Toyota introduces new 2013 Lexus GS 450h hybrid with improved hybrid powertrain at Frankfurt Motor Show
|2013 Lexus GS 450h. Click to enlarge.|
Lexus has introduced its all-new 2013 GS 450h hybrid at the Frankfurt motor show. The hybrid version of the 2013 GS 350 incorporates improvements to its hybrid powertrain and is equipped with a second generation Lexus Hybrid Drive system. GS 450h engineers have aimed for reductions in fuel consumption and emissions without sacrificing performance.
The Lexus Hybrid Drive system features an Atkinson cycle 3.5-liter V6 engine mated to a compact, high-output, water-cooled permanent magnet electric motor. The two powerplants drive the rear wheels both independently and in tandem, as needed. In addition to the gasoline engine and electric motor, the new GS 450h’s hybrid drive system includes a generator; a high-performance nickel-metal hydride battery; a power split device which, via planetary reduction gears, combines and re-allocates power from the engine, electric motor and generator according to operational requirements; and a compact power control unit to govern the high speed interaction of the system components.
Adapted specifically for the hybrid powertrain, the 3.5-liter V6, DOHC engine benefits from several technical improvements including the adoption of the Atkinson Cycle engine design to optimize the fuel-efficient benefits of Lexus Hybrid Drive. Compression is delayed in an Atkinson Cycle engine, because the intake valves close late. This creates a high expansion ratio for less compression, reducing intake and exhaust energy losses and converting combustion energy to engine power more effectively.
A high compression ratio of 13:1; a new, mid-port intake tumble generator; and the adoption of the latest evolution of Lexus’ four-stroke, direct injection technology, D-4S, help the GS 450h achieve better fuel consumption than its predecessor.
With one injector installed in the combustion chamber and a second mounted in the intake port, D-4S combines the strengths of both direct and port injection, realizing optimum engine efficiency throughout the power band and improving torque across the rev range, while minimizing fuel consumption and emissions. The D-4S system features new slit-type injector nozzles with a modified port shape, a higher fuel pressure for more efficient combustion, and idle port injection for improved NVH characteristics.
Engine noise, vibration and friction have been lowered through the adoption of lightweight chain technology.
The cooling performance of the hybrid system’s Power Control Unit (PCU) helps reduce fuel consumption and has been improved through the adoption of dual cooling paths and a single-piece, integrated AC/DC converter.
System control has been enhanced. The PCU boosts motor drive voltage to a maximum 650V in Sport mode and limits it to a maximum of 500V in Eco mode under normal driving conditions where maximum output is not required. The motor is driven at lower voltage to provide a more environmentally–advanced driving performance to help enhance fuel efficiency.
The electric motor features lighter mounts and reduced friction. The system’s regenerative braking operation range has been expanded, contributing to further improvements in fuel efficiency. In addition, the battery layout has been redesigned. A new stacked configuration maximizing luggage space allows the 2013 GS 450h to have more cargo area than the previous generation gas model.
With a total system power output of 338 hp (252 kW), the GS 450h accelerates from 0-60 mph in 5.6 seconds. Conversely, fuel consumption is expected to be improved by more than 30%. The GS 450h is targeting certification as a Super-Ultra Low Emissions Vehicle II (SULEV II). The new GS hybrid also features a Drive Mode selector. In addition to the Normal mode, the driver can customize the driving experience using Eco, Sport S, Sport S+ and EV modes.
All second-generation GS hybrid models have a new platform that is designed to be more rigid compared to the previous models. Engineers conducted extensive platform testing, ultimately increasing the number of spot welds and adding laser welds in very specific locations. The track works in combination with a revised suspension design to assure a more solid stance and superior cornering performance.
The new suspension system is designed to help guide the 2013 GS through corners with precision. In the front, upper and lower control arms are made from aluminum and employ larger bushings. The rear subframe has been completely redesigned to accommodate an all-new multi-link rear suspension, using improved suspension geometry that retains tire cornering force and enhances rear control. With the stiffer platform and lighter components, the shocks can use lighter-viscosity oil, so they move easily and respond to small inputs more quickly.
The use of front and rear aluminum control arms helps reduce unsprung weight and results in significant improvements in agility, roll damping, ride comfort, body control and steering precision. Overall, the suspension is lighter and stronger, allowing it to react to driver input readily, and ride quietly without harshness. Ventilated disc brakes featuring four-piston aluminum front calipers includes the latest electronic enhancements to help provide braking balance and control.
The GS 450h also offers the Lexus Dynamic Handling system, an integrated four-wheel steering system. The leading edge platform technology of the Lexus Dynamic Handling system offers Lexus’ first integration of Adaptive Variable Suspension (AVS); Dynamic Rear Steering (DRS); Variable Gear Ratio Steering (VGRS); and the latest generation of Lexus’ unique Vehicle Dynamics Integrated Management (VDIM) system to help coordinate every aspect of front and rear wheel control and provide agile, sharp and confident driving behavior with a more direct response to the driver’s actions.
The Lexus Dynamic Handling system integrates the control of the Electric Power Steering (EPS), VGRS and newly developed DRS. Monitoring vehicle speed, steering direction and driver inputs, the system calculates the optimum angle for all four wheels. Using VGRS to the front and DRS to the rear, the system can independently control both front and rear wheel steering angles to help improve turn-in response, rear grip, vehicle stability and overall agility when cornering.
The DRS system monitors vehicle speed and yaw rate, steering angle and speed, and lateral G to calculate the required rear wheel steering input, to a maximum of 1.5 degrees. At speeds below 50 mph the front and rear wheels turn in opposite directions. At speeds over 50 mph, front and rear wheels turn in the same direction.
Further coordinating DRS with VGRS, AVS and VDIM, the Lexus Dynamic Handling system will automatically customize the adaptive suspension tuning and active safety systems to suit road conditions, vehicle speed and driving style, giving customers confidence to experience the new GS’ driving performance.
The standard 17-inch alloy wheels are paired with 225/50R17 tires while the optional 18-inch alloy wheels are equipped with 235/45R18 tires. The GS 450h’s Electronically Controlled Braking (ECB) system characteristics have been modified to provide greater responsiveness from the first touch of the pedal.