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.
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
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
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 switch is performing by planetary gear, C1 clutch, B1 brake.
R range: B1 brake - on, C1 clutch - off, C2 clutch - off, synchronizer - engaged
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.
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
- 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:
Crankshaft position sensor A no signal
Vehicle speed sensor A no signal
Control module performance bank 1 watchdog/safety MCU Failure
TCM processor watchdog/safety MCU failure
Starter relay circuit short to battery
Brake switch B circuit short to battery
Transmission range sensor A circuit open
Transmission range sensor A signal compare failure
Transmission fluid temperature sensor A circuit range/performance
Transmission fluid temperature sensor A circuit short to ground
Transmission fluid temperature sensor A circuit short to battery or open
Input/turbine speed sensor A circuit short to battery
Input/turbine speed sensor a circuit short to ground or open
Input/turbine speed sensor a no signal
Output speed sensor circuit short to battery
Output speed sensor circuit short to ground or open
Output speed sensor no signal
Pressure control solenoid a circuit short to battery
Pressure control solenoid a circuit short to ground or open
Pressure control solenoid a actuator stuck off
Pressure control solenoid b circuit short to battery
Pressure control solenoid b circuit short to ground or open
Pressure control solenoid b actuator stuck off
Transmission fluid pressure sensor/switch a circuitrange/performance
Transmission fluid pressure sensor/switch a circuit short to ground
Transmission fluid pressure sensor/switch a circuit short to battery or open
Pressure control solenoid m circuit short to battery
Pressure control solenoid m circuit short to ground or open
Pressure control solenoid m actuator stuck off
Gear shift position circuit range/performance
Gear shift position circuit short to battery
Gear shift position circuit short to ground or open
Acceleration sensor circuit system internal failure
· 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.
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