The new generation of CVT transmissions was introduced in 2018 and debuted on the Corolla 210 and RAV4 50 series vehicles.
The main innovation - launch gear: in addition to the metal belt between pulleys, a gear mechanism is used when starting off, driving at low speeds and reverse.
Thus, the launch gear replaces the belt in the most difficult modes: the extreme position when the bended belt operating along the minimum radius at minimum contact area with the drive pulley, and while slipping, and starting from a full stop.
Formally, the ratio range of the new transmission increased to 7.5 instead of 6-6.5, although the ratio range of the variator itself, on the contrary, decreased to 5.0 - which clearly benefited the belt.
The diameter of pulleys reduced significantly, the belt (pulley) angle has been narrowed from 11° to 9°, resulting in higher shifting speed.
Specs
K120F
Fluid capacity (full): 8.3-8.6 liters
Fluid type: Toyota genuine CVT Fluid FE
Gear ratio: 3.377 (forward) / 3.136 (reverse)
Pulley tatio: 2.236~0.447
Final fear ratio: 4.262
Weight (with fluid): 90-91 kg
K320
Fluid capacity (full): 8.4 liters
Fluid type: Toyota genuine CVT Fluid FE
Gear ratio: 3.362 (forward) / 3.120 (reverse)
Pulley tatio: 2.236~0.447
Final fear ratio: 4.007
Weight (with fluid): 90 kg
General timeline of Toyota's (Aisin AW) CVT:
2000-2009 - K110 - for models with 2.0 1AZ-FSE engine (Opa, Allion/Premio, Wish). The very first belt-type CVT of Toyota.
2001-2008 - P210 - for hybrid models with 2.4 2AZ-FXE engine (Estima/Alphard Hybrid). The only hybrid transaxle with belt-type CVT.
2002-2015 - K210 - for models with 1.5 1NZ-FE or 1.3 2SZ-FE engines (Vitz, Ractis Sienta). Basic type - Aisin AW XA-15LN
2004 - Start of mass-production of metal V-belts at Aisin CVTEC plant (instead of previously imported metal belts produced by Van Doorne's Transmissie (VDT))
2004-2018 - K111/K111F - for 2WD or 4WD models with 2.0 1AZ-FSE, 3ZR-FE, 3ZR-FAE engines (Noah/Voxy, Isis, Allion/Premio, Avensis)
2004-2019 - K410 - for models with 1.0 1KR-FE or 1.3 2SZ-FE engines (Vitz, Ractis, Belta). Basic type - Aisin AW XA-10LN
2005-2019 - K112/K112F - for 2WD or 4WD models with 2.4 2AZ-FE, 3ZR-FE, 3ZR-FAE engines (RAV4/Vanguard, Estima/Alphard/Vellfire, Mark X Zio, Blade)
2006→ K310/K310F - for 2WD or 4WD models with 1.5 1NZ-FE engine (Corolla Axio/Fielder, Auris, Ist, Allion/Premio, Corolla Rumion, Ractis/Verso-S/Trezia, Vitz, Porte/Spade, Sienta, Probox/Succeed). Basic type - Aisin AW XB-20LN
2006→ K311/K311F - for 2WD or 4WD models with 1.8 2ZR-FE, 2ZR-FAE or 1.6 1ZR-FE, 1ZR-FAE engines (Corolla Fielder, Avensis, Corolla, Auris, Verso, Allion/Premio, Isis, Wish, Corolla Rumion)
2008-2016 - K41A - for models with 1.0 1KR-FE engine (iQ)
2009-2016 - K41B - for models with 1.3 1NR-FE engine (iQ)
2010→ K411 - for models with 1.3 1NR-FE engine (Vitz, Corolla Axio, Ractis/Verso-S/Trezia, Probox/Succeed, Porte/Spade). Basic type - Aisin AW XA-12SN
2012→ K312 - for models with 1.5 1NZ-FE or 2NR-FKE engines (Corolla Axio/Fielder, Auris, Sienta, Porte /Spade, Ractis, Probox/Succeed). Basic type - Aisin AW AWFCX12
2013→ K114/K114F - for 2WD or 4WD models with 2.0 3ZR-FAE engine (RAV4, Noah/Voxy, C-HR, Harrier, Avensis)
2013→ K313/K313F - for 2WD or 4WD models with 1.8 2ZR-FE, 2ZR-FAE or 1.2 8NR-FTS engines (Corolla, Auris, Avensis, Verso, C-HR). Basic type - Aisin AW AWFCX18
2015→ K115/K115F - for 2WD or 4WD models with 2.5 2AR-FE engine (Alphard/Vellfire)
2019→ K120/K120F - for 2WD or 4WD models with 2.0 M20A-FKS engine (RAV4, Corolla, Camry/Avalon/ES, Corolla Cross, Harrier, Noah/Voxy, UX). Basic type - Aisin AW AWFCW21
2020→ K320/K320F - for 2WD or 4WD models with 1.5 M15A-FKS engine (Yaris, Yaris Cross)
Quite numerous Daihatsu models sold under the Toyota brand can be added to this list - they can be equipped with own Daihatsu CVTs (D-18C, E-18C, PT-08) or with Akashi Kikai products, as well as Aisin CVTs.
Aisin vs. Jatco
Sometimes you can hear that Toyota repeats the long-known concept of Jatco CVT7. In fact, the fundamental difference of Jatco solution is that an additional planetary gearbox is installed in series with a constantly operating belt variator, while Aisin installed a gear train parallel to the variator and it works alternatively.
The merit of Jatco can be recognized as the largest continuous ratio range (7.3 or 8.7), but the CVT7's area is limited - small cars with engine torque within 150 nm.
Gear mode is used when the vehicle starts off, at low speeds or reverse.
The synchronizer engages/disengages the driven gear #1 and drive gear #2. The system controls the shift fork shaft and synchronizer by varying oil pressure. Synchronizer engagement/release is controlled by the stroke sensor (shift fork shaft position).
Gear-mode: disengaging C2 clutch, engaging C1 clutch or B1 brake (vehicle starts off, is being driven at low speeds or is reversing). Power is transmitted from the sun gear via the drive gear #1 to the gear type mechanism, and then to the reduction drive gear mechanism via the driven gear #2.
Belt-mode: engaging C2 clutch, disengaging C1 clutch and B1 brake. By disengaging C1 clutch and B1 brake, the planetary gear is disengaged and engine torque is transmitted to the belt-type mechanism. Power is transmitted from the primary pulley to the secondary pulley via the belt, then to the reduction drive gear via C2 clutch.
Forward/reverse driving
Forward/reverse switch is performing by planetary gear, C1 clutch, B1 brake.
Forward movement: C1 clutch connects the input shaft with the planetary carrier, then the torque is output to the sun gear.
1 - B1 brake (off), 2 - ring gear, 3 - C1 clutch (on), 4 - planetary carrier, 5 - pinion #2, 6 - pinion #1, 7 - sun gear.
a - input, b - output
Reverse movement: B1 brake keeps the ring gear stationary, the engine torque is input to the planetary carrier and is output to the sun gear with inverse rotation.
1 - B1 brake (on), 2 - ring gear, 3 - C1 clutch (off), 4 - planetary carrier, 5 - pinion #2, 6 - pinion #1, 7 - sun gear. a - input, b - output
Drive modes
D range (starting off and low-speed driving): B1 brake - off, C1 clutch - on, C2 clutch - off, synchronizer - engaged
D range (pulley ratio low): B1 brake - off, C1 clutch - off, C2 clutch - on, synchronizer - disengaged
D range (pulley ratio high): B1 brake - off, C1 clutch - off, C2 clutch - on, synchronizer - disengaged
R range: B1 brake - on, C1 clutch - off, C2 clutch - off, synchronizer - engaged
Components
The reduction gear reduces the rotation from the secondary pulley and transmits the power from the secondary pulley to the differential. In the new CVT the drive gear is supported by ball-type bearings instead of older roller-type.
New CVT obtained a vane type oil pump, driven by chain from input shaft. The pump chain drive is used in modern Aisin transmissions, which is considered more progressive in comparison with the classic (it does not increase the length of the transmission, does not limit the minimum rotor diameter by the dimensions of the input shaft, and gives considerable freedom of maneuver in layout and design).
1 - front support, 2 - drive sprocket, 3 - driven sprocket, 4 - oil pump body, 5 - cam ring, 6 - rotor, 7 - oil pump case, 8 - vane. a - inlet port, b - low pressure discharge port, c - high pressure discharge port
The standard torque converter with flex lock-up clutch.
The lightweight resin side cover turned to the front of vehicle.
Models with stop-start system obtain CVT electric oil pump.
Periodically, the question arises - what is the strange plug or connector located at the bottom of the side cover? Apparently, it is worth to show this pump in a little more detail.
The electric pump is designed to maintain a stable pressure in the CVT hydraulic system when the engine is turned off by the stop-start system and to ensure the subsequent smooth start-off.
1 - electric oil pump for CVT
It is installed in the CVT cover and is not supplied in spare parts separately. It is controlled by PWM signal from the stop-start system control unit.
1 - pump rotor, 2 - magnet, 3 - stator, 4 - yoke, 5 - shaft, 6 - oil pump motor driver. a - oil pump motor driver section, b - DC sensorless and brushless motor section, c - oil pump section.
The CVT fluid warmer (oil cooler) uses engine coolant to warm up the CVT fluid quickly and maintain it within proper limits. The oil cooler is directly installed to the transmission.
Control system utilizes 6 linear solenoid valves:
SLS: oil pressure of the secondary pulley (controls belt clamping force in accordance with the input shaft torque)
SLP: oil pressure of the primary pulley (control the speed ratio)
SLU: oil pressure of the torque converter lock-up clutch
SL1: C1 clutch for gear mode
SL2: C2 clutch for belt mode
SLG: synchronizer mechanism and B1 brake
Another sensors;
- CVT fluid temperature sensor
- Oil pressure sensor
- Clutch stroke sensor (shift fork position)
• "Sport Sequential Shiftmatic" - the function of simulating a sequential gearbox with fixed gear ratios now has 10 virtual steps instead of 8 in the previous generation.
• In a traditional variator, the wheels are straight connected to the secondary pulley, therefore shock loads (during sharp braking, when driving with slipping on uneven surface, and a sharp appearance of grip) are transmitted to the steel belt and the pulley surfaces. In the new CVT, the C2 clutch acts as a damper between the variator and the wheels, plus the function of quickly reducing the belt clamping force on the secondary pulley is provided.
• The pre-tensioning mechanism in the front differential is no longer used (bevel spring between the side gear and the housing).
• The list of factory fault codes, associated with the CVT system, has doubled:
Toyota DTC
Cause
P033531
Crankshaft position sensor A no signal
P050031
Vehicle speed sensor A no signal
P060747
Control module performance bank 1 watchdog/safety MCU Failure
P061347
TCM processor watchdog/safety MCU failure
P061512
Starter relay circuit short to battery
P070312
Brake switch B circuit short to battery
P070513
Transmission range sensor A circuit open
P070562
Transmission range sensor A signal compare failure
P071000
Transmission fluid temperature sensor A circuit range/performance
P071011
Transmission fluid temperature sensor A circuit short to ground
P071015
Transmission fluid temperature sensor A circuit short to battery or open
P071512
Input/turbine speed sensor A circuit short to battery
P071514
Input/turbine speed sensor a circuit short to ground or open
P071531
Input/turbine speed sensor a no signal
P072012
Output speed sensor circuit short to battery
P072014
Output speed sensor circuit short to ground or open
P072031
Output speed sensor no signal
P074512
Pressure control solenoid a circuit short to battery
P074514
Pressure control solenoid a circuit short to ground or open
P07457F
Pressure control solenoid a actuator stuck off
P077512
Pressure control solenoid b circuit short to battery
P077514
Pressure control solenoid b circuit short to ground or open
P07757F
Pressure control solenoid b actuator stuck off
P084000
Transmission fluid pressure sensor/switch a circuitrange/performance
P084011
Transmission fluid pressure sensor/switch a circuit short to ground
P084015
Transmission fluid pressure sensor/switch a circuit short to battery or open
P08C312
Pressure control solenoid m circuit short to battery
P08C314
Pressure control solenoid m circuit short to ground or open
P08C37F
Pressure control solenoid m actuator stuck off
P091400
Gear shift position circuit range/performance
P091412
Gear shift position circuit short to battery
P091414
Gear shift position circuit short to ground or open
P158504
Acceleration sensor circuit system internal failure
Acceleration sensor circuit range / performance internal electronic failure
P158900
Acceleration sensor learning value
P17029F
AT solenoids operation shutdown circuit stuck off
P170300
AT solenoid output malfunction
P175009
Brake ECU malfunction
P274512
Intermediate shaft speed sensor b circuit short to battery
P274514
Intermediate shaft speed sensor b circuit short to ground or open
P274531
Intermediate shaft speed sensor b no signal
P274912
Intermediate shaft speed sensor c circuit short to battery
P274914
Intermediate shaft speed sensor c circuit short to ground or open
P274931
Intermediate shaft speed sensor c no signal
P275600
Torque converter clutch pressure control solenoid control circuit performance/stuck off
P275612
Torque converter clutch pressure control solenoid control circuit short to battery
P275614
Torque converter clutch pressure control solenoid control circuit short to ground or open
P27567E
Torque converter clutch pressure control solenoid control actuator stuck on
P281F00
Pressure control solenoid j performance/stuck off (2 trip detected)
P281F12
Pressure control solenoid j circuit short to battery
P281F14
Pressure control solenoid j circuit short to ground or open
P281F71
Pressure control solenoid j performance/stuck off actuator stuck
P282812
Pressure control solenoid k circuit short to battery
P282814
Pressure control solenoid k circuit short to ground or open
P28287F
Pressure control solenoid k actuator stuck off
U010087
Lost communication with ECM/PCM A missing message
U012587
Lost communication with multi-axis acceleration sensor module missing message
U012987
Lost communication with brake system control module missing message
U110387
Lost communication with stop and start control module missing message
K114F (previous type)
A better assessment of the complexity of the new CVTs is allowed by comparison with the previous CVT of traditional design, which was used for previous RAV4.
K114F
Fluid capacity (full): 7.1 liters
Fluid type: Toyota genuine CVT Fluid FE
Pulley tatio: 2.517~0.3907
Final fear ratio: 5.791
Weight (with fluid): 94-95 kg
Forward driving: forward clutch is engaged, torque input to the sun gear and output through the primary pulley.
1 - reverse brake, 2 - ring gear, 3 - planetary carrier, 4 - sun gear, 5 - pinion, 6 - forward clutch. a - output, b - input
Reverse driving: torque input to the ring gear, then to the sun gear via the pinion (held by the reverse brake), so the gear and primary pulley rotation is reversed.
1 - reverse brake, 2 - ring gear, 3 - planetary carrier, 4 - sun gear, 5 - pinion, 6 - forward clutch. a - output, b - input
· Oil pump - conventional trochoid type, installed on the input shaft.
1 - oil pump, 2 - oil pump body, 3 - drive gear, 4 - driven gear, 5 - stator shaft, 6 - oil pump cover (stator shaft). a - inlet port, b - low pressure discharge port, c - high pressure discharge port
· Oil cooler - external, with additional pipes.
Control system
There are 5 shift solenoid valves and 3 speed sensors:
SC: switch SLU for forward and reverse clutch control
SL: switch SLU for lock-up clutch control
SLU: forward and reverse clutch control or lock-up clutch control
SLP: oil pressure of the primary pulley
SLS: oil pressure of the secondary pulley
Please do not confuse Toyota Direct-Shift CVTs with D-CVT (Dual-mode) used on Daihatsu own models and rebaged for Toyota ones. At low and medium speeds, the D-CVT operates like a conventional belt-type continuously variable transmission, and the gear train is engaged when driving at high speed (so the motive force is splitted and transmitted through both the belt and gears).
