During the next 5 years, Toyota aims to install new powertrains developed for 80% of its future models (including Lexus models) with TNGA (Toyota New Global Architecture) primarily sold in Japan, the USA, Europe, and China. The carmaker forecasts that the TNGA-based powertrain units alone will improve fuel efficiency enough to reduce CO2 emissions from Toyota vehicles by more than 18%.
The new powertrains will include a new CVT (continuously-variable transmission), 6-speed manual transmission, 2-litre engine, 2-litre hybrid system, and 4WD systems. All these powertrains will be developed to complement TNGA and incorporate new technologies for both superb driving performance and high environmental performance.
The new Direct Shift-CVT is said to be a new type of CVT and has been developed with reduced mechanical losses for greater fuel efficiency that is claimed to be 6% better than an existing transmission. The new powertrain features the world’s first launch gear in a passenger vehicle CVT which facilitates improved transmission efficiency in lower gear ratios where belt efficiency is poor.
The transmission system utilizes gear drive when starting from a full stop, resulting in powerful acceleration while at the same time resolving the momentary sluggish feeling that was previously present during accelerator operation. Both smooth and comfortable launch performance are realized.
When switching from gear drive to belt drive, the transmission system uses highly responsive gear change control technologies cultivated from automatic transmission technology. The adoption of launch gears, for example, results in reduced input load. This enables the size of both belt and pulley components to be reduced. The belt angle has been narrowed and pulley diameters reduced, resulting in shifting speeds that are 20% faster.
As for the 6-speed manual transmission (good news for those who have been increasingly distressed by the diminishing number of models with manual transmission), Toyota is continuing to offer this type of transmission as it sees demand, particularly those in Europe. Compared to the existing version, the mass of the new system has been reduced by 7 kgs and it is also shorter. In fact, it is one of the world’s smallest transmissions and its small size contributes to improved fuel efficiency. The use of iMT (Intelligent Manual Transmission) controls makes transitions between gears smoother as the computer automatically adjusts engine speed when changing gears.
In 1980s, Toyota’s powertrain technologies were used in what it called Lightweight Advanced Super Responsive Engines (LASRE) which were the first mass-produced multivalve engines from the company. In the 21st century, the new generation of engines will be Dynamic Force engines and the first one revealed is a 2-litre 4-cylinder petrol unit. This engine has high-speed combustion technologies and a variable control system. It also achieves greater thermal efficiency, resulting in high output, due to a reduction in energy loss associated with exhaust and cooling systems, the movement of mechanical parts, and other aspects.
As a result, models using the engine should be able to achieve world-leading thermal efficiencies of 40% (41% for hybrids). In addition, compared to existing engines, the new engines achieve increased torque at all engine speeds―from low to high rotations―and will comply with expected future exhaust regulations in each country in advance.
Toyota will also be upgrading its hybrid system which has been evolving over 20 years. There will be a new hybrid system for 2.0-litre engines (THS-II) which applies the same size-reducing, weight-reducing, and loss-reducing technologies used in the 4th-generation Prius. The new system realizes improved driving performance while retaining superior fuel efficiency. When accelerating, the hybrid system reduces engine speed while drawing increased electric power from the battery, thereby delivering a linear and lengthened sense of acceleration.
Developing engines with more power is one thing but ensuring that the power reaches the road efficiently is also important. This is where the new Dynamic Torque Vectoring AWD and E-Four 4WD Systems will enhance drivetrain performance in future models. Toyota has developed two new 4WD systems which can improve fuel efficiency and achieve high 4WD handling, stability, and off-road performance.
The new Dynamic Torque Vectoring AWD system will be used in petrol engine vehicles. By adopting a torque vectoring mechanism, which independently distributes torque to the left and right rear wheels according to driving conditions, the system enables the driver to steer the vehicle exactly as intended. It achieves high off-road performance even on the toughest roads. It also incorporates a disconnect mechanism, which features the world’s first ratchet-type dog clutches on both the front and rear wheel shafts. These clutches stop the drive system rotations, which transmit driving force to rear wheels when in 2WD mode, significantly reducing energy loss and improving fuel efficiency.
The new E-Four system will be for hybrid vehicles. The system increases total torque to the rear wheels―which are electrically driven―by 30% compared to existing versions. By adopting a new control system that optimally distributes torque to the rear wheels based on the driving conditions, the E-Four system offers high off-road performance, handling, and stability.
Moreover, both the Dynamic Torque Vectoring AWD system and the new E-Four system feature AWD Integrated Management which harmonizes engine, transmission, braking, and 4WD systems to offer superb handling and stability regardless of road surface conditions.