Aisin–Toyota 8-speed automatic transmission

2006: Aisin TL-80SN for longitudinal engines

The Aisin TL-80SN (Toyota AA 80E/AA 80F/AA 81E) series is the world's first 8-speed automatic transmission for passenger cars.^[12] It is designed for longitudinal engines^[a][1] and was first used in the 2007 model year Lexus LS 460.^[13]

2016: Aisin AW F8 for transverse engines

Beginning with the AW F8 transmission Aisin and Toyota derived a transverse engine variant^[b][2] by adapting this globally patented gearset concept to fit into the same space as the previous generation U6xx Lepelletier gear mechanism-based 6-speed transmissions to increase the overall ratio spread, reduce gear steps, and increase the torque capacity for transverse engine vehicles as well.^[14]

The Aisin AW F8 F45 (Toyota UA 80E/UA 80F) series is the world's first 8-speed automatic transmission designed for use in transverse engine^[b][2] applications.^[15] It is also called EAT8 (PSA), GA 8F 22AW (BMW/Mini), TG-81SC (Volvo),^[16] AF50-8 (Opel/Vauxhall),^[17] AW F8 F45 (Cadillac),^[9] and AQ 450 (Volkswagen Group).^[18]

Toyota

Toyota’s marketing name for the transmission is "Direct Shift – 8AT 8-speed automatic transmission".^[19][20] In contrast to the UB 80E/F transmission, which was developed by Aisin AW for Toyota, the UA 80E/F was developed in a joint venture between Toyota and Aisin AW and rated for 380 N⋅m (280 lb⋅ft).^[10] Due to its worldwide application, development was carried out in a global manner involving R&D resources in Japan and the US. The Aisin AW F8 F35 (Toyota UB 80E/F) transmissions are used for lower torque applications, such as 4-cylinder engines, and rated for 280 N⋅m (207 lb⋅ft).^[10][11]

Improved fuel economy

The main objective in replacing the predecessor model was to improve vehicle fuel economy with extra speeds and a wider gear span to allow the engine speed level to be lowered (downspeeding), which is a decisive factor in improving energy efficiency and thus reducing fuel consumption. In addition, the lower engine speed level improves the noise-vibration-harshness comfort and the exterior noise is reduced. The Lexus IS F and LS 460 (with sport package) use Sport Direct Shift (SPDS) which allows for faster shift times. The torque converter can lockup from 2nd to 8th gears.

Reduced manufacturing complexity

In order to avoid a further increase in manufacturing complexity while expanding the number of gear ratios, Aisin switched from the conventional design method—in which the planetary gearset concept was limited to a purely serial or in-line power flow—to a more modern design method that utilizes a planetary gearset concept with combined parallel and serial power flow. This was only possible thanks to computer-aided design and has resulted in a globally patented gearset concept. After gaining additional gear ratios only with additional components, this time the number of components has to decrease while the number of ratios still increase. The resulting progress is reflected in a much better ratio of the number of gears to the number of components used compared to existing layouts.

Smaller parts and a hydraulic circuit with fewer components allow the transmission to maintain the same size as the previous LS 430's 6-speed transmission. The aluminum die-cast case is 10% lighter, yet 30% more rigid, even with two additional gears and a 22% greater torque capacity. The new transmission weighs 95 kg (209 lb) or 10% more than the previous unit. With new micro-laser technology gear tooth production tolerances have been reduced by 50%. Aluminum has also replaced steel on gear tooth surfaces. Shift times are as low as 0.35 seconds or 41% faster than the previous LS 430's unit.

Two reverse gears

The gearset concept offers two reverse gears. Due to the increasing electronic control of automatic transmissions and engines, a fast reverse gear (i.e. designed to reduce wheel spin) is no longer necessary for problem-free starting in icy conditions (winter mode). It is therefore unlikely that car manufacturers will make use of this special option of a dedicated winter mode with an additional reverse gear R2. For this reason, the representation of R2 in the tables is shaded gray throughout. In some data sheets, the gear ratio of R2 is given, presumably a careless error.^[1][3][4]

The direction is reversed in gearset 3, the outer one of the Ravigneaux gearset. In the fast reverse gear R2, this part of the Ravigneaux gearset is directly connected to the input (turbine) side. To reduce the shaft speed for an appropriate reverse gear R1, the input (turbine) is put through gearset 1 first. This reduction corresponds to the ratio of the 3rd gear. Therefore, the gear step between the two reverse gears reflects the ratio of the 3rd gear.

Quality

All 8-speed automatic transmissions from Aisin and Toyota for passenger cars are based on the same layout^[a][1][b][2] in both engines orientations.^[a][1][b][2] For transverse installation,^[b][2] the layout of the longitudinal installation^[a][1] was merely mirrored.^[a][1][b][2] Gearset 1 is not an ordinary one, but a reversed one. It consists of 2 pinions that mesh with each other. One of these pinions meshes with the sun gear, the other with the ring gear. As a results, the gearset generates different ratios and the sun gear rotates in the same direction as the ring gear when the planetary gear carrier is stationary. This made it possible to manage 8 speeds with 3 gearsets. As a result, the transmission is more compact than 8-speed transmissions from competitors. This means that an 8-speed automatic transmission was also possible for transverse engines.