VDIM is designed to anticipate the onset of a vehicle slide while cornering and then help to automatically correct the situation with a combination of braking, throttle and steering control in a way that is essentially transparent to the driver.

VDIM integrates Electric Power Steering (EPS); Variable Gear Ratio Steering (VGRS); Antilock Braking System (ABS); Electronic Brake-force Distribution (EBD); Brake Assist (BA); Vehicle Stability Control (VSC); Electronically Controlled Brakes (ECB); and Traction Control (TRAC).


"Full Hybrid" Powertrain

A full hybrid, Lexus GS 450h is capable of operating in gas-only or electric-only modes, or a combination of the two. One of a new generation of Lexus engines, the gasoline V6 uses a "dual" fuel-injection system that combines the benefits of direct injection with those of port injection, and an Electronic Throttle Control System with intelligence (ETCS-i). Dual Variable Valve Timing with intelligence (VVT-i) operates on the intake and exhaust valves to further enhance power and torque across a broad engine speed range.

GS 450h hybrid powertrain uses two motor-generators, MG1 and MG2 (the drive motor). Each performs specific functions and can operate as both a motor and a generator, although MG1 is used as a starter motor and provides no motive force. The engine-driven generator (MG1) can charge the battery pack or provide additional power to MG2 as needed.

A 288-volt DC Nickel Metal Hydride (Ni-MH) battery pack is installed behind the rear seat area. The battery's power is directed through a "boost converter" that efficiently raises voltage to a maximum 650V DC. An inverter changes this to AC, providing its elevated power to the 147-kW electric motor, which turns as high as 14,400 rpm. The trunk also contains a 12-volt auxiliary battery that powers various vehicle systems, including audio and navigation.


Unique Hybrid Transmission

Power from the gas engine and electric drive motor (MG2) is distributed to the rear drive wheels via a planetary gear-type Electronically controlled Continuously Variable Transmission (ECVT). This special transmission, which eliminates specific gear ratios, features a two-speed torque-multiplication device that allows drivers to select from among three driving modes: power, normal and snow. "Normal" provides the smoothest operation and is ideal for city or suburban driving; "power" sharpens accelerator pedal response and "snow" mode softens accelerator pedal response making it easier to travel on slippery road surfaces.

The ECVT consists of a motor generator, motive power-dividing mechanism, two-stage motor-reduction device, electrically powered oil pump and hydraulic control system. The two-stage torque-multiplication device varies the gear ratio in two stages by controlling a planetary gear and two wet brakes, similar to a conventional automatic transmission. This configuration allows the electric drive motor to operate in high or low ranges, with seamless transitions between the two. MG2 can therefore contribute power not just for acceleration, but at higher cruising speeds, as well.

The driver will not feel Lexus GS 450h's transmission doing its work but will be keenly aware of its benefits in the powerful and uncannily smooth acceleration and passing performance. Since the GS 450h is driven solely by its electric motors when starting, traveling slowly, and during low-load driving, the noise level is about half that of conventional gasoline engine, enhancing the luxury experience.

previous page | go to page 3