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This year will see the start of the roll­out of nine new Toy­ota en­gines, in 17 ver­sions, that will go right through to 2021, along with four new trans­mis­sions in 10 ver­sions.

At the same time Toy­ota will in­tro­duce new elec­tri­fied com­po­nents for six new hy­brid-elec­tric drive sys­tem which will be com­bined with the new en­gines.

As part of the Toy­ota New Global Ar­chi­tec­ture (TNGA) pro­gramme, the new en­gines com­bine with ba­sic car de­sign changes to lower bon­net heights, low­er­ing the cen­tre of grav­ity and im­ple­ment­ing other in­no­va­tions to im­prove driv­ing per­for­mance.

Toy­ota’s newly de­vel­oped pow­er­train units are light and com­pact and have a low-cen­tre of grav­ity.

In-depth re­con­sid­er­a­tion of fun­da­men­tal ve­hi­cle per­for­mance has re­sulted in en­gines with high­speed com­bus­tion and in highly ef­fi­cient multi-geared trans­mis­sions. To stan­dard­ise the ba­sic struc­ture of these new units, mo­du­lar de­sign (uni­fied de­sign) was used.

The new en­gines em­ploy high­speed com­bus­tion technology and a vari­able con­trol sys­tem. They also achieve greater ther­mal ef­fi­ciency, re­sult­ing in high out­put, due to a re­duc­tion in en­ergy losses associated with, among oth­ers, ex­haust and cooling sys­tems and the move­ment of mechanical parts.

Their line-up in­cludes a 2.5-litre en­gine that has one of the world’s best ther­mal ef­fi­cien­cies – 40 per­cent when used in petrol-pow­ered ve­hi­cles and 41 per­cent when used in hy­brid ve­hi­cles (HVs) – and fea­tures nu­mer­ous new tech­nolo­gies, such as tech­nolo­gies for minute con­trol that make it highly re­spon­sive and al­low it to gen­er­ate am­ple torque at all speeds.

The com­bi­na­tion of high-speed com­bus­tion and vari­able in­take con­trol cre­ates strong air tum­ble and vol­ume in­side the cylin­der. This spreads the fuel into the air to make for bet­ter com­bus­tion. The stroke-bore ra­tio of the en­gine is 1.2, bal­anc­ing power out­puts. The en­gine has a wider valve (41 de­grees) which al­lows for bet­ter in­take/ex­haust. New valve seat ma­te­ri­als and laser valve seat cladding mean lower fric­tion losses as well.

The en­gine runs with a 13:1 com­pres­sion ra­tio for petrol-only and 14:1 for a hy­brid sys­tem. High­en­ergy ig­ni­tion coils, multi-hold di­rect in­jec­tors, and cylin­der bore and pis­ton coat­ings com­plete the pack­age.

And then to the new trans­mis­sions. Again, they are lighter and more com­pact than their pre­de­ces­sors, im­prov­ing both econ­omy and cen­tre of grav­ity, while widened gears and a newly de­vel­oped high-per­for­mance com­pact torque con­ver­tor com­bine for a broader gear lockup range. The re­sult­ing quick and smooth re­sponse to ac­cel­er­a­tor pedal op­er­a­tion cre­ates an “as de­sired” di­rect driv­ing feel.

In the case of the Di­rect Shift-10AT, even though the num­ber of gears has been in­creased to 10 (com­pared to eight gears in the case of the Di­rect Shift-8AT), the use of close-ra­tio gears op­ti­mises the range of use of each gear, par­tic­u­larly in the low-to-mid speed range. The re­sult­ing smooth gear changes, which are among the world’s quick­est re­sponse cre­ate a rhyth­mi­cal and com­fort­able sen­sa­tion that is suit­able for a pre­mium rear­wheel-drive ve­hi­cle.

Ap­ply­ing size-re­duc­ing, weightre­duc­ing and loss-re­duc­ing tech­nolo­gies used in the fourth­gen­er­a­tion Prius, Toy­ota has en­hanced its hy­brid sys­tem for 2.5-litre en­gines and de­vel­oped the new, high­per­for­mance Mul­tistage THS II for rear-wheel-drive ve­hi­cles.

THS II for 2.5-litre en­gines ex­cels in both power and fu­ele­con­omy per­for­mance due to the syn­er­gis­tic ef­fect of size-re­duc­ing, weight-re­duc­ing and loss-re­duc­ing tech­nolo­gies cou­pled with the high ther­mal ef­fi­ciency and out­put of a new TNGA-based en­gine.

Mul­tistage THS II gives hy­brid ve­hi­cles an all-new driv­ing im­age with its start-from-stop ac­cel­er­a­tion per­for­mance and abun­dant di­rect feel. In ad­di­tion to im­prov­ing sys­tem ef­fi­ciency at high speeds, in­ter­mit­tent use of the en­gine at high speeds has also been made pos­si­ble, fur­ther im­prov­ing high-speed fuel econ­omy.

The sys­tem for plugin hy­brid elec­tric ve­hi­cles (PHEVs) has also been en­hanced. A new dual-mode drive sys­tem al­lows the elec­tric mo­tor, which was pre­vi­ously used only as a gen­er­a­tor, to pro­vide di­rect driv­ing power, re­sult­ing in pow­er­ful driv­ing, even when in EV mode. Fur­ther en­hanc­ing the sys­tem for PHEVs is a large-ca­pac­ity lithium-ion bat­tery that largely in­creases the EV-mode cruis­ing range to 60km or more.

The elec­tric mo­tors are new­ly­de­vel­oped and use mag­netic steel and a rolling coil struc­ture, which uses fewer wires. A par­al­lel re­duc­tion gear re­duces power trans­fer losses, and both the mo­tors are smaller and lighter than be­fore while of­fer­ing sim­i­lar or bet­ter power out­put when com­pared to those they’ll re­place.

Toy­ota claims that when com­bined with the 2.5-litre Dy­namic Force en­gine, this transaxle pro­duces 20 per­cent bet­ter fuel econ­omy and has ac­cel­er­a­tion im­proved by 10 per­cent.

By the end of 2021, Toy­ota aims to have the new pow­er­train units fea­ture in 60 per­cent or more of Toy­ota-brand and Lexus-brand ve­hi­cles sold an­nu­ally in Ja­pan, the United States, Europe and China.

Toy­ota fore­casts that Toy­ota and Lexus ve­hi­cles sold that year in those mar­kets will ac­count for a CO2 re­duc­tion in those mar­kets of 15 per­cent or more, count­ing the fu­el­ef­fi­ciency-im­prove­ment con­tri­bu­tions made by the new pow­er­train units alone.

The 10-speed gear­box.

The new TNGA en­gine.

This in­fo­graphic il­lus­trates the en­gine char­ac­ter­is­tics.

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