Press Release
By-Wire Functions
The RX400h features more ???????????????????????????????????by wire???????????????????????????????? technology than any other car on the road. This includes brake and throttle systems that help save weight and space and which respond quicker than mechanical systems, and responsive Electric Power Steering that helps save fuel and reduce noise.It marks the European debut of Vehicle Dynamics Integrated Management (VDIM), an advanced stability control system, and is equipped with the world??????????????????????????????????????s first electric air conditioning compressor.
Electric Power Steering (EPS)
The Electric Power Steering (EPS) is powered by a brushless 42v DC motor. It consumes electricity only when power is required, using no energy, for instance, when the vehicle is moving in a straight line. This helps reduce fuel consumption by about 1.5 per cent.The system structure is also more compact and operates more quietly than comparable hydraulic systems. The absence of power steering fluid also makes it more environmentally friendly when it comes to vehicle disposal.
Electronically Controlled Brake System (ECB)
The ???????????????????????????????????by-wire???????????????????????????????? ECB system not only improves overall braking performance, but also improves the level of brake energy regeneration.A sensor detects the amount of force being applied to the brake pedal and appropriate hydraulic braking power is applied to each wheel, with an ECU adjusting the pressure at the hydraulic source.
The system operation features a combination of hydraulic braking power and regenerative power from the front and rear electric motors under deceleration. A hydraulic pressure control function balances the total braking force between that supplied by hydraulics and by the motors.
Brake Assist (BAS)
The Brake Assist function automatically enhances braking performance when braking speed is judged to be faster than usual and emergency braking is necessary. These conditions are recognised by a computer monitoring data from the master cylinder pressure sensor and the ECB??????????????????????????????????????s pedal stroke sensor.BA has consistently proved effective in circumstances where the driver is panicking and not applying sufficient brake pedal force, or where the driver cannot sustain sufficient pedal pressure over a period of time, resulting in deteriorating braking force.
Vehicle Dynamics Integrated Management (VDIM)
Until now, active safety systems such as ABS, traction control (TRC), stability control (VSC) and Electric Power Steering, have tended to evolve independently, even when fitted to the same vehicle. As such, their successful operational combination has been limited and their optimum performance potential unrealised.VDIM has been developed specifically to integrate these systems, greatly improving active safety and enhancing vehicle performance across the driving spectrum.
Moreover, whereas conventional active systems are only activated after the vehicle??????????????????????????????????????s performance limit has been reached, VDIM activates control before that point. As a result, the performance threshold is improved and the vehicle performs more smoothly, with less obtrusive intervention of the safety systems.
The heart of the VDIM system is a control execution programme built into the ECB??????????????????????????????????????s electronic control unit. The VDIM system constantly gathers information sensors throughout the vehicle, including the brake master cylinder pressure, brake pedal pressure, steering angle and torque, accelerator pedal pressure, vehicle yaw rate, vehicle acceleration, brake calliper pressure at each wheel and torque output from the hybrid vehicle system.
Using this vehicle status data, VDIM not only integrates the RX400h??????????????????????????????????????s ABS, TRC, VSC and EBD functions with the Electric Power Steering, but also co-ordinates control of the Hybrid Synergy Drive and electric four-wheel drive systems.
This helps counter such hazardous driving conditions where, for example, a variation in left and right tyre grip causes the vehicle to pull to one side under braking; where rear tyre grip is lost through braking in a corner; and where stronger braking in a corner causes the rear wheels to lock up.
Air conditioning with electric compressor
Unique to Lexus, the RX400h features the world??????????????????????????????????????s first electric air conditioning compressor with a built-in inverter and brushless DC motor.In conventional air conditioning systems the compressor is powered by the vehicle engine, but in the RX400h it runs off the high voltage battery with revolution speed controlled by the integrated inverter. This means you do not need to have the engine running in order to keep the vehicle cabin cool. The system is also more fuel-efficient and its cooling efficiency is greater.
