The RZ 450e has a new all-wheel drive system Lexus is calling DIRECT4. It uses the RZ's wheel vehicle speed, acceleration and steering angle sensor information to control front-to-rear drive force ratio distribution between 100:0 and 0:100. Meaning that the RZ can have most of its power to the front or rear wheels depending on the situation.
DIRECT4: SUPPORTS A MORE ENGAGING DRIVING PERFORMANCE
PLANO, Texas (April 20, 2022) — Lexus is proud to unveil details of the all-new 2023 RZ 450e, the luxury brand’s first global Battery EV (BEV). Since the launch of the RX 400h in 2005, Lexus has been a pioneer […]
DIRECT4 and the newly developed high-output electronic axle (eAxle) motor continuously controls the drive force of the four wheels with high precision. It works according to the ground contact load of the vehicle regardless of road surface and driving conditions to achieve an exhilarating driving experience in line with the driver’s intention.
The DIRECT4 distribution control uses wheel vehicle speed, acceleration and steering angle sensor information to control front-to-rear drive force ratio distribution between 100:0 and 0:100. This contributes to improved start-up acceleration, handling stability and low power consumption. The system uses an approximate front-to-rear drive force ratio distribution between 60:40 and 40:60 to minimize vehicle pitch during launch and straight-line acceleration, thereby achieving a direct acceleration feel. Vital information such as cornering speed and steering angle help to optimize drive force distribution according to various driving conditions and helps attain excellent handling stability. When the steering wheel is turned, drive force is biased to the front wheels (distributing drive force between 75:25 and 50:50) so RZ responds nimbly and provides excellent steering feel. When exiting a corner, torque distribution to the rear wheels is further increased (between 50:50 and 20:80) to ensure ample traction while controlling vehicle pitch. For RZ, engineers have achieved a refined driving feel by orchestrating the seamless operation of their accumulated electrification and dynamic vehicle movement control technologies.
The newly developed eAxle fully integrates the motor, transaxle and inverter within a compact unit to benefit cruise range, spacious interior and excellent design. The front eAxle is packaged with a short front/rear system layout, while the rear eAxle features a low-profile layout contributing to increased interior and cargo space. In addition, the use of a high-efficiency inverter having an element in the rear, contributes to an increase in cruise range.
A new pressurization unit enables coordinated front and rear regenerative braking through independent front and rear hydraulic control. The new braking system aims to provide seamless, direct and controlled braking under the direction of the Lexus Driving Signature. Based on Lexus’ hybrid electric technology experience and achievements over the years, the regenerative braking system improves regenerative energy efficiency to increase cruise range, while enhancing brake feel. Stable vehicle posture is achieved by optimizing the distribution of braking force to the front and rear wheels in response to the amount of braking by the driver. Furthermore, ergonomic brake pedal pads are used for easy pedal changes and pedal depression.