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Toyota unveils ultra-efficient 'Direct & Smooth' engine, trans and hybrid systems

Danny Kwan
CarsGuide

12 Dec 2016 • 5 min read

Big changes are afoot at Toyota as it steadily implements its new TNGA (Toyota New Global Architecture) structural reform, which will see the company reduce and streamline the number of platforms used globally, and increase its production efficiency and flexibility.

Behind-the-scenes production aside, Toyota also promises to deliver models with improved driving performance with newly developed platforms boasting lower hood heights, lower centre of gravity, and other innovations.

Key to this goal is the development of new hardware including advanced engines and transmissions, and improved hybrid systems. The first fruits of the program will be seen with the introduction of a new Toyota model next year; likely to be the new 2017 Toyota Camry for the North American market.

Developed under the theme of 'Direct & Smooth', Toyota's new powertrains comprise high-speed combustion engines and highly-efficient multi-geared transmissions, which it says will be light, compact, and feature a low-centre of gravity.

Thanks to a standardised structure and modular design, the Japanese giant plans to roll out a huge range of these combinations between 2017 and 2021.

On the cards are nine new engines which will form the basis of 17 different variants, 10 versions of four new transmissions, including a new kind of CVT, and 10 hybrid variants derived from six new hybrid systems. These new powertrains are said to deliver an approximate 10 per cent improvement in performance and 20 per cent better fuel efficiency.

By the end of the planned roll-out in 2021, Toyota aims to have the new drive technology feature in at least 60 per cent of all Toyota and Lexus vehicles sold in Japan, the United States, Europe, and China. Should they achieve that adoption rate, Toyota claims the new powertrains would account for a CO2 emission reduction of at least 15 per cent from Toyota and Lexus vehicles sold in those regions.

The first of Toyota's new family of internal-combustion powerplants - christened "Dynamic Force Engines" - is a 2.5-litre naturally aspirated, direct-injection, inline four cylinder . Though there are no performance figures released, Toyota claims the new engine is one of the world's most thermally efficient - 40 per cent when used in petrol-powered models and 41 per cent when paired with a hybrid system.

Toyota claims the smooth gear changes achieved between its close-ratio gears is among the world's quickest.

According to Toyota the basic structure behind its new internal-combustion engines was completely rethought using TNGA, with the engine's overall structure and configuration developed to deliver both driving and environmental performance.

On the transmission front, Toyota has unveiled two new torque converters, an 8-speed Direct Shift-8AT for front-wheel drive models, and a 10-speed Direct Shift-10AT gearbox variant for rear-wheel drive applications. Both transmissions feature a newly developed high-performance compact torque converter with a broader gear lock-up range, which delivers a quick and smooth response. As for the Direct Shift-10AT, Toyota claims the smooth gear changes achieved between its close-ratio gears is among the world's quickest.

In improving its efficiency, the transmissions' gear tooth surfaces were processed using a new technique to lower the friction coefficient, whereas the material used inside the clutch has been reconfigured to slash clutch torque loss by half - as compared to their six-speed torque converter - during rotation.

Toyota claims the new transmissions are more compact and lighter than comparative conventional transmissions.

With lessons learnt from the downsizing, weight-shaving, and efficiency improvements of the hybrid system aboard the fourth-generation Prius, Toyota will be incorporating those improvements into the hybrid system for 2.5-litre engines with the new high-performance multi-stage THS II (Toyota Hybrid System II).

Developed for rear-wheel drive models, the new THS II is claimed to deliver a better driving experience with improved start-from-stop acceleration performance and abundant direct feel. The new hybrid system is also said to deliver better high-speed fuel economy thanks to improvements in the system's efficiency at high speeds and intermittent use of the engine at high speeds.

Toyota has also improved the hybrid system for their plug-in hybrid models, as it now features a new dual-mode drive system that allows the electric motor to provide direct drive to the wheels rather than serving in limited capacity as an onboard generator. Paired to the plug-in hybrid system is a large-capacity lithium-ion battery boosting its EV-mode range to 60km or more.

Is Toyota on the right track with its tricky powertrain tech? Tell us what you think in the comments below.