Twin Clutch-Sportronic Shift Transmission (TC-SST)
GENERAL INFORMATIONTWIN CLUTCH-SPORTRONIC SHIFT TRANSMISSION (TC-SST)
Due to the addition of RALLIART, TC-SST (twin clutch-sportronic shift transmission) has been adopted. The TC-SST assembly is a twin clutch type automatic M/T that offers the easy driving similar to A/T, excellent sport driving, and enhanced fun to drive. The TC-SST assembly offers the following features.
Good fuel efficiency
^ Because the basic structure is the same as M/T, it is simple and has a high driving force transmission efficiency.
^ Instead of the torque converter, the clutch is used to transfer the driving force from engine, reducing the loss of driving force.
^ Through the precise joint control with the engine, the gears can be shifted at the optimum timing. (With NORMAL mode)
Shift feeling
^ Corresponding to the optimization of shift change timing by the automatic shifting, the shift shock is reduced, and the shifting is made smooth without torque loss.
Easy drive
^ By adopting TC-SST-ECU, solenoid valve, sensor, valve body, and others, the easy driving similar to A/T has been achieved.
Sport drive
^ Drive mode switching function is equipped which enables the selection of NORMAL, SPORT.
Fun to Drive
^ The manual mode and the paddle shift are adopted that allow the driver to shift gears at any timing.
Starting acceleration
^ The clutch and gear shift operation are automatically controlled, reducing the power transfer loss and achieving the ideal starting acceleration.
SPECIFICATIONS
OVERVIEW
DESCRIPTION OF FUNCTION
The TC-SST assembly offers the following features, achieving high-performance as well as the easy driving and sport driving.
SHIFTING MODE
By the operation of shift lever, the automatic mode and manual mode can be selected.
SHIFT MAP
[NORMAL - UPSHIFT]
[NORMAL - DOWNSHIFT]
DRIVE MODE
By the switching of twin clutch SST control mode switch, two types of control modes, which are NORMAL, SPORT, can be selected.
CREEP FUNCTION
With TC-SST, by intentionally making the clutch to slip (half clutch), the creep driving can be performed which is similar to A/T. Because this function allows the forward and backward driving in low speed, the driving becomes easier on congested road and when parking the vehicle.
KICK-DOWN FUNCTION
For the overtakes on expressway and the acceleration on up-slope, when the accelerator pedal is depressed suddenly, the gear is intentionally downshifted for one gear.
Depending on the driving conditions, the downshifting may be performed with 2 or 3 gears skipped, or the downshifting may be rejected.
DESCRIPTION OF CONSTRUCTION AND OPERATION
The TC-SST assembly consists mainly of the clutch, shifting section, valve body, and TC-SST-ECU. The valve body is controlled by TC-SST-ECU, and the clutch and shifting operations are performed by the hydraulic pressure from the valve body.
SHIFT MECHANISM
The shifting mechanism of TC-SST assembly is divided into two systems as the odd number gear axle (reverse, 1st, 3rd, 5th) and even number gear axle (2nd, 4th, 6th). Each mechanism is joined with an independent clutch, establishing a structure with which two 3-speed M/T mechanisms are combined.
WHEN IN P AND N RANGE
In the P range and N range, the 2nd gear and the 1st gear are engaged beforehand with the two clutches kept released.
AT STARTING (P -> D RANGE, N -> D RANGE)
Corresponding to the operations from P to D and from N to D, the clutch for the odd number gears is engaged to perform the 1st gear starting.
WHEN DRIVING IN 1ST GEAR
During driving with the 1st gear, the even number gear clutch is kept released, and the 2nd gear is engaged in advance. (During driving with even number gears, the odd number gears are engaged in advance.)
WHEN DRIVING IN 2ND GEAR
The clutch (for odd number gears) is released at the shifting timing in accordance with the shift map, and the clutch (for even number gears) is engaged to perform driving with the 2nd gear.
Because the shifting is performed only by the alternation of two clutches, the shifting time is short, and the clutch does not become completely released during driving.
HYDRAULIC MECHANISM
By the operation of solenoid valve, the valve body feeds the hydraulic pressure needed for the operation of clutch and each shifting section. The solenoid valve is controlled by TC-SST-ECU, and the hydraulic pump generates the hydraulic pressure by using the engine power.
Also, to prevent the oil performance drop, the oil cooler and oil filter are equipped.
CONTROL MECHANISM
TC-SST-ECU communicates with various systems (engine control module, shift lever, twin clutch SST control mode switch, and others) to recognize the driver operation, driving condition, malfunction of systems, and others, and performs the corresponding control of TC-SST assembly.
TRANSAXLE CONTROL
In order to differentiate the TC-SST assembly shift lever from A/T and CVT, a new exclusive shift lever has been developed whose appearance is made similar to that for M/T. It offers the following features.
^ Sporty, straight type shift lever operation has been adopted, and the operating power at each shift position have been properly tuned, ensuring the firm and smooth operation feel.
^ The manual mode (6-speed) has been installed to allow manual shifting according to the driver's operation.
^ ECU that is incorporated in the shift lever transmits the lever position information and others to TC-SST-ECU via CAN (main circuit) and LIN (auxiliary circuit).
^ For the parking lock mechanism, the transaxle control cable is adopted.
^ The electrical control-type shift lock (shift lever cannot be shifted to the position other than P position unless the brake pedal is depressed) mechanism with the solenoid has been adopted to facilitate the tuning work in assembly. The cable type having an established past record is adopted for the key interlock mechanism.
^ Spherical shift knob is used to achieve the same quality as that for M/T.
^ As a mis-operation preventative mechanism between P and R range, the pull ring has been adopted.
^ The main components have been made of resin to reduce weight and number of components.
ERRONEOUS OPERATION PREVENTION MECHANISMS
SHIFT LOCK MECHANISM
^ This is basically the same as with the electric shift lock mechanism which is used for OUTLANDER.
KEY INTERLOCK MECHANISM
^ This is basically the same as with the cable-type key interlock mechanism which is used for A/T vehicles.
PADDLE SHIFT
The mechanism is basically the same as that of OUTLANDER.
NOTE: With the automatic shifting (shift lever position: D), when the mode is changed to the manual mode by the paddle shift operation, the mode is cancelled by the conditions below.
^ Upshift lever is pulled for 2 seconds or more.
^ Vehicle is stopped.
ACTIVE CENTER DIFFERENTIAL (ACD)
The ACD is the system to improve acceleration performance and straightforward driving ability by controlling the limitation force and driving force distribution of the center differential.
DESCRIPTION OF STRUCTURE AND OPERATION
AWC-ECU performs a calculation based on the information from ECU, sensors, and switches. Then, based on the calculation value, it appropriately operates the hydraulic unit (for ACD) to control in response to the driver's operations and vehicle behaviors.
AWC SWITCH
By pressing the AWC switch, the driving mode can be switched among TARMAC, GRAVEL, and SNOW.
With each pressing of the AWC switch, the ACD control mode shifts in the order as follows: TARMAC -> GRAVEL -> SNOW -> TARMAC
MULTI INFORMATION DISPLAY
The current driving mode is displayed at all times to the upper center of multi information display. When the mode is switched, the mode switching status is displayed automatically to the information screen at the middle, and then the screen returns to the previous screen after the completion of setting.
CONTROL OVERVIEW
ACD CONTROL MODE
^ The ACD control is the same as with previous model, and the control mode can be switched among TARMAC, GRAVEL, and SNOW in response to road conditions.
SENSOR INFORMATION
^ With the information of sensors (throttle position sensor, G sensor, steering sensor, wheel speed sensor, yaw rate sensor), engine torque, and engine speed, the accurate control has been achieved, and the vehicle response to the driving status has been improved.
ADDITION OF TC-SST CONTROL
^ For vehicles with TC-SST, AWC-ECU communicates with TC-SST-ECU via CAN line to suppress unnecessary gear shifts during cornering which hamper the sport driving.