Kia unveils Optima Hybrid sedan at LA Auto Show
18 November 2010
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| Kia Optima Hybrid. Click to enlarge. |
Kia Motors Corporation premiered the hybrid version of its new Optima sedan (earlier post) at the Los Angeles Auto Show. Created primarily with the US market in mind, the Kia-developed powertrain delivers an estimated combined cycle fuel economy is 38 mpg US (6.2 L/100km) (city 36.0 mpg, highway 40.0 mpg).
Arriving in Kia dealer showrooms early next year, the 2011 Optima Hybrid is the brand’s first hybrid for North America and uses a full parallel hybrid system to deliver a 40.7% mpg improvement compared with a regular Optima. Acceleration to 62 mph (100 km/h) takes 9.2 seconds, and the top speed is 121 mph (195 km/h).
The 2.4-liter Theta II gasoline engine is mated to a small electric motor and drives the front wheels via a six-speed automatic transmission without the traditional torque converter. A special clutch is fitted between the engine and motor, enabling the gasoline engine to be de-coupled from the powertrain so that Optima can be operated in zero-emissions, full-electric drive mode from standstill up to 62 mph.
The system’s configuration does not require a high-capacity electric motor and generator, saving weight and cost.
When setting off, the Optima Hybrid operates in Electric Mode. As vehicle speed rises, the Hybrid Starter motor/Generator (HSG) starts the gasoline engine and the clutch is closed, allowing the engine to take over the task of propelling the car. The electric motor switches into hybrid operation and serves as both a secondary engine (during full acceleration and hill-climbing) and a generator to recharge the battery pack as necessary. Whenever the car comes a stop for more than a few seconds, the gasoline engine automatically shuts off to completely eliminate emissions.
When braking, the electric motor converts kinetic energy into electricity for storage in the battery pack. The 8.5 kW HSG also functions as a generator to re-charge the battery pack if the state of charge is low and when the car is stationary. Throughout the entire driving experience, in everyday motoring, under all conditions, the entire hybrid operation is automatic and seamless.
The Optima Hybrid’s 30 kW Interior Permanent Magnet (IPM) synchronous electric motor produces 40.7 ps (30 kW) and 205 N·m (151 lb-ft) of torque from 0-to-1,400 rpm in electric mode. The combined (electric motor plus gasoline engine) hybrid powertrain has an output of 209 ps (154 kW) and 265 N·m (195 lb-ft).
Described by Kia engineers as a Transmission-Mounted-Electric-Drive (TMED), the 30 kW IPM electric motor sits within the car’s extended transmission casing (between the gasoline engine and the automatic gearbox) and is an oil-cooled system.
Kia’s Optima Hybrid employs a lithium polymer battery array developed in partnership with LG Chem. The power and energy density of this battery enabled Kia engineers to create a lighter, more compact power pack with a 34 kW output and weighing just 43.6 kg (95.9 lbs) designed to minimize intrusion of the Optima’s trunk space.
The complete hybrid system is controlled by the Optima's Hybrid Control Unit (HCU) which acts as the car’s mastermind and integrates the smooth operation of the engine’s ECU, transmission’s TCU, battery management system (BMS), low voltage converter (LDC). This brain also gives the Optima a Fail-Safe back-up capability and a Limp-home mode.
Optimizing the Theta II gasoline engine. Taking advantage of the instant and continuously available torque from the electric motor, Kia modified its popular 2.4-liter Theta II engine to operate on an Atkinson cycle, raising the compression ratio by 20% to maximize its efficiency and achieving a 10% fuel saving over a regular Theta engine. This cycle generates a little less torque, but the electric motor compensates for any loss and consequently, the Optima Hybrid’s overall power and torque outputs are greater than the regular model.
For the Optima Hybrid, Kia has modified the six-speed automatic transmission found on the conventional Optima for hybrid application. The traditional torque converter is replaced with an electric motor and a high-efficiency oil pump. This new gearbox allows EV mode operation, maximizes regeneration of kinetic energy during braking and also provides a more responsive drive than a CVT system.
To maximize the Optima Hybrid’s performance and minimize its fuel consumption, special attention has been paid to its aerodynamics. The car is lowered by 5 mm and new features include an active air flap in the front grille, smooth underfloor panels, low-drag wheels and low rolling resistance tires. The drag coefficient is lowered to Cd 0.26.
Energy and fuel-saving technologies features in the Optima Hybrid include a regenerative braking system, electric—rather than hydraulic—assisted power steering, and an electric air compressor capable of delivering high air-conditioning performance.
Two independent liquid cooling systems are fitted to the Optima Hybrid powertrain. The standard high-temperature circuit manages engine cooling and passenger compartment heating. The second low-temperature circuit cools the hybrid starter-generator and the power electronics. The trunk-mounted battery pack does not require liquid cooling and its temperature is controlled by a simple ventilation fan beneath the rear parcel shelf.
Kia eliminated the torque converter, which is what GM should have done with the LaCrosse. GM is so far behind....
Posted by: Engineer-Poet | 18 November 2010 at 04:39 AM
Seems like nice work on the aerodynamics. There is a certain satisfaction from gliding smoothly through the air at high speed and high mpg.
Can anyone tell me what speed the highway mpg is rated at?
Posted by: Thomas Pedersen | 18 November 2010 at 07:20 AM
Half of the world’s known Lithium supply is located in Bolivia, in a nature reserve, which should make greens lose sleep.
Posted by: Mannstein | 18 November 2010 at 06:19 PM
There is some 16,000 tons per year of lithium in Salton Sea geothermal brines alone. There's about 80 grams of active lithium per kWh of battery; if we assume 250 grams/kWh total, 16 thousand tons is enough for 64 million kWh of batteries or about 4 million Chevy Volts per year.
That's ONE geothermal resource... and it's a domestic US deposit that's currently going to waste.
Posted by: Engineer-Poet | 18 November 2010 at 09:06 PM
Good analysis, it seems like they may have enough batteries for next year's production. Price seems to be a larger driving factor in all of this, so we will see if the buying public responds with all the rebates.
Posted by: SJC | 19 November 2010 at 08:41 AM
Mannstein..... please don't manic... as many 5 new Lithium mines may open in Canada before 2015....if lithium's price and demand are high enough. By 2020, a lot less lithium per Kwh may be required. By 2030, no lithium may be required. It is risky to try to predict batteries evolution one of two decades from now.
Posted by: HarveyD | 19 November 2010 at 04:19 PM
The number of lithium powered vehicles will need to be in the billions to make a dent in CO2 emissions from the transportation sector. That's 3 orders of magnitude more than the 4 million Chevy Volts some people yammer about.
Mining the lithium deposits being evaluated in Northern Quebec would be much more expensive than what is available in Bolivia making it uncompetitive for car batteries. Hopefully there are richer deposits in Canada than what is currently being explored.
Posted by: Mannstein | 19 November 2010 at 05:25 PM
4 million Volt-class packs/year * 20 year well lifetime = 80 million packs (which are all recyclable at end of life).
There were 806 milllion LDVs worldwide in 2007, per Wikipedia. The Salton Sea brines alone appear capable of electrifying 10% of them. Further, lithium is a very small part of the price of a battery. If Canadian lithium costs twice as much, it hardly affects the economics.
Posted by: Engineer-Poet | 20 November 2010 at 05:29 AM
This 0ptima hybrid is a living proof of what I and MG have been discussing about a simple hybrid layout that is very simple, cost-effective, and very high performance. You're closer to the 0ptima, MG, since you're proposing a 4-5 speed transmission, while I proposed a two-speed transmission which requires a more robust electric power system that is more appropriate for a PHEV.
The 0ptima is a class-leading full hybrid which beats the (amry hybrid on both efficiency, power performance, and cost, while on par with the Fu$ion hybrid on efficiency but will beat the Fu$ion hybrid on cost and power performance, several thousand dollars less. This has to do with a minimal electric motor of only 30 kW and a starter-generator of only 8 kW, as we have predicted.
If total power is reduced to 156 hp as typical with mid-size car of this class (instead of 209 hp), by downsizing the engine to 1.8 liter, then we can see even higher efficiency rating, perhaps 40 mpg city and 44 mpg hwy mpg's, with a lighter can and even more internal space, and is getting uncomfortably close to the venerable Privs, considering a larger and more powerful vehicle.
The good news is this technology can be easily retrofitted to existing vehicles for a major gain in efficiency by simply swapping the camshaft, the starter-generator, the torque converter, the battery, and the on-board computer for the equivalent "full-hybrid-enabling components," as I've discussed in previous postings. The OEM's and the dealers can take part in this, and the swapped components can be refurbished for used as spare parts, thereby significantly reducing the cost of the "full-hybrid upgrade."
Posted by: Roger Pham | 20 November 2010 at 07:30 PM
That's a very good idea, if you can replace the starter / altenator with a larger motor and replace the torque converter with an electric motor, electrify the steering and heating, then you can add battery capacity to increase the electric range.
Posted by: 3PeaceSweet | 21 November 2010 at 06:29 AM