Lexus RX400h Hybrid Synergy Drive in Operation
- The RX 400h’s powerful Hybrid Synergy Drive system has key characteristics that contribute to its strong fuel efficiency and driving performance
- Energy loss reduction: the system automatically stops the engine at low vehicle speeds and at idle, so saving energy that would normally be lost
- Energy recovery and re-use: kinetic energy that would usually be lost as heat during deceleration and braking is recovered as electric energy and used to power the starter and electric motor
- Motor assist: the electric motor assists the engine during acceleration
- High-efficiency operational control: the system maximises overall efficiency by using the electric motor to power the vehicle in driving conditions where engine efficiency is low.
When engine efficiency is high, it generates electricity Seamless acceleration: smooth acceleration is a characteristic of the RX 400h’s continuously variable transmission (CVT). In the course of any journey, the Hybrid Synergy Drive system will operate in several different modes in order to maximise efficiency. When the engine is cold and the ignition is switched on, the system will start the engine to warm the unit. Whenever the vehicle comes to rest, the engine stops automatically to conserve fuel.
In low-efficiency conditions, such as during start-up and at low to mid-range speeds, the RX 400h will run on its electric motors alone, thus reducing CO2 emissions to zero.
In normal driving conditions, engine output is divided by a power split device, both to drive the wheels directly and also to power the generator. In turn, the generator drives the electric motors and simultaneously charges the high-voltage battery. In such circumstances, the allocation of power is constantly monitored and adjusted between the engine and motors to maintain the highest efficiency. When sudden acceleration is required, the engine and electric motors again work together with extra power from the battery to boost response.