the application snugly.

 

It would be cost effective for the Hybrid Escape and Fusion vehicles to share the exact same hybrid battery pack and external steel case.

 

Does the Fusion/Milan happen to have a storage well in its truck, which just happens to be the same size and shape as the one in the back of the Escape/Mariner????