Design & Technology / Product

The Green Heart of the All-New Optima Hybrid June 23rd, 2011

Hello! Today, we’d like to introduce the new environmentally-friendly Optima Hybrid. With nature and the future in mind, Kia Motors has taken its first steps at becoming a major player in eco vehicle commercialization. We will now tell you more about the all-new Optima Hybrid and how it came to have a green heart.

① Hybrid-exclusive Theta II 2.4 Engine
A new, specially-developed Theta II Hybrid engine replaces the gasoline Theta engine in the new Optima Hybrid. The Theta II hybrid class-leading engine performance offers a maximum output and torque of 168 horsepower and 21.4 kgfm. It also offers comparable performance and approximately 10 percent better fuel economy than a conventional gasoline engine.

In order to develop this kind of high-performance, environmentally-friendly engine, Kia Motors researchers applied various types of new technology.

The Theta II hybrid engine met all of the environment/emissions criteria for AT-PZEVs (Advanced Technology Partial Zero Emission Vehicle) in an environmental evaluation in California, which holds some of the strictest environmental regulations in the world. AT-PZEV’s nitric oxide emissions are about 3.5 times better than the standards of LEVs (Low Emission Vehicles), which have nitric oxide levels of about 0.0125g/km.

②Hybrid-exclusive High-Output Motor

The electric motor is the “second heart” of a hybrid car. An electric motor is what is responsible for the engine and the hybrid’s output.

The Optima Hybrid’s hard-type hybrid electric motor is positioned between the engine and transmission. In other words, the six-speed transmission torque converter was taken out and replaced with a new-concept motor that is the first of its kind.

In order to apply a second heart to this kind of small space, an Interior Permanent Magnet Synchronous Motor (IPM) was selected. In addition, several innovative technologies were applied, such as an interior cooling system for effective cooling.
This type of electric motor provides a maximum output and maximum torque performance of 30kW and 205Nm, respectively, boasting a class-leading average efficiency of 95 percent. When converted to the gasoline engine, the maximum output is 40.8ps with maximum torque of 20kgm, which is similar to the effect of using an additional small engine.

③Hybrid Starter Generator

One of the differentiating factors of the Optima Hybrid is its key feature, the Hybrid Starter Generator (HSG), which allows the car to drive in electric car mode or transition from electric mode to hybrid mode.

HSG powers and moves the engine in electric mode with just the electric motor or in hybrid mode with both the electric motor and engine. While other existing vehicles have both an alternator and starter, the Optima Hybrid employs HSG, which was developed to combine the two parts for simultaneous and optimal control.

④Hybrid-exclusive Six-speed Automatic Transmission

The Optima Hybrid employs a conventional six-speed automatic transmission that has been newly developed specially for the unique hybrid.

As a hybrid car in electric mode can’t run on the transmission found in regular gasoline/diesel cars, and as there are limits to improving fuel economy, it was necessary to develop new concepts for the Optima Hybrid’s transmission.

The Optima Hybrid’s exclusive transmission boldly eliminated the torque converter used in other transmissions, and put a motor and engine clutch in its place. It is an HEV-exclusive configuration that uses a torsion damper.

The Optima Hybrid’s exclusive six-speed transmission and 2-liter engine exceed the fuel economy in its mid-range hybrid class with 21km/liter and helps to match power performance and acceleration standards.

270V Lithium-Ion Polymer Battery
The Optima Hybrid runs on a 270V lithium-ion polymer battery.

It is the first lithium-ion polymer battery in the world to be applied to a hard-type hybrid car. As the Forte LPi Hybrid was the first soft-type vehicle in the world to include a lithium-ion polymer battery, the company has again developed a battery system for hard-type use that is unique to Kia Motors.

The lithium-ion polymer high voltage battery semiconductor control elements are higher voltage than those of competitors and comprise the 270V high voltage battery system. In addition, the battery’s charge/discharge maintains optimal condition through the design of cell balancing and cooling control.

Additionally, in order to secure the battery’s safety, a system to stop the high voltage current and a ceramic-coated filter were developed. High voltage active protection mechanisms, such as relays and fuses, were also applied to the system for reliability and durability.

The Optima Hybrid’s technology offers an eco-friendly approach to high gas mileage. The next posting will be about the design points that are unique to the Optima Hybrid.

Stay tuned for our next posting.